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Sample records for pribrezhnykh ehkosistemakh posle

  1. Fading test using the SAAD-POSL method for retrospective accidental dosimetry of building materials

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Lee, Y. J.; Lee, J. I.; Kim, J. L.; Hong, D. G.

    2015-11-01

    Fading test using the single aliquot additive dose method with pulsed optically stimulated luminescence (SAAD-POSL method) was applied to core-disc samples extracted from heated red brick, tile, roof-tile, and toilet porcelain after X-ray and beta irradiation. From thermoluminescence measurements of each material, the optimal preheat condition of the SAAD-POSL method was first determined as 170 °C for 10 s. Fading characteristics of core-disc samples of heated red brick obtained using the SAAD-POSL method were similar to those of quartz grains (90-250 μm) obtained using the SAR-OSL method, regardless of the differences in the sample and radiation type. Fading evaluations of the core-disc samples of these building materials two weeks after irradiation showed that the equivalent dose (ED) decreased between 5% and 42%. The results indicate that the fading characteristics will be able to contribute to a more accurate estimation of the ED value using the SAAD-POSL method.

  2. Application of pulsed optically stimulated luminescence from surface soil to retrospective dosimetry

    NASA Astrophysics Data System (ADS)

    Fujita, Hiroki

    2014-11-01

    A novel pulsed optically stimulated luminescence (P-OSL) instrument was developed. The performance of the instrument was tested using natural quartz extracted from Japanese surface soil and feldspar in mineral specimens. The different P-OSL signals for quartz and feldspar were detected from their decay shape. It was found that the signal from feldspar decayed for 2-3 μs and the signal from quartz was measured at over 50 μs after the LED stimulation was switched off. By using a mixture of quartz and feldspar, the P-OSL protocol was improved to determine the irradiation dose. After irradiating a soil sample, a dose recovery test was conducted and the P-OSL protocol was found to be successful in reconstructing the irradiated dose with an on-time pulse of 4 and 10 μs for quartz and feldspar, respectively. Finally, a soil sample illuminated by a solar simulator was irradiated by a gamma source and then was used in the dose recovery test. The estimated dose agreed with the expected dose. From these results, it can be concluded that P-OSL dosimetry is suitable for the evaluation of the effects of a radiation accident, although further research using actual Japanese surface soil is required to improve the protocol.

  3. Site characterization using a portable optically stimulated luminescence reader: delineating disrupted stratigraphy in Holocene eolian deposits on the Canadian Great Plains

    NASA Astrophysics Data System (ADS)

    Munyikwa, K.; Gilliland, K.; Gibson, T.; Plumb, E.

    2012-12-01

    The use of portable optically stimulated luminescence (POSL) readers to elucidate on complex depositional sequences has been demonstrated in a number of recent studies. POSL readers are robust versions of the traditional lab-bound luminescence readers and they can be used in the field, allowing for rapid decisions to be made when collecting samples for dating. Furthermore, in contrast with lab-bound readers, POSL readers can perform measurements on bulk samples, negating the need to carry out time-intensive mineralogical separations. The POSL reader is equipped with both infra-red and blue light (OSL) stimulating sources such that signal separation during measurement can be carried out by selectively exciting feldspar using the IR source (IRSL) after which a quartz dominant signal is obtained from the same sample using post-IR blue OSL. The signals obtained are then plotted to give luminescence profiles that depict the variation of the luminescence signal with depth. Signal intensities depend on mineralogical concentrations, grain luminescence sensitivities, dose rates as well as on burial ages of the grains. Where all these variables, apart from the burial age, are held constant up the depositional sequence the luminescence profile serves as a proxy for the chronostratigraphy. As a contribution to a growing archive of studies that have employed POSL readers to unravel complex depositional sequences, this study uses a POSL system developed by the Scottish Universities Environmental Research Centre to characterize the stratigraphy at an archaeological site that lies next to an oilfield plant located on a Holocene fossil dune landscape in southern Alberta, Canada. Oilfield activity was initiated at the site several decades ago and it involved the laying of pipelines below ground which disturbed considerable archaeological deposits. Subsequent work led to the discovery of the archeological site which was previously occupied by ancestral indigenous peoples at various

  4. A short-time fading study of Al2O3:C

    NASA Astrophysics Data System (ADS)

    Nascimento, L. F.; Vanhavere, F.; Silva, E. H.; Deene, Y. De

    2015-01-01

    This paper studies the short-time fading from Al2O3:C by measuring optically stimulated luminescence (OSL) signals (Total OSL: TOSL, and Peak OSL: POSL) from droplets and Luxel™ pellets. The influence of various bleaching regimes (blue, green and white) and light power is compared. The fading effect is the decay of the OSL signal in the dark at room temperature. Al2O3:C detectors were submitted to various bleaching regimes, irradiated with a reference dose and read out after different time spans. Investigations were carried out using 2 mm size droplet detectors, made of thin Al2O3:C powder mixed with a photocured polymer. Tests were compared to Luxel™-type detectors (Landauer Inc.). Short-time post-irradiation fading is present in OSL results (TOSL and POSL) droplets for time spans up to 200 s. The effect of short-time fading can be lowered/removed when treating the detectors with high-power and/or long time bleaching regimes; this result was observed in both TOSL and POSL from droplets and Luxel™.

