INVESTIGATION OF XENON-FILLED TUBE BREAKDOWN VOLTAGE AND DELAY RESPONSE AS POSSIBLE DOSIMETRIC PARAMETERS FOR SMALL GAMMA RAY AIR KERMA RATES

2020 ◽  
Vol 190 (1) ◽  
pp. 84-89
Author(s):  
Milić Pejović ◽  
Emilija Živanović ◽  
Miloš Živanović
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Breakdown Voltage ◽  
Radiation Dosimetry ◽  
Gamma Ray ◽  
Physical Processes ◽  
Rate Range ◽  
Air Kerma ◽  
Delay Response ◽  
Air Kerma Rate

Abstract This paper presents experimental results of dynamic breakdown voltage and delay response as functions of gamma ray air kerma rate for xenon-filled tube at 2.7 mbar pressure. Gamma ray air kerma rate range was considered from 123 nGy h–1 up to 12.3 mGy h–1 in order to investigate the possibility of the application of this tube in gamma radiation dosimetry. It was shown that the variations of the above-mentioned parameters are considerable up to the dose rate of 1.23 μGy h–1, which points to the possibility for application in small dose rate gamma ray dosimetry. Physical processes that make dominant impact to dynamic breakdown voltage and delay response during xenon-filled tube irradiation are also discussed in the paper.

scholarly journals Vertical distribution of 137Cs in soddy-podzolic sandy soil in grasslands and forests of the Bryansk region in 2015–2016

2019 ◽  
Vol 12 (3) ◽  
pp. 27-41 ◽  
Author(s):  
V. P. Ramzaev ◽  
A. N. Barkovsky ◽  
K V. Varfolomeeva
Keyword(s):  
Vertical Distribution ◽  
Gamma Radiation ◽  
Dose Rate ◽  
Activity Concentration ◽  
Sandy Loam ◽  
Soil Layer ◽  
Maximum Activity ◽  
Air Kerma ◽  
Uppermost Layer ◽  
Air Kerma Rate

Vertical distribution of natural and man-made radionuclides in the soil profile is a decisive parameter when calculating the dose rate of gamma radiation in the air above the ground and the effective dose of external human exposure. The main purpose of this work was to determine vertical distribution of 137Cs in soddy-podzolic sandy and sandy-loam soils in forests and grasslands in the south-western districts of the Bryansk region in the remote period after the Chernobyl accident. In 2015–2016, soil cores were sampled in 7 virgin meadows and 13 forested areas to a depth of 20 cm. The cores were cut into horizontal layers 2 cm thick. The 137Cs activity in the samples was determined using a semiconductor gamma spectrometer. The activity concentration in samples of dry soil (n = 200) ranged from 6.35 Bq/kg to 83300 Bq/kg with an average of 4550 Bq/kg. In the meadows in three cases, the maximum activity concentration was determined in the uppermost layer. With increasing depth, the activity concentration decreased and reached a minimum in the deepest layers. A difference between the surface layer and the deepest layer was two to three orders of magnitude. The three other meadows showed a relatively uniform distribution of 137Cs in the upper 4–6 cm, followed by a decrease in activity concentration with an increase in depth. In one meadow area, a peak of the 137Cs activity was found at a depth of 4–6 cm. In the forest, the most typical (in 10 cases) was the presence of a pronounced maximum activity concentration of 137Cs in the uppermost layer. The experimentally obtained values of the 137Cs inventory in the upper 20 cm of soil at the surveyed sites ranged from 42 to 1940 kBq/m2. The values of 137Cs inventory positively and statistically significantly correlated with officially established levels of 137Cs surface ground contamination for the territory of nearby settlements. Vertical migration of 137Cs in the soil in the surveyed areas was mainly limited to the upper 10 centimeters. The layer on average contained 94% of the total 137Cs inventory. Less than 1% of the total 137Cs inventory was found in the deepest soil layer sampled (18–20 cm). The obtained 137Сs activity distributions were used to calculate kerma rate in the air at a height of 1 m above the ground at the surveyed sites. The air kerma rate ranged from 52 to 2240 nGy/h (on average, 807 nGy/h). The caesium-137 deposit in the upper 6 cm of soil determined about 95% and 90% of the air kerma rate in the forests and in meadows, respectively. Radioactive caesium, which migrated into the soil to a depth of more than 10–12 cm, gave a negligible contribution (less than 1%) to the gamma-radiation dose rate in the air. In practical terms, it indicates that the depth of soil sampling equal to 20 cm is currently quite sufficient to estimate the dose rate of gamma radiation in the air in virgin grasslands and in forests.

National primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2019

2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk
Keyword(s):  
Gamma Radiation ◽  
Energy Flux ◽  
Primary Standard ◽  
Average Energy ◽  
Ion Pair ◽  
X Rays ◽  
Exposure Rate ◽  
Ionization Chambers ◽  
Air Kerma ◽  
Air Kerma Rate

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.

scholarly journals Study the Calibration of the High Dose Rate Brachytherapy Radioactive Source 60Co

2020 ◽  
pp. 19-32
Author(s):  
Tania Afroz ◽  
Pretam K. Das ◽  
S. I. Chawdhury ◽  
Shudeb K. Roy
Keyword(s):  
Quality Assurance ◽  
Dose Rate ◽  
High Dose Rate ◽  
Radioactive Source ◽  
Quality Assurance Program ◽  
High Dose ◽  
Hdr Brachytherapy ◽  
Air Kerma ◽  
Air Kerma Rate ◽  
Brachytherapy Source

Aim of this work is to calibrate the high dose rate (HDR) brachytherapy source 60Co. The radioactive source calibration is a very important part of the quality assurance program for dosimetry of brachytherapy source. The goal of this project is the calibration of HDR Brachytherapy source in radiation therapy is the measurement of the air kerma rate which required actual dose to deliver. The source calibration is an essential part of the quality assurance program for dosimetry of brachytherapy source. This research will help the patient who is involving brachytherapy treatment. HDR brachytherapy source 60Co is inserted directly or in close to the tumor. Most commonly using method for calibration of HDR brachytherapy source 60CO is well type ionization chamber. Calibration of the radioactive source 60Co brachytherapy source is very important for the treatment of cancer patient. We have got the variation between RAKR from TPS and measured Air Kerma Rate of 60Co brachytherapy source are 3.2% and 3.04% and which give very good agreement with the Air Kerma Rate (RAKR) is 5% (from BEBIG protocol, Germany). So, our results were satisfied for brachytherapy treatment. From these results, it must be concluded that, 60Co brachytherapy source is suitable for brachytherapy cancer treatment. It is very difficult to calculate treatment deliver dose without calibrating AKR of HDR brachytherapy source. It is very important to verify the calculated Air Kerma Rate by TPS Air Kerma Rate.

ESTABLISHMENT OF A LOW DOSE RATE GAMMA RAY CALIBRATION FIELD FOR ENVIRONMENTAL RADIATION MONITORING DEVICES

2019 ◽  
Vol 187 (1) ◽  
pp. 61-68
Author(s):  
Munehiko Kowatari ◽  
Hiroshi Yoshitomi ◽  
Sho Nishino ◽  
Yoshihiko Tanimura ◽  
Tetsuya Ohishi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Radiation Monitoring ◽  
Dose Equivalent ◽  
Environmental Radiation ◽  
Air Kerma ◽  
Ambient Dose Equivalent ◽  
Reference Air Kerma Rate ◽  
Monitoring Devices ◽  
Air Kerma Rate ◽  
Ambient Dose

Abstract For routine calibration of dosemeters used for environmental radiation monitoring, a low dose rate 137Cs gamma ray calibration field that fully satisfies the requirement of the ISO 4037 series was established in the Facility of Radiation Standards in Japan Atomic Energy Agency. Two different methods were employed to determine the reference air kerma rate, namely a conventional ionisation chamber and a G(E) function method used a newly developed scintillation spectrometer. To fulfil the requirement of the ISO 4037 and suppress scattering of Cs gamma ray within the room as far as possible, a suitable lead collimator was introduced to limit the irradiation area at test points and placed at the middle height in an irradiation room with a grating floor. From measured results of de-convoluted photon fluence spectrum and the variation of evaluated reference air kerma rates between 1.0 m and 3.0 m from the centre of the source, gamma ray scattering from the room structures was found to be negligible. The reference air kerma rate at distances between1.0 m and 3.0 m could be then interpolated by simply considering the inverse square law of the distance and air attenuation. The resulting Cs gamma ray calibration field could provide ambient dose equivalent rates of 0.7–7.2 μSv h−1 for use with environmental radiation monitoring devices. Finally, we attempted to calibrate a widely used NaI(Tl) scintillation survey metre, obtaining a quite satisfactory calibration factor. These results also imply that such survey metres can be employed to monitor affected areas and assess the progress of decontamination, as they can provide appropriate measurements of the ambient dose equivalent rate.

