Speaker
Description
Oak Ridge National Lab (ORNL)’s Electron-Proton/Ion Collider (ePIC) group works on the production and testing of the ePIC LFHCalorimeter. This calorimeter is longitudinally segmented, containing 62,424 read out channels; it will be located in the forward going direction of ePIC. Each module of the calorimeter consists of 65 layer assemblies, made of 8 scintillator tiles placed over a Silicon Photomultiplier (SiPM) flexible PCB board. Over the summer one of these modules was constructed, with most of the process being done in-house with the exception of the production of the materials. The completed module was then sent to CERN’s PS beamline for testing, which took place from August 28 to September 11, 2024.
Each SiPM board was individually tested using a LED inside a dark box so that we could fit their Single Photon Spectrums (SPS). The script used to do this reads multiple files of data, compiles them into a single data frame, and then fits them using a multi-gaussian function. Fits that produce either too small of a Poisson distribution or too large of a standard deviation will then be discarded as these fits are either just electronic noise or not have distinctive enough peaks to read. The gain of the fits that pass this filter are then collected and grouped together by their respective channel. These groups are then fitted to a linear regression model to get the gain of the SiPM channel as a function of the over voltage used. This allows us to calibrate the ADC to the number of photons detected in a single event. While fitting the SPSs we began cosmics testing, for which we stacked 8 layer assemblies together and let them collect MIPS. This allowed us to see what was the most common ADC the readout unit collected, then we could translate that to the number of photo-electro using the gain that was found from the SPSs.
