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Zhang, Y H

Publications and source records attributed to Zhang, Y H.

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Mass Measurements of Proton-rich Nuclides at the Cooler Storage Ring at IMP

Recent results and progress of mass measurements of proton-rich nuclei using isochronous mass spectrometry (IMS) are reported. The nuclei under investigation were produced via fragmentation of relativistic energy heavy ions of {sup 78}Kr and {sup 58}Ni. After in-flight separation by the fragment separator RIBLL-2, the nuclei were injected and stored in the experimental storage ring CSRe, and their masses were determined from measurements of the revolution times. The impact of these measurements on the stellar nucleosynthesis in the rp-process is discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Identification of the {gamma}-vibrational band built on the 11/2{sup -}[505] orbital in {sup 165}Er

Excited states in {sup 165}Er have been populated using the {sup 160}Gd({sup 9}Be, 4n) reaction at beam energies of 42 and 45 MeV. A band consisting of two levels at excitation energies of 1317.6 and 1505.9 keV, both of which decay strongly to the 11/2{sup -}[505] band, is observed and assigned as the {gamma}-vibrational band built on the 11/2{sup -}[505] configuration. In addition, a newly identified level is proposed as a three-quasiparticle state.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Identification of high-spin states in the stable nucleus {sup 195}Pt

Excited states of the stable nucleus {sup 195}Pt have been studied using an in-beam {gamma}-ray spectroscopic technique following the incomplete fusion of {sup 7}Li on an {sup 192}Os target at 44 MeV. A level scheme built on the I{sup {pi}=}13/2{sup +} isomer has been established up to I{sup {pi}=}33/2{sup -} at an excitation energy of about 2.6 MeV. Spin and parity values of these states have been assigned from an analysis of anisotropy ratios of {gamma} rays and by analogy with the neighboring nuclei. A comparison of the observed structures with the yrast states in the neighboring even-even {sup 196}Pt core indicates that the identified levels may be regarded as arising from the weak coupling of a {nu}i{sub 13/2} neutron hole to the core states.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Rotational band properties in {sup 165}Er

High-spin states in {sup 165}Er have been studied experimentally using the {sup 160}Gd({sup 9}Be, 4n) reaction at beam energies of 42 and 45 MeV. The previously known bands based on the 5/2{sup +}[642], 5/2{sup -}[523], and 11/2{sup -}[505] configurations are extended to (49/2{sup +}), (45/2{sup -}), and (31/2{sup -}) states, respectively. The rotational bands in {sup 165}Er generally show gradual alignment processes, indicating strong band interactions associated with the i{sub 13/2} neutron alignments. The band properties are compared with those in the neighboring nuclei and discussed within the framework of the cranked shell model.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Properties of the {pi}h{sub 11/2} band in the stable nucleus {sup 193}Ir

Excited states in the stable nucleus {sup 193}Ir have been investigated through an in-beam {gamma}-ray spectroscopic technique following the {sup 192}Os({sup 7}Li, {alpha}2n) reaction at a beam energy of 44 MeV. A level scheme built on the {pi}h{sub 11/2} isomer has been extended to high-spin states using eleven newly observed {gamma} transitions. The {pi}h{sub 11/2} band is proposed to be formed by coupling an h{sub 11/2} proton to a core with large triaxial deformation. Three-quasiparticle states are suggested in {sup 193}Ir on referring to the similar states in {sup 187}Ir. The features of signature splitting in the {pi}h{sub 11/2} bands of {sup 187-193}Ir are discussed with the help of total Routhian surface calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Direct Mass Measurements of Short-Lived A=2Z-1 Nuclides {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 71}Kr and Their Impact on Nucleosynthesis in the rp Process

Mass excesses of short-lived A=2Z-1 nuclei {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 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 {sup 65}As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of {sup 65}As suggest that the majority of the reaction flow passes through {sup 64}Ge via proton capture, indicating that {sup 64}Ge is not a significant rp-process waiting point.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Properties of the rotational bands in {sup 161}Er

