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E2 interference effects in the 12C(α,γ0)16O reaction.
D B Sayre1, C R Brune, D E Carter
1Ohio University, Athens, Ohio 45701, USA. sayre4@llnl.gov
Physical Review Letters
|October 23, 2012
Summary
Researchers measured the E1-E2 interference sign between an E2 resonance and E1 strength for the first time. This study reveals constructive interference below the resonance energy, aiding in understanding nuclear reactions.
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Mechanics
Background:
- Understanding nuclear reactions requires characterizing the interplay between different excitation modes.
- Previous studies have not directly measured the interference sign between E1 and E2 nuclear strengths.
Purpose of the Study:
- To measure the E1-E2 interference sign between a specific E2 resonance and underlying E1 strength.
- To determine the nature of interference (constructive or destructive) at different energies.
Main Methods:
- Measurement of thick-target gamma-ray yields from a narrow resonance.
- Analysis of angular distributions of gamma rays at 45° and 135°.
- Evaluation of global S(E2) data within a specific energy range.
Main Results:
- The E1-E2 interference sign was measured for the first time, yielding an asymmetry parameter a=0.07±0.05.
- A positive asymmetry parameter indicated constructive interference at forward angles.
- Interference between the E2 resonance and E1 background was identified as constructive below the resonance energy.
Conclusions:
- The study successfully determined the E1-E2 interference sign, providing crucial data for nuclear models.
- The findings clarify the interference scenario, contributing to a better understanding of nuclear structure and reactions.
- The E2-E2 interference analysis yielded a specific value for the S(E2) parameter, S(E2)(300)=62(-6)(+9) keV b.
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