Z. Y. Sun

RIBLL, the radioactive ion beam line in Lanzhou

A fragment separator, the Radioactive Ion Beam Line in Lanzhou, has been constructed at the Heavy Ion Research Facility of Lanzhou and in operation since January 1998. In this paper, the features of the structure and performance are described in detail. Some early stage results are presented also.

Mass Measurement of 45Cr and Its Impact on the Ca-Sc Cycle in X-Ray Bursts

Masses of neutron-deficient 58Ni projectile fragments have been measured at the HIRFL-CSR facility in Lanzhou, China employing the isochronous mass spectrometry technique. Masses of a series of short-lived Tz = –3/2 nuclides including the 45Cr nucleus have been measured with a relative uncertainty of about 10–6-10–7. The new 45Cr mass turned out to be essential for modeling the astrophysical rp-process. In particular, we find that the formation of the predicted Ca-Sc cycle in X-ray bursts can be excluded.

Presence of Functional Mouse Regulatory CD4+CD25+T Cells in Xenogeneic Neonatal Porcine Thymus‐Grafted Athymic Mice

Xenotransplantation with porcine thymus is emerging as a possible means to reconstitute host cellular immunity and to induce immune tolerance in rodents and large animals. However, the presence of regulatory T cells (Treg cells) in this model needs to be determined. We herein demonstrated that efficient repopulation of mouse CD4+CD25+Treg cells was achieved in Balb/c nude mice by grafting neonatal porcine thymic tissue (NP THY). Mouse CD4+CD25+T cells expressed normal levels of Foxp3 in NP THY‐grafted nude mice. Furthermore, these CD4+CD25+Treg cells showed significant inhibitory effects on the cell proliferation or interleukin‐2 products of syngeneic T cells to alloantigens, Con A or a peptide antigen, although the potent immunosuppressive function might be lower than CD4+CD25+Treg cells in Balb/c mice. CD4+CD25+T cells in NP THY‐grafted nude mice showed significantly stronger inhibition on the response to donor porcine antigens of CD4+CD25−T cells than CD4+CD25+Treg cells in Balb/c mice. Both CD4+CD25+Treg cells in NP THY‐grafted nude and Balb/c mice prevented the development of autoimmune disease mediated by syngeneic CD4+CD25−T cells in a similar efficient way in the secondary recipients. These findings provide evidence for the potential involvement of CD4+CD25+Treg cells in keeping self‐tolerance and transplant tolerance in this xeno‐thymus transplantation model.

Examining the exotic structure of the proton-rich nucleus {sup 23}Al

The longitudinal momentum distribution (P{sub //}) of fragments after one-proton removal from {sup 23}Al and reaction cross sections ({sigma}{sub R}) for {sup 23,24}Al on a carbon target at 74A MeV have been measured. The {sup 23,24}Al ions were produced through projectile fragmentation of 135A MeV {sup 28}Si primary beam using the RIPS fragment separator at RIKEN. P{sub parallel} is measured by a direct time-of-flight (TOF) technique, while {sigma}{sub R} is determined using a transmission method. An enhancement in {sigma}{sub R} is observed for {sup 23}Al compared with {sup 24}Al. The P{sub parallel} for {sup 22}Mg fragments from {sup 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 the Few-Body Glauber model. Analysis of P{sub //} demonstrates a dominant d-wave configuration for the valence proton in ground state of {sup 23}Al, indicating that {sup 23}Al is not a proton halo nucleus.

Obvious enhancement of the total reaction cross sections for

The reaction cross sections of

^{27,28}

^{27,28}

P with

P and the corresponding isotones on Si target were measured at intermediate energies. The measured reaction cross sections of the N=12 and 13 isotones show an abrupt increase at

^{28}

% Z=15

Si target and the possible relavent mechanisms

. The experimental results for the isotones with

Isochronous Mass Measurements of Hot Exotic Nuclei

Z\leq 14