A search for double beta decay in ^(136)XE with a time projection chamber

• Main Author: Wong, Henry Tsz-king
• Format: Others
• Language: en
• Published: 1991
• Online Access: https://thesis.library.caltech.edu/6284/1/Wong_ht_1991.pdf; Wong, Henry Tsz-king (1991) A search for double beta decay in ^(136)XE with a time projection chamber. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/w3rp-hf50. https://resolver.caltech.edu/CaltechTHESIS:04112011-094939243 <https://resolver.caltech.edu/CaltechTHESIS:04112011-094939243>

This thesis describes an experimental study of both the Ov and 2v double beta decay in ^(136)Xe with a Time Projection Chamber (TPC). The excellent track reconstruction capability of the TPC enables powerful background rejection. The construction and performance of the TPC, as well as the experimental features for background control are described. The TPC with its lead shielding has been installed in the Gotthard Tunnel Underground Laboratory in May 1990. Results from early background measurements using 5 atm of xenon depleted in ^(136)Xe are presented. Based on the background data, the projected sensitivities to the Ov and 2v modes with one year of run time in 60% enriched ^(136)Xe are 3.2 x 10^(23) years and 1.2 x 10^(21) years, respectively. Both numbers represent an order of magnitude improvements over previous experiments. Adopting the nuclear matrix elements from Vogel, the Ov sensitivity implies a Majorana neutrino mass parameter of 4.5 eV.