Date of Award
Doctor of Philosophy (PhD)
High Purity Germanium (HPGe) detectors are widely used in rare-event physics searches for dark matter, neutrinoless double-beta decay, and solar neutrinos. This dissertation fo- cuses on improving crystal quality by controlling the impurity concentration, dislocation density, and growth environment as well as developing advanced Ge detectors for various physics applications. The dissertation presents experimental investigations of electrical conduction mechanisms in p-type amorphous germanium (a-Ge), which is used as an elec- trical contact material in HPGe detectors. By measuring the surface leakage current from three high-purity planar Ge detectors, we determine the localization length and hopping parameters in a-Ge. The dissertation also explores the possibility of using advanced Ge de- tectors to detect solar neutrinos. We investigate the potential of achieving internal charge amplification at cryogenic temperature, which could significantly reduce the energy reso- lution and energy threshold of Ge detectors. Finally, this dissertation discusses the charge trapping phenomenon of an n-type HPGe detector operated at 5.2 K. We investigate the trapping cross-section and binding energy of cluster dipole states in an HPGe detector, finding that the binding energy of cluster dipole states at 5.2 K is approximately 5 8 meV. This low energy level makes the detector ideal for detecting low-mass dark matter and solar neutrinos.
Materials Science and Engineering | Physics
High Purity Germanium (HPGe)
Number of Pages
University of South Dakota
Bhattarai, Sanjay, "DEVELOPMENT OF ADVANCED GERMANIUM DETECTORS FOR RARE EVENT PHYSICS" (2023). Dissertations and Theses. 141.