Software to predict and analyze neutron scattering patterns in the MoNA and PYXIS Array

The Modular Neutron Array (MoNA) and Large multi-Institutional Scintillator Array (LISA) is a neutron detector built and used by the MoNA Collaboration at the Facility for Rare Isotope Beams (FRIB). Each array consists of 144 individual 200x10x10 cm3 plastic scintillator bars with photomultiplier tubes and light guides at each end that can be easily reconfigured to match the experiment requirements. The MoNA-LISA array is typically located about 5-10 m away from the target, thus detecting forward focused neutrons.

Physicists Inspiring the Next Generation: Exploring the Nuclear Matter (PING) at FRIB used pre-college and undergraduate students to design, characterize and test two 25x5x5 cm3 plastic scintillator prototype modules to complement the MoNA-LISA detector. This PYXIS detector uses 8x8 matrix position sensitive photomultiplier tubes placed on each end of the bars The main goal of PYXIS is to capture lower energy neutrons at higher scattering angles with the additional possibility to surround the target at a closer distance, possible due to its small size. These modules were placed in the S2 vault during experiments e23033 and e23038 conducted by the MoNA Collaboration in the summer 2025 and data were collected and compared with the MoNA-LISA neutron array.

A dedicated data analysis program was developed to analyze and graph the data generated by the PYXIS array. Written in Python 3, this program is able to take root files generated by experiment or through Geant4 simulations of the arrays and parse them to display a heatmap, 3D scatterplot, or angular distribution of neutron events. The program is also able to generate a gaussian or random distribution of points to parse without requiring outside input of data. In the future, this program will have added functionality to make browsing root files easier, the ability to parse multiple root files at one time, built-in statistical analysis of data, and an improved GUI to aid in utilization by all PING students.