Year
2016
Abstract
A tin doped viscous gel scintillation material was developed to increase the peak to total ratio for gamma-ray detection. Detectors with such material would excel at many applications, including characterizing nuclear material for safeguards and nonproliferation. The material is an organo-metallic scintillator hydrocarbon base with tin totaling 20% to 30% by weight. The high electron density due to the tin increases the photoelectric absorption and Compton scatter cross sections, resulting in a high gamma detection efficiency and spectroscopic ability. The effect of electron density on the photopeak of a Cs-137 gamma spectrum is shown in Figure 1. The current iteration of the material has been characterized for its detection properties, including resolution, gamma collection efficiency, energy calibration, Full-width-half-maximum (FWHM) parameters, and pulse shape discrimination (PSD) performance. MCNP 6.1.1b simulations of the detector were performed to assist in understanding the underlying physics. The high gamma collection efficiency is essential for the addition of gadolinium dissolved into the material which will result in several MeV of gammas from thermal neutron absorption, thereby creating a unique neutron measurement signal with low background. Measurements of neutron sources were made to attempt identifying the fast neutron, thermal neutron, and gamma signals. Measurements were taken of Cf-252, PuBe, and the University of Florida Training Reactor (UFTR) thermal beam column sources. The measurements were repeated with Eljen Ej-309 detectors for comparison.