MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Radiation Measurements' source. Fri, 27 Jan 2012 20:53:48 +0100 http://www.medworm.com/index.php?rid=5473015&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22125409%26dopt%3DAbstract Authors: Sholom S, Dewitt R, Simon S, Bouville A, McKeever S Abstract Several materials were tested as possible individual emergency dosimeters using Optically Stimulated Luminescence (OSL) as means to assess the exposure. Materials investigated included human nails, business cards and plastic buttons. The OSL properties of these materials were studied in comparison with those of teeth. Most samples revealed OSL signals only after exposure to ionizing radiation; some samples of business cards, however, displayed a strong initial "native" signal (i.e. existing in the samples prior to irradiation). The sensitivity (minimum measurable dose) of the samples was found to vary significantly from sample to sample of the same material and was in the range from several tens of mGy to a few d... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5473015 Thu, 01 Dec 2011 05:00:00 +0100 5473015 http://www.medworm.com/index.php?rid=5473014&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22125410%26dopt%3DAbstract Authors: He X, Gui J, Matthews TP, Williams BB, Swarts SG, Grinberg O, Sidabras J, Wilcox DE, Swartz HM Abstract Rapid and accurate retrospective dosimetry is of critical importance and strategic value for the emergency medical response to a large-scale radiological/nuclear event. One technique that has the potential for rapid and accurate dosimetry measurements is electron paramagnetic resonance (EPR) spectroscopy of relatively stable radiation-induced signals (RIS) in fingernails and toenails. Two approaches are being developed for EPR nail dosimetry. In the approach using ex vivo measurements on nail clippings, accurate estimation of the dose-dependent amplitude of the RIS is complicated by the presence of mechanically-induced signals (MIS) that are generated during the nail cli... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5473014 Thu, 01 Sep 2011 04:00:00 +0100 5473014 http://www.medworm.com/index.php?rid=5377705&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22003310%26dopt%3DAbstract Authors: Mitchell DG, Quine RW, Tseitlin M, Meyer V, Eaton SS, Eaton GR Abstract The E' defect in irradiated fused quartz has spin lattice relaxation times (T(1)) about 100 to 300 μs and spin-spin relaxation times (T(2)) up to about 200 μs, depending on the concentration of defects and other species in the sample. These long relaxation times make it difficult to record an unsaturated continuous wave (CW) electron paramagnetic resonance (EPR) signal that is free of passage effects. Signals measured at X-band (~9.5 GHz) by three EPR methods: conventional slow-scan field modulated EPR, rapid scan EPR, and pulsed EPR, were compared. To acquire spectra with comparable signal-to-noise, both pulsed and rapid scan EPR require less time than conventional CW EPR. Rapid scan spectroscopy do... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5377705 Thu, 01 Sep 2011 04:00:00 +0100 5377705 http://www.medworm.com/index.php?rid=5294512&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21966241%26dopt%3DAbstract Authors: Williams BB, Dong R, Flood AB, Grinberg O, Kmiec M, Lesniewski PN, Matthews TP, Nicolalde RJ, Raynolds T, Salikhov IK, Swartz HM Abstract In order to meet the potential need for emergency large-scale retrospective radiation biodosimetry following an accident or attack, we have developed instrumentation and methodology for in vivo electron paramagnetic resonance spectroscopy to quantify concentrations of radiation-induced radicals within intact teeth. This technique has several very desirable characteristics for triage, including independence from confounding biologic factors, a non-invasive measurement procedure, the capability to make measurements at any time after the event, suitability for use by non-expert operators at the site of an event, and the ability to provide i... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5294512 Thu, 01 Sep 2011 04:00:00 +0100 5294512 http://www.medworm.com/index.php?rid=5274015&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21949479%26dopt%3DAbstract Authors: Sholom S, Dewitt R, Simon SL, Bouville A, McKeever SW Abstract Human teeth were studied for potential use as emergency Optically Stimulated Luminescence (OSL) dosimeters. By using multiple-teeth samples in combination with a custom-built sensitive OSL reader, (60)Co-equivalent doses below 0.64 Gy were measured immediately after exposure with the lowest value being 27 mGy for the most sensitive sample. The variability of OSL sensitivity, from individual to individual using multiple-teeth samples, was determined to be 53%. X-ray and beta exposure were found to produce OSL curves with the same shape that differed from those due to ultraviolet (UV) exposure; as a result, correlation was observed between OSL signals after X-ray and beta exposure and was absent if compared to OS... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5274015 Thu, 01 Sep 2011 04:00:00 +0100 5274015 http://www.medworm.com/index.php?rid=5274014&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21949480%26dopt%3DAbstract Authors: Redon CE, Nakamura AJ, Gouliaeva K, Rahman A, Blakely WF, Bonner WM Abstract We previously used the γ-H2AX assay as a biodosimeter for total-body-irradiation (TBI) exposure (γ-rays) in a rhesus macaque (Macaca mulatta) model. Utilizing peripheral blood lymphocytes and plucked hairs, we obtained statistically significant γ-H2AX responses days after total-body exposure to 1-8.5 Gy ((60)Co γ-rays at 55 cGy min(-1)). Here, we introduce a partial-body exposure analysis method, Q(γ-H2AX), which is based on the number of γ-H2AX foci per damaged cells as evident by having one or more γ-H2AX foci per cell. Results from the rhesus monkey - TBI study were used to establish Q(γ-H2AX) dose-response calibration curves to assess acute partial-body exposures. γ-H2AX foci were det... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5274014 Thu, 01 Sep 2011 04:00:00 +0100 5274014 http://www.medworm.com/index.php?rid=5274013&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21949481%26dopt%3DAbstract CONCLUSIONS: This framework for evaluating dosimetry in large populations is a useful technique to compare the strengths and weaknesses of different dosimetry methods. It can help policy-makers and planners not only to compare the methods' strengths and weaknesses for their intended use but also to develop an integrated approach to maximize their effectiveness. It also reveals weaknesses in methods that would benefit from further research and evaluation. PMID: 21949481 [PubMed - as supplied by publisher] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5274013 Thu, 01 Sep 2011 04:00:00 +0100 5274013 http://www.medworm.com/index.php?rid=5274012&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21949482%26dopt%3DAbstract Authors: Wilkins RC, Romm H, Oestreicher U, Marro L, Yoshida MA, Suto Y, Prasanna PG Abstract Biological dosimetry is an essential tool for estimating radiation doses received to personnel when physical dosimetry is not available or inadequate. The current preferred biodosimetry method is based on the measurement of radiation-specific dicentric chromosomes in exposed individuals' peripheral blood lymphocytes. However, this method is labour-, time- and expertise-demanding. Consequently, for mass casualty applications, strategies have been developed to increase its throughput. One such strategy is to develop validated cytogenetic biodosimetry laboratory networks, both national and international. In a previous study, the dicentric chromosome assay (DCA) was validated in our cytogeneti... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=5274012 Thu, 01 Sep 2011 04:00:00 +0100 5274012 http://www.medworm.com/index.php?rid=4798786&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21544230%26dopt%3DAbstract Authors: Yepes PP, Brannan T, Huang J, Mirkovic D, Newhauser WD, Taddei PJ, Titt U Treatment planning in proton therapy requires the calculation of absorbed dose distributions on beam shaping components and the patient anatomy. Analytical pencil-beam dose algorithms commonly used are not always accurate enough. The Monte Carlo approach is more accurate but extremely computationally intensive. The Fast Dose Calculator, a track-repeating algorithm, has been proposed as an alternative fast and accurate dose calculation. In this work FDC is applied to a proton therapy patient thoracic anatomy. PMID: 21544230 [PubMed - as supplied by publisher] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=4798786 Wed, 01 Dec 2010 00:00:00 +0100 4798786 http://www.medworm.com/index.php?rid=4396295&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21243044%26dopt%3DAbstract Authors: Kappers LA, Bartram RH, Hamilton DS, Lempicki A, Brecher C, Gaysinskiy V, Ovechkina EE, Thacker S, Nagarkar VV PMID: 21243044 [PubMed - as supplied by publisher] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=4396295 Mon, 01 Mar 2010 00:00:00 +0100 4396295 http://www.medworm.com/index.php?rid=1180659&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18163158%26dopt%3DAbstract Authors: Trompier F, Kornak L, Calas C, Romanyukha A, Leblanc B, Mitchell CA, Swartz HM, Clairand I There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180659 Wed, 01 Aug 2007 04:00:00 +0100 1180659 http://www.medworm.com/index.php?rid=1180658&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18163159%26dopt%3DAbstract Authors: Romanyukha A, Trompier F, Leblanc B, Calas C, Clairand I, Mitchell CA, Smirniotopoulos JG, Swartz HM By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this approach is the presence of artifacts due to mechanically induced EPR signals (MIS) caused by mechanical stress during the collection and preparation of the samples and the so-called background (non-radiation) signal (BKS). The MIS and BKS have spectral parameters (shape, g-factor and linewidth) that overlap with the radiation-induced signal (RIS) and therefore, if not taken into account properly, could result in a considerable overestimation of the dose. We have investigated the use of dif... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180658 Wed, 01 Aug 2007 04:00:00 +0100 1180658 http://www.medworm.com/index.php?rid=1180660&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18037985%26dopt%3DAbstract Authors: Martin PR, Berdychevski RE, Subramanian U, Blakely WF, Prasanna PG Chromosome aberration-based dicentric assay is expected to be used after mass casualty life-threatening radiation exposures to assess radiation dose to individuals. This will require processing of a large number of samples for individual dose assessment and clinical triage to aid treatment decisions. We have established an automated, high-throughput, cytogenetic biodosimetry laboratory to process a large number of samples for conducting the dicentric assay using peripheral blood from exposed individuals according to internationally accepted laboratory protocols (i.e., within days following radiation exposures). The components of an automated cytogenetic biodosimetry laboratory include blood collection kits for ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180660 Sun, 01 Jul 2007 04:00:00 +0100 1180660 http://www.medworm.com/index.php?rid=1180665&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D16094775%26dopt%3DAbstract Authors: Noshad H, Givechi N The range and straggling data obtained from the transport of ions in matter (TRIM) computer program were used to determine the trajectories of monoenergetic 60 MeV protons in muscle tissue by using the Monte Carlo technique. The appropriate profile for the shape of a proton pencil beam in proton therapy as well as the dose deposited in the tissue were computed. The good agreements between our results as compared with the corresponding experimental values are presented here to show the reliability of our Monte Carlo method. PMID: 16094775 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180665 Sat, 01 Oct 2005 04:00:00 +0100 1180665 http://www.medworm.com/index.php?rid=1180664&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D16094776%26dopt%3DAbstract Authors: Iancu G, Flesch F, Heinrich W We have measured fragmentation cross-sections of Ar projectile nuclei at beam energy of 400 A MeV using experimental set-ups with plastic nuclear track detectors and different targets. In this paper total charge changing cross-sections and elemental fragmentation cross-sections for the production of fragments with charges ZF > or = 7 in interactions with H, C, Al, Cu, Ag and Pb target nuclei are presented. The dependence of the cross-sections on the fragment charge number and target charge number are discussed. The experimental results are compared to predictions of semi empirical cross-section models. PMID: 16094776 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180664 Sat, 01 Oct 2005 04:00:00 +0100 1180664 http://www.medworm.com/index.php?rid=1180663&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D16094777%26dopt%3DAbstract Authors: Matiullah , Rehman S, Rehman S, Mati N, Ahmad S Recently, several new etchants have been reported for CR-39 detector (Molten Ba(OH)2. 