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

[摘要] 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 excellenttrack reconstruction capability of the TPC enables powerful background rejection.The construction and performance of the TPC, as well as the experimentalfeatures for background control are described. The TPC with its lead shielding has been installed in the Gotthard Tunnel Underground Laboratoryin May 1990. Results from early background measurements using 5 atm of xenon depleted in ^(136)Xe are presented. Based on the background data, theprojected 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.

[发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy

[关键词] Physics