G. Chourasiya | Homi Bhabha National Institute (HBNI, BARC, MUMBAI) (original) (raw)
Papers by G. Chourasiya
Indian Journal of Physics, 2009
CR-39 (PADC) a Solid State Nuclear Track Detector., is used as a routine personnel monitor. 1800 ... more CR-39 (PADC) a Solid State Nuclear Track Detector., is used as a routine personnel monitor. 1800 workers are being monitored quarterly for fast neutron using CR-39 foils. These foils procured from Pershore Mouldings, UK are very expensive and indigenous development will make the foils cost effective. The aim of this paper is to find a suitable alternative to the imported CR-39 foils for use in personnel monitoring. The foils from three different manufacturers have been compared with the CR-39 foils from Pershore Moulding, UK, presently in use. Out of the three, only sample no 1 is promising. It has a background and sensitivity comparable with CR-39 presently used. The sample 2 is CR-39 being developed in India, has a relatively high background and poor sensitivity. Efforts are being made to improve the quality of this sample. The sample 3 was a poly carbonate from local manufacturer which produced very few tracks and the standard deviation of track counts was very large and hence not useful for Personnel Monitoring.
Radiation Measurements, 2009
Response of thermoluminescent dosimeter (TLD) badge based on CaSO4:Dy phosphor to high energy ele... more Response of thermoluminescent dosimeter (TLD) badge based on CaSO4:Dy phosphor to high energy electron beams from medical linear accelerators was simulated using FLUKA Monte Carlo code and experimentally verified. This study was carried out in order to determine the response of TL discs under different filter regions of the TLD badge and their ratios under different irradiation conditions in the
Radiation Protection and Environment, 2011
Radiation Measurements, 2012
ABSTRACT
Radiation Protection and Environment, 2015
International Journal of Mass Spectrometry and Ion Processes, 1986
The use of 239 Pu as a spike in isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) f... more The use of 239 Pu as a spike in isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) for determining the plutonium concentration in irradiated fuels is demonstrated. The method is based on the high precision better than 0.1% determination of the 240 Pu/ 239 ...
Journal of applied clinical medical physics / American College of Medical Physics, 2011
A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fab... more A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fabricated for use as a reference standard for low-dose rate 137Cs brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin's general cavity theory, as well as by the Monte Carlo simulation and validated experimentally using Amersham CDCS-J-type 137Cs reference source. In the analytical method, the N(K) was calculated for 662 keV gamma rays of 137Cs brachytherapy source. In the Monte Carlo method, the geometry of the measurement setup and physics-related input data of the 137Cs source and the surrounding material were simulated using the Monte Carlo N-Particle code. The photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficient. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber, and the N(K) was det...
Solvent Extraction and Ion Exchange, 1983
ABSTRACT The extraction of Pu (IV) by Aliquat-336 from aqueous nitric acid containing oxalic acid... more ABSTRACT The extraction of Pu (IV) by Aliquat-336 from aqueous nitric acid containing oxalic acid was studied with a view to exploring the feasibility of recovery of Pu (IV) from Pu (IV) oxalate precipitation effluents. Distribution ratio data were obtained as a function of ...
