Abstract

Mass excesses of short-lived A=2Z-1 nuclei (63)Ge, (65)As, (67)Se, and (71)Kr have been directly measured to be -46,921(37), -46,937(85), -46,580(67), and -46,320(141)  keV, respectively. The deduced proton separation energy of -90(85)  keV for (65)As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of (65)As suggest that the majority of the reaction flow passes through (64)Ge via proton capture, indicating that (64)Ge is not a significant rp-process waiting point.

HIRFL was upgraded from beginning 2000. Besides of researches on nuclear physics, atomic physics, irradiative material and biology, the cancer therapy by heavy ion and hadron physics are being developing. The injector system of SFC+SSC can provide all ions from proton to uranium with higher intensity. The Cooling Storage Ring (CSR) has accelerated beams successful. The ions 12 C 6+ , 36 Ar 18+ , 129 Xe 27+ have been accelerated up 1000MeV/u, 235MeV/u with about 10 9 ∼10 8 ions per spill respectively. The beam momentum dispersion was measured from 4×10 −3 to 2×10 −4 after cooling by the electron cooler or ∼4×10 −4 after accelerated to 1000MeV/u without cooling. In order to improve the nuclear structure and heavy isotope research in SFC+SSC energy domain, A Wien filter was added in front of RIBLL and gas was filled in first section of RIBLL; a new spectrometry SHANS has being installed. Presently, there are two starting version experimental setups at CSR.

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The longitudinal momentum distribution (P // ) of fragments after one-proton removal from 23 Al and reaction cross sections (σR) for 23,24 Al on carbon target at 74A MeV have been measured. The 23,24 Al ions were produced through projectile fragmentation of 135A MeV 28 Si primary beam using RIPS fragment separator at RIKEN. P // is measured by a direct time-of-flight (TOF) technique, while σR is determined using a transmission method. An enhancement in σR is observed for 23 Al compared with 24 Al. The P // for 22 Mg fragments from 23 Al breakup has been obtained for the first time. FWHM of the distributions has been determined to be 232±28 MeV/c. The experimental data are discussed by using Few-Body Glauber model. Analysis of P // demonstrates a dominant d-wave configuration for the valence proton in ground state of 23 Al, indicating that 23 Al is not a proton halo nucleus.

The projectile fragmentation reactions of 40 Ar at 57 MeV/nucleon on 9 Be and 181 Ta targets have been studied by the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL). The momentum distributions of fragments have been measured and the competition between different mechanisms are observed. The production cross sections have been obtained and compared with the empirical parametrization of fragmentation cross section (EPAX), abrasion-ablation (AA), and heavy-ion phase space exploration (HIPSE) models, and the target dependence of fragment cross sections has also been discussed.

We measured fragmentation cross sections produced using the primary beam of 86 Kr at 64 MeV/nucleon on 9 Be and 181 Ta targets. The cross sections were obtained by integrating the momentum distributions of isotopes with 25 Z 36 measured using the RIPS fragment separator at RIKEN. The cross-section ratios obtained with the 181 Ta and 9 Be targets depend on the fragment masses, contrary to the simple geometrical models. We compared the extracted cross sections to EPAX; an empirical parametrization of fragmentation cross sections. Predictions from current EPAX parametrization severely overestimate the production cross sections of very neutron-rich isotopes. Attempts to obtain another set of EPAX parameters specific to the reaction studied here to extrapolate the neutron-rich nuclei more accurately have not been very successful, suggesting that accurate predictions of production cross sections of nuclei far from the valley of stability require information of nuclear properties that are not present in EPAX.