Analysis of 113In(α,n)[formula omitted]Sb reaction at astrophysically interesting center-of-mass energies and synthesis of 117Sb⁎ within the Dynamical Cluster-decay Model

Abstract

The Quantum Mechanical Fragmentation Theory (QMFT)-based Dynamical Cluster-decay Model (DCM) analysis of compound nucleus (CN) 117Sb⁎, formed in 4He+113In reaction is done at some astrophysically important energies, which is found to decay via 1n-emission to ground state (g.s.) and metastable state (m.s.) of 116Sb. It is for the first time DCM has been applied to analyze decays to metastable states in a “cold fusion” reaction. The DCM cross sections σ1n are calculated at various astrophysically relevant center-of-mass energies (Ec.m.=9.66–13.64 MeV) corresponding to available experimental data for α-induced reaction with the odd-Z, proton-rich (p-) nuclide 113In, measured with the activation method where, in addition to the radioactive alpha-capture (α,γ), some other reaction channels such as (α,n) and (α,p) of the same isotope can be measured at the same time. The only parameter of DCM is the neck-length parameter ΔR, that is optimized to best fit the experimental data for g.s. to g.s. and g.s. to m.s. decay of 117Sb⁎ CN and predict the cross sections for evaporation-residue (ER), intermediate mass fragments (IMFs) and fusion-fission (ff) fragments. For a best fit to the experimentally observed σ1n (ground and metastable states), we find that, ΔR-values vary smoothly with CN excitation energy ECN⁎ and thus is useful for making predictions at energies where experimental data is unavailable. Possible synthesis of this medically important radionuclide 117Sb⁎ is also studied via all the possible “cold” target-projectile (t–p) combinations, identifying 6Li+111Cd as the best possibility.