Experimental study of the /sup 3/He(n,. gamma. )/sup 4/He reaction

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5984050

Ward, L B

An investigation of fast neutron capture by /sup 3/He has been undertaken. In an effort to resolve major discrepancies in the published values for the total /sup 4/He(..gamma..,n)/sup 3/He cross section, the 90/sup 0/ cross section of the /sup 3/He(n,..gamma..)/sup 4/He reaction was measured for incident neutron energies ranging from 6.0 MeV to 18.0 MeV, corresponding to excitation energies of 25.1 MeV to 34.1 MeV in /sup 4/He. These data when converted by the principle of detailed balance implies a total /sup 4/He(..gamma..,n)/sup 3/He cross section of approx. 1 mb throughout the energy region. This result agrees with the most recently published (..gamma..,n) data, but is in disagreement with earlier published values. When combined with published /sup 4/He(..gamma..,p)/sup 3/H cross section data, a (..gamma..,p) to (..gamma..,n) cross section ratio is obtained which rises from approx. 1 at E/sub x/ = 34 MeV to approx. 1.8 at E/sub x/ = 25 MeV. This result is not predicted by current reaction theories as applied to this nucleus, and has been used by some authors to infer the existence of a Charge Symmetry Breaking component of the nuclear force. Comparison of this result is made to calculations. Angular distributions of cross section and analyzing power were measured at a neutron energy of 9 MeV. The cross section was measured at 7 angles and the analyzing power at 3 angles. An analysis was made based on the assumption that only S = 0.1 E1 and S = 0 E2 transition matrix elements contribute to the reaction. This analysis suggests that there is about the same relative S = 1 to S = 0 E1 strength for the /sup 3/H(p,..gamma..)/sup 4/He and the /sup 3/He(n,..gamma..)/sup 4/He reaction and that the E2 amplitude is about the same magnitude for both reactions.

• Research Organization: North Carolina State Univ., Raleigh (USA)
• OSTI ID: 5984050
• Country of Publication: United States
• Language: English

Related Subjects

651225* -- Nuclear Properties & Reactions
A=1-5
Experimental-- Nuclear Reactions & Scattering-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANALYZING POWER
ANGULAR DISTRIBUTION
BARYON REACTIONS
C INVARIANCE
CAPTURE
CROSS SECTIONS
DATA
DISTRIBUTION
ELEMENTARY PARTICLES
ENERGY RANGE
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
HADRON REACTIONS
HELIUM 3 TARGET
HELIUM 4
HELIUM ISOTOPES
INFORMATION
INVARIANCE PRINCIPLES
ISOTOPES
LIGHT NUCLEI
MASSLESS PARTICLES
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 01-10
MEV RANGE 10-100
NEUTRON REACTIONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUMERICAL DATA
PHOTONS
STABLE ISOTOPES
TARGETS