Li Xue-Qin

Lifetime measurements in chiral nucleus 130Cs

The level lifetimes in partner bands of 130Cs have been measured using the Doppler Shift Attenuation method. 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 manifest the chiral properties.

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.

Shape evolution and test of the critical-point symmetry X(5) in 176Os

The lifetimes of excited states in the yrast band of 176Os have been measured up to I = 20ħ level using the Doppler shift attenuation method. The high-spin states of 176Os were populated via fusion evaporation reaction 152Sm(28Si,4n)176Os at a beam energy of 140 MeV. The results support an X(5) structure for 176Os at low spin. This structure disappears at high spin and shows a symmetry rotor character. The shape change of 176Os is similar to that of 178Os.

High-spin states in 128I

The high-spin states in 128I have been studied by using in-beam γ-ray spectroscopy with the 124Sn(7Li,3n)128I reaction at beam energies of 25, 28 and 42 MeV. A new level scheme including 20 new levels and 27 new γ-transitions for 128I has been established preliminarily.

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.

Structural evolution of the intruder band in 118 Sn

Excited states of the positive-parity intruder band in 118Sn have been studied via the 116Cd(7Li, 1p4n) reaction at 7Li energy of 48 MeV using techniques of in-beam γ-ray spectroscopy. This intruder band has been observed up to 7187 keV with spin (16+). The structural evolution of this intruder band with increasing angular momentum has been discussed in terms of the aligned angular momentum and the ratio of the E-Gamma Over Spin (E-GOS) curve.

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.

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.

Magnetic Dipole Band in 113In

High spin states in the odd-A nucleus 113In have been investigated using the reaction 110Pd(7Li, 4n) at a beam energy of 50 MeV. A new positive parity dipole band with the configuration of π(g9/2)−1 ⊗ ν(h11/2)2 ⊗ ν(g7/2)2 is established. The effective interaction V(θ) values of this band have been successfully described by a semiclassical geometric model based on shear mechanism, which show that the dipole band has the characteristics of magnetic rotation. In addition the collective rotational angular momentum for this band is extracted. The results show that the core contribution increases gradually with the increase of the rotation frequency.