Matter radius of the doubly-magic $$^{56}$$Ni measured in a storage ring

Abstract

AbstractThe matter radius of the doubly magic $$^{56}$$ 56 Ni was extracted from a measurement of the differential cross section by employing, for the first time, elastic proton scattering in inverse kinematics with a radioactive beam at $$E_{kin}=390.2$$ E kin = 390.2  MeV/nucleon circulating in a storage ring and passing an internal hydrogen gas-jet target with a revolution frequency of around 2 MHz. The novel experimental scheme is based on UHV-compatible Si detectors operated as active vacuum windows, which were implemented in the ESR storage ring at GSI. A matter radius $$<r_{m}^{2}>^{1/2}=3.74^{+0.03}_{-0.06}$$ < r m 2 > 1 / 2 = 3 . 74 - 0.06 + 0.03  fm was extracted for the doubly-magic self-conjugate nucleus $$^{56}$$ 56 Ni.