Citation
Fisher, Peter Harrison (1988) A Search for Double Beta Decay in ⁷⁶Ge. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/fmvr-y629. https://resolver.caltech.edu/CaltechTHESIS:01222013-110618869
Abstract
This thesis describes a search for the double beta (ββ) decay of ⁷⁶Ge using an array of eight high purity, high resolution germanium detectors containing a total of 3.9 x 10²⁴ ⁷⁶Ge nuclei. There are three modes of ββ decay: neutrinoless (0ѵ)ββ decay, ββ decay with Majoron emission (x⁰ββ decay) and two neutrino (2ѵ)ββ decay. The first two modes violate lepton number conservation, while the third is allowed by the Standard Model. 0ѵββ decay may take place to the ground state of the daughter nucleus (0⁺ → 0⁺ transition) or to an excited state of the daughter nucleus (0⁺ → 2⁺ transition). The detector was operated for a total time of 2033 h (0.23 y) which translates to 1.30 kg-y. The background at the ββ decay transition energy was 0.53 counts keV⁻¹ y⁻¹ (10²³ ⁷⁶Ge nuclei)⁻¹. No evidence for double beta decay of any sort was found and the half life limits are T0ѵ½(0⁺ → 0⁺) > 1.2 x 10²³ y, T0ѵ½(0⁺ → 2⁺) > 2 x 10²² y, Tχo½ > 8 x 10²⁰ y, and T2ѵ½ > 2 x 10²⁰ y, all at 90% c.l. The limit for the neutrinoless mode translates to an upper limit of between 16 and 1.6 eV on the Majorana mass of the neutrino, depending on the nuclear matrix element used.
Item Type: | Thesis (Dissertation (Ph.D.)) |
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Subject Keywords: | Physics |
Degree Grantor: | California Institute of Technology |
Division: | Physics, Mathematics and Astronomy |
Major Option: | Physics |
Thesis Availability: | Public (worldwide access) |
Research Advisor(s): |
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Thesis Committee: |
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Defense Date: | 1 February 1988 |
Record Number: | CaltechTHESIS:01222013-110618869 |
Persistent URL: | https://resolver.caltech.edu/CaltechTHESIS:01222013-110618869 |
DOI: | 10.7907/fmvr-y629 |
Default Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. |
ID Code: | 7420 |
Collection: | CaltechTHESIS |
Deposited By: | INVALID USER |
Deposited On: | 22 Jan 2013 19:36 |
Last Modified: | 16 Apr 2021 22:54 |
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