Resonant breakup of Be8 in Sn112(Li7,Be8→2α) reaction

Abstract

Background: Reactions involving weakly bound projectiles with $\ensuremath{\alpha}+x$ cluster structure are known to produce a large number of $\ensuremath{\alpha}$ particles, where transfer-induced breakup is one of the possible origins. Detailed investigation on each of these channels is desirable to understand the underlying reaction mechanism.Purpose: Our purpose is to measure the $+1p$ transfer-induced breakup in the $^{112}\mathrm{Sn}(^{7}\mathrm{Li},^{8}\mathrm{Be}\ensuremath{\rightarrow}2\ensuremath{\alpha})$ reaction to understand the possible modes of $^{8}\mathrm{Be}$ breakup and their contribution to inclusive $\ensuremath{\alpha}$ production.Methods: $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ coincidence measurements have been carried out for the above reaction at ${E}_{\mathrm{beam}}=30$ MeV. Projectile-like fragments were detected using five sets of Si-strip-detector telescopes and five sets of single Si-detector telescopes. Optical model analysis of elastic scattering data, coupled reaction channels (CRC), and continuum discretized coupled channels (CDCC) calculations were performed to understand the measured cross sections.Results: The experimental cross sections for $+1p$ transfer-induced breakup in ($^{7}\mathrm{Li},^{8}\mathrm{Be}\ensuremath{\rightarrow}2\ensuremath{\alpha}$) reaction through different resonance states of $^{8}\mathrm{Be}$ have been obtained. Relative energy distribution and Monte Carlo simulation confirm the observation of breakup of $^{8}\mathrm{Be}$ from its ${4}^{+}$ (11.35-MeV) resonant state for the first time along with its well-known ${0}^{+}$ (92-keV) and ${2}^{+}$ (3.12-MeV) resonances. Simultaneous description of elastic scattering, transfer, and breakup cross sections have been made using CDCC plus CRC formalism.Conclusions: Production of $\ensuremath{\alpha}$ particles in $+1p$ transfer-triggered breakup is found to proceed mainly through three resonance (${0}^{+},\phantom{\rule{0.16em}{0ex}}{2}^{+}$, and ${4}^{+}$) states of $^{8}\mathrm{Be}$.