High-spin states in {sup 161}Er have been studied experimentally using the {sup 150}Nd({sup 16}O,5n) reaction at a beam energy of 86 MeV. The 5/2{sup +}[642], 3/2{sup -}[521], and 11/2{sup -}[505] bands are extended up to high-spin states, and particularly the {alpha}=-1/2 branch of the ground state 3/2{sup -}[521] band is revised significantly. The relatively enhanced E1 transitions from the 3/2{sup -}[521] band to the 5/2{sup +}[642] band are observed. The band properties are analyzed within the framework of a triaxial particle-rotor model, and near-prolate shape and triaxial deformation are proposed to the 3/2{sup -}[521] and 5/2{sup +}[642] bands, respectively. Signature inversion occurs in the 3/2{sup -}[521] band after the band crossing in {sup 161}Er, and the systematics of the signature inversion associated with the 3/2{sup -}[521] configuration are discussed. By analyzing the properties of the relatively enhanced E1 transitions, it is found that the R(E1/E2) values show angular momentum dependence before the band crossing, and these enhanced E1 transitions could be attributed to octupole softness.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2010

High-spin states in {sup 188}Au: Further evidence for nonaxial shape

The high-spin level structure of {sup 188}Au has been investigated via the {sup 173}Yb({sup 19}F,4n{gamma}) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new I{sup {pi}}=20{sup +} state associated with {pi}h{sub 11/2}{sup -1} x {nu}i{sub 13/2}{sup -2}h{sub 9/2}{sup -1} configuration and two new rotational bands, one of which is built on the {pi}h{sub 9/2} x {nu}i{sub 13/2} configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around {sup 188}Au for the {pi}h{sub 9/2} x {nu}i{sub 13/2} bands in odd-odd Au isotopes. Evidence for {pi}h{sub 11/2}{sup -1} x {nu}i{sub 13/2}{sup -1} structure of nonaxial shape with {gamma}<-70 deg. has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2010

Microscopic examination of N{sub p}N{sub n} dominance in the evolution of nuclear structure

The proton-neutron interaction in determining the evolution of nuclear structure has been studied by using the Brillouin-Wigner perturbation expansion. The particle-hole and particle-particle p-n interactions are unifiedly described in the theory. The obtained formulas of level energies and excitation energies scaled in the small- and large-N{sub p}N{sub n} limits can well explain the linearity of the extracted proton-neutron interaction energies and the attenuation of the 2{sub 1}{sup +} excitation energies against the valence nucleon product N{sub p}N{sub n}for five mass regions from A=100-200.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2010

Nuclear physics program at HIRFL

With the commissioning of HIRFL-CSR, HIRFL can provide heavy ion beams with energy covering the range of several MeV/u to 1 GeV/u. In this talk, the experiments on nuclear physics at different energies to be carried out with different experimental setups at HIRFL will be introduced.

43 PARTICLE ACCELERATORS↗
DOE OSTI2010

Band properties of the transitional nucleus {sup 189}Pt

High-spin states in {sup 189}Pt have been studied with the in-beam gamma-spectroscopy method via the {sup 176}Yb({sup 18}O,5n) reaction at beam energies of 88 MeV and 95 MeV. A new level scheme of {sup 189}Pt has been established. Rotational bands based on the upsiloni{sub 13/2}{sup -1}, upsilonf{sub 5/2}(p{sub 3/2}) and upsiloni{sub 13/2}{sup -2}upsilonf{sub 5esol2}(p{sub 3/2}) configurations, as well as several structures with irregular level spacings, have been observed. Properties of rotational bands have been analyzed in the framework of triaxial particle-rotor model. A gammaapprox-30 deg. triaxial shape and a near prolate shape have been proposed to the upsiloni{sub 13/2}{sup -1} and upsilonf{sub 5/2}(p{sub 3/2}) bands, respectively. Two DELTAI = 2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the upsiloni{sub 13/2}{sup -2}upsilonf{sub 5/2}(p{sub 3/2}) configuration. According to the relevant Nilsson orbitals, the bands built on the upsiloni{sub 13/2}{sup -2}upsilonf{sub 5/2}(p{sub 3/2}) configuration could be interpreted as a pair of pseudo-spin partner.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