M.D. Shah, C. Marianno, S.P. Khatri, D.R. Boyle, “Simulation Analysis of Scintillation in Sodium Iodide Detector”, 55th Annual Meeting of the Institute of Nuclear Materials Management, Atlanta, Georgia, 20-14 July 2014.
This work investigates using a new type of integrated circuit (IC) as a replacement for photomultiplier tubes (PMT) used for interdiction scenarios. Existing PMTs for such missions can be large, fragile, and have complex power delivery requirements and high-energy consumption. While IC technology has advanced, circuits on these chips are becoming increasingly sensitive to radiation damage and therefore may fail to function properly. Researchers at A&M have designed ICs that contain both radiation sensitive and radiation resistant sectors on the same IC. These chips are extremely sensitive to charge particles (such as betas) that are produced at the photocathode. To effectively use these ICs as a PMT replacement, it is essential that an understanding is developed regarding the location and amount of betas produced on a photocathode. To better understand this process, the transport of visible photons was modeled in a 2′ x 4′ x 16′ NaI detector using Geant4. Simulation results were obtained using a pencil-beam of gammas at 70 keV and 1 MeV. It was observed that optical photons are denser on the surface through which the gammas enter the NaI. Future work will include an analysis of the photoelectrons produced by these optical photons, to accurately assess the capability of replacing PMTs with ICs.