Abstract
Viable theoretical predictions of photon strength functions (PSFs) covering the whole nuclear chart are of great interest for different nuclear applications, including, in particular, nuclear astrophysics. Recently, such a global PSF model consisting of axially deformed Hartree-Fock-Bogolyubov (HFB) + quasiparticle random phase approximation (QRPA) calculations with the D1M Gogny interaction and a phenomenological low-energy contribution was proposed.
In the present paper, we test this model predictions against previously published data from measurements of multistep gamma cascades following neutron capture on isolated resonances performed with the DANCE detector. Such data present a stringent test of the PSFs models, in particular for the properties of the M1 scissors mode and the possible low-energy PSFs enhancement.
A detailed comparison is made for spectra obtained from resonances for spherical, quasispherical, and well-deformed nuclei. This comparison indicates that the location and strength of the scissors mode is reasonably described by the HFB + QRPA approach.
Moreover, a low-energy PSF contribution, not predicted by the HFB + QRPA calculation of the photoabsorption PSF, should be present in all nuclei. A systematics of this low-energy contribution, assumed in the M1 PSF, is proposed.