Development of a new detector and DAQ systems for iBIX

Abstract

A new photon-counting 2D detector and time-of-flight (TOF) data-acquisition (DAQ) electronics were developed as a system for iBIX diffractometer in J-PARC. The detector system is composed of two ceramic ZnS/ 10B 2O 3 scintillator sheets, 256×2 wavelength-shifting (WLS) fibers, eight 64 ch multi-anode photomultipliers (PMT), a high-speed 512-channel amplifier and discriminator, and a 512-channel encoder module with FPGA for time and position determination. The scintillator sheets have high detection efficiency, 30% and 45% at 1.8 Å for 0.2 and 0.3 mm in thickness, respectively. The WLS fibers (0.5-mm square type) are arranged along X and Y directions with gaps of 0.02 mm; therefore the size of one pixel is 0.52 mm. The PMT have 17% of quantum efficiency for the light from WLS fibers. The detective region (133×133 mm 2) has more than 66% in the front face of the detector. The amplifier and discriminator module has 300 MHz of frequency band, fixed gain (60), and 20–300 mV of discriminator level. The encoder module has many coincidence modes including various pattern-matching methods and a centroid-computation method. The pulse-pair resolution is 4–5 μs. For the DAQ module, we can use both of histogram and event modes for measurement. The recording rate is 5×10 5 events/s for the event mode. Maximum number of the time-channel bins is 4096 for the histogram mode.