Experimental study of the electric dipole strength in the even Mo nuclei and its deformation dependence

Abstract

Two methods based on bremsstrahlung were applied to the stable even Mo isotopes for the experimental determination of the photon strength function covering the high excitation energy range above 4 MeV with its increasing level density. Photon scattering was used up to the neutron separation energies Sn and data up to the maximum of the isovector giant resonance(GDR) were obtained by photo-activation. After a proper correction for multi-step processes the observed quasi-continuous spectra of scattered photons show a remarkably good match to the photon strengths derived from nuclear photo effect data obtained previously by neutron detection and corrected in absolute scale using the new activation results. The combined data form an excellent basis to derive a shape dependence of the E1 strength in the even Mo isotopes with increasing deviation from the N = 50 neutron shell, i.e. with the impact of quadrupole deformation and triaxiality. The wide energy coverage of the data allows for a stringent assessment of the dipole sum-rule, and a test of a novel parameterization developed previously which is based upon. This parameterization for the electric dipole strength function in nuclei with A>80 deviates significantly from prescriptions generally used previously. In astrophysical network calculations it may help to quantify the role the p-process plays in the cosmic nucleosynthesis. It also has impact on the accurate analysis of neutron capture data of importance for future nuclear energy systems and waste transmutation.

41 pages; accepted for publication in PRC

References in corpus (15)

• Pygmy dipole strength in 90Zr
• Particle-vibration coupling within covariant density functional theory
• Photon data shed new light upon the GDR spreading width in heavy nuclei
• Second RPA and correlated realistic interactions
• Relativistic RPA plus phonon-coupling analysis of pygmy dipole resonances
• Nuclear level densities and gamma-ray strength functions in 44,45Sc
• Predicted cross sections for photon-induced particle emission
• Self-Consistent Separable Rpa for Skyrme Forces: Giant Resonances in Axial Nuclei
• Photoactivation experiment on 197Au and its implications for the dipole strength in heavy nuclei
• Enhanced radiative strength in the quasi-continuum of 117Sn
• Photodisintegration studies on p-nuclei: The case of Mo and Sm isotopes
• Electromagnetic Dipole Strength in Transitional Nuclei
• Skyrme-Random-Phase-Approximation description of E1 strength in 92-100Mo
• Photon strength distributions in stable even-even molybdenum isotopes
• The energy dependence of the electric dipole strength in heavy nuclei

Cited by in corpus (5)

• The activation method for cross section measurements in nuclear astrophysics
• Feasibility of studying astrophysically important charged-particle emission with the variable energy $\gamma$-ray system at the Extreme Light Infrastructure -- Nuclear Physics facility
• Broken axial symmetry as essential feature to predict radiative capture in heavy nuclei
• Broken axial symmetry as essential feature for a consistent modelling of various observables in heavy nuclei
• Effect of broken axial symmetry on the electric dipole strength and the collective enhancement of level densities in heavy nuclei