8H2O as an etchant for CR-39 detector, Radiat. Meas. 37 (2003) 205; Discovery of new etchants for CR-39 detector, Radiat. Meas. (2004)). We have made further progress in this direction and have unveiled two more new etchants which are reported in this article. CR-39 detectors were irradiated with fission fragments and alpha particles from a thin 252Cf disc source. The irradiated detectors were then etched in our newly introduced etching solutions as well as in conventionally used 6 M NaOH aqueous solution at 70 degrees C. The newly prepared etching solutions included NaOH dissolved in methanol and NaOH dissolved in methanol + water. Optimum valu... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180663 Sat, 01 Oct 2005 04:00:00 +0100 1180663 http://www.medworm.com/index.php?rid=1180662&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D16175732%26dopt%3DAbstract Authors: Oganessian VR, Trofimov VV, Danziger M, Dörschel B, Hermsdorf D, Orelovitch OL Modern dosimetry needs efficient detectors for registering light ions, especially light ions having energies of up to 10 MeV/amu. That is why this research pays attention to the development of materials for such a task. In this work, a CR-39 detector, which is the most efficient detector, was used. It was irradiated with low-energy protons. Using sensitive electrolytic etching and electron scanning microscopy, a complete analysis was carried out of the process of the formation of a pore starting from its opening to the final stage of its formation. The process of sequential track breakthroughs was observed. The data obtained on the shape of the pore and the parameters of its formation allow sim... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180662 Thu, 01 Sep 2005 04:00:00 +0100 1180662 http://www.medworm.com/index.php?rid=1180661&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D16175733%26dopt%3DAbstract Authors: Wahl CG, McLean JG The effect of 5-15 keV electron irradiation on the etch rate of CR-39 nuclear track detectors has been investigated for surface doses from 0.09 to 13.85 J/cm2. Even before etching, electrons produce a surface depression proportional to the surface dose raised to the power 0.78 +/- 0.01. Etch rate enhancement was observed in the surface region (about 4 micrometers deep) and was well approximated by a Gaussian function of depth. The depth and thickness of the etch rate enhancement increase with increasing electron energy, but are independent of dose. The maximum etch rate is proportional to the peak volumetric dose raised to the power of 1.45 +/- 0.06, independent of electron energy. No signs of a saturated response were found in the etch rate. This enhanced e... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180661 Thu, 01 Sep 2005 04:00:00 +0100 1180661 http://www.medworm.com/index.php?rid=1180668&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15884170%26dopt%3DAbstract Authors: Kenner GH, Brik AB, Liu G, Haskell EH, Hayes RB, Knight JA, Vajda EG, Miller SC, Jee WS, Barrus JK The purpose of this study was to gain insights into the variations seen in the electron paramagnetic resonance (EPR) spectroscopy of the native signals of teeth and bones used for retrospective dosimetry measurements. We determined that changes occur in the long-lived free radicals responsible for the native signal of cortical bone in aging or diseased human females and aged ovariectomized rats. This was done by measuring the magnitude of the broad (BC) and narrow (NC) components of the native EPR signal of bone following chemical extraction, aging, crushing and thermal annealing. Bone from the upper midshaft of femora of young (17-34 years old, n=5) and elderly (70-92 years old,... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180668 Wed, 01 Jun 2005 04:00:00 +0100 1180668 http://www.medworm.com/index.php?rid=1180667&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15884172%26dopt%3DAbstract Authors: Spurný F, Trompier F, Bottollier-Depois JF An MDU-Liulin spectrometer based on an Si-diode was mainly used during the last few years with the goal to use them for measurements onboard aircraft. To investigate its ability to obtain such measurements, the detector was tested in some radiation reference fields, like 60Co and other photon beams, neutrons of an AmBe and 252Cf sources and in high-energy radiation fields at CERN. Due to the high geometrical asymmetry of the Si-diode semiconductor, an angular dependence of the response would be expected. This work presents analyses and discusses the results of angular dependence studies obtained at the different radiation sources mentioned. It was found that these angular dependences vary with the type and energy of radiation. Th... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180667 Wed, 01 Jun 2005 04:00:00 +0100 1180667 http://www.medworm.com/index.php?rid=1180666&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15884173%26dopt%3DAbstract Authors: Matiullah , Rehman S, Rehman S, Zaman W After reporting the excellent etching properties of molten Ba(OH)2 8H2O as an etchant, we now report some more new and efficient etchants for CR-39 detector. CR-39 detectors were irradiated with fission fragments and alpha particles with a thin 252Cf source. The irradiated detectors were etched in a number of our newly introduced etching solutions as well as in conventionally used 6 M NaOH at 70 degrees C. The newly prepared etching solutions included NaOH/ethanol and NaOH/1-propanol. Processing conditions were optimized for these etchants. From fission and alpha track diameters, bulk etching velocity (VB), track etching velocity (VT), etching efficiency (eta) and their activation energies were determined and compared with that obtained ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180666 Wed, 01 Jun 2005 04:00:00 +0100 1180666 http://www.medworm.com/index.php?rid=1180679&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856555%26dopt%3DAbstract Authors: Spurný F Semiconductor devices based on a Si-detector are frequently used for charged particle's detection; one application being in the investigation of cosmic radiation fields. From the spectra of energy deposition events in such devices, the total energy deposited by the radiation in silicon can be derived. This contribution presents the results of studies concerning the response of this type of detector to fast neutrons. First, the spectrum of energy deposition was established in fast neutron radiation fields with average energies from 0.5 to 50 MeV. It was found that these spectra vary significantly with the neutron energy. The comparison with the spectra registered in photon beams permitted an estimation of the part of energy deposited that could be attributed to ne... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180679 Tue, 01 Feb 2005 05:00:00 +0100 1180679 http://www.medworm.com/index.php?rid=1180678&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856556%26dopt%3DAbstract Authors: Akopova AB, Manaseryan MM, Melkonyan AA, Tatikyan SSh, Potapov Y The results of an investigation of radiation environment on board the ISS with apogee/perigee of 420/380 km and inclination 51.6 degrees are presented. For measurement of important characteristics of cosmic rays (particles fluxes, LET spectrum, equivalent doses and heavy ions with Z > or = 2) a nuclear photographic emulsion as a controllable threshold detector was used. The use of this detector permits a registration of the LET spectrum of charged particles within wide range of dE/dx and during the last years it has already been successfully used on board the MIR station, Space Shuttles and "Kosmos" spacecrafts. An integral LET spectrum was measured in the range 0.5-2.2 x 10(3) keV/micrometers and the value of... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180678 Tue, 01 Feb 2005 05:00:00 +0100 1180678 http://www.medworm.com/index.php?rid=1180677&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856557%26dopt%3DAbstract Authors: Wissmann F, Dangendorf V, Schrewe U The contribution of the charged component of secondary cosmic radiation to the ambient dose equivalent H*(10) at ground level is investigated using the muon detector MUDOS and a TEPC detector surrounded by the coincidence detector CACS to identify charged particles. The ambient dose equivalent rate H*(10)T as measured with the TEPC/CACS is used to calibrate the MUDOS count rate in terms of H*(10). First results from long-term measurements at the PTB reference site for ambient radiation dosimetry are reported. The air pressure corrected dose rate shows, as expected, a strong correlation with the neutron count rate as measured with the Kiel neutron monitor. The measured seasonal variations exhibit a negative correlation with the temperature ch... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180677 Sat, 01 Jan 2005 05:00:00 +0100 1180677 http://www.medworm.com/index.php?rid=1180674&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856571%26dopt%3DAbstract Authors: Spurný F Thermoluminescent detectors (TLDs) are widely used for the dosimetry of photons and electrons. They are less used for the radiation with higher linear energy transfer (LET). One of the reasons for that is that their TL relative efficiency eta decreases for the most of them with increasing LET. The paper presents first a review of author's experimental results in which eta was established for charged particles having LET of the order from 1 to 100 keV/micrometers in tissue. Among TLDs studied were known materials like LiF:Mn; Ti; Al-P glass; CaSO4:Dy; Al2O3:Na; and Al2O3:C. It was found that the dependence of their eta on LET is not the same for all TLDs studied. The response of the same materials to neutrons was also studied. It was found that both eta as the rel... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180674 Sun, 01 Aug 2004 04:00:00 +0100 1180674 http://www.medworm.com/index.php?rid=1180673&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856574%26dopt%3DAbstract Authors: Gaza R, Yukihara EG, McKeever SW The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelerator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel(TM) dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4He (150 MeV/u), 12C (400 MeV/u), 28Si (490 MeV/us) and 56Fe (500 MeV/u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV/micrometers in water and doses from 1 to 100 mGy (to water). A 90Sr/90Y beta source, calibrated against a 60Co secondary standard, was used for calibration purposes. For OSL, we used both continuou... