Zhang Yu-Hu

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.

A data analysis method for isochronous mass spectrometry using two time-of-flight detectors at CSRe

The concept of isochronous mass spectrometry (IMS) applying two time-of-flight (TOF) detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor γ-value far away from the transition point γt of the storage ring CSRe.

Prolate and Oblate Shape Coexistence in 188Pt

A standard in-beam γ-spectroscopy experiment for 188Pt is performed via the 176 Yb(18O, 6n) reaction at beam energies of 88 and 95MeV, and the level scheme for 188Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in 188Pt by applying the projected shell model. The rotation alignment of i13/2 neutrons drives the yrast sequence changing suddenly from prolate to oblate shape at angular momentum 10h, indicating likely a new type of shape phase transition along the yrast line in 188Pt.

Search for Signature Inversion in the πi13/2⊗νi13/2 Band in Odd-Odd 178Ir

The search for the ?i13/2??i13/2 band in 178Ir has been conducted through the 152Sm(31P,5n?)?178Ir reaction and the excitation functions, x-? and ?-?-t coincidence measurements. Five rotational bands have been newly identified. The low-spin signature inversion in the ?i13/2??i13/2 band has been confirmed by the observations of linking transitions and signature crossing at I = 25.5?. The inversion phenomenon in ?h11/2??i13/2, ?h9/2??i13/2 and ?i13/2??i13/2 structures in 178Ir provides a unique testing ground for different theoretical interpretations.

Fluctuation measurement of excitation function in the dissipative process of 19F + 51V reaction

Abstract Excitation functions of the projectile-like fragments in the dissipative reaction 19F + 51V have been measured from 102.25 MeV to 109.50 MeV in 250 keV steps. The corresponding energy coherence widths Γ were extracted by means of the energy autocorrelation function method. The dependence of Γ on the degree of freedom of neutron excess N Z and the dependence of the charge number Z on the angular momentum coherence width γ are presented and discussed.

Measured and Simulated Performance of a Four-Segmented Clover Detector

Gamma rays with energies between 80 keV and 1500 keV produced by 133Ba and 152Eu standard sources are measured with the clover detector. Relative efficiencies and add-back factors are determined in both crystals and full clover modes. The add-back characteristics have been calculated using Monte-Carlo simulation code Geant4. The simulation and measurements agree very well.

Properties of the β-Delayed Proton Decay of 147Er

The ?-delayed proton decay of 147Er is studied experimentally using the 68Ni+92 Mo reaction at a beam energy of 383 MeV. Based on a He-jet apparatus coupled with a tape transport system, the ?-delayed proton radioactivities both from the ?s1/2 ground state and the ?h11/2 isomer in 147Er are identified by proton-? coincidence measurements. By analyzing the time distribution of the 4+ ? 2+? transition in the grand-daughter nucleus 146Dy, a half-life of 1.6 ? 0.2 s is determined for the ?h11/2 isomer in 147Er. The half-life for the ground state of 147Er is estimated to be 3.2 ? 1.2 s.

A New High-Spin Level Scheme of 128I

High-spin states in the odd-odd nucleus 128I are investigated via the 124Sn(7Li,3n)128I reaction at 28 and 32 MeV beam energies. A new level scheme of 128I is established up to high-spin states at Iπ = 16, including 48 levels and 72 γ transitions. The present level scheme is largely different from the one in a recent publication due to identification of several doublet and triplet γ transitions and their proper placements in the level scheme. The high-spin level structure exhibits no obvious collective properties and is possibly associated with two and multi-quasiparticle configurations.

Dipole bands in nucleus 139Pm

High-spin states in nucleus 139Pm have been studied using the reaction 116Cd(27Al, 4n)139Pm. Two dipole cascades have been found. Spin and parity assignments were based on the Directional Correlation of Oriented Nuclei (DCO) ratios and systematic behavior in neighboring odd-proton nuclei. The level structures of 139Pm are compared with those of the N = 78 isotone 141Eu in which two dipole bands have been confirmed as magnetic rotational bands. The close similarity between them suggests that the dipole bands in 139Pm may be magnetic rotational bands.

Identification of Oblate Band in Odd?Odd 184Au

High-spin states in 184Au have been populated via the 149Sm(29Si, 4n?) 184Au reaction at a beam energy of 140?MeV. Three- or higher-fold ?-ray coincidences have been measured using the multidetector array of GASP. A rotational band built on the 11? oblate ?h11/2?1??i13/2?1 structure has been newly observed, similar to those reported in 186?194Au. This result extends the knowledge of shape coexistence to the currently lightest odd?odd Au isotope.