Radiative decays of the 16.6 and 16.9 MeV states in {sup 8}Be and tests of the conservation of the vector current in the {ital A}=8 multiplet

Journal Article · Mon May 01 04:00:00 EDT 1995 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.51.2778· OSTI ID:44718

De Braeckeleer, L; Adelberger, E G; Gundlach, J H; Kaplan, M; Markoff, D; Nathan, A M; Schieff, W; Snover, K A; Storm, D W; Swartz, K B; Wright, D ^[1]; Brown, B A ^[2]

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1. Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States)
2. Department of Physics, Michigan State University, East Lansing, Michigan 48823 (United States)

We measured the {sup 4}He({alpha},{gamma}) cross section at {theta}{sub {gamma}}=90{degree} across the 16.6 and 16.9 MeV resonances in {sup 8}Be and obtained angular distributions on the peaks of both resonances. The decays of the 16 MeV doublet to the 3.0 MeV 2{sup +} final state have an (isovector {ital E}2)/(isovector {ital M}1) mixing ratio of (0.01{plus_minus}0.03), an (isoscalar {ital E}2)/(isovector {ital M}1) mixing ratio of (0.21{plus_minus}0.04), and an isovector {ital M}1 width of (2.80{plus_minus}0.18) eV. Our result for the isovector {ital E}2 strength disagrees markedly with previous work. We observe ground-state {ital E}2 decays of both members of the doublet. We use our results, plus existing {sup 8}Li and {sup 8}B {beta}-decay data, to test the conservation of the vector current and to constrain the second-class induced-tensor form factor. Finally, we compare our results to shell-model calculations.

• OSTI ID: 44718
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 5 Vol. 51; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ALPHA REACTIONS
ANGULAR DISTRIBUTION
BERYLLIUM 8
BETA DECAY
BORON 8
CROSS SECTIONS
E2-TRANSITIONS
FORM FACTORS
GROUND STATES
HELIUM 4 TARGET
LITHIUM 8
MEV RANGE 10-100
MIXING RATIO
PHOTONS
RADIATIVE DECAY
SHELL MODELS
VECTOR CURRENTS