Development of fast measurement system of neutron emission profiles using digital signal processing technique

Ishikawa, Masao; Itoga, Toshio*; Okuji, Toshio*; Nakhostin, M.*; Baba, Mamoru*; Shinohara, Koji; Hayashi, Takao; Sukegawa, Atsuhiko; Nishitani, Takeo

Line-integrated neutron emission profiles are routinely measured using Stilbene neuron detectors (SNDs) in JT-60U tokamak. Although the SND has excellent pulse shape discrimination (PSD) property between neutrons and rays, the maximum count rate is limited up to 10 cps due to its analog circuit. To overcome this issue, a digital signal processing (DSP) system using a flash ADC has been developed. In this system, anode signals from the photomultiplier of the SND are directory stored and digitized in the Flash ADC. Then, the PSD is performed using software. The DSP system has been installed in JT-60U and started to measure neutrons in deuterium experiments. As a result, it is confirmed that the DSP system is successfully measured neutron fluxes with count rate up to 10 cps.