Experimental determination of the $^{7}$Be + p scattering lengths
Résumé
The 7Be+p elastic cross section has been measured at the Centre de Recherches du Cyclotron RIB facility at Louvain-la-Neuve in the c.m. energy region from 0.3 to 0.75 MeV by bombarding a proton-rich target with a radioactive 7Be beam. The recoil protons have been detected in the angular range θc.m.=120.2°–131.1° and θc.m.=156.6°–170.2° using the LEDA system. From a R-matrix analysis of the cross section data, we obtain the energy and the width of the 1+ resonance (Ex=0.77 MeV). The ℓ=0 scattering lengths a01=25±9 fm (channel spin I=1) and a02=−7±3 fm (channel spin I=2) have been deduced. They are compared to values expected from charge-symmetry properties. Implications on the low energy S-factor of the 7Be(p, γ)8B reaction are discussed.