Improved micro-pixel detector element for neutron measurement under high pressure

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

We are currently developing a two-dimensional neutron detection system that can read out individual signals and consists of a micro-pixel detector element. By increasing the gas pressure, the spatial resolution and detection efficiency of a two-dimensional gas-based detector are improved but the output signal strength is decreased. Therefore, the supply voltage must be increased to obtain output signals under high pressure. In the present study, we have developed a micro-pixel detector element with a high-voltage resistance by an improved fabrication process. The voltage resistance of the element was improved, and the element could operate up to 750 V at a total pressure of 5 atm (4.1 atm of He and 0.9 atm of CF). The measured gas gain was found to be approximately 100, and the thermal neutron detection efficiency was estimated to be 70%. A flat-field image showed good homogeneity, and the average gain spread was about 8.7%.