Gu Long

Proposed Chiral Doublet Bands in 98Tc

High spin states in odd-odd98 Tc nuclei are studied by in-beam γ-ray spectroscopy with the 96Zr(6Li, 4n) fusion-evaporation reaction at a beam energy of 35 MeV. The previous level scheme is updated. A band based on 1090.7 keV is expanded, and another band based on 1920.6 keV is newly identified. The observed two negative parity bands in 98Tc are proposed to be a pair of chiral doublet bands with the configuration πg9/2 ⊗ νh11/2. The evidence supporting the assignment of the chiral doublet bands is discussed. Signature splitting and signature inversion are observed in the πg9/2 ⊗ νh11/2 band in 98Tc.

Reinvestigation of Collective Bands in 107Tc

The high spin states of a neutron-rich 107Tc nucleus are reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. The previous level scheme is updated. A collective band based on the π5/2− [303] orbital is confirmed and extended. Inconsistencies in the configuration assignments for a type of positive parity bands of odd-A 105,107,109Tc in the previous reports are clarified according to the g factor calculations. A new band based on the 1499.5 keV level in 107Tc is proposed as a two-phonon γ-vibrational band.

Electromagnetic Transition Strengths and New Insight into the Chirality in 106Ag

Excited states in 106Ag are populated through the heavy-ion fusion evaporation reaction 100Mo(11 B,5n)106 Ag at a beam energy of 60 MeV. Lifetimes are measured for transitions of the two negative-parity rotational bands in the nucleus 106 Ag. The reduced transition probabilities show a great difference between the two bands. The staggering of the B(M1) and B(M1)/B(E2) values with spin are not observed. The bands are identified to be built on two distinct quasiparticle configurations. These results are contrary to an earlier suggestion that the pair of bands in 106 Ag are chiral doublet bands.

Quest for Chirality in 107 Ag

High spin states in 107Ag have been studied via the 100Mo(11B, 4n)107Ag reaction at a beam energy of 60 MeV on the HI-13 tandem accelerator at the China Institute of Atomic Energy. By analyzing the gamma-gamma coincidence and their DCO ratios, a new level scheme of 107Ag is presented. The structures for the newly constructed bands are briefly discussed and tentatively assigned to be chiral doublet bands.

Collective Band Structures and Identification of One-Phonon and Two-Phonon γ-Vibrational Bands in 109Tc

The high spin states of the neutron-rich 109Tc nucleus are reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. The previously known yrast band based on the 7/2+ state is updated. A side band built on the 11/2+ state is expanded and a new band based on the 15/2+ state is identified. Band crossing in the yrast band occurs around ħω ≈ 0.36MeV. This band crossing is associated with the alignment of two h11/2 neutrons according to the cranked shell model calculations. The band based on the 11/2+ state is proposed as a candidate for the one-phonon γ-vibrational band, and the band built on the 15/2+ state is proposed as a candidate for the two-phonon γ-vibrational band. Other characteristics for the observed bands are discussed.

New band structures in 107Ag

High spin states in 107Ag are studied via the 100Mo(11B, 4n)107 Ag reaction at an incident beam energy of 60 MeV. Prompt γ-γ coincidence and DCO ratios are measured by the detector arrays in CIAE. The level scheme has been updated and a new negative band belonging to 107Ag is identified. The new negative side band has been constructed and its configuration is tentatively assigned to πg9/2 ⊗ νh11/2(g7/2/d5/2).

Extended collective bands in neutron-rich 109 Ru *

Levels in the neutron-rich 109Ru have been studied by observing the prompt γ-rays following the spontaneous fission fragments of 252Cf. The ground state band and the negative parity bands have been confirmed and extended. A positive parity band with the band head level at 332.5 keV is newly identified and suggested as a single-neutron excitation band built on the 7/2+[404] Nilsson orbital. Some structural characteristics of these bands are discussed.

Search for chiral bands in A ∼ 110 neutron-rich nuclei

High spin states in A～110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt γ-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and 112Ru.

High spin states in neutron-rich 106Tc nucleus

The high spin states of the neutron-rich odd-odd 106Tc nucleus have been reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. A previously known collective band is confirmed and expanded, and a new collective band is newly identified. Several levels in previous report in 106Tc are reexamined and they belong to the members of a band in 107Tc. The total Routhian surface (TRS) calculations show that the 106Tc has triaxial shape. The spins and parities as well as the configurations for these bands have been tentatively assigned according to the analysis of the angular momentum alignments.

High-spin states in neutron-rich 102Mo nucleus

High-spin states in neutron-rich 102Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of 252Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ- band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in 102Mo, 104Mo and 106Mo are discussed.