Fine Structure of Beta Decay Strength Function and Anisotropy of Isovector Nuclear Dencity Component Oscillations in Deformed Nuclei

Abstract

The experimental measurement data on theˇne structure of beta-decay strength function S β (E) in spherical, transition, and deformed nuclei are analyzed. Modern high-resolution nuclear spectroscopy methods made it possible to identify the splitting of peaks in S β (E) for deformed nuclei. By analogy with splitting of the peak of E1 giant dipole resonance (GDR) in deformed nuclei, the peaks in S β (E) are split into two components from the axial nuclear deformation. In this report, theˇne structure of S β (E) is discussed. Splitting of the peaks connected with the oscillations of neutrons against protons (E1 GDR), of proton holes against neutrons (peaks in S β (E) of β + /EC-decay), and of protons against neutron holes (peaks in S β (E) of β − decay) is discussed.

Structure of beta-decay strength function Sβ(E) and quenching of axial-vector weak interaction constant in halo nuclei

“…For higher excitation energies that cannot be reached with the β-decay, S β (E) determines the charge-exchange nuclear reaction cross sections, which depend on the nuclear matrix elements of the β-decay type. From the macroscopic point of view, the resonances in the GT βdecay strength function S β (E) are connected with the oscillation of the spin-isospin density without change in the shape of the nucleus [1][2][3].…”

“…The strength function S β (Е) governs [1][2][3] the nuclear energy distribution of elementary charge-exchange excitations and their combinations like proton particle (πp)-neutron hole (νh) coupled into a spin-parity I π :…”

Structure of β-Decay Strength Function Sβ(E) in Halo Nuclei. Borromean Halo, Tango Halo, and Mixed Halo

“…These are [8,9] so called (Figures 1-3) core polarization (CP), back spin flip (BSF), and spin flip (SF) configurations. Coherent superposition [8][9][10] of CP, BSF, and SF configurations forms Gamow-Teller (GT) resonance. Non coherent superposition forms resonances in S β (E) at excitation energy E lower than energy of GT resonance (so called pigmy resonances).…”

“…The strength function S β (Е) governs [8][9][10] [8,9]. From the macroscopic point of view, the resonances in the GT β-decay strength function S β (E) are connected with the oscillation of the spin-isospin density without change in the shape of the nucleus [8][9][10].…”

“…In this work, the structure of resonances in the GT β-decay strength function S β (E) for halo nuclei is discussed. Structure of S β (E) may be studied both in experiments on M1 γ-decay of IAR and in experiments on S β (E) measurements in charge exchenge nuclear reactions and in β-decay [8][9][10].…”