Wang Zhimin

Growth, Characterization and Fermi Surface of Heavy Fermion CeCoIn5 Superconductor

High quality single crystals of heavy Fermion CeCoIn5 superconductor have been grown by flux method with a typical size of (1 − 2) × (1 − 2) × (~ 0.1) mm3. The single crystals are characterized by structural analysis from x-ray diffraction and Laue diffraction, as well as compositional analysis. Magnetic and electrical measurements on the single crystals show a sharp superconducting transition with a transition temperature at Tc,onset ~2.3 K and a transition width of ~0.15K. The resistivity of the CeCoIn5 crystal exhibits a hump at ~45 K, which is typical of a heavy Fermion system. High resolution angle-resolved photoemission spectroscopy (ARPES) measurements of CeCoIn5 reveal clear Fermi surface sheets that are consistent with the band structure calculations when assuming itinerant Ce 4f electrons at low temperature. This work provides important information on the electronic structure of heavy Fermion CeCoIn5 superconductor. It also lays a foundation for further studies on the physical properties and superconducting mechanism of the heavy Fermion superconductors.

An efficient synthesis of (−)-pestalotin and its enantiomer using sharpless asymmetric dihydroxylation

Abstract With Sharpless asymmetric dihydroxylation as a key step, syntheses of (−)-pestalotin and its enantiomer have been accomplished in a four-step sequence in high stereoselectivity.

Circulation model for water circulation and purification in a water Cerenkov detector

Owing to its low cost and good transparency, highly purified water is widely used as a medium in large water Cerenkov detector experiments. The water circulation and purification system is usually needed to keep the water in good quality. In this work, a practical circulation model is built to describe the variation of the water resistivity in the circulation process and compared with the data obtained from a prototype experiment. The successful test of the model makes it useful in the future design and optimization of the circulation/purification system.

Lifetimes of Excited Levels in131Ce

The fusion–evaporation reaction 116Sn (19F, p3n) 131Ce at projectile energy of 95 MeV is used to populate high spin states in 131Ce. The de-exciting γ-rays are detected in γ–γ coincidence measurement with Compton-suppressed BGO-HPGe detectors. Level lifetimes of 131Ce were determined by using the Doppler shift attenuation method. The experimental results indicate that collectivity of 131Ce is reduced relative to that of 130Ce and it follows that deformation decreases with increase of the neutron number on the basis of systematic comparison of transition quadrupole moments for the light cerium isotopes.

Lifetimes of High Spin Yrast States in Odd-Proton Nucleus131Pr

Lifetimes of the high spin yrast states in the odd-proton-nucleus 131Pr have been determined by analysing the Doppler broadened line shapes for the de-exciting ?-rays following the 116Sn (19F,4n) 131Pr reaction at a bombarding energy of 95?MeV. The transition quadrupole moments extracted from the measured lifetimes exhibit a considerable reduction near the rotational frequency of 0.42?MeV, at which the J(1) and J(2) moments of inertia indicate a band crossing. The experimental result demonstrates occurrence of the nuclear shape change induced by band crossing associated with the alignment of a pair of h11/2 protons.

Identification of a 9/2? [505] isomer in the neutron-rich 193Os nucleus

The neutron rich nucleus Os-193 was produced in the Os-192(Li-7, Li-6)Os-193 reaction. An isomeric state based on the 9/2(-)[505] Nilsson orbital was identified in the present work. The half-life of the isomeric state was extracted and discussed in terms of the K quantum number. A level scheme built on the isomeric state was proposed based on the experimental data.

Shell Structures in 91 Nb

High spin states of 91Nb are populated via the fusion-evaporation reaction 76Ge (19F, 4n)91 Nb at the beam energy of 80 MeV. The existing level scheme is modified and extended to higher spins. Its low-lying states are well described by the weakly coupling between a g9/2 proton and the even-even 90Zr core, whereas the higher level structures could be interpreted by the multi-particle excitations in the model space p(1/5/2, 2p1/2,1g9/2) n (1g9/2, 2d5/2, 1g7/2) in the framework of the shell model.

Shears bands in 112In

A new level scheme of 112In have been established up to 6.8 MeV in excitation energy and to a tentative spin of (21+) through the reaction 110Pd(7Li,5n)112In at a beam energy of 50 MeV. In-beam measurements involving γ-γ coincidences and directional correlation of oriented states were performed. M1 bands consisting of I =1 dipole transitions have been observed. Possible quasiparticle configurations suggest that these bands are similar to the shears bands observed in Pb nuclei.

Magnetic Properties and Spin State Transition of Gallium Doped Perovskite Cobaltite Oxide

A series of Ga doping perovskite cobaltite La2/3Sr1/3(Co1−yGay)O3 (y = 0, 0.1, 0.2, 0.3 and 0.4) are prepared by the standard solid-state reaction method. Their magnetic properties and Co ions spin state transitions are studied. Upon doping, no appreciable structure changes can be found. However, the corresponding Curie temperature sharply decreases and the magnetization is greatly reduced, indicating that Ga doping destroys the ferromagnetic interaction in the system. In addition, the high temperature magnetization data follow the Curie–Weiss law. At least one kind of Co ions (Co3+ or Co4+) favours the mixed spin state, and most Co ions are at the lower spin state (low and intermediate state). With increasing Ga content, more Co ions transit to the higher spin state.

Negative parity bands and signature splitting inversion in 80Rb

High spin states in 80Rb were studied via the 65Cu+19F, 66Zn+18O and 68Zn+16O reactions. The 75-MeV 19F, 76-MeV 18O and 80-MeV 16O beams were provided by the CIAE HI-13 Tandem accelerator and the JAERI Tandem accelerator. The prompt γ-γ coincidence and the directional correlation from oriented nuclei (DCO) were measured by the detector arrays in CIAE and JAERI. Twenty-three new states with 28 new transitions have been assigned to 80Rb. The states were observed up to spins of 20+ and 22− in the α = 0 branch for the positive and negative parity yrast bands respectively. The negative parity non-yrast bands were significantly extended up to spins of 22− and 15−. The band crossings with frequencies 0.51 MeV and 0.61 MeV in the α = 0 cascade were observed for the first time. The signature splitting was observed in both negative parity bands. The signature inversions at spins of about 7 and 15 were observed.