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180673 Sun, 01 Aug 2004 04:00:00 +0100 1180673 http://www.medworm.com/index.php?rid=1180672&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856580%26dopt%3DAbstract Authors: Bilski P, Budzanowski M, Olko P, Mandowska E The properties of LiF:Mg,Ti (distributed as, e.g., TLD-100 or MTS-N), the most frequently used thermoluminescent detector, have been optimised for measurements of sparsely ionizing radiation (gamma rays), typically encountered in radiation protection or clinical dosimetry. However, these detectors need also to be applied in conditions of mixed-field dosimetry with a high-LET component, such as those encountered in heavy ion beams or in space. At the Institute of Nuclear Physics in Kraków a new type of LiF:Mg,Ti detector (named MTT) has been recently developed through modification of its dopant composition. This composition is intended to increase the detection efficiency after a dose of high-LET radiation. The concentration of ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180672 Sun, 01 Aug 2004 04:00:00 +0100 1180672 http://www.medworm.com/index.php?rid=1180671&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856581%26dopt%3DAbstract Authors: Hernández A, Cruz-Zaragoza E, Negrón-Mendoza A, Ramos-Bernal S Radiation dosimetry is a very important issue in space research and in experiments that try to simulate chemical processes that may occur in cometary nucleus, interstellar grains, and other extraterrestrial environments, due to their irradiation by cosmic rays. The temperature effect is an important factor that has not been considered in many of these experiments. In this work, this effect was studied in TLD dosimeters exposed to gamma rays. The irradiations were done from 77 to 298 K in a gamma cell unit with a dose rate of 1.0 Gy/s. Results obtained for CaSO4:Dy show that there is a considerable effect in the evaluation of the dose as function of the irradiation temperature. PMID: 15856581 [PubMed -... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180671 Sun, 01 Aug 2004 04:00:00 +0100 1180671 http://www.medworm.com/index.php?rid=1180670&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856584%26dopt%3DAbstract Authors: Lee JI, Kim JL, Chang SY, Chung KS, Choe HS The dosimetric properties of the newly developed KLT-300 (KAERI LiF:Mg,Cu,Na,Si TL detector) in KAERI (Korea Atomic Energy Research Institute) were investigated. The sensitivity of the TL detector was about 30 times higher than that of the TLD-100 by light integration. In the study of the dose linearity of the detector, the dose response was very linear up to 10 Gy and a sublinear response was observed at higher doses. The energy response of the detector was studied for photon energies from 20 to 662 keV. The results show that a maximum response of 1.004 at 53 keV and a minimum response of 0.825 at 20 keV were observed. The reproducibility study for the TL detector was also carried out. The coefficients of variation for each detector... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180670 Sun, 01 Aug 2004 04:00:00 +0100 1180670 http://www.medworm.com/index.php?rid=1180669&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856586%26dopt%3DAbstract Authors: Martínez T, Lartigue J, Frias D, Sanchez-Mejorada G, Negrón-Mendoza A, Ramos-Bernal S A potential dosimeter based on aqueous frozen solutions and solid-state salt are presented for the evaluation of the energy transferred during the interaction of high-energy radiation with matter at low temperature. The foundation of these dosimeters, both the solid state and the frozen solutions, is based on the measurement of the change of the iron oxidation state. The systems were irradiated with gamma radiation at different doses (up to 10 MGy), and at different temperatures (from 77 to 298 K). The irradiated samples were analysed by UV-spectroscopy and Mössbauer spectroscopy. A theoretical model was developed for the chemical reactions system. This model reproduces the exp... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180669 Sun, 01 Aug 2004 04:00:00 +0100 1180669 http://www.medworm.com/index.php?rid=1180676&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856565%26dopt%3DAbstract Authors: Hassan GM, Sharaf MA, Desouky OS Bioglass (Bio-G) samples were irradiated with 60Co gamma-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum of Bio-G is characterized by two main signals. The first signal at g approximately = 4.3 corresponds to Fe3+ impurities and the second signal at g approximately = 2.0130 with line-width 10.85 G is ascribed as a hole center. The gamma-ray dose response and thermal stability were studied to establish the suitability of bioglass as an ESR dosimeter. A radical formation efficiency, G-value, of 0.53 +/- 0.11 was obtained. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 255 +/- 46 days and 0.71 eV, respectively. PMID: 15856565 [PubMe... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180676 Tue, 01 Jun 2004 04:00:00 +0100 1180676 http://www.medworm.com/index.php?rid=1180675&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D15856569%26dopt%3DAbstract Authors: Yukihara EG, Whitley VH, McKeever SW, Akselrod AE, Akselrod MS This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180675 Tue, 01 Jun 2004 04:00:00 +0100 1180675 http://www.medworm.com/index.php?rid=1180680&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D14968783%26dopt%3DAbstract Authors: Mostafa HI Bacteriorhodopsin (bR) is an attractive intelligent material. Understanding the mechanism of its light-driven proton pumping outward the cell implicates it in many technical applications, particularly, in what is called optical computers, and the biotechnology is waiting for this promised biological molecule. An ionizing radiation source handling could be computerized in radiation fields. The computer containing such biological material will not be out of reach of the fields of ionizing radiation. So it is interesting to report on the working of such biological computer if it is subjected to ionizing radiation. The functional unit in this molecule is retinal chromophore. In the present work, it is interested to assess the functionality of bR through determining the ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180680 Thu, 01 Apr 2004 05:00:00 +0100 1180680 http://www.medworm.com/index.php?rid=1180681&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D14672096%26dopt%3DAbstract Authors: Yukihara EG, Gaza R, McKeever SW, Soares CG The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180681 Sun, 01 Feb 2004 05:00:00 +0100 1180681 http://www.medworm.com/index.php?rid=1180682&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12856693%26dopt%3DAbstract Authors: McKeever SW, Banerjee D, Blair M, Clifford SM, Clowdsley MS, Kim SS, Lamothe M, Lepper K, Leuschen M, McKeever KJ, Prather M, Rowland A, Reust D, Sears DW, Wilson JW In this paper we present the concept of a robotic instrument for in situ luminescence dating of near-surface sediments on Mars. The scientific objectives and advantages to be gained from the development of such an instrument are described, and the challenges presented by the Mars surface environment to the design and operation of the instrument are outlined. PMID: 12856693 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180682 Fri, 01 Aug 2003 04:00:00 +0100 1180682 http://www.medworm.com/index.php?rid=1180683&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12521047%26dopt%3DAbstract Authors: Liu F, Wang Y, Xue J, Wang S, Du G, Zhao W The penetration depth of low-energy heavy ions in botanic samples was detected with a new transmission measurement. In the measurement, highly oriented pyrolytic graphite (HOPG) pieces were placed behind the botanic samples with certain thickness. During the irradiation of heavy ions with energy of tens of keV, the energetic particles transmitted from those samples were received by the HOPG pieces. After irradiation, scanning tunneling microscope (STM) was applied to observe protrusion-like damage induced by these transmitted ions on the surface of the HOPG. The statistical average number density of protrusions and the minimum transmission rate of the low-energy heavy ions can be obtained. The detection efficiency of the new method fo... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180683 Sat, 01 Feb 2003 05:00:00 +0100 1180683 http://www.medworm.com/index.php?rid=1180688&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12455499%26dopt%3DAbstract Authors: Badhwar GD, Huff H, Wilkins R, Thibeault S Space radiation transport models clearly show that low atomic weight materials provide a better shielding protection for interplanetary human missions than high atomic weight materials. These model studies have concentrated on shielding properties against charged particles. A light-weight, inflatable habitat module called TransHab was built and shown to provide adequate protection against micrometeoroid impacts and good shielding properties against charged particle radiation in the International Space Station orbits. An experiment using a tissue equivalent proportional counter, to study the changes in dose and lineal energy spectra with graphite, aluminum, and a TransHab build-up as shielding, was carried out at the Los Alamos Nuclear... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180688 Sun, 01 Dec 2002 05:00:00 +0100 1180688 http://www.medworm.com/index.php?rid=1180687&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12455500%26dopt%3DAbstract Authors: Badhwar GD, Robbins DE, Gibbons F, Braby LA The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. PMID: 12455500 [PubMed - indexed for MEDLI... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180687 Sun, 01 Dec 2002 05:00:00 +0100 1180687 http://www.medworm.com/index.php?rid=1180686&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12455507%26dopt%3DAbstract Authors: Akopova AB, Melkonyan AA, Tatikyan SSh, Capdevielle JN The results of investigations of the neutron component (E=1-10 MeV) of cosmic radiation on board the "Armenian Airlines" aircrafts using nuclear photoemulsion are presented. The emulsions were exposed on the flights from Yerevan to Moscow, St.-Petersburg, Beirut, Athens, Frankfurt, Amsterdam, Paris and Sofia, and on Concord supersonic flights from Paris to New York. The dependence of the neutron fluxes, and on absorbed and equivalent doses on the flight parameters were investigated. On the flights of the supersonic Concord, with an altitude of 17 km, the neutron fluxes were essentially higher in comparison to those measured on Armenian airliners. It is interesting to note, that the neutron flux and equivalent dose rate dec... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180686 Sun, 01 Dec 2002 05:00:00 +0100 1180686 http://www.medworm.com/index.php?rid=1180685&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12455514%26dopt%3DAbstract Authors: Szabo J, Feher I, Palfalvi J, Balashazy I, Dam AM, Polonyi I, Bogdandi EN One way of studying the risk to human health of low-level radiation exposure is to make biological experiments on living cell cultures. Two 210Po alpha-particle emitting devices, with 0.5 and 100 MBq activity, were designed and constructed to perform such experiments irradiating monolayers of cells. Estimates of dose rate at the cell surface were obtained from measurements by a PIPS alpha-particle spectrometer and from calculations by the SRIM 2000, Monte Carlo charged particle transport code. Particle fluence area distributions were measured by solid state nuclear track detectors. The design and dosimetric characterisation of the devices are discussed. PMID: 12455514 [PubMed - indexed for MEDLINE] (... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180685 Sun, 01 Dec 2002 05:00:00 +0100 1180685 http://www.medworm.com/index.php?rid=1180684&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12455519%26dopt%3DAbstract Authors: Zdravkova M, Denis JM, Gallez B, Debuyst R This paper reports the first attempt to use L-band spectroscopy for estimating the sensitivity of whole teeth to fast neutrons and gamma-rays. Three teeth were successively irradiated first with fast neutrons with a wide energy spectrum (mean energy around 30 MeV) up to approximately 160 Gy and then with gamma-rays up to approximately 14 Gy. After each irradiation, L-band (approximately 1 GHz) EPR spectra of each whole tooth surrounded by the surface-coil resonator were recorded, yielding a single composite line principally due to CO2- and native radicals. The sensitivities are estimated by the slopes of the linear dose response curves of the dosimetric CO2- radicals. The ratios of the gamma/neutron sensitivities were found to be in t... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180684 Sun, 01 Dec 2002 05:00:00 +0100 1180684 http://www.medworm.com/index.php?rid=1180705&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440427%26dopt%3DAbstract Authors: PMID: 12440427 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180705 Tue, 01 Oct 2002 04:00:00 +0100 1180705 http://www.medworm.com/index.php?rid=1180704&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440428%26dopt%3DAbstract Authors: Apathy I, Deme S, Feher I, Akatov YA, Reitz G, Arkhanguelski VV Exposure of crew, equipment, and experiments to the ambient space radiation environment in low Earth orbit poses one of the most significant problems to long-term space habitation. Accurate dose measurement has become increasingly important during the assembly (extravehicular activity (EVA)) and operation of space stations such as on Space Station Mir. Passive integrating detector systems such as thermoluminescent dosemeters (TLDs) are commonly used for dosimetry mapping and personal dosimetry on space vehicles. The well-known advantages of passive detector systems are their independence of power supply, small dimensions, high sensitivity, good stability, wide measuring range, resistance to environmental effects, ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180704 Tue, 01 Oct 2002 04:00:00 +0100 1180704 http://www.medworm.com/index.php?rid=1180703&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440430%26dopt%3DAbstract Authors: Badhwar GD, Atwell W, Reitz G, Beaujean R, Heinrich W Radiation measurements made onboard the MIR Orbital Station have spanned nearly a decade and covered two solar cycles, including one of the largest solar particle events, one of the largest magnetic storms, and a mean solar radio flux level reaching 250 x 10(4) Jansky that has been observed in the last 40 years. The cosmonaut absorbed dose rates varied from about 450 microGy day-1 during solar minimum to approximately half this value during the last solar maximum. There is a factor of about two in dose rate within a given module, and a similar variation from module to module. The average radiation quality factor during solar minimum, using the ICRP-26 definition, was about 2.4. The drift of the South Atlantic Anomaly was me... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180703 Tue, 01 Oct 2002 04:00:00 +0100 1180703 http://www.medworm.com/index.php?rid=1180702&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440432%26dopt%3DAbstract Authors: Baranov DG, Dergachev VA, Gagarin YF, Lyagushin VI, Nymmik RA, Panasyuk MI, Solov'ev AV, Yakubovskii EA The results are presented of measurements high-energy particles in a customary manned space station orbit (a 350-450-km altitude, a 51.6 degrees inclination; Salyut-6 and 7, MIR). The particles were recorded by the chambers composed of the Lavsan (polyethyleneterephtalate) solid-state nuclear track detector layers mounted outside a spacecraft for 1-3 years. A high resolution has been attained in the charge and energy spectra of 30-200 MeV/n Fe group particles. The results of measuring the particle fluxes in the space station orbits are used to restore the initial particle energy spectra in terms of the models that describe the galactic and solar cosmic rays and their penetra... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180702 Tue, 01 Oct 2002 04:00:00 +0100 1180702 http://www.medworm.com/index.php?rid=1180701&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440435%26dopt%3DAbstract Authors: Beaujean R, Kopp J, Burmeister S, Petersen F, Reitz G The dosimetry telescope (DOSTEL) was flown on the MIR orbital station during October 1997-January 1998. The mission average contributions to the absorbed dose rates (in water) were 126 +/- 4 microGy/d and 121 +/- 13 microGy/d for the GCR and the SAA component, respectively. The mean quality factors (ICRP60) deduced from the LET-spectra are 3.5 +/- 0.2 (GCR) and 1.3 +/- 0.1 (SAA). Separate LET spectra and temporal variations of the absorbed dose rates and of the mean quality factors are presented for these two radiation components as well as for solar energetic particles of the November 6, 1997 event. PMID: 12440435 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180701 Tue, 01 Oct 2002 04:00:00 +0100 1180701 http://www.medworm.com/index.php?rid=1180700&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440436%26dopt%3DAbstract Authors: Benton ER, Benton EV, Frank AL Passive radiation dosimeters were exposed aboard the Mir Orbital Station over a substantial portion of the solar cycle in order to measure the change in dose and dose equivalent rates as a function of time. During solar minimum, simultaneous measurements of the radiation environment throughout the habitable volume of the Mir were made using passive dosimeters in order to investigate the effect of localized shielding on dose and dose equivalent. The passive dosimeters consisted of a combination of thermoluminescent detectors to measure absorbed dose and CR-39 PNTDs to measure the linear energy transfer (LET) spectrum from charged particles of LET infinity H2O > or = 5 keV/micrometers. Results from the two detector types were then combined to yi... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180700 Tue, 01 Oct 2002 04:00:00 +0100 1180700 http://www.medworm.com/index.php?rid=1180699&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12440446%26dopt%3DAbstract Authors: Benton ER, Benton EV, Frank AL This paper reports results from the first measurements made on the exterior of a LEO spacecraft of mean dose equivalent rate and average quality factor as functions of shielding depth for shielding less than 1 g/cm2 Al equivalent. Two sets of measurements were made on the outside of the Mir Orbital Station; one near solar maximum in June 1991 and one near solar minimum in 1997. Absorbed dose was measured using stacks of TLDs. LET spectrum from charged particles of LET infinity H2O > o r= 5keV/micrometers was measured using stacks of CR-39 PNTDs. Results from the TLD and PNTD measurements at a given shielding depth were combined to yield mean total dose rate, mean dose equivalent rate, and average quality factor. Measurements made near solar ma... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180699 Tue, 01 Oct 2002 04:00:00 +0100 1180699 http://www.medworm.com/index.php?rid=1180698&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442742%26dopt%3DAbstract The properties of gamma-radiation and high-energy neutron fluxes in "MIR" station orbit. Radiat Meas. 2002 Oct;35(5):473-83 Authors: Bogomolov AV, Bogomolov VV, Denisov YI, Logachev YI, Svertilov SI, Kudryavtsev MI, Lyagushin VI, Ershova TV The study of radiation background components in the near-Earth space is very important for different branches of space research, in particular for space dosimetry and for the planning of gamma-astronomy experiments. Detailed information on the neutral components (gamma-quanta, neutrons) of background radiation was obtained during the Grif-1 experiment onboard Mir orbital station (OS). The measurements of fluxes of 0.05-50 MeV gamma-quanta and >30 MeV neutrons with a large area instrument (approximately 250 cm2 for gamma-quanta, approximat... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180698 Tue, 01 Oct 2002 04:00:00 +0100 1180698 http://www.medworm.com/index.php?rid=1180697&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442744%26dopt%3DAbstract Authors: Bottollier-Depois JF, Siegrist M, Petrov VM, Shurshakov VV, Bengin V, Koslova SB Measurements of the radiation environment inside the Mir space station were performed with a tissue equivalent proportional counter (TEPC) during the Antares mission in 1992, and over a long period following it. Interesting results concerning radiation measurements show (a) the South Atlantic Anomaly crossing, (b) the increase of radiation near the poles, and (c) the effects of solar particle events (the most important one occurring in early November 1992). This data also provides information about the dose and the quality factor of the radiation to which the cosmonauts were exposed during different missions. These data are compared with measurements obtained using a solid state detector. PMID... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180697 Tue, 01 Oct 2002 04:00:00 +0100 1180697 http://www.medworm.com/index.php?rid=1180696&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442745%26dopt%3DAbstract Authors: Buhler P, Zehnder A, Kruglanski M, Daly E, Adams L During two years, from November 1994 to 1996, the particle detector REM measured the highly energetic electron and proton environment at the outside of the MIR orbital station. Using mission averaged data we investigate various aspects of the proton fluxes in the SAA. Comparison with the radiation belt model AP8 reveal important differences. PMID: 12442745 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180696 Tue, 01 Oct 2002 04:00:00 +0100 1180696 http://www.medworm.com/index.php?rid=1180695&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442746%26dopt%3DAbstract Data failures in the "Riabina-2" experiment on MIR orbital station. Radiat Meas. 2002 Oct;35(5):499-504 Authors: Dmitriev AV, Guilfanov II, Panasyuk MI Experimental data about high-energy particle fluxes obtained in 1990-2000 in the Riabina-2 experiment on board MIR orbital station are analyzed in the sense of data failures. There are two types of failure. The first type is represented as sharp positive or negative spikes on the relatively smooth time profiles of the particle fluxes. The second type is randomly distributed data gaps with durations of up to tens minutes. These two kinds of the data failures are formalized in the form of "failure occurrence probability" (FOP). The comparison analysis of the FOP with solar activity, solar wind conditions and geomagnetic activity s... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180695 Tue, 01 Oct 2002 04:00:00 +0100 1180695 http://www.medworm.com/index.php?rid=1180694&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442747%26dopt%3DAbstract Authors: Doke T, Hayashi T, Kikuchi J, Nagaoka S, Nakano T, Takahashi S, Tawara H, Terasawa K In 1997, four dosimeter packages, each of which contains two CR-39 plates and 18 TLDs (Mg2SiO4:Tb), were placed inside the MIR Space Station and flew on an orbit with an inclination angle of 51.6 degrees and an altitude of approximately 400 km for 40 days. We estimated the absorbed doses, dose equivalents and effective quality factors during the flight by combining CR-39 data and TLD data. We then compared these results to those obtained with the same analysis method from the dosimeter packages on board Space Shuttle missions STS-79, -84 and -91 that flew along the same orbit. Finally, the differences between our results and those obtained by another group using passive dosimeters on the MIR a... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180694 Tue, 01 Oct 2002 04:00:00 +0100 1180694 http://www.medworm.com/index.php?rid=1180693&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442748%26dopt%3DAbstract Authors: Gunther W, Leugner D, Becker E, Heinrich W, Reitz G Stacks of CR-39 plastic nuclear track detectors were mounted inside the MIR spacecraft during the EUROMIR95 space mission for a period of 6 months. This long exposure time resulted in a large number of tracks of HZE-particles in the detector foils. All trajectories of stopping iron nuclei could be reconstructed by optimizing the etching conditions so that an automatic track measurement using image analysis techniques was possible. We found 185 stopping iron nuclei and used the énergy-range relation to calculate their energies at the stack surface. The measured spectrum of iron nuclei inside the MIR station is compared to results of model predictions considering the effect of the solar modulation for the mission period, t... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180693 Tue, 01 Oct 2002 04:00:00 +0100 1180693 http://www.medworm.com/index.php?rid=1180692&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442749%26dopt%3DAbstract Authors: Mitricas VG, Tsetlin VV, Teltsov MV, Shumshurov VI PMID: 12442749 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180692 Tue, 01 Oct 2002 04:00:00 +0100 1180692 http://www.medworm.com/index.php?rid=1180691&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442750%26dopt%3DAbstract Authors: Petrov VM During the flight of the main missions on board the MIR station the individual doses of the crew members and the dose inside the core module was measured by the ID-3M package and R-16 dosimeter, respectively. Comparison of the skin dose measured by ID-3M unit and calculated by the transmission coefficient method on the basis of R-16 data in each of 23 main missions permits estimation of the systematic error of the transmission coefficient method. The mean value of this error is equal to 32%. PMID: 12442750 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180691 Tue, 01 Oct 2002 04:00:00 +0100 1180691 http://www.medworm.com/index.php?rid=1180690&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442751%26dopt%3DAbstract Authors: Shavrin PI, Kuzhevskij BM, Kuznetsov SN, Nechaev OY, Panasyuk MI, Ryumin SP, Yushkov BY, Bratolyubova-Tsulukidze LS, Lyagushin VI, Germantsev YL Neutron measurement results obtained at SINP MSU since 1970 are presented. These measurements were made using techniques based on neutron moderation and subsequent detection in a Li6I(Eu) crystal or a He3 coronal counter. The measurements were mainly carried out in orbits with inclination of 52 degrees and altitudes of 200-450 km. The spatial and angular distributions of the measured neutron fluxes were studied. The albedo neutron flux was estimated according to the count rate difference for opposite detector orientations towards Earth and away from it. This flux is comparable to the local neutron flux outside the Brazil anomaly regio... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180690 Tue, 01 Oct 2002 04:00:00 +0100 1180690 http://www.medworm.com/index.php?rid=1180689&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12442757%26dopt%3DAbstract Authors: Spurny F, Dudkin VE Three types of detectors were used onboard the MIR station during the 28th base expeditions to characterise the radiation field: a linear energy transfer (LET) spectrometer was used to establish the LET spectrum between 7 and 700 keV/micrometers corresponding mostly to secondary charged particles; a set of thermoluminescent detectors was used to characterise the low LET component of the onboard radiation field; and Si-diodes were installed to determine the contribution to the exposure due to fast neutrons. It was found out that the LET spectrum from secondary particles between 7 and 700 KeV/micrometers does not depend on the external radiator; the average quality factors for the region mentioned are about 6.0 with ICRP 26 quality factors and about 6.8 with ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180689 Tue, 01 Oct 2002 04:00:00 +0100 1180689 http://www.medworm.com/index.php?rid=1180736&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11841106%26dopt%3DAbstract Authors: Tawara H, Doke T, Hayashi T, Kikuchi J, Kyan A, Nagaoka S, Nakano T, Takahashi S, Terasawa K, Yoshihira E The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6 degrees) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6 degrees) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4-200 keV/micrometers, fluctuated with standard deviations of +/- 21% to +/- 35% in both flight experiments. The LET distributions obtained from ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180736 Mon, 01 Apr 2002 05:00:00 +0100 1180736 http://www.medworm.com/index.php?rid=1180735&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11841107%26dopt%3DAbstract Authors: Uchihori Y, Kitamura H, Fujitaka K, Dachev TP, Tomov BT, Dimitrov PG, Matviichuk Y We are developing a portable dosimeter (Liulin-4J) based on a silicon semiconductor detector for use in measuring the absorbed dose from primary or secondary cosmic rays to astronauts and airplane crews. The dosimeter can measure not only the flux and dose rate, but also the deposited energy spectrum for silicon in per unit time. In order to calibrate the dosimeter, we have carried out exposures at the NIRS cyclotron and HIMAC heavy ion synchrotron facilities. We obtained a detector response function for using in measuring energy deposition and LET. PMID: 11841107 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180735 Mon, 01 Apr 2002 05:00:00 +0100 1180735 http://www.medworm.com/index.php?rid=1180738&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11688501%26dopt%3DAbstract Authors: Awad EM Response of CR-39 to high-energy heavy ions was investigated by using optical microphotographs of track profiles for Ar (480 MeV/n) and Ni (300 MeV/n). The depth dependence of track etch rate (VT) was determined experimentally by track length measurement. The results indicate that VT for the low REL Ar tracks is depth independent but for the high REL Ni tracks VT is gradually decreasing with depth. The region beyond 30 m depth inside the detector shows a stable region regarding the detector response for both ions. PMID: 11688501 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180738 Sat, 01 Dec 2001 05:00:00 +0100 1180738 http://www.medworm.com/index.php?rid=1180737&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11762393%26dopt%3DAbstract In this study, radiation-induced morphological/cytological changes i.e., number of root formation and its length, shooting length, reduction in mitotic index, micronuclei formation and chromosomal aberrations in the root tip cells of gamma-irradiated onions at lower doses (50-2000 cGy) are reported. The capabilities of this biological species to store the radiation-induced information are also studied. PMID: 11762393 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180737 Mon, 01 Oct 2001 04:00:00 +0100 1180737 http://www.medworm.com/index.php?rid=1180744&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678150%26dopt%3DAbstract Authors: Rusov V, Zelentsova T, Melentchuk I, Beglaryan M A new cascade-stochastic approach to solve the direct and inverse problems of radiation-induced effect statistics in track biodetectors is presented in this paper. The analysis of the experimental data has made it possible to establish a non-linear nature of the "dose-effect" dependence in low dose area. For the first time, a new determination of the relative biological efficiency and quality coefficient of ionizing radiation in area of low doses are proposed. PMID: 11678150 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180744 Fri, 01 Jun 2001 04:00:00 +0100 1180744 http://www.medworm.com/index.php?rid=1180743&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678151%26dopt%3DAbstract Authors: Gunther W, Heinrich W, Flesch F, Reitz G To measure the energy spectra of low energy ions inside the International Space Station (ISS) we will expose three stacks of CR-39 plastic nuclear track detectors aligned to the three coordinate axes of the space station. The energies of cosmic ray nuclei at the stack surfaces can be determined by reconstructing the trajectories of ions stopping inside the detector material and by measuring their ranges. To measure only HZE (high charge Z and energy E) ions with charges of Z6 stopping in our experiment a special batch of CR-39 detectors with low sensitivity will be used. This detector material has been already tested by an exposure to carbon ions at the GSI accelerator in Darmstadt, Germany. PMID: 11678151 [PubMed - indexed for MEDL... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180743 Fri, 01 Jun 2001 04:00:00 +0100 1180743 http://www.medworm.com/index.php?rid=1180742&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678152%26dopt%3DAbstract Authors: Donnelly J, Thompson A, O'Sullivan D, Drury LO, Wenzel KP The DIAS-ESTEC Ultra Heavy Cosmic Ray Experiment (UHCRE) on the Long Duration Exposure Facility, collected approximately 3000 cosmic ray nuclei with Z > 65 in the energy region E > 1.5 GeV nucleon-1 during a six year exposure in Earth orbit. The entire accessible collecting area of the solid state nuclear track detector (SSNTD) array has been scanned for actinides, yielding a sample of 30 from an exposure of approximately 150 m2 sr yr. The UHCRE experimental setup is described and the observed charge spectrum presented. The current best value for the cosmic ray actinide relative abundance, (Z > 88)/(74 < or = Z < or = 87), is reported. PMID: 11678152 [PubMed - indexed for MEDLINE] (Source: Radiation M... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180742 Fri, 01 Jun 2001 04:00:00 +0100 1180742 http://www.medworm.com/index.php?rid=1180741&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678153%26dopt%3DAbstract Authors: O'Sullivan D, Zhou D, Flood E A very extensive study of the radiation field at aircraft altitudes has been carried out over the last few years. These investigations formed part of a European wide collaboration involving several laboratories with extensive experience in cosmic ray research and/or dosimetry. Among the main topics investigated were the charge spectra, LET spectra, anisotropy and dose values. The measurements were performed on subsonic and supersonic flights covering a wide range of altitudes and latitudes. Several active and passive instruments were employed in these studies and some results obtained with nuclear track detectors are described here. Comparisons are made with the results of other experiments and theoretical estimates using computer codes. PMID:... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180741 Fri, 01 Jun 2001 04:00:00 +0100 1180741 http://www.medworm.com/index.php?rid=1180740&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678154%26dopt%3DAbstract Authors: Meier MM, Reitz G The effective charge state is an important particle parameter which is required for the calculation of many effects concerning the interaction between radiation and matter such as an estimate of the radial dose of swift heavy projectiles, stopping power and so on. A new method for the determination of effective charge states of heavy ions is based on the measurement of the number of high-energy delta-electrons which are ejected from a target by the penetrating ion. These electrons are detectable with a CCD-detector and their number can be correlated to the effective charge state of the projectile for known particle velocities. This method is even applicable to operation with single swift heavy ions within statistical bounds. PMID: 11678154 [PubMed - index... