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古渡 意彦; 谷村 嘉彦; Kessler, P.*; Neumaier, S.*; R
ttger, A.*
Radioisotopes, 70(1), p.1 - 18, 2021/01
For proper environmental radiation monitoring, a method to simultaneously determine ambient dose equivalent rate and radioactivity concentration in the air by using a newly developed scintillation spectrometer, namely a CeBr
spectrometer was investigated. The performance of the proposed method, including energy dependence and linearity of the spectrometer, was verified by a series of measurements, conducted according to the procedure of inter-comparison of detectors used for early warning network performed by the European Radiation Dosimetry Group (EURADOS). Measurement results show that the proposed method is suitable for environmental monitoring purposes. After thorough tests, the activity concentration in air was determined in the laboratory by using a point-like sealed 
Ba source to mimic a radioactive cloud containing 
I and Xe. The photon fluence rate was obtained from the pulse height distribution by using the unfolding method, and the activity concentration in air for radioisotopes of interest, mainly Xe, was estimated from the obtained photon fluence rate by applying the conversion coefficient evaluated via a Monte Carlo calculation. The results additionally show that the method presented in this study is reliable and suitable for the environmental radiation measurement.
scintillation spectrometer due to terrestrial gamma ray components; Application in environmental radiation monitoring古渡 意彦; 谷村 嘉彦; Kessler, P.*; Rttger, A.*
Radiation Measurements, 138, p.106431_1 - 106431_6, 2020/11
被引用回数：1 パーセンタイル：8.72(Nuclear Science & Technology)In radiological emergency, timely and reliable radiological information such as dose rate or radioactive concentrations due to artificial radionuclides is indispensable to protect general public and the first responder of the situation. The authors have investigated the method for effectively identifying and determining the radioactivity concentration using a scintillation spectrometer. In this study, the authors demonstrate how influence of terrestrial background (BG) component on measured pulse height spectrum can be minimized to obtain the peaks from gamma rays emitted by artificial radioactivity. In some cases of radiological emergency monitoring, subtraction of BG components was probe to be difficult, because the prior measurement of BG component at the place to be monitored is compulsory. By removing the BG component appropriately from measured pulse height spectrum without any prior BG measurement, the effective minimum detection limit of the spectrometer would be declined.
古渡 意彦; 吉富 寛; 西野 翔; 谷村 嘉彦; 大石 哲也; Kessler, P.*; Neumaier, S.*; Rttger, A.*
Radiation Protection Dosimetry, 187(1), p.61 - 68, 2019/12
被引用回数：3 パーセンタイル：25.69(Environmental Sciences)A low dose rate Cs 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 ionization chamber and a G(E) function method used a newly developed scintillation spectrometer. To fulfill 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 evaluated reference air kerma rates between 1.0 m and 3.0 m from the center of the source, gamma ray scattering from the room structures was found to be negligible. The resulting Cs gamma ray calibration field could provide ambient dose equivalent rates of 0.7-7.2 
Sv h
for use with environmental radiation monitoring devices.
古渡 意彦; 吉富 寛; 西野 翔; 谷村 嘉彦; 大石 哲也; Kessler, P.*; Neumaier, S.*; Rttger, A.*
Radiation Protection Dosimetry, 186(4), P. 538, 2019/12
被引用回数：0 パーセンタイル：0.00(Environmental Sciences)原著論文の表5(B)中の単位について、nSv hとすべきところSv hと記載するミスがあったため、訂正する。
and SrI
(Eu) scintillation detectors for environmental monitoring古渡 意彦; 谷村 嘉彦; Kessler, P.*; Neumaier, S.*; Roettger, A.*
Progress in Nuclear Science and Technology (Internet), 6, p.81 - 85, 2019/01
The simultaneous evaluation of dose rate and radioactivity using newly developed scintillation detectors, i.e. CeBr and SrI(Eu) was investigated for environmental radiation measurement in emergency situation. Energy dependence and linearity tests of both detectors were conducted in a low background laboratory operated by the German metrological institute and found to be applicable to environmental monitoring purposes. As a result of environmental 
ray measurements in normal condition, evaluated air kerma rate and radioactivity in/on soil for 
Cs, 
Cs and 
K seemed consistent. Results also support that methods developed in the study are reliable and applicable to the environmental radiation measurement.
