Double beta decay in Ge sup 76

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7142321

Grumm, D M

Double beta decay in Ge{sup 76} was search for using a multi-detector germanium spectrometer system. The modes of decay searched for were {beta}{beta}{sub 0{nu}}(0{sup +} {yields} 0{sup +}), {beta}{beta}{sub 0{nu}}(0{sup +} {yields} 2{sup +}), {beta}{beta}{sub 2{nu}}, and {beta}{beta}{sub 0{nu}} with Majoron emission. Analysis of the neutrinoless modes allows stringent limits to be placed on physics beyond the standard electroweak model, including lepton number nonconservation, right-handed leptonic currents, and the coupling between the Majoron and the electron neutrino. The experiment, located in the powerhouse of the Oroville Dam in Northern California, employs the 660 foot overburden of the dam and 8 inch of lead as passive shielding and a 4{pi} anticoincidence shield of sodium iodide scintillators. The germanium detectors provide a relatively large number of nuclei of the {beta}{beta} decay candidate Ge{sup 76} (7.8% of the detector volume), offer good resolution (3.4 keV FWHM at the {beta}{beta}{sub 0{nu}} decay energy of 2.041 MeV), and low intrinsic background radioactivity. A comprehensive analysis of the components of the background radioactivity allowed the most stringent limits to be set on the lifetimes of the decay modes. The lower half-life limit of 7 {times} 10{sup 23} years for the {beta}{beta}{sub 0{nu}}(0{sup +} {yields} 0{sup +}) decay correspond to an upper limit of {approx} 1 eV for a massive Majorana neutrino, lower than any other experimental limit. The lower limit on the half-life of 1.4 {times} 10{sup 21} years for {beta}{beta}{sub 0{nu}} decay with Majoron emission corresponds to an upper limit of the Majoron-electron neutrino coupling <10{sup {minus}3}. Lower half-life limits of 1.3 {times} 10{sup 23} years and 1.9 {times} 10{sup 20} years were set for the {beta}{beta}{sub 0{nu}}(0{sup +} {yields} 2{sup +}) decay and {beta}{beta}{sub 2{nu}} decay respectively.

• Research Organization: California Univ., Santa Barbara, CA (USA)
• OSTI ID: 7142321
• Country of Publication: United States
• Language: English

Related Subjects

651100* -- Nuclear Physics-- Experimental Techniques-- (1980-)
651420 -- Nuclear Properties &amp; Reactions
A=20-38
Experimental
653005 -- Nuclear Theory-- Radioactive Decay
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BETA DECAY
BETA-MINUS DECAY
DATA
DATA ANALYSIS
DECAY
DOUBLE BETA DECAY
ENERGY RANGE
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
GERMANIUM 76
GERMANIUM ISOTOPES
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
KEV RANGE
MEASURING INSTRUMENTS
MEASURING METHODS
NUCLEAR DECAY
NUCLEI
NUMERICAL DATA
STABLE ISOTOPES