PYXIS neutron detector prototype: from raw events to physics

The MoNA collaboration at the Facility for Rare Isotope Beams (FRIB) studies netron-rich isotopes along the neutron dripline using the MoNA-LISA modular array. Each of the 288 MoNA-LISA bars consists of 10x10x200 cm3 organic plastic scintillator coupled to two photo-multiplier tubes (PMT) each placed on either end. A novel position sensitive scintillator detector design was proposed as part of the Physicists Inspiring the Next Generation (PING) program. A prototype of this PYXIS detector that consists of two modules was strategically positioned beside the MoNA-LISA array to detect neutrons emerging at larger polar angles during the first two experiments conducted by this collaboration at FRIB during the Summer of 2025. Each PYXIS module consists of a scintillating bar measuring 5x5x25 cm3 with a 8x8 position sensitive photomultiplier tube placed on each end. The 64-channel PMTs are used in order to improve the position reconstruction accuracy. A dedicated data acquisition (DAQ) system was developed to acquire the data in addition to an unpacker to convert the raw data into ROOT file(s) for the data analysis. The PYXIS data are being compared with the MoNA—LISA data to determine its performance. A review of the DAQ, unpacker and preliminary analysis of the PYXIS prototype detector will be presented and discussed.