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Journal Articles

Simulation study on unfolding methods for diagnostic X-rays and mixed $$gamma$$ rays

Hashimoto, Makoto; Otaka, Masahiko; Ara, Kuniaki; Kanno, Ikuo; Imamura, Ryo*; Mikami, Kenta*; Nomiya, Seiichiro*; Onabe, Hideaki*

Journal of Nuclear Science and Technology, 46(1), p.76 - 82, 2009/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

A photon detector for unfolding X-ray energy distribution has been previously reported. Simulation studies on the unfolding method for this detector are discussed for diagnostic X-rays and mixed-source $$gamma$$ rays of $$^{137}$$Cs/$$^{60}$$Co. Response functions for diverse diagnostic X-rays are almost indistinguishable and an unfolding using error reduction method is not sufficiently worked. The spectrum surveillance method is effective in this case. However, a simple error reduction method is useful for mixed $$gamma$$ rays. For both techniques, the neural network method is promising.

JAEA Reports

Basic study on the development of low exposure CT with Frisch grid avalanche diode, JAERI's nuclear research promotion program, H13-011 (Contract research)

Imanishi, Nobutsugu*; Ito, Akio*; Kanno, Ikuo*; Yoshida, Koji*; Onabe, Hideaki*

JAERI-Tech 2005-007, 45 Pages, 2005/03

JAERI-Tech-2005-007.pdf:6.84MB

no abstracts in English

Oral presentation

Beam hardening free CT measurement method, 3; Feasibility study on current mode detector

Kanno, Ikuo*; Uesaka, Akio*; Otaka, Masahiko; Hashimoto, Makoto; Ara, Kuniaki; Nomiya, Seiichiro*; Onabe, Hideaki*

no journal, , 

The beam hardening free CT imaging, which is not effected with the size of speciman, was obtained with the energy and the energy differential of X-rays. However, measurement of X-ray energy in high density as in CT is hard. To solve this problem, current mode X-ray detector (CMD) was designed. CMD is configured with several detective elements aligned with X-ray fluence, and read the current from each detective element. Relatively low energy photon is mainly absorbed in front detective elements of CMD and high energy photon can reach to deep, rough X-ray spectrum can be expected with current from each element. The ability of CMD is examined by simulation. Current from each element with particular X-ray field was calculated. To evaluate the X-ray spectrum expectation from current readout are evaluated with two ways, one is using response matrix solution, and the other is unfolding with SAND-II. It looks represent the iodine effective thickness.

Oral presentation

X-ray measurement and energy estimation with current mode detector

Hashimoto, Makoto; Mikami, Kenta*; Uesaka, Akio*; Kanno, Ikuo; Otaka, Masahiko; Ara, Kuniaki; Nomiya, Seiichiro*; Onabe, Hideaki*

no journal, , 

X-ray energy spectrum measurement in a short time is necessary for CT picture measurement with energy difference method. For this purpose, current mode detector, which is applied X-ray detectors used with current mode and can obtain rough X-ray energy spectrum, is examined. X-ray detector array is used as the electric current mode detector and unfolding of output of the detector to energy spectrum is studied. Furthermore, optimized detector array constitution is also discussed.

Oral presentation

A Comparison between neutron diffraction and EBSD images for a TlBr crystal

Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Ito, Chikara; Tanno, Takashi; Onabe, Hideaki*

no journal, , 

TlBr is a compound semiconductor with a high atomic number, high density and a wide bandgap, and is being developed as a gamma-ray detector material that can be operated at room temperature and has high detection efficiency. There is neutron diffraction in order to establish a crystal quality evaluation method for improving the yield in device fabrication, but the facilities that can be implemented are limited to large facilities such as J-PARC. The Electron Backscatter Diffraction (EBSD) image, which is one of the electron beam diffractions, can be obtained with an electron microscope, but only the information on the crystal surface can be obtained. In this study, the crystal orientation image was acquired for the TlBr crystal by neutron Bragg dip imaging, which is one of the neutron diffractions, and EBSD. By comparing both images, the applicability to a simple EBSD crystal quality evaluation method was examined.

Oral presentation

Observation of crystal origentation distribution of TlBr in crystal growth direction

Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Onabe, Hideaki*

no journal, , 

TlBr is a compound semiconductor with a high atomic number and density, and a wide bandgap. TlBr detector is being developed as a gamma-ray detector material that can operate at room temperature and has high detection efficiency. The current issue is to improve the yield in device manufacturing, and it is required to establish a process that can stably manufacture high quality devices. The crystal growth process is one of the most important processes in producing a good quality detector, and it is very important to understand how crystals are grown. This time, we tried to obtain knowledge about crystal growth by observing the crystal orientation distribution in the crystal growth direction.

Oral presentation

Crystal quality evaluation of a large TlBr crystal using neutron Bragg-dip imaging

Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Onabe, Hideaki*

no journal, , 

Thallium bromide (TlBr) is a compound semiconductor attractive for gamma-ray spectrometers. TlBr detectors have shown excellent energy resolution, however, these results were obtained from relatively small crystal detectors. The next phase of TlBr development is to increase the detector size and improve the yield rate of detector production. So far, we have evaluated crystal quality of TlBr by using the neutron Bragg-dip imaging, which is one of the neutron diffraction techniques. In this study, we prepared a large TlBr crystal wafer with a diameter and thickness of 50 mm and 12 mm, respectively. We evaluated the quality of the large crystal by the neutron Bragg-dip imaging. The center region of the large TlBr crystal confirmed to be uniform and well-aligned. As a future work, we will evaluate the electric properties, such as the mobility-lifetime product, at various positions in this large crystal.

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