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1.
A mean lifetime of τ = 35 ± 3 ps of the 2+1 state in 76Kr has been measured with the recoil distance method via the reaction 63Cu(19F, α2n)76Kr. The B(E2; 0+1 → 2+1) values and lifetimes of the 2+1 states in 82, 84Kr have been measured via Coulomb excitation using the 1.4 MeV/A UNILAC krypton beams. The intensities of the γ-rays from the Coulomb excited levels of 82, 84Kr were interrelated with those of the target nuclei 27Al, 64, 66Zn and 70, 72, 74, 76Ge and yielded the values B(E2; 0+1 → 2+1 = 0.255±0.009 and 0.122 ± 0.005 e2 · b2 for82, 84Kr, respectively. In turn, these B(E2) values and the (E2; 0+1 → 2+1 values of the even Ge and Zn isotopes from the literature were used in a Doppler-shift attenuation analysis to obtain experimentally lacking electronic stopping power for Kr ions slowing down in Al, Zn and Ge. for Ge ions in Ge and for Zn ions in Zn.  相似文献   

2.
Fluorine and carbon induced fusion-evaporation reactions were used to excite high-spin states in 79Rb and 79Kr. The level scheme of 79Rb was established on the basis of neutron multiplicity measurements, γγ coincidence data and excitation functions. From recoil distance and Doppler shift attenuation lifetime measurements, E2 strengths of the positive-parity yrast states in 79Kr (up to Iπ = 212+) and the favored and unfavored states in 79Rb (up to Iπ = 252+) were derived. An interpretation of these data in terms of the asymmetric rotor-plus-particle model and the interacting boson fermion model (with or without separate proton and neutron bosons) is proposed. Energies and lifetimes of a second stretched band in 79Rb (probably with negative parity) were also measured.  相似文献   

3.
The 65Cu(p, t)63Cu reaction has been studied with 18.0 and 19.5 MeV protons. The states in 63Cu at 1.547 and 2.498 MeV are each assigned Jπ = 32? on the basis of angular distributions indicating mixed L = 0 and L = 2 transfer. Relative cross sections for L = 2 transfer to the low-lying states are compared with predictions of the shell model and particle-core model.  相似文献   

4.
High-spin levels in 129, 131Ce have been produced by the reactions 116, 118Sn(16O, 3n) 129, 131Ce and studied by in-beam γ-ray spectroscopic techniques. Two strongly populated band structures are observed. The odd-parity levels based on a 92? state constitute a system explained in the triaxial-rotor-plus-particle model as the result of the coupling of an h112 neutron-hole to a prolate-type triaxial core. The even-parity band built on a 72+ state corresponds to collective excitations associated with a neutron-hole in the g72 shell. Backbending effect observed in the yrast cascade is discussed.  相似文献   

5.
6.
The level schemes of the odd-neutron nuclei 197Hg and 191Pt have been studied using in-beam spectroscopic methods. Energies, intensities, angular distributions and coincidences of the γ-rays following (α, 2n) reactions were measured. Also conversion electrons and delayed γ-ray spectra were recorded. Most of the levels in both nuclei are de-populated via the 132+ isomers. Besides the yrast states, several additional states with spin values between 132 and 212 were identified. The negative parity of a side band in 197Hg starting with an f = 212 state was proved by the conversion electron measurement. The families of positive-parity states were compared with model calculations where the core was described as rigid triaxial rotor or anharmonic vibrator. For 197Hg both models give similarly good results for the energy spectrum and the branching ratios of electromagnetic transitions. Several negative-parity states found in 197Hg are compared with the predictions of a pairing-plus-quadrupole model.  相似文献   

7.
The half-lives of the 72? states at 522.6 and 393.9 keV in 113Cd and 115Cd have been determined to be 0.322±0.012 and 0.75± 0.03 ns, respectively. Values of the B(E2, 72?112?) and the energy difference E72? ? E112? in odd Cd (A = 113–119) are compared with those in neighbouring even Cd. The level properties are interpreted in the framework of the triaxial rotor model.  相似文献   

8.
The lifetimes of 9 states in 63Cu up to an excitation energy of 2092 keV have been determined by means of the Doppler-shift attenuation method using the 60Ni(α, pγ) reaction. A search was made for a suitable set of M1 and E2 single-particle matrix elements for use with shell-model eigenstates throughout the Ni, Cu and Zn isotopes. The theoretical predictions for the level spectroscopy and electromagnetic transitions and static moments in 63Cu are in satisfactory agreement with the experimental findings.  相似文献   

9.
The ground-state rotational band in 181Ta has been observed up to a spin of 212+ using Coulomb excitation with 84Kr ions. The nuclear lifetimes of the band members have been determined from the Doppler-broadened lineshapes of the de-excitation γ-rays, and the angular distributions of the γ-rays have been measured. It is found that the E2 transition rates from higher spin states (≧ 172+) are retarded relative to the rotational model predictions. A suggestion is made that this retardation may be due to the Coriolis antipairing effect.  相似文献   

10.
Levels of the N = 81 nucleus 145Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the 144Sm(3He, 2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin 212+, five other high-spin non-yrast states and a new 20.4 ns 132 isomer at 2200.2 keV in 145Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 ± 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1 + M2 + E3 transition to the vh?1112 state. We propose an octupole vf72j?2 × 3? main configuration for the isomer, analogous to the 997 keV 132+ isomer in 147Gd. The levels of 145Gd are discussed on the basis of the spherical shell model.  相似文献   

