Search

Abstract: The neutron-rich nucleus 13B was studied via the proton transfer reaction 4He(12Be, 13Bγ) at . The known 4.83-MeV excited state was strongly populated and its spin and parity were assigned to by comparing the angular differential cross section data with DWBA calculations. This low-lying state is interpreted as a proton intruder state and indicates a deformation of the nucleus. [Copyright &y& Elsevier]

Abstract: Mean lifetime τ of the isomeric state in 12Be has been determined by measuring decay spectra of delayed γ-rays from stopped 12Be nuclei produced by the projectile fragmentation of 18O at 100 A MeV. A consistent value of was obtained from the time spectra of the E2 γ decay to the state and the positron annihilation following the E0 decay to the ground state. Based on the observed branching ratio between the E2 and E0 decays, transition strengths of the two decay modes were deduced to be and , respectively. [Copyright &y& Elsevier]

With using low-energy RI beams from an in-flight RIB separator, CRIB, the most crucial stellar reaction 14O(α,p)17F for the onset of the high-temperature rp-process was directly investigated and the transitions through the states at around 6.2 MeV in 18Ne were first observed, confirming the importance predicted before. The (α,p) reaction leading to the first excited state in 17F was also found to have a large contribution. A proton resonance search experiment of 23Mg + p was also discussed, which is a part of our series of resonance search studies relevant to the early stage of the rp-process. [Copyright &y& Elsevier]

A technique for providing high-spin isomers as probes of the fusion reaction and the measurement of g-factor has been worked out at RIKEN. In the study of the fusion reaction 12C(145mSm,xn)157-xEr, the γ rays emitted from the fusion-evaporation residue 154Er have been successfully observed. The nuclear g-factor of the T1/2 = 28 ns high-spin isomer in 149Dy has been measured with the γ-ray TDPAD method. [Copyright &y& Elsevier]

The stellar reaction 14O(α,p)17F, that critically determines the onset of the high-temperature rp-process, has been studied through a direct measurement with a low-energy radioactive 14O beam and a gaseous helium target cooled down to 30 K. The reaction cross section was measured directly by means of a thick target technique in the energy range of Ec.m.(14O+α) = 0.8-3.8 MeV. The 14O(α,p)17F* reaction leading to the first excited state in 17F was clearly observed for the first time, suggesting an increase of about 50% for the stellar reaction rate through resonance at around 7.1 MeV in 18Ne. [Copyright &y& Elsevier]