Excitation function and isomeric ratio of Tc-isotopes from the 93Nb(α, xn) reaction

Abstract

Abstract The excitation functions of 94–96Tc isotopes and independent isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc from the 93Nb(α, xn) reaction within the energy range below 40 MeV have been determined by using a stacked-foil activation and an off-line γ-ray spectrometric technique at the Variable Energy Cyclotron Center, Kolkota, India. The excitation function of 94–96Tc in the 93Nb(α, xn) reaction was also calculated by using the computer code TALYS 1.6. The present data are found to be in general agreement with the literature data but have similar trend with some deviation from calculated data of the TALYS 1.6 code. The isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc in the 93Nb(α, xn) reactions from the present work and literature data were compared with similar data in the 93Nb(3He, xn) and 96Mo(p, xn) reactions. In all the three reactions, the isomeric ratios increase with the increasing excitation energy. However, at all excitation energies, the isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc in the 93Nb(α, xn) and 93Nb(3He, xn) reactions are higher than those in the 96Mo(p, xn) reactions, which indicate the role of input angular momentum besides excitation energy. Above the excitation energy of 35–55 MeV, the isomeric ratios of 95m, gTc, 94m, gTc, and 93m, gTc decrease in all the 93Nb(α, xn), 93Nb(3He, xn) and 96Mo(p, xn) reactions. This decreasing trend at higher excitation energy indicates the starting of pre-equilibrium reaction, which depends on the target, projectile, and type of reaction products.