Radiation Protection Dosimetry, 2009
In order to evaluate and report the personal doses in terms of personal dose equivalent, the perf... more In order to evaluate and report the personal doses in terms of personal dose equivalent, the performance of the CaSO(4):Dy based thermoluminescence dosemeter (TLD) badge used for countrywide personnel monitoring in India is investigated using monoenergetic and narrow spectrum radiation qualities equivalent to those given in ISO standards. Algorithms suitable for evaluating H(p)(10) and H(p)(0.07) within +/- 30 % are developed from the responses of dosemeter elements/discs under different filters for normal as well as angular irradiation conditions using these beams. The algorithm is tested for TLD badges irradiated to mixtures of low- and high-energy ((137)Cs) beams in various proportions. The paper concludes with the results of test of algorithm by evaluation of badges used in the IAEA/RCA intercomparison studies and discussion on inherent limitations.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1985
A comparative study of different methods of preparation of sources for alpha spectrometry of plut... more A comparative study of different methods of preparation of sources for alpha spectrometry of plutonium is presented. Typical values of the percentage tail contribution per unit alpha activity ratio 238Pu/(239Pu + 240Pu), fwhm and peak to valley ratios are given for (1) drop deposited sources from aqueous medium without using a spreading agent, (2) drop deposited sources from aqueous medium
Journal of Radioanalytical and Nuclear Chemistry Letters, 1987
A reverse isotope dilution alpha spectrometric /R-IDAS/ method using239Pu as a spike is described... more A reverse isotope dilution alpha spectrometric /R-IDAS/ method using239Pu as a spike is described for the determination of plutonium concentration in high burn-up fuel samples wth238Pu/(239Pu+240Pu) alpha activity ratio >0.5, without resorting to any purification from241Am and a bulk of other impurities. It involves the addition of a pre-clibrated spike solution to a known aliquot of the plutonium sample solution
Journal of Radioanalytical and Nuclear Chemistry Letters, 1984
K-factors (= certified isotope ratio/observed isotope ratio) are determined for the isotope abund... more K-factors (= certified isotope ratio/observed isotope ratio) are determined for the isotope abundance measurements of uranium and plutonium by thermal ionisation mass spectrometry. An mdf of 0.07% and 0.18% per mass unit differing by a factor of about 3, is obtained for uranium and plutonium, respectively, employing double rhenium filament assembly in the ion source and Faraday cup as the detector using the presently available isotopic reference materials of uranium and plutonium.
Journal of Radioanalytical and Nuclear Chemistry Letters, 1985
A method is described for the determination of plutonium concentration in the presence of a bulk ... more A method is described for the determination of plutonium concentration in the presence of a bulk of other impurities by isotope dilution mass spectrometry /IDMS/ using239Pu as a spike. The method involves the addition of239Pu spike / 90 atom%/ to samples with239Pu / 70 atom%/ and vice versa. After ensuring chemical exchange between the sample and the spike isotopes, plutonium
Journal of Radioanalytical and Nuclear Chemistry Articles, 1985
A direct evaporation method is described for the preparation of sources using stainless steel as ... more A direct evaporation method is described for the preparation of sources using stainless steel as the backing material and tetraethylene glycol (TEG) as a spreading agent in the presence of large amounts of uranium. It i~ sho*vn that FWHM and tail contribution at the low energy peak due to energy degradation of the high energy peak can be optimized by heating the source under controlled conditions-in a furnace at 500-600 ~ for about 15 rain, An accuracy of 0.5-1'; is demonstrated for the determination of 23Spu/(239pu + a4~ alpha activity ratio in the U/Pu range of 10 to 1500 generally encountered in dissolver solution of irradiated fuel,
Journal of Radioanalytical and Nuclear Chemistry Articles, 1989
A differential speetrophotometric method has been developed for plutonium in hexavalent state usi... more A differential speetrophotometric method has been developed for plutonium in hexavalent state using a double beam spectrophotometer. The absorbance measurements were made at 835 um in 4M sulfuric acid using a 5 era cell. In the method developed the absorbance of six Pu(VI) standards, taken in the sample cell, were recorded against a molybdenum blue solution of appropriate intensity in the reference cell. A least-squares fit of data on absorbance and concentration of plutonium standards gave slope F and intercept Co which were used to determine the unknown concentrations using the relationship, C = C O + F.Ar where Ar is the absorbance of a plutonium solution of unknown concentration C mg/g. Various parameters like choice of acid and acidity, slit width, oxidant etc. were studied and the conditions optimized. Plutonium in the concentration range of 0.1-0.3 mg/g could be determined with a precision of • Uranium does not interfere. The method is useful for the analysis of a large number of samples on a routine basis.
