Constraints on the dipole photon strength functions from experimental multistep cascade spectra

Viable theoretical predictions of photon strength functions (PSFs) covering the whole nuclear chart are ofgreat interest for different nuclear applications, including, in particular, nuclear astrophysics. Recently, sucha global PSF model consisting of axially deformed Hartree-Fock-Bogolyubov (HFB) + quasiparticle randomphase approximation (QRPA) calculations with the D1M Gogny interaction and a phenomenological low-energycontribution was proposed. In the present paper, we test this model predictions against previously published datafrom measurements of multistep γ cascades following neutron capture on isolated resonances performed withthe DANCE detector. Such data present a stringent test of the PSFs models, in particular for the properties of theM1 scissors mode and the possible low-energy PSFs enhancement. A detailed comparison is made for spectraobtained from resonances for spherical, quasispherical, and well-deformed nuclei. This comparison indicatesthat 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 photoabsorptionPSF, should be present in all nuclei. A systematics of this low-energy contribution, assumed in the M1 PSF, isproposed.
SCOPUS: ar.j
info:eu-repo/semantics/published