S. Nishimura

Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238 U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identi...

Low-lying non-normal parity states in 8B measured by proton elastic scattering on 7Be

Abstract A new measurement of proton resonance scattering on 7Be was performed up to the center-of-mass energy of 6.7 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study of the University of Tokyo. The excitation function of Be 7 + p elastic scattering above 3.5 MeV was measured successfully for the first time, providing important information about the resonance structure of the 8B nucleus. The resonances are related to the reaction rate of 7Be( p , γ )8B, which is the key reaction in solar 8B neutrino production. Evidence for the presence of two negative parity states is presented. One of them is a 2 − state observed as a broad s-wave resonance, the existence of which had been questionable. Its possible effects on the determination of the astrophysical S-factor of 7Be( p , γ )8B at solar energy are discussed. The other state had not been observed in previous measurements, and its spin and parity were determined as 1 − .

Exploring the Southern Boundaries of the “Island of Inversion” at the RIBF

The nuclear structure of neutron rich Ne isotopes has been investigated at the recently commissioned Radioactive Ion Beam Factory (RIBF) at the RIKEN Nishina Center by means of inelastic scattering and knockout reactions. A cocktail beam of unstable nuclei around 32Ne was provided by the BigRIPS fragment separator and incident on a natural carbon target at energies [approximate]220 A MeV. Reaction products were identified with the Zero Degree Spectrometer and de-excitation gamma-rays detected by the DALI2 array. The reported results demonstrate the potential for in-beam gamma-ray experiments at the RIBF.

Experimental Study of Stellar Reactions at CNS

After a brief review on low‐energy RI beam production technology, nuclear astrophysics programs at CNS are presented including a scope of the field in the Wako campus. The CRIB project involves a total development of the whole facility to maximize the low‐energy RI beam intensities, including the ion source, the AVF cyclotron and the low‐energy RI beam separator CRIB, Some recent nuclear astrophysics experiments performed with the RI beams were discussed, including the measurement of the 14O(α,p)17F reaction, the key stellar reaction for the onset of the high‐temperature rp‐process. The first experiment performed with a newly installed high‐resolution magnetic spectrograph PA of CNS was also presented. Collaboration possibilities for nuclear astrophysics in the RIKEN campus are also touched.