Abstract
The reaction was studied from MeV corresponding to MeV in covering the region of the lowest states as well as the giant dipole resonance (GDR). The reaction measurements were extended for excitation regions from MeV thus covering the analogous regions in and . Angular distributions obtained in the first reaction at the resonance energies of MeV indicated large negative coefficients in all cases. The new narrow ( keV) resonance at 6.925 MeV has and . A careful comparison of the and reactions is used to extract the components of the GDR in . Most of the strength is located near MeV. A microscopic calculation of states with in a 2h-1p and 1h basis of good isospin gives good agreement with the observed depleted values from the lowest states and reproduces the location of the collective states near 26 MeV. It also describes well the distribution of collective strength. Using this agreement with the theory which contains no adjusted parameters an effective symmetry potential of MeV is extracted from the isospin energy splitting. This value is smaller than the typical 60 MeV found in heavier nuclei but agrees with a recent model-independent limit and with other cases of nuclei.
NUCLEAR REACTIONS , , MeV, measured , angular distributions. , , MeV, measured . Calculated 2h-1p, 1h states of and . Deduced location of component of GDR and effective symmetry potential.
- Received 13 August 1975
DOI:https://doi.org/10.1103/PhysRevC.12.1410
©1975 American Physical Society