REACTION RATE SENSITIVITY OF {sup 44}Ti PRODUCTION IN MASSIVE STARS AND IMPLICATIONS OF A THICK TARGET YIELD MEASUREMENT OF {sup 40}Ca({alpha}, {gamma}){sup 44}Ti

Journal Article · Tue Jun 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/715/2/1383· OSTI ID:21486860

Hoffman, R D; Sheets, S A; Burke, J T; Scielzo, N D; Norman, E B; Tumey, S; Brown, T A; Grant, P G; Hurst, A M; Stoyer, M A; Wooddy, T; Fisker, J L; Bleuel, D ^[1]; Rauscher, T ^[2]; Phair, L ^[3]

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1. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551 (United States)
2. Department of Physics, Basel University, Basel (Switzerland)
3. Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

We evaluate two dominant nuclear reaction rates and their uncertainties that affect {sup 44}Ti production in explosive nucleosynthesis. Experimentally we develop thick target yields for the {sup 40}Ca({alpha}, {gamma}){sup 44}Ti reaction at E {sub {alpha}} = 4.13, 4.54, and 5.36 MeV using {gamma}-ray spectroscopy. At the highest beam energy, we also performed an activation measurement which agrees with the thick target result. From the measured yields a stellar reaction rate was developed that is smaller than current statistical-model calculations and recent experimental results, which would suggest lower {sup 44}Ti production in scenarios for the {alpha}-rich freezeout. Special attention has been paid to assessing realistic uncertainties of stellar reaction rates produced from a combination of experimental and theoretical cross sections. With such methods, we also develop a re-evaluation of the {sup 44}Ti({alpha}, p){sup 47}V reaction rate. Using these two rates we carry out a sensitivity survey of {sup 44}Ti synthesis in eight expansions representing peak temperature and density conditions drawn from a suite of recent supernova explosion models. Our results suggest that the current uncertainty in these two reaction rates could lead to as large an uncertainty in {sup 44}Ti synthesis as that produced by different treatments of stellar physics.

• OSTI ID: 21486860
• Journal Information: Astrophysical Journal, Vol. 715, Issue 2; Other Information: DOI: 10.1088/0004-637X/715/2/1383; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
ALPHA REACTIONS
CALCIUM 40 TARGET
CROSS SECTIONS
GAMMA SPECTROSCOPY
NUCLEOSYNTHESIS
REACTION KINETICS
STATISTICAL MODELS
SUPERNOVAE
TITANIUM 44
TITANIUM 44 TARGET
VANADIUM 47
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BINARY STARS
CHARGED-PARTICLE REACTIONS
ELECTRON CAPTURE RADIOISOTOPES
ERUPTIVE VARIABLE STARS
EVEN-EVEN NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
KINETICS
MATHEMATICAL MODELS
MINUTES LIVING RADIOISOTOPES
NUCLEAR REACTIONS
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
SPECTROSCOPY
STARS
SYNTHESIS
TARGETS
TITANIUM ISOTOPES
VANADIUM ISOTOPES
VARIABLE STARS
YEARS LIVING RADIOISOTOPES