First investigation on the isomeric ratio in multinucleon transfer reactions: Entrance channel effects on the spin distribution
D. Kumar (GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany)
; T. Dickel (GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany, II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany); A. Zadvornaya (Helmholtz Research Academy Hesse for FAIR (HFHF), GSI Helmholtz Center for Heavy Ion Research, Campus Gießen, Gießen, Germany, II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany, University of Jyväskylä, Department of Physics, Accelerator laboratory, P.O. Box 35(YFL), University of Jyväskylä, Finland); O. Beliuskina (University of Jyväskylä, Department of Physics, Accelerator laboratory, P.O. Box 35(YFL), University of Jyväskylä, Finland); A. Kankainen (University of Jyväskylä, Department of Physics, Accelerator laboratory, P.O. Box 35(YFL), University of Jyväskylä, Finland); et al - Show all 43 authors
The multinucleon transfer (MNT) reaction approach was successfully employed for the first time to measure the isomeric ratios (IRs) of $^{211}$Po isomer (25/2$^{+}$) and its ground state (9/2$^{+}$) at the IGISOL facility using a 945 MeV $^{136}$Xe beam impinged on $^{209}$Bi and $^{nat}$Pb targets. The dominant production of isomers compared to the corresponding ground states was consistently revealed in the α-decay spectra. Deduced IR of $^{211}$Po populated through the $^{136}$Xe+$^{nat}$Pb reaction was found to have an enhancement of ≈1.8-times than that observed for the $^{136}$Xe+$^{209}$Bi. State-of-the-art Langevin-type model calculations have been utilized to estimate the spin distribution of an MNT residue. The computations qualitatively corroborate with the considerable increase in the IRs of $^{211}$Po produced from $^{136}$Xe+$^{nat}$Pb compared to $^{136}$Xe+$^{209}$Bi. Theoretical investigations indicate a weak dependence of target spin on the IRs. The enhancement of the $^{211}$Po isomer in the $^{136}$Xe+$^{nat}$Pb over $^{136}$Xe+$^{209}$Bi can be attributed to the different proton (p)-transfer production routes. Estimations demonstrate an increment in the angular momentum transfer, favorable for isomer production, with increasing projectile energy. Comparative analysis reveals the two entrance channel parameters, projectile mass and p-transfer channels, strongly influencing the population of the high-spin isomer of $^{211}$Po (25/2$^{+}$). This letter reports the first experimental and theoretical study on the IRs of nuclei formed from two different p-transfer channels via two independent MNT reactions.
