Determining the Energy Resolution of BGO Scintillator Crystals as a Detector for ProRad*

In an attempt to further understand the Proton Radius Puzzle, the ProRad experiment at IPN Orsay seeks to measure the electric form factor of the proton with a much higher precision than before. To do this, they must construct a detector capable of taking precise enough measurements. The purpose of this project was to test Bismuth Germanate Oxide (BGO) crystals from two different manufacturers to use as a scintillator detector. Additionally, two different light insulations for the crystals were tested. Using a ¹³⁷Cs radioactive source, the energy deposit spectrum of the crystal was measured and used to determine the energy resolution of the crystals. Using this method, the energy resolution was measured at different points along the crystal to make sure that the resolution was independent of where the radiation hit the crystal, an important trait for them to have. The findings will provide ProRad with insight on the optimal crystal to build their detector with and will also provide an experimental setup to quality test the crystals that they order for the detector.