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1.
Anwer A 《中国物理C(英文版)》2015,39(8):084101-084101
Energy levels and the reduced probability of E2–transitions for ytterbium isotopes with proton number Z=70 and neutron numbers between 100 and 106 have been calculated through phenomenological(Ph M)and interacting boson(IBM-1)models.The predicted low-lying levels(energies,spins and parities)and the reduced probability for E2–transitions results are reasonably consistent with the available experimental data.The predicted low-lying levels(gr–,β1–andγ1–band)produced in the Ph M are in good agreement with the experimental data compared with those by IBM-1 for all nuclei of interest.In addition,the phenomenological model was successful in predicting theβ2–,β3–,β4–,γ+2–and 1+–band while it was a failure with IBM-1.Also,the 3–band is predicted by the IBM-1 model for172Yb and174Yb nuclei.All calculations are compared with the available experimental data.  相似文献   

2.
High spin states of 128La have been studied through the fusion-evaporation reaction 118Sn(14N, 4n)128La at a beam energy of 69 MeV. A positive-parity side band with the same configuration as that of the yrast band has been identified. Moreover, it is noted that the energy separation ΔE(I)=E(I)side-E(I)yrast of all doublet bands reported in odd-odd nuclei in the A~130 mass region exhibit a staggering pattern systematically, and they stagger up at even-spin and stagger down at odd-spin.  相似文献   

3.
Two-quasiparticle bands and low-lying excited high-K four-, six-, and eight-quasiparticle bands in the doubly-odd 174, 176Lu are analyzed by using the cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. The proton and neutron Nilsson level schemes for 174, 176Lu are taken from the adjacent odd-A Lu and Hf isotopes, which are adopted to reproduce the experimental bandhead energies of the one-quasiproton and one-quasineutron bands of these odd-A Lu and Hf nuclei, respectively. Once the quasiparticle configurations are determined, the experimental bandhead energies and the moments of inertia of these two- and multi-quasiparticle bands are well reproduced by PNC-CSM calculations. The Coriolis mixing of the low-K (K=|Ω1-Ω2|) two-quasiparticle band of the Gallagher-Moszkowski doublet with one nucleon in the Ω = 1/2 orbital is analyzed.  相似文献   

4.
The angular distribution of 1H(6He,p)6He elastic scattering has been measured at Ec.m.=4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set. The real part of CH89 is reduced comparing with other potentials, which may be attributed to the couplings necessary for the weakly bound nuclei.  相似文献   

5.
The properties of γ instability in rapidly rotating even-even132-138 Nd isotopes have been investigated using the pairing-deformation self-consistent total-Routhian-surface calculations in a deformation space of(β2, γ,β4). It is found that even-even134-138 Nd nuclei exhibit triaxiality in both ground and excited states, even up to high-spin states. The lightest isotope possesses a well-deformed prolate shape without a γ deformation component.The current numerical results are compared with previous calculations and available observables such as quadrupole deformation β2 and the feature of γ-band levels, showing basically a general agreement with the observed trend ofγ correlations(e.g. the pattern of the odd-even energy staggering of the γ band). The existing differences between theory and experiment are analyzed and discussed briefly.  相似文献   

6.
Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the difference between simulation and data in track reconstruction e ciency reduces from 1% to 0.5% averagely for the pion in J/Ψπ+π-π0, and the momentum resolution agreement improves signi cantly for the proton in J/Ψ→pp.  相似文献   

7.
Mixing between the 23S1 and 13D1 Ds is studied within the 3P0 model. If mixing between these two 1- states exists, Ds1*(2700)± and DsJ*(2860)± could be interpreted as the two orthogonal mixed states with mixing angle θ≈ -80° in the case of a special β for each meson. However, in the case of a universal β for all mesons, Ds1*(2700)± could be interpreted as the mixed state of 23S1 and 13D1 with mixing angle 12° < θ < 21° but DsJ*(2860)± seems difficult to interpret as the orthogonal partner of Ds1*(2700)±.  相似文献   

