Study of the $\mathbf{p}{+}^6$Li$\to \mathbf{\eta }{+}^7$Be reaction 11.3 MeV above threshold

Abstract

The cross section for the reaction $p{+}^6\text{Li}\to \eta {+}^7\text{Be}$ was measured at an excess energy of 11.28 MeV above threshold by detecting the recoiling ${}^7$Be nuclei. A dedicated set of focal plane detectors was built for the magnetic spectrograph Big Karl and was used for identification and four momentum measurement of the ${}^7$Be. A differential cross section of $\frac{d\sigma }{d\Omega }=(0.69\pm 0.20\text{(stat.)}\pm 0.20\text{(syst.)})\text{nb/sr}$ for the ground state plus the 1/2${}^{-}$ was measured. The result is compared to model calculations.

Comments: accepted by Phys. Rev. C as rapid communication