Study of the νi13/2－1 band in 189Pt

High-spin levels of ^189Pt have been studied with the in-beam T-spectroscopy method via the ^176Yb（^18O,5n） reaction at the beam energies of 88 and 95 MeV. The previously known ＂vi-1 13/2 band has been confirmed, and its unfavored signature branch extended up to the 31/2^＋ state. Within the framework of the triaxial particle-rotor model, the vi-1 13/2 band is suggested to be associated with the 11/2[615] configuration, and to have triaxial deformation.     

Properties of the 3/2~-[521] band in the odd-N rare-earth nuclei

High-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2+[642], 3/2-[521], and 11/2-[505] configurations have been extended up to high-spin states, and particularly, the α = -1/2 branch of the ground state 3/2-[521] band has been revised significantly. It is found that signature inversion occurs in the 3/2-[521] band after the band crossing in 161Er. The systematics of the signature inversion associated wit...     

Identification of a New Band and Its Signature Inversion in ^174Re

High spin states in ^174Re are investigated via the ^152Sm（^27 AL,5nγ）^174Re reaction and γ - γ coincidence relationships are analysed carefully. A new band is identified due to its spectroscopic connection with the known π1/2^-[541] × ν1/2^-[521] band. This band is proposed to be the ground-state band built on the π1/2^-[541]× ,ν5/2^-[512] configuration in view of the low-lying intrinsic states in the neighbouring odd-mass nuclei. It is of particular interesting that the new band exhibits a phenomenon of low-spin signature inversion, providing a new situation for theoretical investigations.     

Identical Superdeformed Bands in ^171Ta and ^173Re

The rotational band built on the i13/2 proton [660,1/2] Nilsson state in ^173Re is proven to be identical to that in ^171Ta.The close similarity of the two bands in ^171Ta and ^173Re suggests that the ^173Re nucleus with the odd proton based on the i13/2 [660,1/2] Nilsson state may be triaxially superdeformed.     

High Spin Band Structure in ^112Ru

Levels in the neutron-rich ^112Ru nucleus have been investigated by observing prompt gamma-rays from the spontaneous fission of ^252Cf with the Gammasphere detector array. The ground state band and the one-phonon γ-vibrational band have been confirmed and extended with spin up to 16h and 15h, respectively. The other two side bands, one proposed as two-phonon γ-vibrational band and the other proposed as two-quasiparticle band, have been observed for the first time. The total-Routhian-surface calculations show that rotational 112 Ru nucleus has triaxial deformation with parameters β2 - 0.27 and γ= -29°. The observed band crossing in the yrast band is due to the alignment of a pair of h11/2 neutrons according to the cranked shell model calculations. The possible configuration for the quasiparticle band has also been discussed.     

Observation of High-j Two-Quasiparticle Bands in Odd-Odd ^174Re

High spin states in ^174Re have been investigated via the ^152Sm （^27 Al, 5nγ） ^174Re reaction. Gamma-ray excitation functions, x-γ and γ-γ coincidences have been measured. Two rotational bands built on the πh9/2 × vi13/2 and πh11/2 × vi13/2 configurations have been identified and extended up to high-spin states. The relative spin and parity of the band levels have been unambiguously fixed due to observations of several inter-band transitions. Both the bands show the low-spin signature inversion, which is consistent with systematic expectations for the high-j two-quasiparticle bands in the A = 170 mass region.     

Negative Parity Bands and Signature Splitting Inversion in ^80Rb

High spin states in ^80Rb were studied via the ^65Cu ^19F, ^66Zn ^180 and ^68Zn ^160 reactions. The 75-MeV ^19F,76-MeV ^180 and 80-MeV ^160 beams were provided by the CIAE HI-13 Tandem accelerator and the JAERI Tandem accelerator. The prompt γ-γ coincidence and the directional correlation from oriented nuclei (DCO)were measured by the detector arrays in CIAE and JAERI. Twenty-three new states with 28 new transitionshave been assigned to ^80Rb. The states were observed up to spins of 20^ and 22^- in the α= 0 branch for thepositive and negative parity yrast bands respectively. The negative parity non-yrast bands were significantlyextended up to spins of 22^- and 15^-. The band crossings with frequencies 0.51 MeV and 0.61 MeV in the α= 0cascade were observed for the first time. The signature splitting was observed in both negative parity bands. Thesignature inversions at spins of about 7h and 15h were observed.     

