Beta decay and rhenium cosmochronology

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7296079

Ashktorab, K

Among the problems which limit the use of the [sup 187]Re/[sup 187]Os isobaric pair as a cosmochronometer for the age of the galaxy and the universe are the uncertainties in the partial half-lives of the continuum and bound state decays of [sup 187]Re. While the total half-life of the decay is well established, the partial half-life for the continuum decay is uncertain, and several measurements are not compatible. A high temperature quartz proportional counter was used in this work to remeasure the continuum [beta][sup [minus]] decay of [sup 187]Re. The [beta] endpoint energy for the decay of neutral [sup 187]Re to singly ionized [sup 187]Os of 2.75 [+-] 0.06 keV agrees with the earlier results. The corresponding half-life of (45 [+-] 3) [times] 10[sup 9] years improves and agrees with the earlier measurement of Payne and Drever and refutes other measurements. Based on the new half-life for the continuum decay and a total half-life of (43.5 [+-] 1.3) [times] 10[sup 9] years reported by Linder et al., the branching ratio for the bound state decay into discrete atomic states is estimated to be (3 [+-] 6)% in agreement with the most recent calculated theoretical branching ratio of approximately 1%. Anomalies in beta spectra reported by J.J. Simpson and others have been attributed to a 17 keV heavy-neutrino admixture. If confirmed, the implications from the existence of such a neutrino for particle and astrophysics would be significant. A multiwire [open quotes]wall-less[close quotes] stainless steel proportional counter has been used in the present work to investigate the spectral shape of the [beta] decay of [sup 63]Ni. No anomalies in the spectral shape were observed which could be attributed to the presence of 17 keV heavy neutrino.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 7296079
• Country of Publication: United States
• Language: English

Related Subjects

663210* -- Ground-State Radioactivity-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
AGE ESTIMATION
BETA DECAY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY
BETA-MINUS DECAY RADIOISOTOPES
COSMOLOGY
DECAY
EVEN-ODD NUCLEI
GALAXIES
HEAVY NUCLEI
ISOBARIC NUCLEI
ISOTOPES
MILKY WAY
NUCLEAR DECAY
NUCLEI
ODD-EVEN NUCLEI
OSMIUM 187
OSMIUM ISOTOPES
RADIOISOTOPES
RHENIUM 187
RHENIUM ISOTOPES
STABLE ISOTOPES
UNIVERSE
YEARS LIVING RADIOISOTOPES