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ABSTRACT: There are only a few methods of dosimetry which can estimate the contribution of different particles to onboard spacecraft
and/or aircraft exposure. This contribution describes an attempt to estimate the contribution of different components to the
exposure level using MDU-Liulin energy deposition spectrometer and thermoluminescent detectors (TLD’s), in combination with
a spectrometer of linear energy transfer (LET) based on track etch detectors. This equipment was exposed onboard: the International
Space Station for a long period and two shorter shuttle missions and a commercial subsonic aircraft for several long-term
monitoring periods from 2001 to 2006. The data obtained are analyzed from several points of view and the obtained results
are presented, analyzed, and discussed.
Physics of Particles and Nuclei Letters 04/2012; 6(1):70-77.
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ABSTRACT: Active mobile dosimetry unit (Liulin), passive plastic nuclear track detectors (PNTD) and thermoluminescent detectors (TLD) were exposed in a C290 MeV/n beam at HIMAC-BIO (NIRS, Japan). Two different types of beam configuration were used--monoenergetic beam (MONO) and spread-out Bragg peak (SOBP); the detectors were placed at several depths from the entrance up to the depths behind the Bragg peak. Relative response of TLDs in beams has been studied as a function of the depth, and it was re-proved that it can depend on the linear energy transfer (LET). Liulin measures energy deposition in Si; the spectra of energy deposited in Si can be transformed to the spectra of lineal energy or LET. PNTDs are able to determine the LET of registered particles directly. The limitation of both methods is in the range in which they can determine the LET-Liulin is able to measure perpendicularly incident charged particles up to ∼35 keV/µm (in water), PNTD can measure from ∼7 to 400 keV/µm, independently of the registration angle. The results from both methods are compared and combined for both beams' configuration, and a good agreement is observed.
Radiation Protection Dosimetry 01/2011; 143(2-4):519-22. · 0.82 Impact Factor
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ABSTRACT: The main purpose of Liulin-type spectrometry-dosimetry instruments (LSDIs) is cosmic radiation monitoring at the workplaces. An LSDI functionally is a low mass, low power consumption or battery-operated dosemeter. LSDIs were calibrated in a wide range of radiation fields, including radiation sources, proton and heavy-ion accelerators and CERN-EC high-energy reference field. Since 2000, LSDIs have been used in the scientific programmes of four manned space flights on the American Laboratory and ESA Columbus modules and on the Russian segment of the International Space Station, one Moon spacecraft and three spacecraft around the Earth, one rocket, two balloons and many aircraft flights. In addition to relative low price, LSDIs have proved their ability to qualify the radiation field on the ground and on the above-mentioned carriers.
Radiation Protection Dosimetry 12/2010; 144(1-4):675-9. · 0.82 Impact Factor
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ABSTRACT: Liulin-type spectrometers can characterise the type of predominant particles and their energy in the radiation environment. The results from calibrations and space and aircraft experiments revealed that the most informative is by the shape of the deposited energy spectrum. Spectra generated by galactic cosmic rays (GCR) protons and their secondaries look like straight lines in the coordinates deposited energy/deposited per channel dose rate. The position of the maximum of the deposited energy spectra depends on the incident energy of the incoming protons. Spectra generated by relativistic electrons in the outer radiation belt have a maximum in the first channels. For higher energy depositions, these spectra are similar to the GCR spectra. All types of spectra have a knee close to 6.3 MeV of deposited energy, which corresponds to the stopping energy of protons in the detector.
Radiation Protection Dosimetry 12/2010; 144(1-4):680-3. · 0.82 Impact Factor
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ABSTRACT: Silicon energy deposition spectrometer Liulin was primarily developed for cosmic radiation monitoring onboard spacecrafts. Nowadays, Liulin type detectors are also used to characterise radiation field on board aircraft, at alpine observatories and behind the shielding of heavy ion accelerators. In this work, experiments and calibrations performed in these radiation fields are presented and the method developed for calculation of ambient dose equivalent H*(10) on board aircraft is described. Since 2001, a simple method employing the energy deposition spectra had been used to determine H*(10) on board aircraft but, in 2004, it became clear that the resulting values were strongly biased at locations close to Earth's equator. An improved method for the determination of H*(10) on board aircraft using the Liulin detector was developed. It took into account the composition of the radiation field via the ratio of absorbed doses D(low) and D(neut) reflecting the contributions from low-LET particles and neutrons, respectively. It resulted in much better agreement with the EPCARD computer code for all aircraft locations; relative differences were within 11 % for low-LET and 20 % for neutron components of H*(10).
