High-Spin Level Scheme of Odd-odd 142Pm

The level structure of doubly odd nucleus ¹⁴²Pm has been studied via the ¹²⁸Te(¹⁹F,5nγ)¹⁴²Pm reaction in the energy region from 75 to 95MeV. In-beam γ rays were measureed including the excited function, γ-ray singles and γ-γ coincidences in experiment. The level scheme of ¹⁴²Pm has been extended up to excitation energy of 7030.0keV including 25 new γ rays and 13 new levels. Based on the measured γ-ray anisotropies, the level spins in ¹⁴²Pm have been suggested.     

Study of Multi-Quasiparticle Excited States in 139Ce

High-spin states in ¹³⁹Ce have been populated using the ¹³⁰Te(¹²C,3n) reaction at beam energy of 50MeV. The level scheme of ¹³⁹Ce has been revised and extended greatly up to E=5765.0keV. The level structure of ¹³⁹Ce shows typical characteristics of spherical nucleus, and the high-spin states were formed by the excitations of valence nucleons. Energies of the yrast and near yrast high-spin states in ¹³⁹Ce have been calculated by the empirical shell model, and the multi-quasiparticle nature of high-spin excited states has been discussed.     

High-Spin Level Scheme of Odd-Odd 140Pr Nucleus

High spin level structure of doubly odd nucleus ¹⁴⁰Pr has been investigated using in beam γ spectroscopy techniques by means of the ¹³⁰Te(¹⁴N,4n)¹⁴⁰Pr reaction at beam energy of 58MeV.γ-ray excitation functions,γ-ray singles and γ-γ-t coincidences were measured experimentally.The level scheme of ¹⁴⁰Pr,including 27 new levels and 42 new γ-rays,was established for the first time up to 4717.3keV in excitation energy.Based on the measured γ-ray anisotropies,spin values were suggested to the levels in ¹⁴⁰Pr.Several quasiparticle configurations are discussed on the basis of systematics in the neighboring odd odd nuclei,and interpreted qualitatively.     

Nuclear structure in odd-odd nucleus138Pr

With the view of extending the systematics of odd-odd Pr nuclei toward the N=82 closed shell, high-spin states in¹³⁸Pr nucleus have been investigated with the¹²⁸Te(¹⁴N, 4nγ) reaction. Configurations and spin assignments are suggested for three of the observed band-structures.     

Levels in doubly odd 138Pr

The band structures of the doubly odd ¹³⁸Pr nucleus have been investigated using the ¹²⁸Te(¹⁴N, 4n)¹³⁸Pr reaction at a beam energy of 55-65 MeV. Altogether six distinct structures have been established, of which the lower part of the yrast band and two side bands were known from earlier works. The observed level properties of the members of the yrast band have been compared with theoretical calculations performed within the Particle Rotor Model (PRM) with axially symmetric core. The experimental branching ratios and B(M1)/B(E2) values when compared with the theoretical results of the PRM, suggest an oblate core.     

β-Delayed Proton Decay of 93Pd

The β-‘waiting point’nucleus ⁹³Pd has been produced via ⁵⁸Ni(⁴⁰Ca,3n2p) reaction. A helium-jet fast tape transport system was used in combination with p-γ coincidence measurement to identify the β-delayed proton precursor ⁹³ Pd, whose half-life has been measured to be 1.3±0.2s. The measured energy spectrum of β-delayed protons and relative branching ratios to the final states in the daughter nucleus ⁹²Ru are fitted by a revised statistic model calculation, and then the ground state spin of ⁹³Pd are assigned to be 9/2. Meanwhile, a nuclear energy-potential-surface (EPS) calculation is performed by using the Woods-Saxon Strutinsky method. The calculated result supports the ground state spin and parity of 9/2⁺ assignment.     