8.
A chiral quark model is applied to calculate the spectra of pseudoscalar mesons η and η'. By analyzing the obtained spectra, we find that the mesons η'(21S0), η(41S0), η'(31S0) and η'(41S0) are the possible candidates of η(1760), X(1835), X(2120) and X(2370). The strong decay widths of these pseudoscalars to all the possible two-body decay channels are calculated within the framework of the 3P0 model. Although the total width of η'(21S0) is compatible with the BES Collaboration's experimental value for η(1760), the partial decay width to ωω is too small, which is not consistent with the BES result. If X(1835) is interpreted as η(41S0), the total decay width is compatible with the experimental data, and the main decay modes will be mπ a0(980) and m π a0(1450), which needs to be checked experimentally. The assignment of X(2120) and X(2370) to η'(31S0) and η'(41S0) is disfavored in the present calculation because of the incompatibility of the decay widths.  相似文献   

9.
This work is concerned with the analyses of the shower and gray particle production in 4.5 A GeV/c 24Mg collision with emulsion nuclei. The highest particle production occurs in the region of the low impact parameters. While the multiplicity of the shower particles emitted in the forward direction depends on the projectile mass number and energy, the multiplicity of the backward ones shows a limiting behaviour. The source of the emission of the forward shower particles is completely different from that of the backward ones. The target fragments are produced in a thermalized system of emission.  相似文献   

10.
The scaling behaviors of anisotropic flows of light charged particles are studied for 25 MeV/u 40Ca+40Ca collisions at different impact parameters by the isospin-dependent quantum molecular dynamics model. The nucleon-number scaling of elliptic flow exists and the scaling of the ratios of v4/v22 and v3/(v1v2) is applicable to collisions at almost all impact parameters except for peripheral collisions.  相似文献   

11.
In this paper, we calculate the branching ratios of Λb→pK- and pπ- decays in the avor changing Z' model. We nd that the branching ratios for these two decay modes are sensitive to the contributions of the Z' boson. For Λb→pK- decay, if the left-handed couplings are equal to the right-handed couplings, the branching ratio of this decay could match up to the currently experimental data for ξs=0.01 and -52°<φsL<132°, or ξs=0.004 and 0°<φsL<84°; if only the left-handed couplings are considered, it could match up to the experimental data for ξs=0.01 and -10°φsL<138°. And for Λb→pK- decay, if the left-handed and right-handed couplings are equal, the branching ratio of Λb→pK- decay may be consistent with the currently experimental data with ξd=0.05 and -135°φdL<43°, if only the left-handed couplings are considered, it may be consistent with ξd=0.05 and -114°φdL<8°.  相似文献   

12.
Differential and integrated directed flow and elliptic flow of light charged particles (z ≤ 2) are studied systematically for semi-central (b = 5 fm) 197Au+197Au collisions at incident energies from 25 to 250 MeV/nucleon by the isospin-dependent quantum molecular dynamics model. The changes of directed and elliptic flow with incident energy reflect the dynamic competition between mean field and nucleon-nucleon collisions and also between collective rotation and expansion.  相似文献   

13.
Motivated by the rst measurement on B(Bs→φμ+μ-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic Bs→φμ+μ- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(Bs→φμ+μ-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δLLu)23 as well as (δLL,RRu)23 mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(Bs→φμ+μ-), B(B→K(*)μ+μ-) and (Bs→φμ+μ-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of Bs→φμ+μ-are highly sensitive to the squark exchange contribution and the (δLLu)23 mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC.  相似文献   

14.
We analyze the theoretical prediction on the branching ratio of B→Xsγ to order ΛEW2/ΛKK2 in extension of the standard model with a warped extra dimension and the custodial symmetry SU(3)c×SU(2)L×SU(2)R×U(1)X×PLR, where ΛKK denotes the energy scale of low-lying Kaluze-Klein excitations and ΛEW denotes the electroweak energy scale. Contributions from the in nite series of Kaluze-Klein excitations are summed over through the residue theorem. The numerical result indicates that the present experimental data constrain the parameter space of the concerned model strongly.  相似文献   

