The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electr...The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electrons when gamma rays traversed a silicon or silicon dioxide cube were calculated. A simplified model of a 500 × 500 CIS array was established, and the transient effects of gamma rays in the CIS were simulated. The raw images were captured when the CIS was irradiated by gamma rays. The experimental results were compared with the simulation results. The characteristics of the typical events induced by transient effects were analyzed.展开更多
In a deuterium operation on the Large Helical Device, the measurement and control equipment placed in the toms hall must survive under an environment of radiation, To study the effects of gamma-ray irradiation on the ...In a deuterium operation on the Large Helical Device, the measurement and control equipment placed in the toms hall must survive under an environment of radiation, To study the effects of gamma-ray irradiation on the equipment, an irradiation experiment is performed at the Cobalt-60 irradiation facility of Nagoya University. Transient and permanent effects on a personal computer, media converters, programmable logic controllers, isolation amplifiers, a web camera, optical flow meters, and water sealing gaskets are experimentally surveyed. Transient noise appears on the web camera. Offset of the signal increases with an increase of the integrated dose on the programmable logic controller. The DeviceNet module on the programmable logic controller is broken at the integrated dose of 72 Gy, which is the expected range of the integrated dose of the toms hall. The other equipment can survive under the gamma-ray field in the toms hall.展开更多
Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole（MBT） is known as a widespread, toxic and...Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole（MBT） is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate（S2O82-） on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals（SO4-U）, greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of –SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation,indicating the improvement of biodegradability and reduction of toxicity.展开更多
The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The ...The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The average values of the radionuclides 226Ra, 232Th and 40K in the soil samples are 14.34, 25.78 and 566.05 Bq/kg respectively. For rock samples, the average activity concentration for 226Ra, 232Th and 40K are 45, 106 and 1235 Bq/kg respectively. Low concentration values of 137Cs in soil and rock samples under investigation, are not radiologically important. The radium equivalent activity (Raeq) and external hazard index (Hex) of all samples are less than the limits of 370 Bq·kg-1 and unity, respectively. The average values of total absorbed dose rate due to three primordial radionuclides in soil and rock samples are 46.5 nGy/h and 138.36 nGy/h, respectively, where the absorbed average value of the granite is higher than the permitted limit. So, the local people must avoid using these granite samples as the interior decorative materials of dwelling without radioactivity control.展开更多
Solid wastes are generated from common manufacturing and industrial processes, and can also be caused by disposing commerce products. The natural radionuclide (238U, 226Ra, 232Th and 40K) concentrations in various sol...Solid wastes are generated from common manufacturing and industrial processes, and can also be caused by disposing commerce products. The natural radionuclide (238U, 226Ra, 232Th and 40K) concentrations in various solid waste samples were determined by using a high pure germanium detector. The obtained average concentration values of 226Ra, 232Th, and 40K in various solid wastes were: Iron (173.29, 141.99 and 32.68 Bq·kg-1), Copper (2.63, 0.60 and 30 Bq·kg-1), Aluminum (3.97, 4.89 and 41.67 Bq·kg-1) and in Wood (4.22, 3.11 and 30.20 Bq·kg-1), respectively. The total average values of radium equivalent and the absorbed dose rate were 95.87 Bq·kg-1 and 44.56 nGyh-1, respectively. The effective dose rates in outdoor and indoor average values were 0.05 and 0.20 mSvy-1, respectively. These health hazard parameters were considered to be below the safe limit of UNSCEAR 2000. The presented results show no significant radiological health risks for the workers in the industrial workshops and inhabitance health.展开更多