Comparison BIPM.RI(I)-K8 of high dose rate 192Ir brachytherapy standards for reference air kerma rate of the NPL and the BIPM

Metrologia ◽  
2014 ◽  
Vol 51 (1A) ◽  
pp. 06024-06024 ◽  
Author(s):  
J T Alvarez ◽  
T Sander ◽  
J A de Pooter ◽  
P J Allisy-Roberts ◽  
C Kessler
Keyword(s):  
Dose Rate ◽  
High Dose Rate ◽  
High Dose ◽  
Air Kerma ◽  
Reference Air Kerma Rate ◽  
Air Kerma Rate

scholarly journals Correlation between calculated and measured values of gamma dose rate in air in forests contaminated with 137Cs: the remote period after the Chernobyl accident

2020 ◽  
Vol 12 (4) ◽  
pp. 37-46 ◽  
Author(s):  
Valery P. Ramzaev ◽  
Anatoly N. Barkovsky
Keyword(s):  
Vertical Distribution ◽  
Dose Rate ◽  
Chernobyl Accident ◽  
Gamma Dose ◽  
Dose Equivalent ◽  
Air Kerma ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Air Kerma Rate ◽  
Ambient Dose

In 2015–2016, 13 forest and 7 virgin grassland plots located in the south-western districts of the Bryansk region were surveyed. The aim of the work was to experimentally test the possibility of using a method for calculating the dose rate of gamma radiation in air in radioactively contaminated forests in a remote period after the Chernobyl accident. According to the results of gamma-spectrometric analysis of soil samples obtained at the sites in another study, the values of inventory and vertical distribution of 137Cs in the upper 20 cm layer were established. In this paper, these data were used to calculate the air kerma rate using a method taken from literature. In addition, at the sites of soil sampling, ambient dose equivalent rate in air was measured, and the contribution of 137Cs to the total gamma dose rate was determined with a field gamma spectrometer-dosemeter. The measured values of the ambient dose equivalent rate from 137Cs correlated positively and statistically significantly with the calculated values of the air kerma rate. The Spearman correlation coefficient was 0.989 (P < 0.01) for the location “forest” and 0.893 (P < 0.05) for the location “grassland”. There was no statistically significant difference between the “forest” and “grassland” locations when analyzing the ratio of the measured dose rate values to the calculated dose rate values (the Mann-Whitney U test, P > 0.05). Results of this work show that, when calculating gamma radiation dose rate in air in forests at a remote stage after the Chernobyl accident, it is enough to know the 137Cs inventory in the upper 20 cm soil layer and a detailed picture of vertical distribution of the radionuclide in this layer. The presence of woody biomass can be neglected. This dose rate estimate is conservative. However, a degree of overestimation of the dose rate in air is small, within +10%, which is quite acceptable for determining the external effective dose rate for an individual in the radioactively contaminated forest.

scholarly journals RESEARCH PROCESSES OF GAMMA RADIATION DETECTOR FOR DEVELOPING A PORTABLE DIGITAL SPECTROMETER

2020 ◽  
pp. 5-12 ◽  
Author(s):  
O.V. Banzak ◽  
O.V. Sieliykov ◽  
M.V. Olenev ◽  
S.V. Dobrovolskaya ◽  
O.I. Konovalenko
Keyword(s):  
Gamma Radiation ◽  
Dose Rate ◽  
Power Plants ◽  
Gamma Ray ◽  
Dynamic Range ◽  
Radiation Detector ◽  
Minimum Energy ◽  
Sampling Rate ◽  
Nuclear Materials ◽  
Wide Range

When considering methods of combating the illicit circulation of nuclear materials, it is necessary to detect trace amounts of materials, and in many cases not to seize them immediately, but to establish the place of storage, processing, routes of movement, etc. As a result, there is a new demand for isotope identification measurements to meet a wide range of different requirements. Measurements should be carried out in the field in a short time, when results need to be obtained within tens of seconds. The devices with which the personnel work should be small and low-background. Such requirements appear when working to identify cases of illegal trade in nuclear materials and radioactive sources, as well as when solving radiation protection problems and when handling radioactive devices and waste. In this work, new generation radiation sensors and measuring systems based on them have been created, which open up previously unknown possibilities in solving problems of nuclear fuel analysis, increasing the accuracy and efficiency of monitoring technological parameters and the state of protective barriers in nuclear power plants, and creating means for IAEA inspections. For the first time a portable digital gamma-ray spectrometer for radiation reconnaissance in the field was developed and created. Distinctive features of such devices are: The analysis showed that the required value of error due to energy dependence of the sensitivity can be achieved using, for example, Analog Devices 10-bit AD9411 ADCs with a sampling rate of 170 MHz. The number of quantization levels is determined by the requirement to measure the dose rate of gamma radiation with an energy of at least 10 keV. This minimum energy corresponds to the use of 10-bit ADCs. On the basis of the developed model, an ionizing radiation detector for dosimetry was created. Its fundamental difference from known devices is the use of CdZnTe crystals as a primary gamma-ray converter (sensor). The advantages of such a solution, proved by previous studies, made it possible to create a detector with: high resolution, no more than 40 keV; a wider dynamic range of values of the recorded radiation dose rate - from background to emergency operating modes of the reactor; lower value of the energy equivalent of noise.

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