15.
In the two-quark model supposition for K0*(1430), which can be viewed as either the first excited state (Scenario Ⅰ) or the lowest lying state (Scenario Ⅱ), the branching ratios and the direct CP-violating asymmetries for decays Bs0→K0*0(1430)η(') are studied by employing the perturbative QCD factorization approach. We find the following results: (a) The CP averaged branching ratios of Bs0→K0*0(1430)η and Bs0→K0*0(1430)η' are small and both in the order of 10-7. If one views K0*(1430) as the lowest lying state, B (Bs0→K0*0(1430)η)≈3.9×10-7 and B (Bs0→K0*0(1430)η')≈7.8×10-7. (b) While the direct CP-violating asymmetries of these two decays are not small: if we still take the parameters of K0*(1430) in scenario Ⅱ, ACPdir (Bs0→K0*0(1430)η)≈56.2% and ACPdir (Bs0→K0*0(1430)η')≈2.4%. (c) The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.  相似文献   

16.
Based on 58 million J/ψ events collected by the BESⅡ detector at the BEPC, J/ψ→ΛΛ π+π- is observed for the first time. The branching fraction is measured to be Br(J/ψ→ΛΛ π+π-)=(4.30±0.13±0.99)×10-3, excluding the decays to intermediate states, namely J/ψ→Ξ-Ξ+, J/ψ→Σ(1385)-Σ(1385)+, and J/ψ→Σ(1385)+Σ(1385)-. The branching fractions for these intermediate resonance channels are measured to be:Br(J/ψ→Ξ-Ξ+)=(0.90±0.03±0.18)×10-3, Br(J/ψ→Σ(1385)-Σ(1385)+)=(1.23±0.07±0.30)×10-3,and Br(J/ψ→Σ(1385)+Σ(1385)-)=(1.50±0.08±0.38)×10-3, respectively. The angular distribution is of the form dN/d(cosθ)α(1+αcos2θ) with α=(0.35±0.29±0.06) for J/ψ→Ξ-Ξ+, α=(-0.54±0.22±0.10) for J/ψ→Σ(1385)-Σ(1385)+, and α=(-0.35±0.29±0.06) for J/ψ→Σ(1385)+Σ(1385)-.  相似文献   

17.
High spin states in 107Ag are studied via the 100Mo(11B, 4n)107Ag 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).  相似文献   

18.
The decay ψ(2S)→Ω-Ω+ is analyzed using 14×106 ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ(2S)→Ω-Ω+ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω+ signal with a statistical signi cance of 3.1|σ. The branching fraction of ψ(2S)Ω+ is determined to be (4.80±1.56(stat)±1.30(sys))105.  相似文献   

19.
The η photon production reaction on nuclei is studied by employing N*(1535) resonance model. The parameters of the model are extracted by using experimental data of N* decay channels and fitting γp→ηp reaction cross section. The result shows that the theoretical values are in good agreement with experimental data if MN*=1550MeV. The total cross section of the η photoproduction on 12C is calculated. We find that the width of N*(1535) in nuclei increases because of corrections of many-body effects, and the interaction between N* and nuclei has the feature of repulsion.  相似文献   

20.
We have applied the theory of the single-particle Schrodinger fluid to the nuclear collective motion of axially deformed nuclei. A counter example of an arbitrary number of independent nucleons in the anisotropic harmonic oscillator potential at the equilibrium deformation has been also given. Moreover, the ground states of the doubly even nuclei in the s-d shell 20Ne,24Mg,28Si,32S and 36Ar are constructed by filling the single particle states corresponding to the possible values of the number of quanta of excitations nx,ny, and nz. Accordingly, the cranking-model, the rigid-body model and the equilibrium-model moments of inertia of these nuclei are calculated as functions of the oscillator parameters ωxyand ωz which are given in terms of the non deformed value ω00 , depending on the mass number A, the number of neutrons N, the number of protons Z, and the deformation parameter β. The calculated values of the cranking-model moments of inertia of these nuclei are in good agreement with the corresponding experimental values and show that the considered axially deformed nuclei may have oblate as well as prolate shapes and that the nucleus 24Mg is the only one which is highly deformed. The rigid body model and the equilibrium model moments of inertia of the two nuclei 20Ne and 24Mg are also in good agreement with the corresponding experimental values.  相似文献   

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