Coincidence Detection for Neutron Activation Analysis

Citation

Lee, Patricia Jui-Ting (2000) Coincidence Detection for Neutron Activation Analysis. Senior thesis (Major), California Institute of Technology. doi:10.7907/ht1g-0a74. https://resolver.caltech.edu/CaltechTHESIS:01102018-103323300

Abstract

A new large neutrino detector called KamLAND (Kamioka Liquid scintillator AntiN eutrino Detector) is currently being constructed in the underground site in Japan that used to be the home of the Kamiokande experiment. The principal goal of this international collaboration will be to investigate neutrino oscillations by studying the flux and energy spectra of neutrinos produced by nuclear reactors in Japan. KamLAND will also be measuring solar neutrinos in an effort to solve the solar neutrino deficit puzzle. In addition, it is possible to extract the ratio of uranium to thorium in the crust and mantle of the Earth from the background of the reactor neutrino spectra.

To achieve high precisions in the measurements, KamLAND must first minimize its background signals. The collaborators at Caltech have been involved in measuring the radioactivity of the materials used in constructing the detector. Gamma sources in the materials are typically detected by placing them next to a Germanium detector in a wellshielded box. However, as will be shown in the next section, conventional detectors can not achieve the level of sensitivity necessary to detect the small amounts of radioactivity allowed in the KamLAND scintillator. The purpose of this thesis project is to design and build a coincidence setup that will be able to measure the radioactivity of the liquid scintillator at KamLAND using Neutron Activation Analysis of an irradiated sample.