Zhao Yan-Xin

Observation of Three-Quasiparticle Doublet Bands in 123I: Possible Evidence of Chirality

A new band in the odd proton nucleus 123I is identified via in-beam γ-ray spectroscopy using the 14N+116Cd reaction. This band shows up as doublets with the previously assigned πg7/2 ⊗ (νh11/2)2 band. Possible configurations of the new band are discussed in the framework of the cranked shell model and the geometrical model. It is argued that the new band might be a chiral partner of the previously known πg7/2 ⊗ (νh11/2) band.

Clarification of Confusion in Level Scheme of 124Cs

Low-lying and high-spin states of 124Cs are studied through the 116 Sn(11 B,3n)124 Cs reaction at a beam energy of 45 MeV. Several new linking transitions are observed, including three transitions between the yrast and πh11/2 ⊗ νd3/2 bands and two transitions between the yrast and πh11/2 ⊗ ν(d5/2, g7/2) bands. These transitions fix the excitation energy of the yrast band and its decay path, and confirm the existence of eight E1 linking transitions between the yrast and πh11/2 ⊗ ν(d5/2, g7/2) bands observed before. These E1 linking transitions infer the octupole correlation in Cs. The decay paths of the yrast band are investigated, and discrepancies in the level scheme of 124Cs in the latest two studies are clarified. The reason for the discrepancies is discussed. A new decoupled band is established and temporarily assigned as the unfavored signature partner of πh11/2 ⊗ νd3/2 configuration.

Band Structures of the Nucleus 129Cs

High-spin states in 129Cs are populated via the 122Sn (11B, 4n) reaction at beam energies of 55 and 60 MeV. Two additional bands are placed in the level scheme and the previously known bands are extended to higher spins. The results are compared to the cranked shell model calculations and to the systematics of the adjacent Cs isotpoes. One of the new bands is interpreted as the γ-vibrational band built on the πh11/2 orbital. The possible configuration for another new band is discussed. Upbend caused by (vh11/2)2 alignment is observed both in the favored and unfavored sequences of the πh11/2 configuration. The band based on the πg7/2 configuration at low spins forks around spin 17/2, and the two different S-bands are attributed to (vh11/2) and (πh11/2)2 rotational alignments, respectively.

Test of Chirality in Nucleus 130Cs

The level lifetimes in partner bands of 130Cs have been measured using the Doppler Shift Attenuation method (DSAM). The high-spin states of 130Cs were populated via fusion evaporation reaction 124Sn(11B; 5n)130Cs at a beam energy of 65 MeV. The absolute M1 and E2 transition probabilities have been deduced. The results indicate that the partner bands of 130Cs indeed manifest chiral properties.

Lifetimes of High Spin States in an Odd-Proton Nucleus 129Cs

Lifetimes of high spin states in 129Cs are measured using the Doppler shift attenuation method. The high spin states of 129Cs are populated following the fusion evaporation reaction 124Sn(11B, 6n)129Cs at a beam energy of 65 MeV. The reduced transition probabilities B(E2) and the transition quadrupole moments Qt in the negative- and positive-parity bands are deduced. The experimental results indicate that the Qt values of the negative parity band are smaller than those of the positive parity bands, probably due to different ?-deformation driving effects of different proton orbitals. The Qt values exhibit a considerable increase near the band crossing region in these bands. This behavior demonstrates that nuclear shape changing results from the neutron or proton alignments. The signature splitting of the ?h11/2 and ?g7/2 bands shows the opposite changing trend after backbending due to the h11/2 neutron and h11/2 proton alignments, respectively.

New Structures in odd-odd 120 I

The excited states of the doubly-odd 120I have been investigated via the 110Pd(14N, 4n) and the 114Cd(10B, 4n) reactions at beam energies of 64 MeV and 48 MeV, respectively. The previously known bands are extended, and a new band structure is established. The yrast band is assigned to the πh11/2 ⊗ νh11/2 configuration instead of the previously assigned πg7/2 ⊗ νh11/2 configuration. Possible configurations of the other observed bands are also discussed.

Yrast Band in 122I and Band Termination

High spin states of the odd-odd nucleus 122I have been investigated via the fusion-evaporation reaction 116Cd(11B, 5n) at a beam energy of 68 MeV. The yrast band is extended up to Iπ = (29+). The band termination at Iπ = (22+) reported in previous studies is confirmed and interpreted as arising from a shape change from collective prolate to noncollective oblate according to Total-Routhian-Surface (TRS) calculations. In addition, the Iπ=(29+) state is assigned to the [πh11/2(πg7/2)2]23/2-⊗[(νh11/2)3(νd5/2)2]35/2− configuration corresponding to the full alignment of all valance nucleons outside the semi-closed shell.

Yrast Band in 122 I and Band Termination

High spin states of the odd-odd nucleus 122I have been investigated via the fusion-evaporation reaction 116Cd(11B, 5n) at a beam energy of 68 MeV. The yrast band is extended up to Iπ = (29+). The band termination at Iπ = (22+) reported in previous studies is confirmed and interpreted as arising from a shape change from collective prolate to noncollective oblate according to Total-Routhian-Surface (TRS) calculations. In addition, the Iπ=(29+) state is assigned to the [πh11/2(πg7/2)2]23/2-⊗[(νh11/2)3(νd5/2)2]35/2− configuration corresponding to the full alignment of all valance nucleons outside the semi-closed shell.

Level structure of 159Lu

The high-spin states of 159Lu were populated by fusion-evaporation reaction 144Sm (19F, 4n) with beam energy 106 MeV. A new level scheme was established, which consists of the yrast band with negative parity, the octupole vibration band based on the states and quasipartical band with positive parity. The high spin states of 159Lu were discussed by systemic characteristics.

High Spin States in Odd?Odd 160Tm Nucleus

High-spin states of 160Tm are studied by the 146Nd(19F, 5n) reaction at a beam energy of 102 MeV. The previously known πh11/2 ⊕νi13/2 yrast band and πh11/2 ⊕νh9/2 side band are confirmed. The level scheme is enriched and more low-lying levels are observed. A new side band is observed and assigned as the favoured signature partner of πd3/2 ⊕νi13/2. The spin of this band is assigned with the energy level systematics. It is pointed out that the B(M1)/B(E2) ratios increase rapidly at the high frequency approaching the second crossing in the πh11/2 ⊕νi13/2 band, which is closely related to the alignment gain of the aligned i13/2 quasineutron.