Jiang Dong-Xing

Extraction of MeV C2+C8+ cluster beams

Abstract Beams of C 2 + C 8 + clusters have been accelerated to 3 MeV in our 1.7 MV tandem accelerator without any modification of the machine. The beam intensity of the smaller C-cluster is large enough for some physics experiments. The change of charge from C-cluster negative ions to positive ions was achieved by collisions with N 2 molecules in a gas cell at the high voltage terminal. The gas density in the stripper cell is an important parameter for obtaining maximum C m + cluster beam.

Elastic Scattering of 6He + p at 82.3 MeV/nucleon

Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results are well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.

Measurement of One- and Two-Neutron Transfers in Reaction of 6He+9Be at 25 MeV/u

The cross sections of one- and two-neutron transfers induced by 6He at 25 MeV/u on a 9Be target were measured in RIKEN. Clear identification of the recoiled Be isotopes was achieved. In total five 11Be and 371 10Be events, the corresponding two- and one-neutron transfers were obtained and analysed for transfer reaction cross sections. The results are useful to determine the spectroscopic factors of the internal halo structure of the 6He nucleus.

The β Decay of 21N

The β-delayed neutron and γ energy spectra taken from the decay of neutron-rich nucleus 21N were measured by using the β–γ and β – n coincidence detection method. Thirteen new neutron groups ranging from 0.28MeV to 4.98MeV and with a total branching ratio of 88.7 ± 4.2% were observed and presented. One γ transition with an energy of 1222keV emitted from the excited state of 21O, and four γ transitions with energies of 1674, 2397, 2780, and 3175keV emitted from the excited states of 20O were identified in the β decay chain of 21N. The β decay half-life for 21N is determined to be 82.9 ± 1.9 ms. The uncertainty of half-life is much smaller than the previous result.

Efficiency of position sensitive PPAC for various ions

The detection efficiencies of a position sensitive parallel plate avalanche counter, measured with 40 MeV/u 17 N beam bombarding on a 621 mg/cm 2 197 Au target, were observed to be significantly different for different ions from helium to oxygen. Furthermore, for a given type of ion, the efficiency decreases with the increase of the incident energy. r 2002 Elsevier Science B.V. All rights reserved. PACS: 25.60.� t; 29.40.Cs

Stopping powers of A1 for MeV Si ions

Abstract Stopping powers of A1 film for Si ions (0.8–6.4 MeV) have been measured with Rutherford backscattering (RBS) technique. A new method to determine the stopping powers for low-velocity heavy projectiles was used. The experimental results of the stopping powers for low-velocity Si ions are smaller than those of the TRIM code and LSS theory.

Recoiled Proton Tagged Knockout Reaction for 8He

An experiment for knockout reaction induced by 8He beam at 82.5 MeV/nucleon on CH2 and C targets was carried out. The 6He and 4He core fragments at forward angles and the recoiled protons at large angles were detected coincidently. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism are separated, which can be applied to the exclusive spectroscopic study on the structure of exotic nuclei.

New Measurements for 8He Excited States

Breakup reactions of the double borromean nucleus 8He were measured at 82.3 MeV/u on CH2 and C targets. The coincident detection of two decaying neutrons and the high performance for neutron cross talk rejection are realized in this experiment. The relative energy spectrum for 8He was reconstructed with good statistics. The spectrum exhibits a structure of two resonant peaks, one at an excitation energy of about 3.0 and the other at about 4.14 MeV, respectively. Substantially larger cross section for the first resonance is observed in comparison to the results reported previously.

Knockout reaction induced by 6He at 61.2 MeV/u

A knockout reaction induced by 6He at 61.2 MeV/u was carried out at the HIRFL-RIBLL radioactive beam line. The α core fragments at forward angles were detected in coincidence with the recoiled protons at large angles. From this coincident measurement the valence nucleon knockout mechanism and the core knockout mechanism can be separated according to the polar angle correlation between the core fragments and the recoiled protons. It is demonstrated that, when reconstructing the resonant state of a weakly bound nucleus, the contamination resulting from the core knockout mechanism should be eliminated in order to obtain the correct structure information.

Quasi-Elastic Scattering of 16C from 12C at 47.5 MeV/Nucleon

Differential cross sections for the quasi-elastic scattering of C-16 at 47.5 MeV/nucleon from C-12 target are measured. Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.