Development of a neutron-imaging detector based on pulse-height correlation between two superconducting tunnel junctions on a LiBO crystal

Nakamura, Tatsuya; Katagiri, Masaki; Chen, Y. E.*; Ukibe, Masahiro*; Okubo, Masataka*

Nuclear Instruments and Methods in Physics Research A, 559(2), p.766 - 768, 2006/04

https://doi.org/10.1016/j.nima.2005.12.131

We have been developing a position-sensitive neutron detector, which exhibits a high spatial resolution of the order of 10 microns and high detection efficiency. The analysis on the pulse-heights or on the time-delay between the STJs gives incident positions of the neutrons. In this paper, the response of the STJs/LBO neutron detector measured using a cold neutron beam is presented. The two STJs have the same size of 50 50 m and their distance is 1.3 mm. The count intensity in the correlation map varied depending on the incident position of the neutron beam which gives an evidence for the position-sensitivity of the detector. These experimental results were qualitatively understood by a simple solid-angle model.

Development of 2-d position-sensitive neutron detector with individual readout; Operation test and establishment of detection system by means of neutron beam

Tanaka, Hiroki; Yamagishi, Hideshi; Nakamura, Tatsuya; Soyama, Kazuhiko; Aizawa, Kazuya

JAERI-Research 2005-010, 16 Pages, 2005/04

JAERI-Research-2005-010.pdf:3.39MB

We have been developing the 2-d position-sensitive neutron detector with individual readout as next-generation-type detector system for neutron scattering experiments using intense pulsed neutron source. The detection system is designed to fulfill the specifications required for each neutron spectrometer, such as a count rate, efficiency, neutron/-ray ratio, a spatial resolution and a size, by using suitable detector heads. The fundamental and imaging performances of the developed system assembled with a Multi-wire proportional counter head were evaluated using a collimated neutron beam. The system worked stably for long hours at the gas pressure of 5 atm with a mixture of 30% CH (0.26 atm He)at gas gain of 450. The spatial resolutions were 1.4, 1.6 mm (FWHM) for a cathode- and a back strip- direction, respectively, considering a beam size. It was also confirmed that the spatial uniformity of the detection efficiency over the whole sensitive detection area was rather good, 8 % deviation from the average with the optimum discrimination level.

Development of a high-performance microstrip gas chamber with a capability of track discrimination for neutron detection

Nakamura, Tatsuya; Yamagishi, Hideshi; Masaoka, Sei; Soyama, Kazuhiko; Aizawa, Kazuya

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.336 - 341, 2004/08

https://doi.org/10.1016/j.nima.2004.05.008

A microstrip gas chamber (MSGC) with a capability of track discrimination for neutron detection was developed whilst ensuring the stability of the MSGC and fulfilling the specifications required for detectors using in high-flux reactors and high-intensity pulsed-neutron sources. The developed two-dimensional detector system comprises a MSGC with individual signal channel read-outs and a new instrument system with a capability of secondary-particle discrimination (InSPaD). The InSPaD identifies the particles -proton and triton- created in the nuclear reaction by a simple, fast and cost-effective method using the difference in the track length, and it enables a small amount of heavy gas such as with helium-3 to be used as the filling gas whilst achieving a high spatial resolution.

Neutron detection by superconducting tunnel junctions on a LiBO single-crystal absorber

Nakamura, Tatsuya; Katagiri, Masaki; Ukibe, Masahiro*; Ikeuchi, Takashi*; Okubo, Masataka*

Nuclear Instruments and Methods in Physics Research A, 520(1-3), p.67 - 69, 2004/03

https://doi.org/10.1016/j.nima.2003.11.222

We succeeded in detecting neutrons using superconducting tunnel junctions (STJs) fabricated on a single crystal of LiBO. Neutrons are captured in the crystal by the nuclear reactions Li + n T+ + 4.78 MeV and B + n Li + + 2.3 MeV, and generated phonons propagate in the absorber and are measured by the STJs. We selected a single crystal of LiBO as the absorber material because of properties such as the large neutron cross-section of Li and B, low -ray sensitivity, short particle range in the substrate, and fast phonon velocity. Series-connected or multiple STJs on the crystal would enable two-dimensional neutron imaging with high detection efficiency, low gamma-ray background, and a high spatial resolution of a few microns. We demonstrate neutron detection by the STJs and show their X-ray response and neutron detection. The correlation in pulse heights between two junctions located 1.3mm apart clearly indicates the possibility of neutron imaging.

Dosimetry for 3-45 MeV/u ion beams using thin film dosimeters

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki; Hanaya, Hiroaki; Tachibana, Hiroyuki*

JAERI-Review 2002-035, TIARA Annual Report 2001, p.123 - 124, 2002/11

Thin film dosimeters of about 10-200 mm in thickness, which were well -characterized for Co -rays or 2-MeV electrons, have been applied to dosimetry for ion beams. For development of dosimetry covering the dose range of 0.005 to 200 kGy with high precision within 5%, the linear energy transfer (LET) characteristics of thin films were studied involving development of precise fluence measurement. Dose mapping technique was also developed achieving high spatial resolution values of about 1m and 10m for lateral and depth directions respectively. The outline of the recent development is summarized in this paper.

Design and characteristics of the JRR-3M thermal neutron radiography facility and its imaging systems

Matsubayashi, Masahito; Kobayashi, Hisao*; Hibiki, Takashi*; Mishima, Kaichiro*

Nuclear Technology, 132(2), p.309 - 324, 2000/11

https://doi.org/10.13182/NT00-A3146

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