Properties of N=84, even-even nuclei populated in the spontaneous fission of 248Cm

Excited states in the neutron-rich, N=84 nuclei ¹³⁴Sn, ¹³⁶Te and ¹³⁸Xe, populated in the spontaneous fission of ²⁴⁸Cm, were studied to medium spins using the EUROGAM2 array. OXBASH code calculations support the experimental identification of maximum aligned configurations in these isotopes. Empirical shell model calculations agree with the proposed excitation energy of the neutron h_9/2 excitation in the ¹³²Sn region. A discrepancy between the observed and calculated excitation energy of the I^π= 12⁺ level in ¹³⁶Te indicates possible admixtures of collective excitations in this nucleus. Clear signs of collective excitations are observed in ¹³⁸Xe. Received: 10 November 1999 / Revised version: 22 December 1999     

RELATIVISTIC DESCRIPTION OF PROTON-NUCLEUS ELASTIC SCATTERING AT HIGH ENERGIES

In the framework of relativistic Dirac's equation, a fermion elastic scattering from a nucleus has been discussed. The cross sections, analyzing power and spinrotation parameters for 500MeV proton scattered from He⁴,Ca^40,48 and Pb²⁰⁸ have been calculated in the eikonal approximation. The agreement between theoretical and experimental results is satifactory.     

Collective Bands in Neutron-Rich 107Ru Nucleus

Through measuring prompt γ-rays emitted in the spontaneous fission of ²⁵²Cf with higher statistic data,level structures in the neutron rich,odd A¹⁰⁷Ru nucleus have been re investigated. New level scheme of ¹⁰⁷Ru has been established. The ground state band was extended with spin up to 27 2h. The νh_11/2 band structure observed in our previous publication has been confirmed and extended. These results clear up the inconsistence between our earlier work and results from another experiment published recently. A collective band built on (9/2^－) level has been observed for the first time. Some important features of the level scheme have been discussed.     

Octupole Deformed Band and Quasi-γ Band in 146Ce Nucleus

High-spin structures in ¹⁴⁶Ce nucleus have been re-investigated by measuring the prompt γ rays from spontaneous fission of ²⁵²Cf. The previously reported level scheme of ¹⁴⁶Ce has been updated. The octupole deformed collective bands have been extended up to higher spin states. A possible quasi-γ band structure was examined and reconstructed according to our data analysis. In addition, the reflection asymmetric shell model was applied to describe the octupole deformed bands in ¹⁴⁶Ce, and the calculated results are in good agreement with the experimental data at lower spins.     

稀磁半导体Zn1-xMnxTe吸收光谱压力红移的理论研究

以自由Mn²⁺离子的径向波函数为基础,通过引入电子云延伸效应系数κ来修正这一径向波函数,得到了稀磁半导体Zn_1-xMn_xTe晶体中Mn²⁺离子的径向波函数.以此波函数为基础,研究了Zn1-xMnxTe晶体吸收光谱的高压谱移特性,并且得到了吸收谱中四条谱线随压力的红移规律.     

A Comparison Between Two Different Optical Potentials for the 3He+ 12C Scattering at the Energy 72MeV

Through the analysis of the ³He elastic scattering on the ¹²C nucleus, two different folded optical potentials, one is constructed based on the α-particle model of the ¹²C nucleus, another is constructed based on the nucleon component model of ¹²C, are compared. The comparison shows that the former optical potential has some advantages.     

Excitation of isobaric analogue resonances by inelastic scattering of polarized protons from 126Te

An experimental study of inelastic scattering of polarized protons from ¹²⁶Te, leaving this nucleus in its first excited state, is presented. The scattering proceeds through isobaric analogue resonances in ¹²⁷I.A method has been developed and applied to extract partial width amplitudes from measured cross sections and analyzing powers. From these amplitudes coefficients of fractional parentage are deduced, characterizing the relation between five negative parity parent states in ¹²⁷Te and the first excited state of ¹²⁶Te.     

Electromagnetic Transition Rates and Deformation Feature in 130Ce

Lifetimes of the excited states in light rare-earth nucleus ¹³⁰Ce have been measured using heavy ion reaction ¹¹⁶Sn(¹⁶O,2n)¹³⁰Ce at beam energy of 73MeV through analyzing the Doppler-broadened line shapes. The reduced transition probabilities B(E2) are extracted from these measurements. The experimental results show that the previously reported anomalously high B(E2) value has not been observed in the present work. The transition quadrupole moment for the yrast band varies with spin and corresponds to a triaxial deformation with γ≈7°.     

