A Micro pixel chamber based neutron imaging detector ( NID) with boron converter for energy-resolved neutron imaging at J-PARC

Parker, J. D.*; Shinohara, Takenao   ; Harada, Masahide   ; Hayashida, Hirotoshi*; Hiroi, Kosuke  ; Kai, Tetsuya   ; Matsumoto, Yoshihiro*; Oikawa, Kenichi   ; Segawa, Mariko   ; Su, Y. H.  ; Takada, Atsushi*; Taniguchi, Tomoyuki*; Tanimori, Toru*; Kiyanagi, Yoshiaki*

At the Energy-Resolved Neutron Imaging System RADEN of the J-PARC MLF, we take advantage of the accurate measurement of neutron energy by time-of-flight to perform energy-resolved neutron imaging. To carry out measurements at RADEN, we have been developing and testing cutting-edge detector systems employing micro-pattern detectors and high-speed, all-digital data acquisition systems. One such detector, the Micro Pixel Chamber based Neutron Imaging Detector (NID), provides a spatial resolution of less than 250 m FWHM, 26% detection efficiency for thermal neutrons with He for conversion, and count rate capacity of 8 Mcps. By replacing the He gas with a boron-based converter, we aim to increase the count rate capacity three-fold while maintaining good spatial resolution. This is made possible by the significantly reduced event size for the alpha from the B-neutron interaction as compared to the lighter proton and triton in the He case.