  5. WE-D-17A-06: Optically Stimulated Luminescence Detectors as ‘LET-Meters’ in Proton Beams

    SciTech Connect

    Granville, D; Sahoo, N; Sawakuchi, GO

    2014-06-15

    Purpose: To demonstrate and evaluate the potential of optically stimulated luminescence (OSL) detectors (OSLDs) for measurements of linear energy transfer (LET) in therapeutic proton beams. Methods: Batches of Al2O2:C OSLDs were irradiated with an absorbed dose of 0.2 Gy in un-modulated proton beams of varying LET (0.67 keV/μm to 2.58 keV/μm). The OSLDs were read using continuous wave (CW-OSL) and pulsed (P-OSL) stimulation modes. We parameterized and calibrated three characteristics of the OSL signals as functions of LET: CW-OSL curve shape, P-OSL curve shape and the ratio of the two OSL emission band intensities (ultraviolet/blue ratio). Calibration curves were created for each of these characteristics to describe their behaviors as functions of LET. The true LET values were determined using a validated Monte Carlo model of the proton therapy nozzle used to irradiate the OSLDs. We then irradiated batches of OSLDs with an absorbed dose of 0.2 Gy at various depths in two modulated proton beams (140 MeV, 4 cm wide spread-out Bragg peak (SOBP) and 250 MeV, 10 cm wide SOBP). The LET values were calculated using the OSL response and the calibration curves. Finally, measured LET values were compared to the true values determined using Monte Carlo simulations. Results: The CW-OSL curve shape, P-OSL curve shape and the ultraviolet/blue-ratio provided proton LET estimates within 12.4%, 5.7% and 30.9% of the true values, respectively. Conclusion: We have demonstrated that LET can be measured within 5.7% using Al2O3:C OSLDs in the therapeutic proton beams used in this investigation. From a single OSLD readout, it is possible to measure both the absorbed dose and LET. This has potential future applications in proton therapy quality assurance, particularly for treatment plans based on optimization of LET distributions. This research was partially supported by the Natural Sciences and Engineering Research Council of Canada.

  6. SU-E-T-592: OSL Response of Al2O3:C Detectors Exposed to Therapeutic Proton Beams

    SciTech Connect

    Granville, DA; Flint, DB; Sawakuchi, GO

    2015-06-15

    Purpose: To characterize the response of Al{sub 2}O{sub 3}:C optically stimulated luminescence (OSL) detectors (OSLDs) exposed to therapeutic proton beams of differing beam quality. Methods: We prepared Al{sub 2}O{sub 3}:C OSLDs from the same material as commercially available nanoDot dosimeters (Landauer, Inc). We irradiated the OSLDs in modulated proton beams of varying quality, as defined by the residual range. An absorbed dose to water of 0.2 Gy was delivered to all OSLDs with the residual range values varying from 0.5 to 23.5 cm (average LET in water from ∼0.5 to 2.5 keV/µm). To investigate the beam quality dependence of different emission bands within the OSL spectrum, we performed OSLD readouts using both continuous-wave stimulation (CW-OSL) and pulsed stimulation (P-OSL) with two sets of optical filters (Hoya U-340 and Kopp 5113). For all readout modes, the relative absorbed dose sensitivity (S{sub rel}) for each beam quality was calculated using OSLDs irradiated in a 6 MV photon beam as a reference. Results: We found that the relative absorbed dose sensitivity was highly dependent on both readout mode and integration time of the OSL signal. For CW-OSL signals containing only the blue emission band, S{sub rel} was between 0.85 and 0.94 for 1 s readouts and between 0.82 and 0.93 for 10 s readouts. Similarly, for P-OSL readouts containing only the blue emission band S{sub rel} ranged from 0.86 to 0.91, and 0.82 to 0.93 for 1 s and 10 s readouts, respectively. For OSLD signals containing only the UV emission band, S{sub rel} ranged from 1.00 to 1.46, and 0.97 to 1.30 for P-OSL readouts of 1 s and 10 s, respectively. Conclusion: For measurements of absorbed dose using Al{sub 2}O{sub 3}:C OSLDs in therapeutic proton beams, dependence on beam quality was smallest for readout protocols that selected the blue emission band with small integration times. DA Granville received financial support from the Natural Sciences and Engineering

