Simulations through Geomega & GEANT4

This project aims to develop a detailed radiation simulation that will inform design parameters for the UVI-Gamma-Ray Experiment for Astrophysical Transients (UVI-GREAT) mission. This gamma-ray detecting instrument will focus on detecting sources like Gamma-Ray Bursts and other cosmological sources of gamma-rays from a high-altitude (100,000 ft) balloon flight aboard the High-Altitude Student Platform (HASP).

A key element of UVI GREAT is the scintillator crystal which detects the Gamma-rays from a GRB. When the GRBs occur, the light interacts with the crystal which then produces UV light that is converted into a digital signal and read by the SiPM (Silicon Photomultiplier). This research project focused on simulating the behavior of high energy photons as they interact with the UVI-GREAT instrument. Processes that are simulated include the photoelectric effect, Compton scattering, and pair production. To begin the research, MEGAlib and GEANT4(Cosima) were downloaded to simulate the high-energy Gamma-Ray photons that are produced by GRBs. Geomega, a package included in the MEGAlib software, was downloaded to create a simulation model of the scintillator crystal as well as define and specify properties such as the density, material, volume and shape while Cosima was used to simulate high energy Gamma-Ray particles at the simulation model. Cosima then records the amount of trigger events and save them to “sim” files which can only be read by REVAN(Real Event Analyzer). REVAN combines the Cosima (detectors) and Geomega (simulation model) file to produce detailed results on the events which aids in the ability of the UVI GREAT CubeSat to characterize GRBs.

Acknowledgement: NASA MIRO program grant #NNX15AP95A