Usage of a capillary plate as a pre-gas-amplification device for a neutron microstrip gas chamber

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

A capillary plate (CP) comprising an assembly of fine glass tubes was applied as a pre-gas-amplification device for a microstrip gas chamber (MSGC) operating under high-gas pressure of helium-3 for use in neutron detection. The collection efficiency of the electrons between the CP and MSGC was maximally 17% using neutrons. The effective gas gain of the detector system was 600 at a gas pressure of 3 atm with a 10% mixture of ethane with helium-3, confirming the feasibility of the CP as a pre-gas-amplification device. Moreover, we demonstrated that the coincidence measurement of the signals between the CP and the anodes of MSGC decreased the background levels of electronics noise, electronic discharges, and -rays, indicating that a detector system with a low background can be constructed using the CP.