Identification of New Isotope 238Th

Unreported heavy neutron-rich nuclide ²³⁸Th has been produced via a multinucleon transfer reaction by 60MeVIu ¹⁸0 ions bombardment of natural uranium.Thorium was radiochemically separated from the mixture of uranium and reaction products. ²³⁸Pa as a daughter nucleus of ²³⁸Th has been identified according to the growth and decay of ²³⁸Pa γ rays which has been observed. The half-life of ²³⁸Th was determined to be (9.4 + 2.0) min. At the same time, a new γ ray of (89.0 + 0.3) keV with T_1/2= (8.9 + 1.5)min was found in the γ spectrum gated with the K_α1, X ray of Pa and assigned to ²³⁸Th decay based on the measurements of its transition energy and the half-life.

     

The Study of Unbound Nuclei 11N Resonance Energy Level

The excitation functions of elastic scattering proton which were measured with inverse kinematics of elastic resonance scattering reactions in GANIL and MSU have been fitted by the multi-energy level $R$-matrix theory. The final result shows that the new energy levels order for nucleus ¹¹N should be 1/2⁺,1/2^－,5/2⁺,3/2⁺, 3/2^－,5/2⁺,7/2^－,which is consistent with the experimental results of ¹¹Be (the mirror nucleus of ¹¹N) and the theoretical calculation of ¹¹N with GCM theory.     

Band Gap Energies and Refractive Indices of Epitaxial Pb1-xSrxTe Thin Films

Pb1-x Srx Te thin films with different strontium （St） compositions axe grown on BaF2 （111） substrates by molecular beam epitaxy （MBE）. Using high resolution x-ray diffraction （HPLXRD）, we obtain Pb1-xSrxTe lattice constants, which vary in the range 6.462-6.492 A. According to the Vegard law and HRXRD data, Sr compositions in Pb1-xSrxTe thin films range from 0.0-8.0%. The Pb1-xSrxTe refractive index dispersions are attained from infrared transmission spectrum characterized by Fourier transform infrared （FTIR） transmission spectroscopy. It is found that refractive index decreases while Sr content increases in Pb1-xSrx Te. We also simulate the Pb1-xSrxTe transmission spectra theoretically to obtain the optical band gap energies which range between 0.320 e V and 0.449 e V. The simulated results are in good agreement with the FTIR data. Finally, we determine the relation between Pb1-xSrx Te band gap energies and Sr compositions （Eg = 0.320＋0.510x-0.930x^2 ＋184x^3 （eV））.     

Study of Nuclear Level Structure in Tc Isotopes with Mass A～100

In the present work, the structures of the excited positive/negative-parity yrast states of ¹⁰¹Tc are discussed by using a projected shell model, and a band diagram calculated for the positive-parity yrast band is also shown in order to extract physics out of numerical results. In addition, the analysis of other three bands originated from 3/2^－[301], 5/2^－[303], and 1/2⁺[431] Nilsson states, respectively, is also performed in the framework of this model. Until recently, very little property about the N=52—54 intermediate nuclei in the Z～42—44 region has been known. In order to understand these "transitional nuclei", we select the nucleus ⁹⁵Tc as an example. So in this work, we also present our investigation of the level structure in the ⁹⁵Tc nucleus.     

A POSSIBLE EXPLANATION OF THE DOUBLE BACKBENDING OF YRAST BAND FOR NUCLEI 122,124,126Te

A possible explanation of the mechanism for the double backbending in the yrastband of nuclei ^122,124,126Te is given.     

Structure of 136Te and the problem of mass of 134Te

Neutron-rich, N=84 nuclei from the ₁₃₂Sn region, populated in spontaneous fission of ₂₄₈Cm, have been studied with EUROGAM 2. Excited states and their spins and parities in the ₁₃₆Te nucleus were established up to 17ħ. OXBASH code calculations support the experimental identification of maximum aligned configurations in ₁₃₆Te. Empirical shell model calculations for the I_π= 14₊ level in ₁₃₆Te indicate that the adopted mass of the ₁₃₄Te nucleus should be lowered by 200(80) keV. Received: 3 August 1998