Journal of Radioanalytical and Nuclear Chemistry Articles, 1991
ABSTRACT
Fresenius' Zeitschrift f�r Analytische Chemie, 1986
Zusammenfassung. Bei dem beschriebenen Verfahren der Isotopenverdiinnungs-Alpha-Spektrometrie (ID... more Zusammenfassung. Bei dem beschriebenen Verfahren der Isotopenverdiinnungs-Alpha-Spektrometrie (IDAS) wird 238pu als Spike benutzt. Eine vorgeeichte Spike-L6sung wird zu einem bekannten Aliquot der Probe gegeben und anschliel3end die Strahlungsquelle unter Verwendung von Tetraethylenglykol als Spreading-Reagens vorbereitet. Die nach diesem Verfahren erhaltenen Ergebnisse werden in bezug auf Pr/izision und Genauigkeit mit solchen verglichen, die mit Isotopenverdfinnungs-Massenspektrometrie unter Verwendung yon 242Pu als Spike oder mit IDAS unter Verwendung von Thenoyltrifluoraceton zur Reinigung erhalten wurden. Eine Pr/izision von 0,3 -0,5% und eine Genauigkeit yon 0,5% wurden erzielt. Durch das beschriebene Verfahren erfibrigt sich eine Reinigung des Pu von 24~Am und anderen Verunreinigungen.
Journal of cancer research and therapeutics
Statistical analysis of pre-treatment dose verification of intensity-modulated radiotherapy (IMRT... more Statistical analysis of pre-treatment dose verification of intensity-modulated radiotherapy (IMRT) fields to assess the quality of the IMRT practice at different radiotherapy centers. The dose verification data acquired by the institutional physicist of 10 different hospitals for various types of patients were collected and analyzed for mean, median, standard deviation (SD), range, minimum and maximum % deviation. The percentage of cases having positive and negative dose differences as well dose differences within ± 3% were also determined. The mean values of percentage variation in difference between treatment planning systems calculated dose and difference between measured dose (D(TPS) and D(Meas)) are found to be from -1.79 to 1.48 and median from -1.79 to 1.51. The SDs are found to be from 0.76 to 3.70. The range of variation at these centers varies from 3.99 to 16.45 while minimum and maximum values of percentage variation in difference between D(TPS) and D(Meas) ranges from -1...
Indian Journal of Physics, 2009
CR-39 (PADC) a Solid State Nuclear Track Detector., is used as a routine personnel monitor. 1800 ... more CR-39 (PADC) a Solid State Nuclear Track Detector., is used as a routine personnel monitor. 1800 workers are being monitored quarterly for fast neutron using CR-39 foils. These foils procured from Pershore Mouldings, UK are very expensive and indigenous development will make the foils cost effective. The aim of this paper is to find a suitable alternative to the imported CR-39 foils for use in personnel monitoring. The foils from three different manufacturers have been compared with the CR-39 foils from Pershore Moulding, UK, presently in use. Out of the three, only sample no 1 is promising. It has a background and sensitivity comparable with CR-39 presently used. The sample 2 is CR-39 being developed in India, has a relatively high background and poor sensitivity. Efforts are being made to improve the quality of this sample. The sample 3 was a poly carbonate from local manufacturer which produced very few tracks and the standard deviation of track counts was very large and hence not useful for Personnel Monitoring.
Radiation Measurements, 2009
Response of thermoluminescent dosimeter (TLD) badge based on CaSO4:Dy phosphor to high energy ele... more Response of thermoluminescent dosimeter (TLD) badge based on CaSO4:Dy phosphor to high energy electron beams from medical linear accelerators was simulated using FLUKA Monte Carlo code and experimentally verified. This study was carried out in order to determine the response of TL discs under different filter regions of the TLD badge and their ratios under different irradiation conditions in the
Radiation Protection and Environment, 2011
Radiation Measurements, 2012
ABSTRACT
Radiation Protection and Environment, 2015
International Journal of Mass Spectrometry and Ion Processes, 1986
The use of 239 Pu as a spike in isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) f... more The use of 239 Pu as a spike in isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) for determining the plutonium concentration in irradiated fuels is demonstrated. The method is based on the high precision better than 0.1% determination of the 240 Pu/ 239 ...
