Cherenkov Glass Detectors for Gamma and Neutron Detection

Abstract

Cherenkov detectors have been developed and used in several fields since the discovery of Cherenkov radiation. They do have several advantages compared with other detector types, such as low noise due to the low-energy threshold of Cherenkov radiation, and short decay constant (on the order of picoseconds). However, the light yield of Cherenkov detectors is low. Only several hundreds of Cherenkov photons can be generated per MeV. The objective of this work is to manufacture and test Cherenkov glass detectors for detection of high energy gammas and neutrons. 60Co was used for gamma ray measurements, and PuBe source was used for neutrons measurements. Gd2O3 was used as an activator to capture thermal neutrons. As a result of this capture, gamma rays were generated and interacted with Cherenkov detectors to produce Cherenkov light. The focus was to improve the light output of Cherenkov detectors by adding high Z materials and implementing Wavelength Shifting (WLS) fibers inside the glass samples. Increasing the Z number of the glass samples increases the interaction probability, and without the WLS materials, most Cherenkov photons are likely to be absorbed within the glass sample before they could reach the photon sensor. WLS fibers do not directly increase the number of Cherenkov photons, but they can reduce the energy of Cherenkov photons and direct them towards the photon sensor. A Geant4 simulation toolkit was used to create a detailed model, and to understand and confirm that the measured observations were reasonable.