11.
High-spin states in 169, 170W have been populated in 154Gd(20Ne, xn) reactions. In-beam γ-ray spectroscopic techniques with multi-detector set-ups, multiplicity filters and an anti-Compton shield have been used. Levels up to about spin 30 (tentatively up to 36) in 170W and up to 572 (tentatively up to 612) in 169W have been identified. The data are interpreted within the framework of a pairing-selfconsistent cranking model. The nuclear shape evolution with increasing spin is studied theoretically within a configuration-controlled shell correction approach and also pairing effects are studied. The behaviour of the yrast states around 28+ in 170W can be related in a model-dependent way to a reduction of the neutron-pairing correlations.  相似文献   

12.
R. Opila  R. Gomer 《Surface science》1983,127(3):569-597
The UPS and XPS spectra of Xe adsorbed on clean, O, CO, and Xe covered W(110) surfaces and the UPS spectrum for Kr on clean and O covered W(110) surfaces have been investigated. On clean W, Xe and Kr show a splitting of the 5p32 and 4p32 hole states respectively. For Xe the coverage dependence of this splitting was investigated in detail; neither the positions nor the intensity ratio of the substates are coverage dependent for θ ? 0.04, suggesting that splitting is due to differences in the image interaction of the mj = ±32 and mj = ±12 components. For Xe equal shifts, relative to vacuum, of ~1.0 eV were observed for 5p, 4d, and 3d levels, suggesting that initial state effects are small. Image interaction for Xe and Kr on clean W could best be fitted by assuming an increase, rather than a decrease in the effective hole-image separation from the nominal value, suggesting that the image plane is moved back into the metal by a screening length. For Xe adsorbed on XeW(110), or on virgin-COW(110) polarization of the intermediate layers was found to contribute significantly to relaxation. Coadsorbed oxygen broadened Xe 5p and Kr 4p peaks. There was an almost linear relation between O 2p UPS intensity at the energies of the various peaks and the amounts of broadening, suggesting that the latter results from resonance neutralization by electrons from the O 2p states.  相似文献   

13.
The g-factors of the 10+ isomeric states in 194Hg and 196Hg have been measured using the in beam IPAD method. The results g(194Hg) = ?0.24(4) and g(196Hg) = ?0.18(9) are in agreement with the value expected for an (i132?2) neutron satructure and clearly contradict the previous assignment as (h112?2) proton configurations. Cranking model calculations show that the neutron excitation energies in the rotating frame agree satisfactorily with the experimental energies and that the proton excitations are expected ≈2 MeV above the experimental yrast line  相似文献   

14.
15.
High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jπ assignment of 152?, if 172? and 192?, respectively. The previously known level at 2524 keV was assigned to have Jπ = 132?. These together with the known 92?(1224 keV) and 112?(1690 keV) levels constitute the yrast states of 57Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10?0.07+0.06, 1.5?0.54 and 0.17?0.07+0.08 ps, respectively. Comparisons with some theoretical calculations are presented.  相似文献   

16.
17.
Excited states in the neutron-deficient nucleus 168W, populated in the 148Sm(24Mg, 4n)168W reaction, have been studied using γ-ray spectroscopy. The yrast band, which is identified up to about spin 28, shows a very strong backbend at low frequency, h?ωc = 0.235 MeV, attributed to the (i132)2 neutron alignment. Evidence for a second backbend is also observed. A strongly populated odd-spin (probably negative-parity) sideband is also identified to the spin, and shows several band-crossing anomalies. The characterisation of the anomalies is made by comparison with CSM calculations. Proton and neutron alignments are probably present in the sideband, and the second backbend in the yrast sequence may be due to alignment of i132 protons.  相似文献   

18.
The decay of 185m + gHg has been studied on-line with mass-separated sources from the ISOCELE facility. Precise conversion-electron measurements were performed with a 180° spectrograph. The 132+ isomeric state of 185Hg (T12 = 28 ± 5 s) was located with respect to the 12? ground state (T12 = 55 ± 10 s). A level scheme of 185Au has been established. Two abnormally converted M1 transitions de-excite a state local at 330.2 keV. Excited states of 185Au have been discussed in the framework of a “quasi-particle + axial rotor” approach, quasi-particle states being issued from Hartree-Fock plus BCS calculations using the SIII Skyrme force. Most of the low-spin negative-parity levels have been identified as h92 + f 52 or p32 + f72 mixed states. The h112 system has also been discussed using a model of asingle-j quasi-particle coupled to a triaxial rotor.  相似文献   

19.
The yrast line of 42Ca has been investigated with the reaction 27Al(19F, 2p2nγ)42Ca at Elab=47–108 MeV by means of an anti-Compton γ-spectrometer. The particular feeding and structure of the yrast line in 42Ca up to J=14 is understood by weak-coupling calculations.  相似文献   

20.
The decay of 187Hg is studied using “on-line” mass-separated sources. A decay scheme is proposed. The negative parity states are analysed within the “quasi-particle + triaxial rotor” model of Meyer-ter-Vehn: it is found that the 112? state at 224 keV corresponds to a nuclear deformation β = 0.14 and γ = 35 and the 92? state at 120.6 keV to a deformation β = 0.2 and γ = 21°. A systematic analysis of the heavier odd-mass gold isotopes is given in the framework of this model.  相似文献   

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