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180740 Fri, 01 Jun 2001 04:00:00 +0100 1180740 http://www.medworm.com/index.php?rid=1180739&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11678155%26dopt%3DAbstract Authors: Kondratyeva MA, Tretyakova CA, Tretyakova SP, Zhuravlev DA For observation of low energy cosmic ray particles we used CN-Kodak nuclear track detectors on Cosmos satellites. In solar quiet periods during solar minima conditions the detectors registered anomalous cosmic rays (ACRs). The ACRs are characterized by flux enhancements of several elements and it is known that the carbon enhancement is small compared with that of oxygen. In all of our quiet-time exposures the relation between carbon and oxygen was extremely small (C/O ~ 0.03). But in two quiet-time periods of 14.03.96-11.06.96 and of 15.12.97-14.04.98 we have identified many tracks as carbon in a L-R diagram. As a result the observed C/O ratio appears to be more than 0.5, whereas other experiments show no evidence of e... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180739 Fri, 01 Jun 2001 04:00:00 +0100 1180739 http://www.medworm.com/index.php?rid=1180734&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11852942%26dopt%3DAbstract Authors: Armstrong TW, Colborn BL As part of a study funded by NASA MSFC to assess thecontribution of secondary particles in producing radiation damage to optoelectronics devices located on the International Space Station (IS), Monte Carlo calculations have been made to predict secondary spectra vs. shielding inside ISS modules and in electronics boxes attached on the truss (Armstrong and Colborn, 1998). The calculations take into account secondary neutron, proton, and charged pion production from the ambient galactic cosmic-ray (GCR) proton, trapped proton, and neutron albedo environments. Comparisons of the predicted neutron spectra with measurments made on the Mir space station and other spacecraft have also been made (Armstrong and Colborn, 1998). In this paper, some initial result... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180734 Fri, 01 Jun 2001 04:00:00 +0100 1180734 http://www.medworm.com/index.php?rid=1180733&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11852943%26dopt%3DAbstract Authors: Badhwar GD, Keith JE, Cleghorn TF The radiation environment inside a shielded volume is highly complex, consisting of both charged and neutral particles. Since the inception of human space flights, the charged particle component has received virtually all of the attention. There is however, a significant production of secondary neutrons, particularly from the aluminum structure in low earth orbiting spacecrafts. The interactions of galactic cosmic rays (GCR), and solar energetic particles with the earth's atmosphere produce a non-isotropic distribution of albedo neutrons. Inside any reasonable habitable module, the average radiation quality factor of neutrons is about 4-5 times larger than the corresponding average quality factor of charged particles. The measurement of neutro... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180733 Fri, 01 Jun 2001 04:00:00 +0100 1180733 http://www.medworm.com/index.php?rid=1180732&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11852944%26dopt%3DAbstract Authors: Bartlett DT, Hager LG, Tanner RJ, Steele JD Measurements of the complex cosmic radiation field in aircraft at altitude are made with a passive survey meter comprising routine-use thermoluminescent detectors and etched track detectors. The energy dependence of response of the etched track detectors used to determine the neutron component has been characterized, partly, up to a neutron energy of 180 MeV. The neutron detectors are routinely calibrated in the CERN/EC Reference Field. The 15% determination level for total dose equivalent is 100 microSv. The evidence is that the passive survey meter provides a reliable determination of route dose. PMID: 11852944 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180732 Fri, 01 Jun 2001 04:00:00 +0100 1180732 http://www.medworm.com/index.php?rid=1180731&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11852945%26dopt%3DAbstract Authors: Benton ER, Benton EV, Frank AL This paper summarizes neutron dosimetry measurements made by the USF Physics Research Laboratory aboard US and Russian LEO spacecraft over the past 20 years using two types of passive detector. Thermal/resonance neutron detectors exploiting the 6Li(n,T) alpha reaction were used to measure neutrons of energies <1 MeV. Fission foil neutron detectors were used to measure neutrons of energies above 1 MeV. While originally analysed in terms of dose equivalent using the NCRP-38 definition of quality factor, for the purposes of this paper the measured neutron data have been reanalyzed and are presented in terms of ambient dose equivalent. Dose equivalent rate for neutrons <1 MeV ranged from 0.80 microSv/d on the low altitude, low inclination STS-4... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180731 Fri, 01 Jun 2001 04:00:00 +0100 1180731 http://www.medworm.com/index.php?rid=1180730&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855407%26dopt%3DAbstract Authors: Braby LA, Badhwar GD A technique to separate out the dose, and lineal energy spectra of neutrons and charged particles is described. It is based on using two proportional counters, one with a wall, and the other with similar characteristics but wall made from a non-hydrogen containing material. Results of a calibration in a neutron field are also shown. PMID: 11855407 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180730 Fri, 01 Jun 2001 04:00:00 +0100 1180730 http://www.medworm.com/index.php?rid=1180729&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855408%26dopt%3DAbstract Authors: Heilbronn L, Townsend LW PMID: 11855408 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180729 Fri, 01 Jun 2001 04:00:00 +0100 1180729 http://www.medworm.com/index.php?rid=1180728&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855409%26dopt%3DAbstract Authors: Ing H Like all other radiation monitors currently used in the space program, the bubble detector (which has flown on several missions) was adapted from a technology that was developed for terrestrial radiation. Bubble detectors are the most recent technology for applications in personal neutron dosimetry. They are now regarded as a mature technology and are used in many countries as a neutron dosimeter of record with approval from the respective regulatory authorities. Extensive type testing and QA of bubble detectors has been done by numerous groups, many of these to show that bubble detectors meet national radiation protection requirements prior to their acceptance as a dosimeter of record. In fact, it has been stated "Only bubble detectors achieve a sufficiently low detecti... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180728 Fri, 01 Jun 2001 04:00:00 +0100 1180728 http://www.medworm.com/index.php?rid=1180727&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855410%26dopt%3DAbstract This report discusses these results. PMID: 11855410 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180727 Fri, 01 Jun 2001 04:00:00 +0100 1180727 http://www.medworm.com/index.php?rid=1180726&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855411%26dopt%3DAbstract In this study, a feedforward neural network using the error back-propagation method with Bayesian optimization was applied for the response unfolding procedure. The validation of the proposed algorithm was investigated by unfolding the 10 measured responses of alpha-Al2O3:C for arbitrarily mixed photon fields which range from 20 to 662 keV. PMID: 11855411 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180726 Fri, 01 Jun 2001 04:00:00 +0100 1180726 http://www.medworm.com/index.php?rid=1180725&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855412%26dopt%3DAbstract Authors: Luszik-Bhadra M, Matzke M, Schuhmacher H A passive neutron dosemeter with thermoluminescence and etched-track detectors was used in the space station MIR in 1995 and 1997 and during some shuttle flights to MIR. High neutron doses of about 200 microSv d-1 were measured with track detectors, while the contribution of protons to the track density was estimated to be small. An active personal dosemeter based on silicon diodes providing a direct readout, improved sensitivity and spectrometric properties is proposed for additional monitoring. Firstly, measurements with a prototype were performed in the stray radiation fields of the CERN-EU Reference Radiation Facility. When mounted on a phantom at different positions, both the passive and the active dosemeter provide the directional... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180725 Fri, 01 Jun 2001 04:00:00 +0100 1180725 http://www.medworm.com/index.php?rid=1180724&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855413%26dopt%3DAbstract Authors: Lyagushin VI, Dudkin VE, Potapov YV, Sevastianov VD Results of the experiments on neutron energy spectra measurements within broad energy range from 5 x 10(-7) to 2 x 10(2) MeV aboard the Mir orbital station and equivalent neutron dose estimation are presented. Four measurement techniques were used during the experiments. The shape of spectra and their absolute values are in good agreement. According to those experiments, an equivalent neutron dose depends upon effective shielding thickness and spacecraft mass. The neutron dose mentioned is comparable with that of ionizing radiation. Neutron flux levels measured aboard the Mir station have shown that a neutron spectrometer involving broad energy range will be used within the radiation monitoring systems in manned space flights... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180724 Fri, 01 Jun 2001 04:00:00 +0100 1180724 http://www.medworm.com/index.php?rid=1180723&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855414%26dopt%3DAbstract Authors: Matsumoto H, Goka T, Koga K, Iwai S, Uehara T, Sato O, Takagi S We have developed a real-time, Bonner Ball-type (neutron energy range is from thermal to 15 MeV) neutron spectral measurement system (Bonner Ball Neutron Detector (BBND)) for use on board the International Space Station (ISS). From measurements taken inside STS-89 (S/MM-8), we successfully distinguished neutrons from protons and other particles in a mixed radiation field; a task hitherto considered difficult. Although the experimental period was short, only 3.5 days (January 24-27, 1998), we were able to obtain energy spectral data and the Earth's neutron dose-equivalent map for the ISS orbital conditions (altitude 400 km, orbit inclination angle 51.6 degrees). A method for calculating the neutron energy spectrum ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180723 Fri, 01 Jun 2001 04:00:00 +0100 1180723 http://www.medworm.com/index.php?rid=1180722&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855415%26dopt%3DAbstract Authors: Pinsky L, Carminati F, Ferrari A FLUKA is an integrated particle transport code that has enhanced multigroup low-energy neutron transport capability similar to the well-known MORSE transport code. Gammas are produced in groups but many important individual lines are specifically included, and subsequently transported by the main FLUKA routines which use a modified version of EGS4 for electromagnetic (EM) transport. Recoil protons are also transported by the primary FLUKA transport simulation. The neutron cross-section libraries employed within FLUKA were supplied by Giancarlo Panini (ENEA, Italy) based upon the most recent data from JEF-1, JEF-2.2, ENDF/B-VI, JENDL-3, etc. More than 60 different materials are included in the FLUKA databases with temperature ranges including do... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180722 Fri, 01 Jun 2001 04:00:00 +0100 1180722 http://www.medworm.com/index.php?rid=1180721&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855416%26dopt%3DAbstract The objectives of the investigations are to provide data on charge and energy spectra of heavy ions, and the contribution of events with low-energy deposit (protons, electrons, gamma, etc.) to the dose, as well as the contribution of secondaries, such as nuclear disintegration stars and neutrons. For neutron dosimetry 6LiF (TLD600) and 7LiF (TLD700) chips were used both of which have almost the same response to gamma rays but different response to neutrons. Neutrons in space are produced mainly in evaporation and knock-on processes with energies mainly of 1-10 MeV and up to several 100 MeV, respectively. The energy spectrum undergoes continuous changes toward greater depth in the attenuating material until an equilibrium is reached. In equilibrium, the spectrum is a wide continuum extendin... