Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied becauseof their importance in a wide variety of stellar burning scenarios. However, due to extremely low cross secti...Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied becauseof their importance in a wide variety of stellar burning scenarios. However, due to extremely low cross sectionsand signal/background ratio, all the measurements could only be carried out at energies well above the regionof astrophysical interest. The reaction rates in stellar environment could be estimated only by extrapolating theexisted cross sections or the astrophysical S-factors at higher energies. The situation is even more complicated bythe strong, relatively narrow resonances in some reactions, such as 12C+12C, 12C+16O. Traditionally, optical modelor equivalent square-well optical model (ESW) were used to fit the average cross section and predict the reactioncross sections at the energies of astrophysical interest[1]. Recently, a new model, the hindrance model, was proposedto provide systematic fits to fusion reaction data at extreme sub-barrier energies[2]. Lacking of experimental datawithin this energy range, large discrepancies exist among different nuclear reaction models.展开更多
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
文摘Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied becauseof their importance in a wide variety of stellar burning scenarios. However, due to extremely low cross sectionsand signal/background ratio, all the measurements could only be carried out at energies well above the regionof astrophysical interest. The reaction rates in stellar environment could be estimated only by extrapolating theexisted cross sections or the astrophysical S-factors at higher energies. The situation is even more complicated bythe strong, relatively narrow resonances in some reactions, such as 12C+12C, 12C+16O. Traditionally, optical modelor equivalent square-well optical model (ESW) were used to fit the average cross section and predict the reactioncross sections at the energies of astrophysical interest[1]. Recently, a new model, the hindrance model, was proposedto provide systematic fits to fusion reaction data at extreme sub-barrier energies[2]. Lacking of experimental datawithin this energy range, large discrepancies exist among different nuclear reaction models.
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.
