Properties of the 635.4 keV level in171Tm

The properties of some high excited states of¹⁷¹Tm have been studied using Ge(Li) detectors. The directional angular correlation measurements for 277.4-210.5 keV cascade are in agreement with the spins of the 635.4 keV© and 912.8 keV(5/2) levels. The magnetic momentμ=(1.15±0.21)μ _N of the 635.4 keV level was determined by integral perturbed angular correlation (IPAC) in external magnetic field.     

Nuclear resonance fluorescence from the 58keV level in159Tb

The half-life of the 58keV level of¹⁵⁹Tb was determined by classical resonance absorption using the centrifuge technique and by Mössbauer spectroscopy measuring the natural line width and found to beτ _1/2=(58±10)ps. Mössbauer spectra for Tb and Tb₂O₃ absorbers and for Dy₂O₃ and GdFe₂ sources were investigated for temperatures between 9 and 385 K. Results for hyperfine interactions and Debye Waller factors are given. The Debye Waller factors are compared with predictions obtained from other experimental results.     

Diode-pumped Q-switched Tm:YAP laser with a pump recycling scheme

We reported on a diode end-pumped AO Q-switched Tm:YAP laser at 1937 nm. The average output power was 3.9 W, with a slope efficiency of 29.4% and optical-optical conversion efficiency of 21.6% at a 5-kHz repetition rate. The temperature dependency of the output power and the pulse width at different repetition rates were investigated in details.     

Crystalline-electric-field level scheme of NdB6

We have determined the crystalline-electric-field (CEF) level scheme of NdB₆ by means of Raman spectroscopy. We could resolve two CEF-transitions at 92 cm^–1 and 98 cm^–1 due to the spectral resolution of 2 cm^–1 (=0.25 meV). The temperature dependent Raman scattering reveals the two transitions to be on top of one another, in agreement with fits of the temperature dependence of the magnetic susceptibility. The spectroscopically determined CEF level scheme yields a good fit of the elastic constants and hence the mean field prediction of a ferroquadrupolar ordering near 6 K. This result sheds new light on the phase transition in NdB₆ nearT _N =8.6 K which has so far been interpreted only in terms of antiferromagnetic ordering.Work supported by Deutsche Forschungsgemeinschaft, SFB 125Work supported by Deutsche Forschungsgemeinschaft, SFB 126     

The level scheme of133Sb

Nuclear spectroscopy studies of ₅₁ ¹³³ Sb₈₂ have been performed at the recoil fission product separators JOSEF and LOHENGRIN. A tentative level scheme has been established for this nucleus with one proton in addition to the doubly closed shell core¹³²Sn. Two isomeric states with half-lives of 3 and 16 μs have been found at excitation energies of >4300 keV and 4526 keV, respectively. Lower limits of 15/2 are deduced for the spins of these levels. The h_11/2 proton state is suggested at 2792 keV in agreement with the systematics of the lighter Z=51 isotopes and the heavier N=82 isotones. Several states have been observed between 4300 and 4600 keV which are probably due to the coupling of the single proton to core-excited states which have energies between 4000 and 4800 keV.     

The level scheme of 134Cs

Low-lying states in ¹³⁴Cs have been investigated using the ¹³³Cs(n, γ)¹³⁴Cs and ¹³³Cs(d, p)¹³⁴Cs reactions with various spectroscopic techniques. Numerous excited states in ¹³⁴Cs have been established with energies up to 1267 keV. The experimental data on the lowest negative- and positive-parity states are in fair agrement with the calculations based on two quasiparticles coupled to a vibrator. For higher excited states the multiplets appear more mixed than predicted by the simple model.     

Identification and structure of yrast levels in theN=89 odd-odd158Tm nucleus

Excited levels have been identified in the odd-odd¹⁵⁸Tm nucleus produced in the¹⁵⁰Sm (¹⁴N,6n) reaction. The observed level structure based on an isomeric state (T_1/216±4 ns) is interpreted as a rotational aligned band.     

On the relativistic description of the nucleus

We present a formalism able to generalise to a relativistically covariant scheme the standard nuclear shell model. We show that, using some generalised nuclear Greens functions and their Lehmann representation we can define the relativistic equivalent of the non-relativistic single-particle wave function (not losing, however, the physical contribution of other degrees of freedom, like mesons and antinucleons). It is shown that the mass operator associated to the nuclear Greens function can be approximated with the equivalent of a shell model potential and that the corresponding single-particle wave functions can be easily derived in a specified frame of reference and then boosted to any other system, thus fully restoring the Lorentz covariance.PACS:   21.60.Cs Shell model     

A revised level scheme for 158Tb

Four separate reaction studies have been performed which show how the accepted nuclear level scheme for ¹⁵⁸Tb must be modified. This nuclide is of current interest because of the recent suggestion that its electron-capture decay may yield a means of determining the neutrino mass.     

