[sup 8]Li burning and primordial nucleosynthesis

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7295985

Mao, Z

A QCD phase transition in the early universe may have led to inhomogeneities in the density of baryons. The nucleosynthetic yield from an inhomogeneous big bang might be fundamentally different from that expected within the framework of a standard big bang; nuclei more massive than [sup 7]Li could be produced via the [sup 8]Li ([alpha],p)[sup 11]B reaction. The rate of [sup 8]Li([alpha],n)[sup 11]B-a reaction which direct the flow of nucleosynthesis toward heavy elements is unknown at astrophysical temperatures. This thesis pursues indirect measurements and theoretical calculations to determine rates for the [sup 8]Li([alpha],n)[sup 11]B and [sup 8]Li(n,[gamma])[sup 9]Li reactions. States in [sup 12]B were studied using the high resolution QDDD spectrometer. Excitation energies, total widths and spins were measured using the [sup 9]Be([alpha],p)[sup 12]B and [sup 11]B(d,p)[sup 12]B reactions at E[sub [alpha]] = 35 and 40 MeV, and E[sub d] = 26 MeV, using self-supporting [sup 9]Be and [sup 11]B targets. The excitation energies have been determined to within [+-]5 keV for states of interest in [sup 12]B. Total widths for the states were extracted, and tentative spin-parity assignments were obtained. The [sup 9]Be([alpha],p)[sup 12]B*(n)[sup 11]B*([gamma])[sup 11]B coincidence reaction was used to measure the decay neutron and neutron-delayed gamma rays, using a 29-MeV DC [alpha] beam. The relative neutron partial widths for the states were obtained. The resonant rate from all the resonant states at astrophysical energies has been obtained experimentally for the [sup 8]Li([alpha],n)[sup 11]B reaction. Shell model calculations were used to predict the spectroscopic properties for low-lying states in [sup 9]Li. New estimates were obtained for the rate of the presumed important leakage reaction, [sup 8]Li(n,[gamma])[sup 9]Li. The astrophysical implications were discussed of the new rates for the [sup 8]Li(n,[gamma])[sup 9]Li and [sup 8]Li([alpha],n)[sup 11]B reactions.

• Research Organization: Drexel Univ., Philadelphia, PA (United States)
• OSTI ID: 7295985
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
LITHIUM 8 REACTIONS
REACTION KINETICS
NUCLEOSYNTHESIS
ALPHA REACTIONS
ASTROPHYSICS
BARYONS
BORON 11
COSMOCHEMISTRY
LITHIUM 9
PHOTONUCLEAR REACTIONS
SHELL MODELS
ALKALI METAL ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BORON ISOTOPES
CHARGED-PARTICLE REACTIONS
CHEMISTRY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEAVY ION REACTIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LITHIUM ISOTOPES
MATHEMATICAL MODELS
MILLISEC LIVING RADIOISOTOPES
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES
SYNTHESIS
663450* - Heavy-Ion-Induced Reactions & Scattering- (1992-)
700360 - Fusion Reactions- (1992-)