19F+27Al耗散反应中双核系统的转动与形变

测量了¹⁹F+²⁷Al耗散反应产物B,C,N,O,F和Ne的激发函数,入射束流的能量从110.25MeV到118.75MeV, 能量步长为250keV. 从产物的 能量自关联函数中提取了反应中所形成的中间双核系统的转动惯量, 与相粘模型计算的刚体转动惯量相比较, 结果表明形成的双核系统有大的形变.     

HIGH-ORDER CRANKING CALCULATION IN THE INTERACTING BOSON MODEL AND INTERACTING BOSONFERMION MODEL

Considering that the IBM and IBFM cranking calculations in the lowest order of angular frequency can give reasonably good estimates for the moment of inertia,we extend them to study the dependence of the moment of inertia on the higher order terms.We find that the analytic expressions for the correction terms can be derived.Numerical calculations for ¹⁵⁴Gd and ¹⁶¹Er are performed and compared with experiment.The Hamiltonian is taken from a microscopic approach.Calculated results show that the properties of higher order terms depend on the deformation of rotating system but the correction yields only limited effect when ω is small.     

Derivation of microscopic uni-axial unified adiabatic Bohr–Mottelson rotational model

For a rotational motion about a single axis, we derive a microscopic, quantum version of the phenomenological Bohr–Mottelson unified adiabatic rotational model without using redundant coordinates, imposing constraints on the intrinsic state or the particle coordinates, or assuming explicitly a deformed intrinsic state. The model Schrödinger equation is derived from the direct action of the multi-particle Hamiltonian operator on the rotational-model wavefunction. We show that the Coriolis-coupling terms in the derived Schrödinger equation vanish exactly only for a choice of the Euler angle that is consistent with the rotational model requirement that the intrinsic wavefunction be invariant under rotation. For this angle, which also satisfies the conjugate commutation relation, the kinematic moment-of-inertia tensor, collective-rotation velocity field, and flow vorticity have the rigid-flow characteristics. Pairing interaction and fluctuations in the rigid-flow moment of inertia are shown to reduce the rigid-flow value of the kinematic moment of inertia in closer agreement with the experimental value. The derivation shows that a multi-fermion system with unpaired or paired (quasi) particles rotates nearly rigidly and a single-particle system rotates irrotationally if the intrinsic system is rotationally invariant, regardless of the value of the moment of inertia and the nature of the rotationally-invariant momentum-independent interaction.     

The shape of fast-rotating nuclei in the region of subshellN=82

The fast rotating erbium nuclei in the vicinity ofN=82 are investigated in the framework of the Strutinsky shell-correction method using the Woods-Saxon potential including non-axial hexadecapole deformations. The equilibrium deformation and moment of inertia are calculated for different spin values. The influence of nuclear temperature on the shell-effects is also discussed.     

The O(6) description of the nuclear rotation

A recently developed algebraic version of the collective model has shown that a full range of Bohr model calculations can be executed in bases that range continuously from those of a spherical vibrator to a beta-vibrational Wilets-Jean limit. Thus, the establishment of close relationships between the algebraic structure of this model and the IBM is of special importance because one can learn from the complementary perspectives they afford. In this paper, we show by calculations that the familiar rotor-gamma vibrational spectra of the Bohr model can be obtained in the IBM by the addition of a scalar cubic in the quadrupole moment operators, of the type considered recently by Van Isacker, to an O(6) Hamiltonian. Simple fits of the low-lying spectra, electromagnetic transition rates and moments of inertia of the ground and gamma bands of¹⁶²Dy and¹⁶⁸Er are presented.     

刚体绕任意轴转动惯量的简便计算

利用微元求和的方法给出几种刚体对于过质心任意轴的转动惯量公式，并由此引出转动惯量与刚体几何对称性的联系，以及与转动惯量有关的几何形体等价性的一些结果．     

Rotational bands in the proton emitter (141)Ho

Rotational bands feeding the ground state and the isomeric state in the proton emitter (141)Ho were observed using the recoil-decay tagging method. This constitutes direct evidence that (141)Ho is deformed. A quadrupole deformation of beta(2) = 0.25(4) was deduced for the ground state from the extracted dynamic moment of inertia. Based on observed band crossings and signature splittings the 7/2(-)[523] and 1/2(+)[411] configurations were proposed for the ground state and the isomeric state, respectively. Comparison with particle-rotor calculations for beta(2) = 0.25 indicates, however, that (141)Ho may have significant hexadecapole deformation and could be triaxial in the 7/2(-)[523] ground state.     

Experimental moments of inertia in Pd and Cd isotopes and their interpretation within the extended Nilsson-Strutinsky model

High-spin properties of even Pd and Cd isotopes have been studied by means of a 118 MeV ¹²C beam impinging onto a ¹⁰⁰Mo target. The γ-rays following the reaction were recorded using six NaI(Tl) detectors in a two-dimensional coincidence arrangement. Energy-correlation spectra were extracted from the coincidence matrix and used to obtain information on the collective moment of inertia $\text{I}$. The gross properties of the behaviour of this moment of inertia are discussed within an extended Nilsson-Strutinsky model. The experimentally observed variation of the moment of inertia at high rotational frequencies is tentatively explained as being due to an increase of $\text{I}$ as the band approaches its termination.     