The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the co...The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the concentration levels of natural radionuclides (40K, 226Ra and 232Th). The activity concentrations of the natural radionuclides in the samples were determined via gamma-ray spectrometry using a 76 mm × 76 mm NaI(Tl) detector. Different common food crops representing the major sources of dietary requirements to the local population were collected for the measurements. The collected food crops were prepared into their different derivable composite diets using preparation techniques locale to the population. Using available food consumption data and the activity concentrations of the radionuclides, the ingestion effective doses were evaluated for the food crops and diet types per preparation techniques. For the tuberous food crop samples, the annual ingestion effective doses in the raw and different composite diets were 0.02 - 0.04 μSv and cumulatively 0.04 - 0.05 μSv while in the non-tuberous crops the doses were 0.44 - 0.70 μSv and cumulatively greater than 1 μSv respectively. Results of the study indicate that method of diet preparation is seen to play a major role in population ingestion dose reduction especially for tuberous crops than in non-tuberous crops. The study also showed that more ingestion dose could be incurred in diets prepared by roasting techniques. The result of the study will serve as a useful radiometric data for future epidemiological studies in the area and for food safety regulations and policy implementations in the country.展开更多
In gamma spectrometry of voluminous samples, inhomogeneous distribution of radioactivity caused by the presence of hot particles can create significant Bias in the results of activity determinations. We developed a no...In gamma spectrometry of voluminous samples, inhomogeneous distribution of radioactivity caused by the presence of hot particles can create significant Bias in the results of activity determinations. We developed a novel method to reduce this Bias using the gamma-peak ratio. We show that the peak area ratio of two gamma peaks of different energies, emitted by the same radionuclide, is a sensitive measure of emitting source location and thus the inhomogeneity. A new calibration formula was then derived for true gamma efficiency <em>p<sub>i</sub></em> as a function of efficiency ratio <em>p<sub>i</sub></em>/<em>p<sub>j</sub></em> of two peaks. This approach was verified by Monte Carlo simulations for a sample of 1-L volume containing from 1 up to 2048 of hot particles randomly distributed in a soil matrix. A <sup>152</sup>Eu radionuclide was selected for calculations and we used various combinations of two gamma spectral peaks selected from three gamma energies of 121.8, 344.3, and 1408.0 keV. This new method is shown to reduce the Bias range and Bias standard deviation by several times when compared with the traditional homogeneous calibration applied to measuring hot particles. The method is independent of the number, location, and distribution of hot particles in the samples, and can be applied to a mixture of radionuclides. It complements our previous calibration model based on the peak-to-total ratio.展开更多
The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional informat...The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid （GABA）. We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions： no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-arninobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11805155,11875223,and 11690043)the Chinese Academy of Sciences strategic pilot science and technology project(No.XDA15015000)+1 种基金the Innovation Foundation of Radiation Application(No.KFZC2018040201)the Foundation of State Key Laboratory of China(Nos.SKLIPR1803 and 1610)
文摘The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electrons when gamma rays traversed a silicon or silicon dioxide cube were calculated. A simplified model of a 500 × 500 CIS array was established, and the transient effects of gamma rays in the CIS were simulated. The raw images were captured when the CIS was irradiated by gamma rays. The experimental results were compared with the simulation results. The characteristics of the typical events induced by transient effects were analyzed.
基金supported partly by the LHD project budget(NIFS15ULHH003 and NIFS15ULGG801)
文摘In a deuterium operation on the Large Helical Device, the measurement and control equipment placed in the toms hall must survive under an environment of radiation, To study the effects of gamma-ray irradiation on the equipment, an irradiation experiment is performed at the Cobalt-60 irradiation facility of Nagoya University. Transient and permanent effects on a personal computer, media converters, programmable logic controllers, isolation amplifiers, a web camera, optical flow meters, and water sealing gaskets are experimentally surveyed. Transient noise appears on the web camera. Offset of the signal increases with an increase of the integrated dose on the programmable logic controller. The DeviceNet module on the programmable logic controller is broken at the integrated dose of 72 Gy, which is the expected range of the integrated dose of the toms hall. The other equipment can survive under the gamma-ray field in the toms hall.
基金the National Hi-Tech Research and Development Program(863)of China(No.2009AA063905)supported by the Chinese Ministry of Science and Technology and the Independent Research Project(No.20101081929)supported by Tsinghua University
文摘Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole（MBT） is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate（S2O82-） on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals（SO4-U）, greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of –SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation,indicating the improvement of biodegradability and reduction of toxicity.
