Speaker
Description
The nuclear dipole polarizability is mainly governed by the dynamics of the giant dipole resonance and, assuming validity of the brink-Axel hypothesis, has been investigated along with the effects of the low-energy enhancement of the photon strength function for nuclides in medium- and heavy-mass nuclei. Cubic-spline fits to both data sets extrapolated down to a gamma-ray energy of 0.1 MeV show a significant reduction of the nuclear dipole polarizability for semi-magic nuclei, with magic numbers $N=$28, 50 and 82, which supports shell effects at high-excitation energies in the the quasi-continuum region. This work assigns $\sigma_{_{-2}}$ values as sensitive measures of long-range correlations of the nuclear force and provides a new spectroscopic probe to search for old'' andnew'' magic numbers at high-excitation energies.