粒子－转子模型分析超形变转动带

利用三轴粒子－转子模型计算了（１９３）Ｔｌ超形变带γ跃迁能量，运动学转动惯量Ｊ（１）和动力学转动惯量Ｊ（２），并与实验值进行比较得到了满意的结果；预言了Ｂ（Ｍ１）值以及动力学电四极矩Ｑ（１）和Ｑ（２）指出在超形变带的分析中粒子－转子模型是一种可以采用的方法．     

Spin Cut-off Parameter of Nuclear Level Density and Effective Moment of Inertia

The spin cut-off parameter of the nuclear level density and effective moment of inertia for a large number of nuclei have been determined from analysis of the experimental data on S-wave neutron resonances and spins of low-lying levels. Contrary to claims made before, it is shown the spin cut-off parameter differs considerably from their corresponding rigid body values, and the energy dependence of the effective moment of inertia confirms the interacting fermion model prediction.     

利用刚体转动惯量实验仪验证转动定律的设计

介绍了设计性实验“利用刚体转动惯量实验仪验证转动定律”.该实验要求学生理解刚体动力学原理;利用实验室现有的仪器,对刚体转动惯量实验仪进行改装;提出新的实验原理,可以对阻力矩进行估测,利用该实验装置验证刚体定轴转动定律.     

关于惯量张量的注释

本文从物理学中转动惯量的传统定义出发，导出以并矢形式表示的惯量张量，然后又反过来，用这一张量重新给转动惯量及惯量积下定义。     

气垫导轨在刚体转动惯量测定实验中的应用

本文介绍了一种测量刚体转动惯量的新方法。即把气垫导轨和刚体转动仪结合起来来测量刚体的转动惯量,使传统的气垫导轨实验和刚体转动惯量测定实验得以更新,提高了实验测量的精度,拓展了实验内容。     

Signature splitting in 129Ce

The high spin states of 129Ce have been populated via heavy-ion fusion evaporation reaction 96Mo (37C1, 1p3n) 129Ce. The γ-γ coincidence and intensity balance used to measure the B(M1; I→I-1)/B(E2; I→I-2) (the probability ratio of the dipole and quadrupole transition) in v7/2[523] rotational band of 129Ce. And the energy splitting (Δe') has been got through the experimental Routhians. The lifetimes and quadrupole moments Qt have been extracted from the lineshape analyses using DSAM. The deformation of the v7/2[523] rotational band of 129Ce was extracted from the Qt and moment of inertia JRR.     

Coupling of the rotational motion with the axial vibrations of multipolarity 2 and 4

The unadiabatic effects related to the coupling between the rotational and vibrational degrees of freedom are investigated. The collective Hamiltonian is constructed using the concepts of the Bohr theory and includes the degrees of freedom corresponding to the axial quadrupole and hexadecapole vibrations. The coupling of the nuclear vibrations with the rotational motion is so strong that one has to multiply the inertial parameters and the moment of inertia by the factor 1.7 in order to get the experimental energies spacing in the ground state bands. The dynamical effects to the electric quadrupole and hexadecapole moments are considered. The parameter of unadiabaticityα calculated within the model agrees well with the experimental data.     

On oblate-prolate transition in the ground state rotational band of light mercury isotopes

The transition from an oblate to a prolate shape in the ground state band of even mass Hg isotopes and in the ground states of the chain of odd mass Hg isotopes are studied. The shape is found by minimizing the deformation energy which is calculated by means of Strutinsky's shell correction method. The rotational energy corresponds to the axialsymmetric rotator. The moment of inertia is calculated with the help of the cranking model. Pairing and hexadecupole deformation are included. The results are in good agreement with the available experimental data.     

Cranking Calculation in the sdg Interacting Boson Model

A self-consistent cranking calculation of the intrinsic states of the sdg interacting boson model is performed. The formulae of the moment of inertia are given in a general sdg IBM multipole Hamiltonian with one- and two-body terms. In the quadrupole interaction, the intrinsic states, the quadrupole and hexadecapole deformation and the moment of inertia are investigated in the large N limit. Using a simple Hamiltonian, the results of numerical calculations for ¹⁵²,¹⁵⁴Sm and ^154-160 Gd satisfactorily reproduce the experimental data.     

中子星的转动惯量与表面红移的研究

在温度、密度及同位旋相关的核物质状态方程的基础上,通过求解Tolman–Oppenheimer–Volkoff方程,得到了中子星的转动惯量与表面红移.计算结果表明,中子星的转动惯量较强地依赖于核物质的不可压缩系数与对称能强度系数,而对核子有效质量不太敏感;中子星的表面红移却对对称能强度系数不太敏感,而较强地依赖于不可压缩系数与核子有效质量.     

Dynamic response of a prestressed,orthotropic thick plate strip to a moving line load

This paper is a study of the steady state response of an orthotropic plate strip to a moving line load. The plate is of infinite length and subjected to initial in-plane stresses parallel and perpendicular to the edges. The solution is obtained on the basis of a thick plate theory which takes into account the effects of shear deformation and rotatory inertia. The critical speed of the load which brings about a resonance effect in the system is determined. Further, the bending moment in the plate is calculated for several values of the load speed and the initial stress parameters and shown graphically as a function of the space variable moving with the load.