Journal of applied clinical medical physics / American College of Medical Physics, 2011
A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fab... more A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fabricated for use as a reference standard for low-dose rate 137Cs brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin's general cavity theory, as well as by the Monte Carlo simulation and validated experimentally using Amersham CDCS-J-type 137Cs reference source. In the analytical method, the N(K) was calculated for 662 keV gamma rays of 137Cs brachytherapy source. In the Monte Carlo method, the geometry of the measurement setup and physics-related input data of the 137Cs source and the surrounding material were simulated using the Monte Carlo N-Particle code. The photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficient. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber, and the N(K) was det...
Solvent Extraction and Ion Exchange, 1983
ABSTRACT The extraction of Pu (IV) by Aliquat-336 from aqueous nitric acid containing oxalic acid... more ABSTRACT The extraction of Pu (IV) by Aliquat-336 from aqueous nitric acid containing oxalic acid was studied with a view to exploring the feasibility of recovery of Pu (IV) from Pu (IV) oxalate precipitation effluents. Distribution ratio data were obtained as a function of ...
Radiation Protection Dosimetry, 2009
In order to evaluate and report the personal doses in terms of personal dose equivalent, the perf... more In order to evaluate and report the personal doses in terms of personal dose equivalent, the performance of the CaSO(4):Dy based thermoluminescence dosemeter (TLD) badge used for countrywide personnel monitoring in India is investigated using monoenergetic and narrow spectrum radiation qualities equivalent to those given in ISO standards. Algorithms suitable for evaluating H(p)(10) and H(p)(0.07) within +/- 30 % are developed from the responses of dosemeter elements/discs under different filters for normal as well as angular irradiation conditions using these beams. The algorithm is tested for TLD badges irradiated to mixtures of low- and high-energy ((137)Cs) beams in various proportions. The paper concludes with the results of test of algorithm by evaluation of badges used in the IAEA/RCA intercomparison studies and discussion on inherent limitations.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1985
A comparative study of different methods of preparation of sources for alpha spectrometry of plut... more A comparative study of different methods of preparation of sources for alpha spectrometry of plutonium is presented. Typical values of the percentage tail contribution per unit alpha activity ratio 238Pu/(239Pu + 240Pu), fwhm and peak to valley ratios are given for (1) drop deposited sources from aqueous medium without using a spreading agent, (2) drop deposited sources from aqueous medium
Journal of Radioanalytical and Nuclear Chemistry Letters, 1987
A reverse isotope dilution alpha spectrometric /R-IDAS/ method using239Pu as a spike is described... more A reverse isotope dilution alpha spectrometric /R-IDAS/ method using239Pu as a spike is described for the determination of plutonium concentration in high burn-up fuel samples wth238Pu/(239Pu+240Pu) alpha activity ratio >0.5, without resorting to any purification from241Am and a bulk of other impurities. It involves the addition of a pre-clibrated spike solution to a known aliquot of the plutonium sample solution
Journal of Radioanalytical and Nuclear Chemistry Letters, 1984
K-factors (= certified isotope ratio/observed isotope ratio) are determined for the isotope abund... more K-factors (= certified isotope ratio/observed isotope ratio) are determined for the isotope abundance measurements of uranium and plutonium by thermal ionisation mass spectrometry. An mdf of 0.07% and 0.18% per mass unit differing by a factor of about 3, is obtained for uranium and plutonium, respectively, employing double rhenium filament assembly in the ion source and Faraday cup as the detector using the presently available isotopic reference materials of uranium and plutonium.
