Measurement of the sup 8 Li(d,n) sup 9 Be and sup 8 Li(. alpha. ,n) sup 11 B reaction cross sections at astrophysical energies by radioactive beam techniques

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5833842

Corn, P B

A preliminary direct measurement of the {sup 8}Li(d,n){sup 9}Be cross section has been obtained by means of a radioactive beam facility used with the Lawrence Livermore National Laboratory FN van de Graaff accelerator. The cross section at a {sup 8}Li energy of 13.3 MeV agrees plausibly with values estimated from data for the reverse reaction, {sup 9}Be(n,d){sup 8}Li, and for the related {sup 7} Li(d,n){sup 8}Be reaction to within the large estimated experimental error. This result thus demonstrates the feasibility of the technique. In addition, a design for a similar radioactive beam measurement of the {sup 8}Li({alpha},n){sup 11}B reaction cross section is given. The two reactions figure prominently in network calculations for current inhomogeneous models of primordial nucleosynthesis in the early universe, and because of the short 838 millisecond half life of the radioactive {sup 8}Li nuclide, their cross sections have not been measured directly before. The radioactive beam apparatus employs a 16.0 MeV {sup 7}Li beam from the accelerator incident on a thin, deuterated polyethylene primary reaction target foil. A secondary beam containing {sup 8}Li produced in the {sup 7}Li(d,p){sup 8}Li reaction is concentrated by a spectrometer incorporating twin triplet magnetic quadrupole elements and an electrostatic dipole, and is focussed on a second deuterated polyethylene reaction target foil in which the reaction of interest takes place. Reaction products are identified and measured by means of a pair of surface barrier charged particle detector telescopes, and {sup 8}Li flux is measured via a CaF{sub 2} scintillator and photomultiplier tube at the rear of the detector chamber. Future efforts will use improved gas cell production and reaction targets and detector systems, and will focus in the near term on a definitive measurement of the {sup 8}Li(d,n){sup 9}Be cross section at several energies.

• Research Organization: Ohio State Univ., Columbus, OH (USA)
• OSTI ID: 5833842
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COSMOLOGY
NUCLEOSYNTHESIS
DEUTERON REACTIONS
THERMONUCLEAR REACTIONS
LITHIUM 8
ACCELERATORS
BERYLLIUM 9
COMPARATIVE EVALUATIONS
COSMOLOGICAL MODELS
CROSS SECTIONS
EXPERIMENTAL DATA
FEASIBILITY STUDIES
HALF-LIFE
MEASURING METHODS
MEV RANGE 10-100
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
BERYLLIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
DATA
ENERGY RANGE
EVEN-ODD NUCLEI
INFORMATION
ISOTOPES
LIGHT NUCLEI
LITHIUM ISOTOPES
MATHEMATICAL MODELS
MEV RANGE
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES
SYNTHESIS
640106* - Astrophysics & Cosmology- Cosmology
651320 - Nuclear Properties & Reactions
A=6-19
Experimental