Radiation Protection Dosimetry 12/2010; 144(1-4):611-4. · 0.82 Impact Factor
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ABSTRACT: Individual monitoring of aircrew of airline operators registered in the Czech Republic has been performed since 1998. In this work, annual effective doses and annual collective effective doses of aircrew from occupational exposure in the period from 1998 to 2008 are presented, methods used for their evaluation and verification are described, and general trends observed in the data are discussed. Annual effective doses were calculated using the computer code CARI from flight schedules provided by airline operators and typical flight profiles. The method was verified via a comparison with (i) measurements using different types of detectors and (ii) calculations using the CARI and EPCARD codes with actual flight data. It was found that average annual effective doses in the period from 1998 to 2008 were in the range from 1.2 to 2.0 mSv and followed the trend of the solar cycle. Annual collective effective doses increased from 1.4 manSv in 1998 to 4.1 manSv in 2008 as the number of aircrew increased from 857 to 2158 during this period. Combined relative uncertainties (coverage factor ) of reported individual and collective effective doses were ∼ 25 %, which is well within the range given by the factor of 1.5. More work is needed to achieve a higher accuracy of this estimate.
Radiation Protection Dosimetry 11/2010; 144(1-4):684-7. · 0.82 Impact Factor
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ABSTRACT: The neutron contribution to the spacecraft crew exposure could represent an important part of the total dose equivalent value. The determination of this contribution represents a rather complex and difficult task, both through experimental and theoretical estimation. This paper will present an attempt to determine the neutron contribution onboard the International Space Station and Foton capsule using the data measured by means of a Si-diode based energy deposition spectrometer. As such a spectrometer, the MDU-Liulin equipment, developed in one of our laboratories was used. The equipment allows the data accumulated during the passage in or out of the South Atlantic Anomaly (SAA). In this paper, only the data obtained out of the SAA were analysed, assuming that the neutron spectra are similar to those onboard aircraft and/or at the CERF high-energy radiation field. The excess of deposited energy in the region above 1 MeV, when comparing with the aircraft field, was expected to represent the primary high-energy charged particles. Total dosimetry characteristics obtained in this way are in reasonable agreement with other data, neutron contribution representing approximately 40% of the total dose equivalent for the flight duration outside of the SAA.
Radiation Protection Dosimetry 02/2007; 126(1-4):519-23. · 0.82 Impact Factor
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ABSTRACT: This contribution presents new results related to the aircraft crew exposure onboard aircraft of Czech air companies. First, the results of long term monitoring onboard of an aircraft of Czech Airlines are presented. In the period May–December 2005, 494 individual flights have been followed using MDU-Liulin Si-diode based spectrometer, together with thermoluminescent and track detectors. The results of measurements are analyzed and compared with those of calculation performed with CARI6 and EPCARD3.2 codes. Monitoring period represented about 4.6 times more than usual annual engagement of an aircrew (600 hours). Total effective dose during these 2 755 hours was between 11 and 12 mSv, following the considered method of evaluation. Both the measuring and calculation methods correlate well. This fact leads to confirmation of the routine method evaluating the level of aircraft crew exposure using CARI6 code as correct for this purpose. Second, the results of individual monitoring of aircrew members obtained during few last years by this routine method are presented; general tendencies of aircraft crew onboard exposure of Czech air companies are outlined. The contribution of aircrew exposure to total occupational exposure in the Czech Republic represents about 20%. Monitorage à long terme de l’exposition du personnel navigant à bord d’un avion de la compagnie aérienne Czech Airlines. Cette contribution présente de nouveaux résultats concernant l’exposition aux rayonnements cosmiques du personnel navigant de la compagnie Czech Airlines. Les résultats d’un monitorage à long terme sont présentés dans un premier temps. Entre les mois de mai et décembre 2005, des mesures ont été réalisées au cours de 494 vols individuels. En complément des dosimètres thermoluminescent et à traces habituellement utilisés, un spectromètre silicium de type MDU-Liulin a également été utilisé. Les résultats des mesures sont comparés avec ceux de calculs réalisés avec les codes CARI6 et EPCARD3.2. La période de monitorage représente environ 4,6 fois plus que la durée annelle habituelle de l’engagement d’un membre du personnel navigant (600 heures) : la dose efficace totale sur ces 2 755 heures varie entre 11 et 12 mSv, suivant la méthode considérée. Dans un deuxième temps, les résultats du suivi dosimétrique individuel du personnel navigant obtenus au cours des dernières années sont résumés et l’évolution des tendances pour l’exposition du personnel des différentes compagnies est soulignée. La contribution de l’exposition du personnel navigant au rayonnement cosmique à la dose collective des travailleurs exposés en république tchèque se situe autour de 20 %.
