Optical potential for incident and emitted low-energy $\alpha$ particles. III. Non-statistical processes induced by neutrons on Zr, Nb, and Mo nuclei

Abstract

The reliability of a previous $\alpha$-particle optical-model potential (OMP) on nuclei with mass number 45$\le$$A$$\le$209 was proved for emitted $\alpha$ particles as well, for proton--induced reactions on Zn isotopes [Phys. Rev. C {\bf 91}, 064611 (2015), Paper I]. However, the same was not the case of neutrons on Zr stable isotopes [Phys. Rev. C {\bf 96}, 044610 (2017), Paper II]. A recent assessment of this potential also for nucleon--induced $\alpha$-emission on $A$$\sim$60 nuclei, including pickup direct reaction and eventual Giant Quadrupole Resonance (GQR) $\alpha$-emission, is completed for neutrons incident on Zr, Nb, and Mo stable isotopes. Consistent sets of input parameters, determined through analysis of independent data, is involved while no further empirical rescaling factors of the $\gamma$ and nucleon widths have been involved. A suitable account of all competitive reaction channels is confirmed by careful uncertainty analysis, to avoid parameter ambiguities and/or error compensation. Additional validation of this potential is also supported by recently measured $(\alpha ,\gamma )$ and $(\alpha ,n)$ cross--sections of Zr and Mo nuclei. An increase of the $\alpha$-emission beyond the statistical predictions, through consideration of additional reaction channels of the pickup direct interaction and {\it like}--GQR decay, makes possible the description of both absorption and emission of $\alpha$ particles by the same optical potential.

21 pages, 16 figures

References in corpus (9)

• Further explorations of the alpha-particle optical model potential at low energies for the mass range A=45-209
• Reference Database for Photon Strength Functions
• Analysis of uncertainties in alpha-particle optical-potential assessment below the Coulomb barrier
• Measurement of alpha induced reaction cross-sections on ${}^{nat}$Mo with detailed covariance analysis
• Consistent optical potential for incident and emitted low-energy $\alpha$ particles. II. $\alpha$-emission in fast-neutron induced reactions on Zr isotopes
• Shell-gap reduced level densities in ${}^{89,90}$Y
• Role of consistent parameter sets in an assessment of the alpha-particle optical potential below the Coulomb barrier
• Determination of $\alpha$-optical potential for reactions with p-nuclei from the study of ($\alpha$,n) reactions in the astrophysically relevant energy region
• Measurements of the ${}^{96}$Zr($\alpha$,n)${}^{99}$Mo cross section for astrophysics and applications

Cited by in corpus (1)

• Long-standing problem: The nuclear level density angular-momentum dependence and isomeric data assessment