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Nonquenched Isoscalar Spin-M1 Excitations in sd-Shell Nuclei
H Matsubara1, A Tamii1, H Nakada2
1Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047, Japan.
Physical Review Letters
|September 19, 2015
Summary
Proton scattering experiments reveal no quenching in isoscalar spin-M1 transitions but significant quenching in isovector spin-M1 transitions for light nuclei. This finding aligns with observations in analogous Gamow-Teller transitions.
Area of Science:
- Nuclear Physics
- Particle Physics
Background:
- Spin-M1 transitions are crucial for understanding nuclear structure.
- Previous studies suggested quenching in certain nuclear transitions.
Purpose of the Study:
- To measure differential cross sections of isoscalar and isovector spin-M1 transitions.
- To deduce squared spin-M1 nuclear transition matrix elements.
- To compare experimental results with shell-model predictions.
Main Methods:
- High-energy-resolution proton inelastic scattering at 295 MeV.
- Measurements conducted on 24Mg, 28Si, 32S, and 36Ar nuclei.
- Analysis based on empirical unit cross sections and isospin symmetry.
Main Results:
- No quenching observed for isoscalar spin-M1 transitions (ratio 1.01(9)).
- Significant quenching found for isovector spin-M1 transitions (ratio 0.61(6)).
- Quenching in isovector transitions is comparable to Gamow-Teller transitions.
Conclusions:
- Experimental data supports shell-model predictions for isoscalar transitions.
- Isospin symmetry plays a role in understanding nuclear transition quenching.
- Findings provide insights into nuclear structure and reaction mechanisms.
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