The future experimental campaign with the SAMURAI setup at RIKEN will explore a wide range of neutron-deficient nuclei with a particular focus on the most critical(p, γ) reaction rates relevant to the astrophysical r...The future experimental campaign with the SAMURAI setup at RIKEN will explore a wide range of neutron-deficient nuclei with a particular focus on the most critical(p, γ) reaction rates relevant to the astrophysical rp-process in type-I X-ray bursts(XRB). Intense radioactive-ion(RI) beams at an energy of a few hundred Me V/nucleon will be deployed to populate proton-unbound states in the nuclei of interest through the Coulomb excitation or nucleon-removal processes. The decay of these states into a proton and a heavy residue will be measured using complete kinematics and the information about time reversal proton-capture process will be obtained. This method will provide the vital experimental data on the resonances, which dominate the stellar(p, γ) reaction rates, as well as on the direct proton-capture process for some other cases. The experimental setup will utilize for the first time the High-Resolution90?-mode of the SAMURAI spectrometer in combination with the existing detection systems, including custom-designed Si-strip detectors for simultaneous detection and tracking of heavy ions and protons emitted from the target. The details of the experimental method and the utilized apparatus are discussed in this paper.展开更多
The lifetime of the first excited 2+ state in 18C was measured using an upgraded recoil shadow method to determine the electric quadrupole transition. The measured mean lifetime is 18.9±0.9(stat)±4.4(syst)ps...The lifetime of the first excited 2+ state in 18C was measured using an upgraded recoil shadow method to determine the electric quadrupole transition. The measured mean lifetime is 18.9±0.9(stat)±4.4(syst)ps,which corresponds to a B(E2; 2+1→0+gs) value of (4.3± 0.2±1.0) e2fm4,or about 1.5 Weisskopf units. The mean lifetime of the first 2+ state in 16C was remeasured to be about 18 ps,about four times shorter than the value reported previously. This discrepancy was explained by incorporating the γ-ray angular distribution measured in this work into the previous measurement. The observed transition strengths in 16,18C are hindered compared to the empirical transition strengths,indicating that the anomalous hindrance observed in 16C persists in 18C.展开更多
文摘The future experimental campaign with the SAMURAI setup at RIKEN will explore a wide range of neutron-deficient nuclei with a particular focus on the most critical(p, γ) reaction rates relevant to the astrophysical rp-process in type-I X-ray bursts(XRB). Intense radioactive-ion(RI) beams at an energy of a few hundred Me V/nucleon will be deployed to populate proton-unbound states in the nuclei of interest through the Coulomb excitation or nucleon-removal processes. The decay of these states into a proton and a heavy residue will be measured using complete kinematics and the information about time reversal proton-capture process will be obtained. This method will provide the vital experimental data on the resonances, which dominate the stellar(p, γ) reaction rates, as well as on the direct proton-capture process for some other cases. The experimental setup will utilize for the first time the High-Resolution90?-mode of the SAMURAI spectrometer in combination with the existing detection systems, including custom-designed Si-strip detectors for simultaneous detection and tracking of heavy ions and protons emitted from the target. The details of the experimental method and the utilized apparatus are discussed in this paper.
基金Ministry of Education, Culture,Sports,Science and Technology of Japan(15204017,20740163)
文摘The lifetime of the first excited 2+ state in 18C was measured using an upgraded recoil shadow method to determine the electric quadrupole transition. The measured mean lifetime is 18.9±0.9(stat)±4.4(syst)ps,which corresponds to a B(E2; 2+1→0+gs) value of (4.3± 0.2±1.0) e2fm4,or about 1.5 Weisskopf units. The mean lifetime of the first 2+ state in 16C was remeasured to be about 18 ps,about four times shorter than the value reported previously. This discrepancy was explained by incorporating the γ-ray angular distribution measured in this work into the previous measurement. The observed transition strengths in 16,18C are hindered compared to the empirical transition strengths,indicating that the anomalous hindrance observed in 16C persists in 18C.
