The first data of elastic scattering of the unstable nucleus, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ ($T_{1/2}$=53.3 d), are presented for a ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ target at 140 MeV. Secondary beams of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ were produced by using a polyethylene target with the reaction of ${}_{}{}^1{}_{}{}^{}\mathrm{H}$${(}^7$Li, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$) at ${\theta }_{\mathrm{lab}=0\mathrm{}}$°. A magnetic spectrograph was used to focus ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ particles ejected from the polyethylene target onto a carbon target. The beam-spot size at the carbon target was less than 2 mm×2 mm. The energy resolution of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ beams was 1.6 MeV (full width at half maximum) with intensity of 2×${10}^4$ ${\mathrm{s}}^{\mathrm{-}1}$. Data were analyzed in terms of the double-folding model. It was found that a 25% reduction in the real-potential strength is required to fit the experimental cross section. Coupled-channel calculations demonstrated that such a reduction is due to the effect of projectile breakup.

• Received 25 October 1988

DOI:https://doi.org/10.1103/PhysRevC.39.873