Collective states and shape competition in ~(126)Te

High-spin states in ~(126)Te have been investigated by using in-beam γ ray spectroscopy with the ~(124)Sn(~7Li,1p4n)~(126)Te reaction at a beam energy of 48 MeV.The previously known level scheme has been enriched,and a new negative-parity sequence has been established.The yrast positive-parity band shows a shape change between triaxial shape and collective oblate shape as a function of spin.In particular,three competitive minima appear in the potential energy surface for the I~π=8~+ states,with one aligned state at γ =-120° and two triaxial states atγ ~30° and-45°,respectively.The signature splitting behavior of the negative-parity band is discussed.The shape change with increasing angular momentum and the signature splitting can be interpreted well in terms of the Cranked Nilsson-Strutinsky-Bogoliubov and Cranked Nilsson-Strutinsky model calculations.     

稀土区奇质子Lu和Ta核旋称反转研究

研究了奇质子核Lu和Ta同位素链h11/2质子9／2[514]转动带旋称劈裂的系统规律，并与同一核区奇奇核的πh11/2×vi13/2两准粒子转动带低自旋区旋称劈裂规律进行了比较，指出奇质子Lu和Ta核三准粒子带的旋称反转很可能是来源于h11/2准质子和 i13/2准中子之间的相互作用。The systematic features of signature splitting of the h11/2 9/2 [ 514] rotational band in Lutetium and Tantalum isotope chains have been investigated and compared with that of πh11/2×vi13/2 2-quasiparticle band in oddodd nuclei of the same nuclear region. It is shown that signature inversion of 3-quasiparticle band of some odd- Z Lutetium and Tantalum nuclei most probably caused by the p-n interaction of h11/2 quasiproton and i13/2 quasineutron.     

Decay properties of D and D_s mesons in coulomb plus power potential （CPPν）

The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V （r） =-4 /3 α s /r＋ Ar ν with different choices of ν.Numerical method to solve the Schrdinger equation has been used to obtain the spectroscopy of qQ mesons.The numerically obtained radial solutions are employed to obtain the decay constant and leptonic decay widths.It has been observed that predictions of the ground state masses and the decay widths are consistent with other model predictions as well as with the known experimental values.     

Gound State Properties of Nuclei in ^295118 α-Decay Chain

The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.     

Isospin and F-spin symmetry structure in low-lying levels of 48，50Cr isotopes

The low-energy level structure and electromagnetic transitions of ^48.50Cr nuclei have been studied using the interacting boson model with isospin (IBM-3). A sequence of isospin excitation bands with isospin T = Tz, Tz 1and Tz 2 has been assigned, and compared with available data. According to this study, the 2^3 and 2^2 states are the lowest mixed symmetry states in ^48Cr and ^50Cr, respectively. In particular, the present calculations suggest that a combination of isospin and F-spin excitation can explain the structure in these nuclei. The transition probabilities between the levels are analysed in terms of isoscalar and isovector decompositions which reveal the detailed nature of the energy levels. The results obtained are in good agreement with recent experimental data.     

Intrinsic charm production of doubly charmed baryons:Collider vs. fixed-target

The LHCb Collaboration has measured the doubly charmed baryon,■^++cc(ucc),through two different decay channels[1,2]in p+p collisions at center-of-mass energies of 7,8 and 13 TeV.While they have performed similar searches for the doubly charmed baryon ■^+cc(dcc),it has not yet been observed by LHCb[3].However,the fixed-target experiment,SELEX,at Fermilab,reported the observation of the ■^+cc in two different decay channels with a 600 GeV charged hyperon beam[4,5].The beam was composed of an admixture of π^±,p,p components as well as the Σ^- hyperon.Much discussion has arisen over the fact that the fixed-target observations have not been easily reproduced by the collider experiments at higher energies,where one might have expected the production rates to be much higher due to the orders of magnitude increase in the center of mass energy with LHCb.     

