Gamow-Teller strength from the sup 20 Ne( n , p ) sup 20 F reaction at E sub n =198 MeV

Journal Article · Sun Dec 01 04:00:00 EST 1991 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.44.2430· OSTI ID:5081644

Pointon, B W; Haeusser, O; Henderson, R; Celler, A; Hicks, K; Jackson, K P; Jeppesen, R; Larson, B; Mildenberger, J; Trudel, A; Vetterli, M; Yen, S ^[1]

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1. Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6 TRIUMF 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada) University of Western Ontario, London, Ontario, N6A 3K7 (Canada)

Cross sections for the {sup 20}Ne({ital n},{ital p}){sup 20}F reaction at {ital E}{sub {ital n}}=198 MeV were measured at five angles using the TRIUMF charge-exchange facility and a novel high-pressure (20 atm, or 2.03 MPa) gas target. The {ital L}=0, {ital L}=1, and {ital L}{ge}2 contributions to the cross sections were obtained from a multipole decomposition. Using an empirical proportionality between the cross section and Gamow-Teller (GT) strength from {beta} decay, GT strength was deduced up to an excitation of 10 MeV in {sup 20}F. Most of the strength is concentrated in a discrete state at {ital E}{sub {ital x}}=1.0 MeV, with the extracted strength of the {Delta}{ital L}=0 continuum at high excitation having a large error. These results are compared with measurements of GT strength using other probes. Comparison with the measured magnetic dipole ({ital M}1) strength in {sup 20}Ne shows that there is constructive interference between the spin part and a large orbital part of the {ital M}1 transition to the 11.26 MeV state in {sup 20}Ne (analog of the 1.0 MeV state in {sup 20}F). If all the strength from the multipole decomposition is used, we find agreement of the total GT strength compared to untruncated {ital sd} shell-model calculations which use free-nucleon operators, although experimental and theoretical distributions differ in detail. The confirmation of strong orbital {ital M}1 contributions at the beginning of the {ital sd} shell together with systematics of GT quenching in heavier {ital sd} shell nuclei may provide evidence for meson exchange currents in {ital M}1 transitions.

• OSTI ID: 5081644
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 44:6; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

663450* -- Heavy-Ion-Induced Reactions & Scattering-- (1992-)
663530 -- Nuclear Mass Ranges-- A=20-38-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHARGE-EXCHANGE REACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
FERMIONS
FLUORINE 20
FLUORINE ISOTOPES
GAMOW-TELLER RULES
HADRON REACTIONS
HADRONS
ISOTOPES
LIGHT NUCLEI
M1-TRANSITIONS
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 100-1000
MULTIPOLE TRANSITIONS
NEON 20 TARGET
NEUTRON REACTIONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
ODD-ODD NUCLEI
OSCILLATOR STRENGTHS
PROTONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
TARGETS