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180721 Fri, 01 Jun 2001 04:00:00 +0100 1180721 http://www.medworm.com/index.php?rid=1180720&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855417%26dopt%3DAbstract This study shows that the expected GCR dose equivalent is lower than previously calculated for water shields that are less than 110 g cm-2 thick. Calculations of neutron energy spectra in low Earth orbit indicate substantial contributions from relativistic neutrons. PMID: 11855417 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180720 Fri, 01 Jun 2001 04:00:00 +0100 1180720 http://www.medworm.com/index.php?rid=1180719&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855418%26dopt%3DAbstract Authors: Singleterry RC, Badavi FF, Shinn JL, Cucinotta FA, Badhwar GD, Clowdsley MS, Heinbockel JH, Wilson JW, Atwell W, Beaujean R, Kopp J, Reitz G The interaction of high-energy space radiation with spacecraft materials generates a host of secondary particles, some, such as neutrons, are more biologically damaging and penetrating than the original primary particles. Before committing astronauts to long term exposure in such high radiation environments, a quantitative understanding of the exposure and estimates of the associated risks are required. Energetic neutrons are traditionally difficult to measure due to their neutral charge. Measurement methods have been limited by mass and weight requirements in space to nuclear emulsion, activation foils, a limited number of Bonner spheres... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180719 Fri, 01 Jun 2001 04:00:00 +0100 1180719 http://www.medworm.com/index.php?rid=1180718&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855419%26dopt%3DAbstract Authors: Badhwar GD, Truong AG, O'Neill PM, Choutko V A very high-momentum resolution particle spectrometer called the Alpha Magnetic Spectrometer (AMS) was flown in the payload bay of the Space Shuttle in a 51.65 degrees x 380-km orbit during the last solar minimum. This spectrometer has provided the first high statistics data set for galactic cosmic radiation protons, and helium, as well as limited spectral data on carbon and oxygen nuclei in the International Space Station orbit. First measurements of the albedo protons at this inclination were also made. Because of the high-momentum resolution and high statistics, the data can be separated as a function of magnetic latitude. A related investigation, the balloon borne experiment with a superconducting solenoid spectrometer (BESS), h... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180718 Fri, 01 Jun 2001 04:00:00 +0100 1180718 http://www.medworm.com/index.php?rid=1180717&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855420%26dopt%3DAbstract Authors: Badhwar GD, Watts J, Cleghorn TE In estimating the crew exposures during an extra vehicular activity (EVA), the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more that 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not signific... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180717 Fri, 01 Jun 2001 04:00:00 +0100 1180717 http://www.medworm.com/index.php?rid=1180716&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11855421%26dopt%3DAbstract Authors: Doke T, Hayashi T, Kikuchi J, Sakaguchi T, Terasawa K, Yoshihira E, Nagaoka S, Nakano T, Takahashi S Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared. PMID: 11855421 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180716 Fri, 01 Jun 2001 04:00:00 +0100 1180716 http://www.medworm.com/index.php?rid=1180746&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543368%26dopt%3DAbstract Authors: Cucinotta FA, Wilson JW, Williams JR, Dicello JF We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180746 Thu, 01 Jun 2000 04:00:00 +0100 1180746 http://www.medworm.com/index.php?rid=1180745&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543369%26dopt%3DAbstract Authors: Benton ER, Frank AL, Benton EV The efficiency of 7 LiF TLDs (TLD-700) in registering dose from high-LET (> or = 10 keV/micrometers) charged particles (relative to 137Cs gamma rays) has been measured for a number of accelerated heavy ions at various particle accelerator facilities. These measured efficiency values have been compared with similar results obtained from the open literature and a dose efficiency function has been fitted to the combined data set. While it was found that the dose efficiency is not only a function of LET, but also of the charge of the incident particle, the fitted function can be used to correct the undermeasured value of dose from exposures made in mixed radiation fields where LET information is available. This LET-dependent dose efficiency functi... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180745 Thu, 01 Jun 2000 04:00:00 +0100 1180745 http://www.medworm.com/index.php?rid=1180757&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543137%26dopt%3DAbstract Authors: Shea MA, Smart DF, Dreschhoff GA Large transient concentrations of nitrates in polar ice cores have been identified as the signature of some major solar proton fluence events between 1940 and 1991. We review this solar proton proxy identification technique using nitrate concentration measurements in ice cores from the Arctic and Antarctic. Using this identification technique we go back in time in an attempt to identify major solar proton events during the past several centuries. There is a very large nitrate increase corresponding to the Carrington flare of 1859 evident in the Arctic ice core. Other significant nitrate increases may indicate that major solar proton events occurred toward the end of the last century. The problems associated with this new technique of using nitr... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180757 Tue, 01 Jun 1999 04:00:00 +0100 1180757 http://www.medworm.com/index.php?rid=1180756&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543138%26dopt%3DAbstract Authors: Shurshakov VA, Petrov VM, Ivanov YuV , Bondarenko VA, Tzetlin VV, Makhmutov VS, Dachev TsP , Semkova JV Radiation impact of the SPEs on board the MIR space station and in the interplanetary space is discussed in the report. The data of the on-board radiation dosimeter R-16 were used to measure the SPE absorbed doses. Some of SPEs (such as September-October 1989 series of very large SPEs) were measured in detail by Liulin active high sensitive dosimetric instrument installed on board MIR station. MIR station orbit measurements of the absorbed doses are compared with the interplanetary absorbed doses from SPEs estimated by the data obtained by the METEOR satellite spectrometer. The equivalent dose beyond the magnetosphere resulting from the September 29, 1989 solar flare in a sp... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180756 Tue, 01 Jun 1999 04:00:00 +0100 1180756 http://www.medworm.com/index.php?rid=1180755&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543139%26dopt%3DAbstract Authors: Smart DF, Shea MA There is a need to understand the calibration and response of the GOES solar particle detectors since the GOES data are being used to evaluate high energy solar particle events. We share some of our experience in utilizing these data in the analysis of solar particle ground-level events (GLEs). For the 29 September 1989 event, we have evaluated the solar proton and alpha particle spectral characteristics throughout the event. The results show that the solar cosmic ray spectrum is extremely hard at low energies with the magnitude of the slope increasing with increasing energy and with time. PMID: 11543139 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180755 Tue, 01 Jun 1999 04:00:00 +0100 1180755 http://www.medworm.com/index.php?rid=1180754&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543140%26dopt%3DAbstract Authors: Townsend LW, Zapp EN The true uncertainties in estimates of body organ absorbed dose and dose equivalent, from exposures of interplanetary astronauts to large solar particle events (SPEs), are essentially unknown. Variations in models used to parameterize SPE proton spectra for input into space radiation transport and shielding computer codes can result in uncertainty about the reliability of dose predictions for these events. Also, different radiation transport codes and their input databases can yield significant differences in dose predictions, even for the same input spectra. Different results may also be obtained for the same input spectra and transport codes if different spacecraft and body self-shielding distributions are assumed. Heretofore there have been no systemati... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180754 Tue, 01 Jun 1999 04:00:00 +0100 1180754 http://www.medworm.com/index.php?rid=1180753&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543141%26dopt%3DAbstract Conclusions based on such studies should therefore be re-assessed. The significant event-to-event variability observed in the high-energy solar heavy ions also has important implications for strategies in building probabilistic models of solar particle radiation hazards. PMID: 11543141 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180753 Tue, 01 Jun 1999 04:00:00 +0100 1180753 http://www.medworm.com/index.php?rid=1180752&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543142%26dopt%3DAbstract Authors: Yang TC This paper briefly reviews proton radiobiology. Clinical applications of protons produced by accelerators have led to a significant biological literature that contributes to our goal of estimating the proton shielding requirements for human interplanetary missions. Protons are primarily a low-LET radiation with biological effects much like gamma radiation. There are however data indicating enhanced biological effectiveness for small doses of very low energy (<10 MeV) stopping protons, and some limited data for extremely high energy protons (>0.5 GeV). PMID: 11543142 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180752 Tue, 01 Jun 1999 04:00:00 +0100 1180752 http://www.medworm.com/index.php?rid=1180751&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543143%26dopt%3DAbstract Authors: Zapp EN, Ramsey CR, Townsend LW, Badhwar GD Calculations of total dose and equivalent dose as functions of time, as well as dose-rate and equivalent dose rate since event start are presented for fifteen of the larger solar particle events that occurred during the period between November 1987 and August 1991. The doses, dose-equivalents, and rates presented are for exposures to the skin, ocular lens, and bone marrow behind a thickness of aluminum shielding which provides protection comparable to that of a thin spacecraft. The calculated dose vs time profiles are parameterized using a Weibull cumulative distribution as the fitting function. Parameters are determined using least-squares techniques. Fitted curves are then differentiated to produce smoothed dose-rate curves for eac... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180751 Tue, 01 Jun 1999 04:00:00 +0100 1180751 http://www.medworm.com/index.php?rid=1180750&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543144%26dopt%3DAbstract Authors: Badhwar GD Current models of the inner trapped belt describe the radiation environment at times of solar minimum and solar maximum, respectively. These two models were constructed using data acquired prior to 1970 during a small solar cycle, and no valid model for the past two high solar cycles exists. There is a clear need to accurately predict the radiation exposure of astronauts at all times between the solar minimum and solar maximum, not only on the short duration Space Shuttle flights, but on the longer term stay onboard the Mir orbital station and the planned International Space Station (ISS). An analysis of the trapped absorbed dose rate, D, at six fixed locations in the habitable volume of the Shuttle shows a power law relationship, D=A rho-n, where rho is the atmosph... