X.H. Zhang

Mean climate state simulated by a coupled ocean-atmosphere general circulation model

SummaryThe result of a 100-year integration of a coupled ocean-atmosphere general circulation model (CGCM) is analyzed, and compared with that of a 25-year integration of the corresponding uncoupled atmospheric general circulation model (AGCM) and observed data. The large-scale circulation patterns of mean climate state simulated by the CGCM are in good agreement with the observed ones, although differences exit in the positions and intensities between the simulated and the observed patterns. Having compared the standard deviations of monthly mean sea level pressure simulated by the CGCM to those by the AGCM, we found that the interaction between ocean and atmosphere mainly increases the interannual variability in the tropics especially in summer. The CGCM can also produce El Niño and Southern Oscillation (ENSO) events, whereas the AGCM cannot reproduce the main features of the Southern Oscillation. This implies that the air-sea interaction may be a principal mechanism for the occurrence of ENSO phenomena. The fundamental features of simulated regional climates are also analyzed. The CGCM can reproduce principal characteristics of surface air temperature and precipitation at five selected typical regions (desert region, plain region, monsoon region etc.). The distributions of annual mean surface ait temperature and precipitation in East Asia can also be reasonably simulated.

A new isotope of protactinium:239Pa

A new nuclide239Pa was produced by 50MeV/u18O bombardment of uranium. A radiochemical separation method was employed for preparing sources of239Pa. The protactinium isotope239Pa has been identified for the first time by the results observed from the decay of the239Pa and its daughter239U. The half-life of239Pa has been determined to be 106 ±30min.

7Be, 8B+208Pb Elastic Scattering at Above-Barrier Energies

Angular distributions for the elastic scattering of 7Be and 8B by an enriched 208Pb target were measured at the Radioactive Ion Beam Line at Lanzhou (RIBLL). The incident energies of the radioactive beams were about three times the respective Coulomb barriers. A suppressed Coulomb-nuclear Interference Peak (CNIP) is not observed for 8B, a pronounced proton halo nucleus. Optical model fits were performed using Woods-Saxon potentials and the total reaction cross sections deduced. The results are discussed.

A method to measure the transition energy γ t of the isochronously tuned storage ring

Abstract The Isochronous Mass Spectrometry (IMS) is a powerful technique developed in heavy-ion storage rings for measuring masses of very short-lived exotic nuclei. The IMS is based on the isochronous setting of the ring. One of the main parameters of this setting is the transition energy γ t . It has been a challenge to determine the γ t and especially to monitor the variation of γ t during experiments. In this paper we introduce a method to measure the γ t online during IMS experiments by using the acquired experimental data. Furthermore, since the storage ring has (in our context) a relatively large momentum acceptance, the variation of the γ t across the ring acceptance is a source of systematic uncertainty of measured masses. With the installation of two time-of-flight (TOF) detectors, the velocity of each stored ion and its revolution time are simultaneously available for the analysis. These quantities enabled us to determine the γ t as a function of orbital length in the ring. The presented method is especially important for future IMS experiments planned at the new-generation storage ring facilities FAIR in Germany and HIAF in China.

Production and identification of new neutron-deficient isotope235Am in region of transuranium

A new transuranium neutron-deficient isotope235Am was produced by 35 MeV proton to bombard the rare radioactive238Pu target. The products were transported and collected by the He-jet system. The Am isotopes were separated and purified by radiochemistry method and the y-ray, X-ray and y-X(y) coincidence of the samples was measured. The synthesis of235Am was definitely identified. Its measured half-life is (15±5) min.

A Forty-Channel Optical-Fiber Telecommunication System for Manipulation of High-Voltage Terminals in Ion Implanters

Basic principles and characteristics of a remote-control telemetry system for the high-voltage terminal of a 600 keV heavy-ion implanter are described. A time-sharing multichannel-signal sampling method, and high-speed V-F converters are used. All controls and signal measurements in each channel are ensured to be synchronous and capable of resisting strong interference.