Experimental Study of ExcitedH4,He4, andLi4Nuclear Systems

Abstract

${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{H}$ have been produced as residual nuclear systems in various reactions induced by deuterons, tritons, and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ ions bombarding deuterium, tritium, and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ targets. The bombarding energy was varied from 12 to 22 MeV, and proton and deuteron spectra were measured at angles from 10° to 35°. The first excited state of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ was seen in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}(d, p){}_{}{}^4{}_{}{}^{}\mathrm{He}_{}^{*}{}_{}{}^{}$ reaction at an excitation of 20.08±0.04 MeV with a center-of-mass width of 0.43±0.05 MeV. It was also observed in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}(t, d){}_{}{}^4{}_{}{}^{}\mathrm{He}_{}^{*}{}_{}{}^{}$ reaction at an excitation of 20.00±0.04 MeV with a c.m. width of 0.36±0.05 MeV. There was weak evidence for a second excited state at about 1.2 MeV above the $t+p$ mass. Upper limits on cross sections were set for possible bound states. No direct evidence for unbound states in the ${}_{}{}^4{}_{}{}^{}\mathrm{Li}$ or ${}_{}{}^4{}_{}{}^{}\mathrm{H}$ systems was observed. Both the continuous spectra and the spectral peaks are discussed and are compared with previous experimental results. Absolute cross sections were measured and are presented.