文摘The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The average values of the radionuclides 226Ra, 232Th and 40K in the soil samples are 14.34, 25.78 and 566.05 Bq/kg respectively. For rock samples, the average activity concentration for 226Ra, 232Th and 40K are 45, 106 and 1235 Bq/kg respectively. Low concentration values of 137Cs in soil and rock samples under investigation, are not radiologically important. The radium equivalent activity (Raeq) and external hazard index (Hex) of all samples are less than the limits of 370 Bq·kg-1 and unity, respectively. The average values of total absorbed dose rate due to three primordial radionuclides in soil and rock samples are 46.5 nGy/h and 138.36 nGy/h, respectively, where the absorbed average value of the granite is higher than the permitted limit. So, the local people must avoid using these granite samples as the interior decorative materials of dwelling without radioactivity control.
文摘Solid wastes are generated from common manufacturing and industrial processes, and can also be caused by disposing commerce products. The natural radionuclide (238U, 226Ra, 232Th and 40K) concentrations in various solid waste samples were determined by using a high pure germanium detector. The obtained average concentration values of 226Ra, 232Th, and 40K in various solid wastes were: Iron (173.29, 141.99 and 32.68 Bq·kg-1), Copper (2.63, 0.60 and 30 Bq·kg-1), Aluminum (3.97, 4.89 and 41.67 Bq·kg-1) and in Wood (4.22, 3.11 and 30.20 Bq·kg-1), respectively. The total average values of radium equivalent and the absorbed dose rate were 95.87 Bq·kg-1 and 44.56 nGyh-1, respectively. The effective dose rates in outdoor and indoor average values were 0.05 and 0.20 mSvy-1, respectively. These health hazard parameters were considered to be below the safe limit of UNSCEAR 2000. The presented results show no significant radiological health risks for the workers in the industrial workshops and inhabitance health.
文摘The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the concentration levels of natural radionuclides (40K, 226Ra and 232Th). The activity concentrations of the natural radionuclides in the samples were determined via gamma-ray spectrometry using a 76 mm × 76 mm NaI(Tl) detector. Different common food crops representing the major sources of dietary requirements to the local population were collected for the measurements. The collected food crops were prepared into their different derivable composite diets using preparation techniques locale to the population. Using available food consumption data and the activity concentrations of the radionuclides, the ingestion effective doses were evaluated for the food crops and diet types per preparation techniques. For the tuberous food crop samples, the annual ingestion effective doses in the raw and different composite diets were 0.02 - 0.04 μSv and cumulatively 0.04 - 0.05 μSv while in the non-tuberous crops the doses were 0.44 - 0.70 μSv and cumulatively greater than 1 μSv respectively. Results of the study indicate that method of diet preparation is seen to play a major role in population ingestion dose reduction especially for tuberous crops than in non-tuberous crops. The study also showed that more ingestion dose could be incurred in diets prepared by roasting techniques. The result of the study will serve as a useful radiometric data for future epidemiological studies in the area and for food safety regulations and policy implementations in the country.
文摘In gamma spectrometry of voluminous samples, inhomogeneous distribution of radioactivity caused by the presence of hot particles can create significant Bias in the results of activity determinations. We developed a novel method to reduce this Bias using the gamma-peak ratio. We show that the peak area ratio of two gamma peaks of different energies, emitted by the same radionuclide, is a sensitive measure of emitting source location and thus the inhomogeneity. A new calibration formula was then derived for true gamma efficiency <em>p<sub>i</sub></em> as a function of efficiency ratio <em>p<sub>i</sub></em>/<em>p<sub>j</sub></em> of two peaks. This approach was verified by Monte Carlo simulations for a sample of 1-L volume containing from 1 up to 2048 of hot particles randomly distributed in a soil matrix. A <sup>152</sup>Eu radionuclide was selected for calculations and we used various combinations of two gamma spectral peaks selected from three gamma energies of 121.8, 344.3, and 1408.0 keV. This new method is shown to reduce the Bias range and Bias standard deviation by several times when compared with the traditional homogeneous calibration applied to measuring hot particles. The method is independent of the number, location, and distribution of hot particles in the samples, and can be applied to a mixture of radionuclides. It complements our previous calibration model based on the peak-to-total ratio.
基金supported by the National Natural Science Foundation of China,No.81271090 and the Beijing Natural Science Foundation,No.7112055
文摘The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid （GABA）. We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions： no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-arninobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect.