Journal of Radioanalytical and Nuclear Chemistry Letters, 1985
A method is described for the determination of plutonium concentration in the presence of a bulk ... more A method is described for the determination of plutonium concentration in the presence of a bulk of other impurities by isotope dilution mass spectrometry /IDMS/ using239Pu as a spike. The method involves the addition of239Pu spike / 90 atom%/ to samples with239Pu / 70 atom%/ and vice versa. After ensuring chemical exchange between the sample and the spike isotopes, plutonium
Journal of Radioanalytical and Nuclear Chemistry Articles, 1985
A direct evaporation method is described for the preparation of sources using stainless steel as ... more A direct evaporation method is described for the preparation of sources using stainless steel as the backing material and tetraethylene glycol (TEG) as a spreading agent in the presence of large amounts of uranium. It i~ sho*vn that FWHM and tail contribution at the low energy peak due to energy degradation of the high energy peak can be optimized by heating the source under controlled conditions-in a furnace at 500-600 ~ for about 15 rain, An accuracy of 0.5-1'; is demonstrated for the determination of 23Spu/(239pu + a4~ alpha activity ratio in the U/Pu range of 10 to 1500 generally encountered in dissolver solution of irradiated fuel,
Journal of Radioanalytical and Nuclear Chemistry Articles, 1989
A differential speetrophotometric method has been developed for plutonium in hexavalent state usi... more A differential speetrophotometric method has been developed for plutonium in hexavalent state using a double beam spectrophotometer. The absorbance measurements were made at 835 um in 4M sulfuric acid using a 5 era cell. In the method developed the absorbance of six Pu(VI) standards, taken in the sample cell, were recorded against a molybdenum blue solution of appropriate intensity in the reference cell. A least-squares fit of data on absorbance and concentration of plutonium standards gave slope F and intercept Co which were used to determine the unknown concentrations using the relationship, C = C O + F.Ar where Ar is the absorbance of a plutonium solution of unknown concentration C mg/g. Various parameters like choice of acid and acidity, slit width, oxidant etc. were studied and the conditions optimized. Plutonium in the concentration range of 0.1-0.3 mg/g could be determined with a precision of • Uranium does not interfere. The method is useful for the analysis of a large number of samples on a routine basis.
Journal of Radioanalytical and Nuclear Chemistry Articles, 1991
ABSTRACT
Fresenius' Zeitschrift f�r Analytische Chemie, 1986
Zusammenfassung. Bei dem beschriebenen Verfahren der Isotopenverdiinnungs-Alpha-Spektrometrie (ID... more Zusammenfassung. Bei dem beschriebenen Verfahren der Isotopenverdiinnungs-Alpha-Spektrometrie (IDAS) wird 238pu als Spike benutzt. Eine vorgeeichte Spike-L6sung wird zu einem bekannten Aliquot der Probe gegeben und anschliel3end die Strahlungsquelle unter Verwendung von Tetraethylenglykol als Spreading-Reagens vorbereitet. Die nach diesem Verfahren erhaltenen Ergebnisse werden in bezug auf Pr/izision und Genauigkeit mit solchen verglichen, die mit Isotopenverdfinnungs-Massenspektrometrie unter Verwendung yon 242Pu als Spike oder mit IDAS unter Verwendung von Thenoyltrifluoraceton zur Reinigung erhalten wurden. Eine Pr/izision von 0,3 -0,5% und eine Genauigkeit yon 0,5% wurden erzielt. Durch das beschriebene Verfahren erfibrigt sich eine Reinigung des Pu von 24~Am und anderen Verunreinigungen.
Journal of cancer research and therapeutics
Statistical analysis of pre-treatment dose verification of intensity-modulated radiotherapy (IMRT... more Statistical analysis of pre-treatment dose verification of intensity-modulated radiotherapy (IMRT) fields to assess the quality of the IMRT practice at different radiotherapy centers. The dose verification data acquired by the institutional physicist of 10 different hospitals for various types of patients were collected and analyzed for mean, median, standard deviation (SD), range, minimum and maximum % deviation. The percentage of cases having positive and negative dose differences as well dose differences within ± 3% were also determined. The mean values of percentage variation in difference between treatment planning systems calculated dose and difference between measured dose (D(TPS) and D(Meas)) are found to be from -1.79 to 1.48 and median from -1.79 to 1.51. The SDs are found to be from 0.76 to 3.70. The range of variation at these centers varies from 3.99 to 16.45 while minimum and maximum values of percentage variation in difference between D(TPS) and D(Meas) ranges from -1...