Spin distribution measurements in ¹⁶O+¹⁵⁹Tb system: incomplete fusion reactions

Abstract

The spin distributions of complete and incomplete fusion residues populated in the 16O+159Tb system have been measured using the particle-γ coincidence technique to investigate the role of high angular momentum values in the production of direct-α-emitting channels. Spin distributions of various αxn channels are measured at ELab ≈ 6.2 MeV A−1. Entirely different de-excitation patterns are observed in direct-α-emitting channels and fusion-evaporation channels. The fusion-evaporation channels are found to be strongly fed over a broad spin range. While narrow range feeding for only high-spin states was observed in the case of direct-α-emitting channels. To have a better insight into the associated angular momenta values in different reaction channels, the present data are compared with similar data from [, ]. The mean driving angular momenta involved in the production of direct-α-emitting channels are found to be higher than those involved in the production of fusion-evaporation channels.

Effect of projectile on incomplete fusion reactions at low energies

“…The detailed methodology and experimental setups have been discussed in refs. [5,7,21,22]. However, a short account of experimental conditions are given here for the ready reference.…”

“…Further, the fast-α-particles (which are expected to be emitted only in forward cone) produced via ICF have been identified from forward(F)-α-gated spectra obtained by subtracting backward (B)-α-gated spectra from forward(F)-α-gated spectra. The intensity and area under the photo-peak (efficiency corrected) of the characteristic prompt α-transitions were used to determine the relative production yield [21] …”

“…As shown in this figure, there is a difference in the spin-distributions which indicate the involvement of entirely different mode of reactions in the production of these residues. The intensity of α3n (B)- The value of the mean angular momenta i.e., the value of < > deduced from the best fitting procedure of spin distributions [21] involved in 167 Lu isotope populated via CF and ICF processes as a function of modes of reaction. channels (CF residues) falls off rather quickly with observed spin (J obs ), indicating strong feeding and/or broad spin population during the de-excitation of CN.…”

“…Concerning the usefulness of incomplete fusion as a tool to populate high-spin states in final reaction products the mean input angular momenta (< >) associated with α3n channel (populated via both CF and ICF modes) have been deduced as suggested in Ref [21] and is plotted in Fig.7. As can be seen in Fig.…”

“…High quality data for ICF processes has been obtained and reported so far worldwide [1-8, 19, 20], and conclusively demonstrate the low energy ICF, but are limited only for a few projectile-target combinations. Therefore, for better understanding of ICF dynamics, several inclusive experiments at the Inter-University Accelerator e-mail: phy.vijayraj@gmail.com e-mail: bpsinghamu@gmail.com Center (IUAC), New Delhi, India were performed by our group [5,7,8,21,22]. Based on experimental findings an attempt has been made to correlate data with suitable set of physical parameters viz., (a) projectile energy, (b) mass-asymmetry of interacting partners (µ), (c) α-Q value, and (d) input values.…”