  7. RIF RuleML Rosetta Ring: Round-Tripping the Dlex Subset of Datalog RuleML and RIF-Core

    NASA Astrophysics Data System (ADS)

    Boley, Harold

    The RIF RuleML overlap area is of broad interest for Web rule interchange. Its kernel, Dlex, is defined syntactically and semantically as the common sublanguage of Datalog RuleML and RIF-Core restricted to positional arguments and non-conjunctive rule conclusions, and allowing equality plus externals in rule premises (only). Semantics-preserving mappings are then defined between the Dlex subset of the RIF Presentation Syntax and RIF/XML, RIF/XML and RuleML/XML, as well as RuleML/XML and the Prolog-like RuleML/POSL. These mappings are the basis for RIF RuleML feature comparison and translation. The slightly augmented mappings can be composed into a ('Rosetta') ring for round-tripping between all pairs of Dlex representations.

  8. The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles.

    PubMed

    Gaza, R; Yukihara, E G; McKeever, S W S

    2004-01-01

    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 continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. PMID:15856574

  9. The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles

    NASA Technical Reports Server (NTRS)

    Gaza, R.; Yukihara, E. G.; McKeever, S. W. S.

    2004-01-01

    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 continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. c2004 Elsevier Ltd. All rights reserved.

  10. Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams.

    PubMed

    Granville, Dal A; Sahoo, Narayan; Sawakuchi, Gabriel O

    2014-08-01

    Optically stimulated luminescence (OSL) detectors (OSLDs) have shown potential for measurements of linear energy transfer (LET) in proton therapy beams. However, the technique lacks the efficiency needed for clinical implementation, and a faster, simpler approach to LET measurements is desirable. The goal of this work was to demonstrate and evaluate the potential of calibrating Al2O3:C OSLDs for LET measurements using new methods. We exposed batches of OSLDs to unmodulated proton beams of varying LET and calibrated three parameters of the resulting OSL signals as functions of fluence-averaged LET (ϕ-LET) and dose-averaged LET (D-LET). These three parameters included the OSL curve shape evaluated under continuous wave stimulation (CW-OSL), the OSL curve shape evaluated under pulsed stimulation (P-OSL), and the intensity ratio of the two main emission bands in the Al2O3:C OSL emission spectrum (ultraviolet [UV]/blue ratio). To test the calibration, we then irradiated new batches of OSLDs in modulated proton beams of varying LET, and used the OSL signal parameters to calculate ϕ-LET and D-LET under these new test conditions. Using the P-OSL curve shape, D-LET was measured within 5.7% of the expected value. We conclude that from a single 10 s readout (following initial calibration), both the absorbed dose and LET in proton therapy beams can be measured using OSLDs. This has potential future applications in the quality assurance of proton therapy treatment plans, particularly for those that may account for LET or relative biological effectiveness in their optimization. The methods demonstrated in this work may also be applicable to other particle therapy beams, including carbon ion beams. PMID:25029434

  11. Transitioning to Intel-based Linux Servers in the Payload Operations Integration Center

    NASA Technical Reports Server (NTRS)

    Guillebeau, P. L.

    2004-01-01

    The MSFC Payload Operations Integration Center (POIC) is the focal point for International Space Station (ISS) payload operations. The POIC contains the facilities, hardware, software and communication interface necessary to support payload operations. ISS ground system support for processing and display of real-time spacecraft and telemetry and command data has been operational for several years. The hardware components were reaching end of life and vendor costs were increasing while ISS budgets were becoming severely constrained. Therefore it has been necessary to migrate the Unix portions of our ground systems to commodity priced Intel-based Linux servers. hardware architecture including networks, data storage, and highly available resources. This paper will concentrate on the Linux migration implementation for the software portion of our ground system. The migration began with 3.5 million lines of code running on Unix platforms with separate servers for telemetry, command, Payload information management systems, web, system control, remote server interface and databases. The Intel-based system is scheduled to be available for initial operational use by August 2004 The overall migration to Intel-based Linux servers in the control center involves changes to the This paper will address the Linux migration study approach including the proof of concept, criticality of customer buy-in and importance of beginning with POSlX compliant code. It will focus on the development approach explaining the software lifecycle. Other aspects of development will be covered including phased implementation, interim milestones and metrics measurements and reporting mechanisms. This paper will also address the testing approach covering all levels of testing including development, development integration, IV&V, user beta testing and acceptance testing. Test results including performance numbers compared with Unix servers will be included. need for a smooth transition while maintaining