The nucleosynthesis of /sup 180/Ta

Technical Report · Fri Jun 12 04:00:00 EDT 1987

OSTI ID:5827960

Kellogg, S E

It has been proposed that the abundance of nature's rarest isotope, /sup 180/Ta, could be quantitatively accounted for in the standard stellar slow (s) and/or rapid (r) neutron-capture processes through the existence of small, previously unmeasured ..beta..-branches which drain and feed the population of the t/sub 1/2/ = 5.5 hour isomer of /sup 180/Hf. We have conducted a series of experiments designed to measure these small ..beta..-branches. We have: measured the direct (isomer-to-isomer) 214-keV-endpoint ..beta.. branch from /sup 180/Hf/sup m/ to /sup 180/Ta/sup m/ to be f/sub ..beta../ = 0.30 +- 0.07 +- 0.07%, observed a new ..gamma.. ray in the decay of /sup 180/Hf/sup m/ which indicated a small ..beta..-branch of 0.023% to an excited state in /sup 180/Ta, established a stringent limit of 0.023% on the fraction f/sub m/ of /sup 180/Lu decays which populate /sup 180/Hf/sup m/, sought to identify a possible high-spin, short-lived isomer of /sup 180/Lu, and established upper limits on its possible half-life, established limits on the /sup 180/Ta/sup m/ photodeexcitation cross-section via resonant and nonresonant processes, and calculated upper-limits on the life-time of /sup 180/Ta/sup m/ in a stellar environment. Taken together, this body of work makes it unlikely that the previous proposal can account for the observed solar-system abundance of /sup 180/Ta. Other possible production schemes are reviewed and directions for further research are suggested. 97 refs., 53 figs., 14 tabs.

• Research Organization: Washington Univ., Seattle (USA)
• DOE Contract Number: AC06-81ER40048
• OSTI ID: 5827960
• Report Number(s): DOE/ER/40048-199-L7; ON: DE88003361
• Country of Publication: United States
• Language: English

Related Subjects

651820* -- Nuclear Properties & Reactions
A=150-189
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALI METAL ISOTOPES
BARYON REACTIONS
BETA DECAY
BETA DECAY RADIOISOTOPES
BETA SPECTRA
BETA-MINUS DECAY RADIOISOTOPES
BRANCHING RATIO
CESIUM 113
CESIUM ISOTOPES
CHEMICAL ANALYSIS
CROSS SECTIONS
DAYS LIVING RADIOISOTOPES
DECAY
ELECTROMAGNETIC RADIATION
ELECTRON CAPTURE RADIOISOTOPES
ENERGY LEVELS
EQUILIBRIUM
EVEN-ODD NUCLEI
GAMMA RADIATION
HADRON REACTIONS
HAFNIUM 180 TARGET
HALF-LIFE
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LUTETIUM 180
LUTETIUM ISOTOPES
MINUTES LIVING RADIOISOTOPES
NANOSEC LIVING RADIOISOTOPES
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEOSYNTHESIS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PROTON DECAY RADIOISOTOPES
QUANTITATIVE CHEMICAL ANALYSIS
R PROCESS
RADIATIONS
RADIOCHEMICAL ANALYSIS
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
S PROCESS
SPECTRA
STAR EVOLUTION
SYNTHESIS
TANTALUM 180
TANTALUM 180 TARGET
TANTALUM ISOTOPES
TARGETS
THERMAL EQUILIBRIUM
TIN 113
TIN ISOTOPES