The low-lying rotational bands of the neutron-rich nucleus <Superscript>172</Superscript>Tm

The microscopic mechanism of four experimentally observed bands in 172Tm is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions.The experimental results,including the moments of inertia and angular momentum alignments of four bands in 172Tm are reproduced well by the particle-number conserving calculations.The ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each c...     

On the structure of9He nucleus

The comparison of the calculated widths of⁹He with the measured ones shows that: 1) the shell occupation in⁹He has a normal order (1/2^?-1/2⁺) contrary to some shell model predictions of the parity inversion; 2) strong core polarization in⁹He takes place which explains the existence of narrow levels in⁹He and their absence in⁷He.     

Isospin dependence of the nuclear level width in the compound nucleus 30P

The excitation functions of ²⁹Si(p, α₀)²⁶Al, ²⁹Si(p, α₁)²⁶Al and ²⁹Si(p, α₂)²⁶Al were measured with high beam energy resolution in order to determine the isospin dependence of the nuclear level width of the composite nucleus, ³⁰P, at an average excitation energy of 19.6 MeV. From an auto-correlation analysis of these excitation functions, the level widths of the T_< = 0 and T_> = 1 isospin states are determined as 81 ± 17 keV and 104 ± 35 keV, respectively. An analysis including isospin mixing is also performed. With the aid of the statistical theory of nuclear reactions, the coherence energies are used to deduce the relative densities of two isospin states. The predictions of the Fermi gas model of level densities including isospin are in good agreement with the obtained results.     

Angular-correlation study of the level scheme of 193Ir

The decay of ¹⁹³Os to ¹⁹³Ir has been studied by γγ angular correlations. Inconsistencies between previous angular correlations, internal conversion coefficients, and nuclear orientation angular distributions have been satisfactorily resolved by the present results. These data are used to derive a set of $\text{E2}\text{M 1}$ multipole mixing ratios of the transitions between low-lying states. The resulting electromagnetic transition moments are compared with calculations based on the Nilsson model with Coriolis mixing and on the interacting boson-fermion model.     

The decay of78Rb and the level scheme of78Kr

The level scheme of⁷⁸Kr has been studied with the techniques of γ ray spectroscopy: decay spectra of⁷⁸Rb produced by the reactions⁶⁴Zn(¹⁶O,pn) and⁶⁵Cu(¹⁶O,3n) have been measured; in-beam γγ coincidences have been taken during the irradiation of⁶⁴Zn with¹⁶O ions; and an angular distribution measurement of γ rays from the reaction⁶⁴Ni(¹⁶O, 2n)⁷⁸Kr has been performed. Fifteen excited states in⁷⁸Kr have been observed and spins have been proposed for most of these levels. A⁷⁸Rb decay with a half-life of 17.5 ± 2 min has been found in addition to the previously known 6.0 ±0.2 min decay.     

Properties of the lowest states in the odd-odd160Tm and160Tm nuclei

Detailed study of the lowest states in the odd-odd¹⁶⁰Tm and¹⁶²Tm deformed nuclei and of corresponding electromagnetic transitions has been performed. In the theoretical analysis, performed within the framework of the two-quasiparticle + rotor model, the nondiagonal matrix elements of the residual p-n interaction have been included. Comparison of calculated energies and reduced transition probabilitiesB(XL) with experimental ones have proved importance of these matrix elements in the model calculations. More complex interpretation of the lowest states in both Tm nuclei has been achieved although some ambiguity has not been removed.     

Description of the Triaxial Strongly Deformed Bands in 160,161Tm and 163Tm

Properties of the triaxial strongly deformed （ TSD） bands of 160,161 Tin and 163Tm are investigated systematically within the supersymmetry scheme including ma~y-body interactions and a perturbation possessing SO（5）（or SU（5）） symmetry on the rotational symmetry. Quantitatively good results of the γ-ray energies, the dynamical moments of inertia and the spin of the TSD bands in 160,161Tm and 163Tm are obtained. The calculation shows that competition between the pairing and anti-pairing effects exist in these TSD bands. Meanwhile, the SU（3） symmetry in TSD bands is broken more seriously than that in superdeformed bands.     

Levels in159Ho as populated from decay of159Er

The level scheme of the odd proton nucleus¹⁵⁹Ho has been investigated using Ge(Li) and Si(Li) detectors. Results ofγ-ray singles, conversion electron spectra and coincidence experiments are reported. Assignments are made for several energy levels.