Blocking Effect and Moments of Inertia of K = 1/2 Rotational Band in 171Yb

The K = 1/2 rotational band in 171yb is investigated using the particle number conserving (PNC) method for treating the cranked shell model with monopole and quadrupole pairing interactions. The experimental moments of inertia of 171 Yb [521]1/2 (signature α = 1/2) are reproduced well by the PNC calculation, in which no free parameter is involved. The difference in the contribution to the moment of inertia between protons and neutrons is mainly due to the blocking effect of neutron normal orbitals. The ω variation of the occupation probability of each cranked orbital and the contribution to the moment of inertia from each major shell and from each cranked orbital are investigated.     

Investigation into the rotational bands of ~(185)Pt with the particle-rotor model

Theoretical calculations have been performed for the ν9/2+[624](i13/2) and ν7/2-[503](f7/2) bands of 185Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is pro posed to be dominated by the ν9/2+[624](i13/2) component, while the negative-parity band shows strong mixing of ν7/2-[5...     

Ground State Properties of New Element Z=113 and Its Alpha Decay Chain

We investigate the ground state properties of the new element ^278 113 and of the α-decay chain with different models, where the new element Z=113 has been produced at RIKEN in Japan by cold-fusion reaction [Morita et al. J. Phys. Soc. Jpn. 73 (2004) 2593]. The experimental decay energies are reproduced by the deformed relativistic mean-field model, by the Skyrme-Hartree-Fock (SHF) model, and by the macroscopic-microscopic model.Theoretical half-lives also reasonably agree with the data. Calculations further show that prolate deformation is important for the ground states of the nuclei in the α-decay chain of ^278 113. The common points and differences among different models are compared and discussed.     

Search for Double γ-Vibrational Bands in Neutron-Rich 105Mo Nucleus

Levels in the neutron-rich ^105Mo nucleus have been investigated by observing prompt γ-rays following the spontaneous fission fragments of^252 Cf with the Gammasphere detector array. The yrast band has been confirmed and updated. The other two collective bands with the band head levels at 870.5 and 1534.6 keV are newly observed, and they are suggested as the candidates for one-phonon K= 9/2 and two-phonon K = 13/2 double γ-vibrational bands, respectively. Systematic characteristics of these bands have been discussed.     

Clarification of Confusion in Level Scheme of 124Cs

Low-lying and high-spin states of ^124 Cs 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 vd3/2 bands and two transitions between the yrast and πh11/2 v（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 finking transitions between the yrast and πh11/2 v（d5/2, 97/2） bands observed before. These E1 linking transitions infer the oetupole correlation in ^124Cs. 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 vd3/2 configuration.     

Decay properties of D and D_s mesons in coulomb plus power potential (CPP_ν)

The decay properties of the D and D s mesons are computed in a nonrelativistic phenomenological quark-antiquark potential of the type V (r) =-4 3 α s r+ Ar ν with different choices of ν.Numerical method to solve the Schrdinger equation has been used to obtain the spectroscopy of qQ mesons.The numerically obtained radial solutions are employed to obtain the decay constant and leptonic decay widths.It has been observed that predictions of the ground state masses and the decay widths are consistent with other model predictions as well as with the known experimental values.     

非常缺中子Re核的负三轴形变研究(英文)

利用在束核谱学实验技术,建立了169Re基于9/2-[514]组态的强耦合转动带.该带在已知的奇ARe核中具有最大的低自旋旋称劈列.对于奇ARe中的9/2-[514]转动带,研究了它们的能量旋称劈列和M1跃迁矩阵元相对旋称劈列与核形状偏离轴对称的关系,揭示了非常缺中子的奇ARe核具有相当的负三轴形变. High-spin states in~(169)Re were studied and resulted in the identification of a strongly coupled band based on the 9/2~(-)\ Nilsson state. The 9/2~(-)\ band in~(169)Re shows the largest signature splitting at low spin among the known odd mass Re isotopes. For the 9/2~(-)\ bands in light odd-A Re isotopes, the signature splitting of the Routhians and its relation with the signature dependence of M1 transition matrix elements are investigated in connection with the deviation of nuclear shape from axial symme...