http://dx.doi.org/10.1051/radiopro:2006024.
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ABSTRACT: Onboard aircraft exposure to cosmic radiation has been monitored during the period May–December 2005. Mobile Dosimetry Unit (MDU) Si-spectrodosimeter has been used as an active measuring equipment, it has been installed onboard of an A310–300 aircraft. Some passive detectors were placed on the body of MDU. Three types of thermoluminescent detectors (TLD) were used as well as track etch detectors (TEDs). TEDs were treated both as a neutron dosimeter and as a spectrometer of linear energy transfer. Available navigation data permitted us also to calculate onboard exposure during more than 400 individual flights. MDU established and calculated data for each individual flight are compared and analyzed, from the data conclusions as to aircrew exposure are outlined. Particular attention is devoted to the influence of:•geomagnetic characteristics and flight altitude on the calculated and MDU-Liulin measured dosimetry characteristic of onboard radiation field;•some solar events (Forbush decreases) registered by MDU-Liulin on the level of aircraft crew exposure during monitoring period.Integral data on the exposure due to non-neutron and neutron-like component obtained on the base of MDU and calculated data are compared with the data obtained by TLDs and TEDs, respectively. Total effective dose during the period mentioned (494 flights and 2940 h between taking offs and landings) was found to be about 11–12 mSv for. Results obtained by means of different approaches are analyzed and discussed, it was found that in general good agreement of all data sets could be stated.
Advances in Space Research.
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ABSTRACT: The contribution presents new results related to the aircraft crew exposure onboard aircraft of Czech air companies. First the results of long term monitoring onboard of an aircraft of Czech Airlines are presented. The monitoring has been performed in the period May - December 2005, more than 500 individual flights have been followed. MDU-Liulin Si-diode based spectrometer was used, together with thermoluminescent and track detectors. Total effective dose was about 12 mSv, the results obtained with dosimeters mentioned are analyzed and compared with the results of calculation performed with CARI and EPCARD codes. Individual monitoring of aircrew members has been started in the Czech Republic since 1998 year. The results obtained during few last years are presented, general tendencies of aircraft crew onboard exposure of Czech air companies are outlined.
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ABSTRACT: Aircraft crew exposure represents an important challenge of actual occupational exposure. The accumulation of new data on its level is therefore an important task of radiation dosimetry. There are few types of equipment able to characterize it. One of them is an Si-diode-based spectrodosemeter “Liulin”. It is an active device which measures total energy depositions in the semiconductor unit and after appropriate calibration, is also able to provide a separate estimation for both radiation components (non-neutron and neutron-like) of the radiation field on board. The device was fixed on board couple times in 2001, 2002, 2005 and 2006 for long-term measurements (60 days of operational time). This contribution brings the analysis of the database generated from accumulated data measured with this device and calculated by means of codes CARI-6 and EPCARD v3.2. Reasonably good agreement of all data sets could be stated in ordinary solar conditions. More measurements on aircraft flights in areas with higher vertical cut-off rigidities should be accomplished to accumulate more data to reach better statistics of integral and spectral values.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