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180750 Tue, 01 Jun 1999 04:00:00 +0100 1180750 http://www.medworm.com/index.php?rid=1180749&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543145%26dopt%3DAbstract Authors: Badhwar GD, Kushin VV, Akatov YuA , Myltseva VA Trapped protons in the South Atlantic Anomaly (SAA) have a rather narrow pitch angle distribution and exhibit east-west anisotropy. In low Earth orbits, the E-W effect results in different amounts of radiation dose received by different sections of the spacecraft. This effect is best studied on missions in which the spacecraft flies in a fixed orientation. The magnitude of the effect depends on the particle energy and altitude through the SAA. In this paper, we describe a clear example of this effect from measurements of radiation dose rates and linear energy transfer spectra made on Space Shuttle flight STS-94 (28.5 degree inclination x 296 km altitude). The ratio of dose rates from the two directions at this location in the mid... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180749 Tue, 01 Jun 1999 04:00:00 +0100 1180749 http://www.medworm.com/index.php?rid=1180748&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543146%26dopt%3DAbstract Authors: Bashkirov VF, Kuznetsov NV, Nymmik RA In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR particles and SEPs) to the SEU rate is discussed with an allowance for the shielding thickness. PMID: 11543146 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180748 Tue, 01 Jun 1999 04:00:00 +0100 1180748 http://www.medworm.com/index.php?rid=1180747&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D11543147%26dopt%3DAbstract Authors: Gold R More than a decade has elapsed since the serious nature of the discrepancy between neutron dosimetry experiments (E) and neutron transport calculations (C) for the Hiroshima site was identified. Since that time extensive efforts to resolve this Hiroshima neutron dosimetry enigma have not only failed, but now demonstrate that the magnitude of this discrepancy is much greater than initially estimated. The currently evaluated E/C ratio for thermal neutron fluence at the Hiroshima site increases rapidly with increasing slant range from the epicenter. In the slant range region beyond 1000 m, E/C exceeds unity by one to two orders of magnitude depending on the specific dosimetry data that are utilized. Principal features that characterize the Hiroshima neutron dosimetry enigm... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180747 Tue, 01 Jun 1999 04:00:00 +0100 1180747 http://www.medworm.com/index.php?rid=1180715&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025837%26dopt%3DAbstract Authors: Hill MA A wide variety of biological effects are induced by ionizing radiation, from cell death to mutations and carcinogenesis. The biological effectiveness is found to vary not only with the absorbed dose but also with the type of radiation and its energy, i.e., with the nature of radiation tracks. An overview is presented of some of the biological experiments using different qualities of radiation, which when compared with Monte Carlo track structure studies, have highlighted the importance of the localized spatial properties of stochastic energy deposition on the nanometer scale at or near DNA. The track structure leads to clustering of damage which may include DNA breaks, base damage etc., the complexity of the cluster and therefore its biological repairability varying wi... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180715 Tue, 01 Jun 1999 04:00:00 +0100 1180715 http://www.medworm.com/index.php?rid=1180714&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025838%26dopt%3DAbstract Authors: Katz R, Cucinotta FA Studies of the structure of particle tracks have led to models of track effects based on radial dose and radiobiological target theory that have been very successful in describing and predicting track effects in physical, chemical, and biological systems. For describing mammalian cellular inactivation two inactivation modes are required, called gamma-kill and ion-kill, the first due to synergistic effects of delta rays from adjacent ion paths thus resembling the effects from gamma rays, and the second to the effects of single ion transits through a cell nucleus. The ion-kill effect is more severe, where the fraction of cells experiencing ion kill is responsible for a decrease in the oxygen enhancement ratio, and an increase in relative biological effective... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180714 Tue, 01 Jun 1999 04:00:00 +0100 1180714 http://www.medworm.com/index.php?rid=1180713&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025839%26dopt%3DAbstract Authors: Tommasino L Limited sensitivity and unpredictable background are the major drawbacks of damage track detectors in the assessment of low neutron doses and low concentrations of alpha emitters in biological and environmental samples. The simplest way to increase the sensitivity of the damage track detectors is to increase both the exposure time and the detector area. However, the strong variability of the background may make this task often impossible. This background problem has been finally solved by a new registration method based on counting coincidence spots in geometrically matched pair of detectors. By using spark counting and electrochemical etching, both of which produce spots visible at low magnification, coincidences induced in two matched detector-surfaces by a few-m... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180713 Tue, 01 Jun 1999 04:00:00 +0100 1180713 http://www.medworm.com/index.php?rid=1180712&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025840%26dopt%3DAbstract Authors: Luszik-Bhadra M, Matzke M, Otto T, Reitz G, Schuhmacher H A passive neutron dosemeter based on nuclear track detectors and TLD's was used in 1995 and 1997 on the MIR station and in Space Shuttle flights to MIR. As it is equipped with neutron converters and shieldings of different types the track detector system allows the neutron dose equivalent to be determined in rough energy intervals. The results of the measurements on the MIR station and in the Space Shuttle flights are presented and the influence of charged particles in the complex mixed radiation field in space is discussed. Improvements are possible by means of a new active neutron dosemeter which is under development at the PTB. First measurements with a prototype in the high-energy reference fields at CERN are presen... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180712 Tue, 01 Jun 1999 04:00:00 +0100 1180712 http://www.medworm.com/index.php?rid=1180711&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025841%26dopt%3DAbstract Authors: Kopp J, Beaujean R, Reitz G, Enge W Plastic nuclear track detectors were used to measure the contribution of High charge Z and energy E (HZE) particles to the radiation exposure of manned space missions. Results from numerous space missions in the orbit planned for the International Space Station are compared. The measurements cover the declining phase of the last solar cycle during the past 7 years and various shielding conditions inside the US Space Shuttle and the Russian MIR-station. PMID: 12025841 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180711 Tue, 01 Jun 1999 04:00:00 +0100 1180711 http://www.medworm.com/index.php?rid=1180710&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025842%26dopt%3DAbstract We report here on measurements and analysis of short range tracks which were produced by high LET particles generated mainly by neutron interactions at aviation altitudes. In order to test the overall validity of the technique measurements were also carried out at the CERN-CEC field which simulates the radiation field at aviation altitudes and good agreement was found with dose values obtained using mainly heavy ion calibration. PMID: 12025842 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180710 Tue, 01 Jun 1999 04:00:00 +0100 1180710 http://www.medworm.com/index.php?rid=1180709&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025843%26dopt%3DAbstract Authors: Gunther W, Leugner D, Becker E, Flesch F, Heinrich W, Huntrup G, Reitz G, Rocher H, Streibel T We have exposed stacks of CR-39 plastic nuclear track detectors inside the MIR space craft during the EUROMIR95 space mission for almost 6 months. Over this long period a large number of tracks of high LET events was accumulated in the detector foils. The etching and measuring conditions for this experiment were optimized to detect tracks of stopping iron nuclei. We found 185 stopping iron nuclei inside the stack and identified their trajectories through the material of the experiment. Based on the energy-range relation the energy at the surface of the stack was determined. These particles allow the determination of the low energy part of the spectrum of iron nuclei behind shielding ... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180709 Tue, 01 Jun 1999 04:00:00 +0100 1180709 http://www.medworm.com/index.php?rid=1180708&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025844%26dopt%3DAbstract Authors: Fujii M, Hatano Y, Osawa A, Saito T, Yamamoto K, Hasebe T, Nakamura T, Sasaki H, Yanagita T, Aglietta M, Vernetto S, Castellina A, Fulgione W, Saavedra O, Trinchero GC We should be careful about the effect of oxygen deficiency on polymeric track detectors even at balloon altitude. Results of balloon experiments and calibration experiments in a vacuum chamber at different pressures show that the effect of oxygen deficiency becomes serious at a pressure below 10 hPa. PMID: 12025844 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180708 Tue, 01 Jun 1999 04:00:00 +0100 1180708 http://www.medworm.com/index.php?rid=1180707&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025845%26dopt%3DAbstract Authors: Leicher M, Beaujean R, Enge W In a series of COSMOS satellite flights plastic nuclear track detectors have been exposed in low-earth orbits to monitor anomalous cosmic rays (ACR) at energies below 25 MeV/nuc. The analysis of energy spectra has now been extended to energies up to 40 MeV/nuc for two exposures aboard COSMOS 2260 in 1993 and COSMOS 2311 in 1995. Our data on trapped ACR (TACR) oxygen energy spectra might indicate the influence of energy-dependent stripping probabilities and the presence of multiply charged ACR oxygen at high energies as reported by latest SAMPEX observations. PMID: 12025845 [PubMed - indexed for MEDLINE] (Source: Radiation Measurements) Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180707 Tue, 01 Jun 1999 04:00:00 +0100 1180707 http://www.medworm.com/index.php?rid=1180706&cid=s_36752_75_f&fid=36752&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D12025846%26dopt%3DAbstract Authors: Perelygin VP, Petrova RI, Stetsenko SG, Brandt R, Vater P, Rebetez M, Spohr R, Vetter J, Perron C A new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on fossil track study of extraterrestrial olivine crystals has been developed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (Z=50-92) in meteoritic olivine crystals are presented. The technique was based on calibration of olivine crystals with accelerated Xe, Au, Pb and U ions and well-controlled partial annealing of "fresh" and "fossil" tracks. It allows us to determine the charge spectra and abundances of cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra... Radiation Measurements journals http://www.medworm.com/rss/comments.php?id=1180706 Tue, 01 Jun 1999 04:00:00 +0100 1180706