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Journal Articles

Storage characteristics of SrBPO$$_{5}$$:Eu$$^{2+}$$ phosphors by fast neutron irradiation

Sakasai, Kaoru; Iwamoto, Yosuke; Soyama, Kazuhiko

Proceedings of 2008 IEEE Nuclear Science Symposium and Medical Imaging Conference (2008 NSS/MIC), Vol.1, p.424 - 427, 2009/07

Storage characteristics of SrBPO$$_{5}$$:Eu$$^{2+}$$ phosphor were investigated when the phosphor was irradiated by fast neutron with energy of 14.8 MeV. To improve the fast neutron sensitivity, polyethylene (PE) sheets as a proton generator were set in front of the phosphors. The maximum PSL yields were obtained at a PE thickness of about 3 mm. These experimental results well agreed with those by Monte Carlo simulation using PHITS code. Estimated PSL yields by $$gamma$$-ray associated with fast neutron fields were negligible. The neutron sensitivities of 5 MeV- and 14.8 MeV-neutrons were estimated and were also agreed with those by MC simulation. This combination use of such phosphors and PE sheets will be usable for fast neutron monitoring or imaging in a high $$gamma$$-ray fields.

Journal Articles

High detection efficiency ZnS scintillator for a fiber-coded linear neutron detector for thermal neutron scattering instruments

Nakamura, Tatsuya; Schooneveld, E. M.*; Rhodes, N. J.*; Katagiri, Masaki; Tsutsui, Noriaki*; To, Kentaro; Sakasai, Kaoru; Soyama, Kazuhiko

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.1215 - 1219, 2009/02

High detector efficiency ZnS/$$^{6}$$LiF scintillator and ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator were developed for a fiber-coded linear neutron detector for thermal neutron detection. Detector performances of the detector equipped with such scintillator strips were evaluated in terms of neutron detector efficiency, $$gamma$$ sensitivity, and quiet counts rate. The detector equipped with the ZnS/$$^{6}$$LiF scintillator that contained twice amount of $$^{6}$$Li compared to the conventional scintillator (ZnS/$$^{6}$$LiF scintillator produced by AST Co Ltd) exhibited about 30% higher detector efficiency for 1-${AA}$ neutrons. The fiber-coded detector equipped with the ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator also exhibited about 30% larger neutron counts than the detector made with the conventional scintillator and exhibited 40% shorter decay time than the conventional scintillator, indicating a potential for higher count rate capability.

Journal Articles

Performance of a high speed and high density data acquisition system for multiple $$gamma$$-ray detection

Kimura, Atsushi; Toh, Yosuke; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Kin, Tadahiro; Oshima, Masumi

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.2107 - 2111, 2008/10

In order to measure neutron capture cross sections with time of flight method and multiple $$gamma$$-rays coincidence method, the present authors decided to construct a large Ge detector array at MLF in the J-PARC project. Time-integrated neutron flux in thermal region at the MLF is expected to be 1.1$$times$$10$$^{8}$$ n/s/cm$$^{2}$$. Because of the high neutron flux, the DAQ reported in NSS 2004 can not handle the signals from the spectrometer. The authors, therefore, have improved the DAQ and report performance of our system in this NSS 2008. Total energy resolution of this system was 2.4 keV in FWHM for 1.33-MeV $$gamma$$-rays. The dead time of this system is only 3.3 $$mu$$s per event and the maximum event rate was more than 300 k events/s.

Journal Articles

Basic characteristics of a newly developed Si/CdTe Compton camera for medical imaging

Kawachi, Naoki; Watanabe, Shigeki; Sato, Takahiro; Arakawa, Kazuo; Takeda, Shinichiro*; Ishikawa, Shinnosuke*; Aono, Hiroyuki*; Watanabe, Shin*; Yamaguchi, Mitsutaka*; Takahashi, Tadayuki*; et al.

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.1540 - 1543, 2008/10

Journal Articles

Monte Carlo simulation of multi-head Si/CdTe Compton camera for medical imaging

Yamaguchi, Mitsutaka*; Kawachi, Naoki; Watanabe, Shin*; Odaka, Hirokazu*; Takeda, Shinichiro*; Ishikawa, Shinnosuke*; Aono, Hiroyuki*; Takahashi, Tadayuki*; Arakawa, Kazuo; Nakano, Takashi*

2008 IEEE Nuclear Science Symposium Conference Record (CD-ROM), p.4000 - 4002, 2008/10

Oral presentation

Observation of neutron-induced signals with two-dimensional micro-pixel gas chamber

To, Kentaro; Yamagishi, Hideshi; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko

no journal, , 

A gas-based neutron detection system with individual readout capability and consisting of a micro-pixel detector array was constructed, and preliminary experiments using a Cf-252 neutron source and JRR-3 fission reactor were conducted. The detector array exhibited a fast temporal response and the full width at half maximum (FWHM) of the response time was 160 ns. The gas gain was about 50 at a supplied anode-cathode voltage of 560 V and a gas pressure of 5 atm. Signal pulse peaks of neutrons could be identified and their output voltages at an anode and a cathode are 2.4 and 5.3 mV, respectively, while the output voltage of all anodes is 105 mV. The micro-pixel gas chamber system easily discriminated neutron signals from background noises, and there was no degradation of the gas gain due to a charge up effect.

Oral presentation

Charged-particle-induced luminescence of Sr$$_{4}$$Al$$_{14}$$O$$_{25}$$:Eu$$^{2+}$$,Dy$$^{3+}$$

To, Kentaro; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko; Shikama, Tatsuo*; Nagata, Shinji*; Tsuchiya, Bun*

no journal, , 

The fluorescence and long-lasting emission properties of Sr$$_{4}$$Al$$_{14}$$O$$_{25}$$:Eu$$^{2+}$$,Dy$$^{3+}$$ are examined by irradiating it by protons and helium and oxygen particles. The fluorescence spectra exhibit three strong peaks at 400, 480, and 570 nm. The first two peaks are attributed to the luminescence of Eu, and they confirm the long-lasting emission property of Sr$$_{4}$$Al$$_{14}$$O$$_{25}$$:Eu$$^{2+}$$,Dy$$^{3+}$$. The peak at 570 nm is attributed to the luminescence of Dy; it exhibits no luminescence after the cessation of the irradiation. Radiation damages exhibit activator dependence. Eu is more sensitive to the incident particles than Dy is. The radiation damages also exhibit incident particle dependence, and the magnitude of damage is related to the electric and nuclear linear energy transfer of the particles.

Oral presentation

Multiple X-ray coincidence method and its application to element quantification

Oshima, Masumi; Murakami, Yukihiro*; Koizumi, Mitsuo; Toh, Yosuke

no journal, , 

So far we have demonstrated that the $$gamma$$-ray coincidence method (the multiple $$gamma$$-ray detection method) is a versatile method to achieve high resolution and high signal-to-noize ratio in nuclide determination. To extend this method we propose the X-ray coincidence method (the multiple X-ray detection method). We present a result of this method by using two low energy photon spectrometers and a standard $$gamma$$-ray source of $$^{152}Eu$$ for activation of atoms. We could observe a peak in two dimensional X-ray matrix, which originates from coincidence of K-X and L-X rays. We demonstrated that background is reduced on the matrix.

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