Assignment of the spin and parity to the excited states of the (85-86)^Rb nuclei

Abstract

Background: The isotopes of Rb (Z=37) are one proton away from semi-magic (Z=38) proton number and deficits the characteristic of a spherical nucleus. In the 85,86Rb nuclei, the γ-ray spectroscopy are already performed and given an indication of Magnetic Rotation (MR) which usually observed in nearly spherical nuclei. The angular correlation measurements were used to find the spin and parity of the states.Purpose: To confirm the spin and parity of the states in both the nuclei using Directional Correlation of Oriented (DCO) states ratio and polarization asymmetry (Δ) measurements.Methods: The excited states of the 85,86Rb nuclei were populated via the 76Ge(13C,p3n/p2n) reaction at a beam energy of 45 MeV. The γ-rays emitted from the excited states were detected using Indian National Gamma Array (INGA) spectrometer at the Tata Institute of Fundamental Research (TIFR), Mumbai India.Results: The values of the DCO states ratio and polarization asymmetry (Δ) were obtained and utilized to confirm the spin-parity of the states in the 85,86Rb nuclei. The polarization asymmetry (Δ) values were obtained for the first time using Compton-suppressed clover detectors.Conclusions: In 85Rb, the spin and parity of 3491.1-, 4135.4-, 4757.2- and 5419.3 keV levelsare confirmed and for the 5312.2-, 5611.8 and 6335.9 keV states, only the spin is established. The mul-tipolarity assignment of the 224.3-, 331.5-, 732.8-, 778.1-, 865.4-, 973.5-, 1002.4-,1427.5-, 1453.7-, 1598.2-, 1814.1- and 1881.5 keV γ-ray transitions allowed to confirm the spinand parity of most of the levels above the 6- isomer in 86Rb.