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1.
Experimentally observed ground state band based on the 1/2-[521] Nilsson state and the first exited band based on the 7/2-[514]Nilsson state of the odd-Z nucleus ~(255)Lr are studied by the cranked shell model(CSM) with the paring correlations treated by the particle-number-conserving(PNC) method. This is the first time the detailed theoretical investigations are performed on these rotational bands. Both experimental kinematic and dynamic moments of inertia(J~(1)and J~(2)) versus rotational frequency are reproduced quite well by the PNC-CSM calculations. By comparing the theoretical kinematic moment of inertia J~(1) with the experimental ones extracted from different spin assignments, the spin 17/2~-→13/2~- is assigned to the lowest-lying 196.6(5) ke V transition of the 1/2~-[521] band, and 15/2~-→11/2~- to the 189(1) ke V transition of the 7/2~-[514] band, respectively. The proton N = 7 major shell is included in the calculations. The intruder of the high- j low-? 1 j_((15)/2)(1/2~-[770]) orbital at the high spin leads to band-crossings at ω≈0.20( ω≈0.25) Me V for the 7/2~-[514] α =-1/2(α = +1/2) band, and at ω≈0.175 Me V for the1/2~-[521] α =-1/2 band, respectively. Further investigations show that the band-crossing frequencies are quadrupole deformation dependent. 相似文献
2.
The levels of 151Eu have been investigated in the ( n,n′γ) reaction using nuclear reactor fast neutrons. The energies, intensities and angular distributions of the γ-rays have been measured with the Ge(Li) spectrometer. Four rotational bands with the following band heads and Nilsson configurations have been identified: ground state band, 5/2 + [402]; 21.5 keV, 7/2 +[404]; 196.5 keV, 3/2 +[411]; 260.5 keV, 5/2 +[413]. The low spin states at 332.2 and 336.2 keV have been tentatively assigned to the l/2 +[411] Nilsson orbital, but 522.8, 580.0 and 587.0 keV states to the 1/2 +[420] Nilsson orbital. The negative parity levels at 353.7, 522.1 and probably 546.2 keV have been proposed basing on the h 11/2 proton state. 相似文献
3.
Integral yields of spontaneous emission at wavelengths of 1.73, 2.03, and 2.65 μm have been measured upon excitation of pure xenon by a pulsed electron beam. These yields have been analyzed and experimental data have been obtained on time constants of radiative transitions 5 d[3/2] 1 → 6 p[5/2] 2, 5 d[3/2] 1 → 6 p[3/2] 1, and 5 d[3/2] 1 → 6 p[1/2] 0 of XeI, which appeared to be equal to (2300 ± 400) × 10 ?9, (300 ± 40) × 10 ?9, and (1300 ± 200) × 10 ?9 s, respectively. It is shown that the experimental data are in a qualitative agreement with the results of computational and theoretical investigations. The results of averaging the experimental and calculated data are proposed for use as recommended values of the corresponding constants. 相似文献
4.
High-spin states in 101Pd have been investigated by means of in-beam γ-ray spectroscopic techniques via the 76Ge( 28Si, 3n) reaction at beam energies of 85 and 95 MeV. The previously known d 5/2 and 1/2 ?[550] bands were extended to higher spins, and the unfavored signature branch of the 1/2 ?[550] band was built. The band crossings observed experimentally are explained by the alignment of g 9/2 protons. The band properties in 101Pd are compared with those in the neighboring nuclei and are discussed within the framework of the cranked shell model (CSM). 相似文献
5.
220 neutron capture Gamma rays of Dy 165 were measured with the Risø curved crystal spectrometer. The intense transitions permitted the construction of a level scheme for this odd N nucleus. The rotational bands K=7/2 +[633], K=1/2 ?[521] and K=5/2 ?[512] were precisely localized, including the spin 11/2 states. Gammavibrational bands built on these Nilsson orbits were observed with their band heads at 538.6, 573.5 and 570.2 keV. The I=5/2 term at 533 keV can be considered as the 5/2 ?[523] Nilsson state. The branching ratios allowed the determination of ( g K?g R) 2-factors for the [633], [521] and [512] bands and yielded E 1-hindrance factors. 相似文献
6.
The structure of 183W has been studied by employing the 176Yb( 14C, α3n) reaction at 68 MeV. Five previously known rotational structure with one-quasiparticle configurations have been extended to higher spin states, and five new rotational bands with three- and five-quasiparticle configurations and a γ-vibration of a one-quasiparticle structure have been newly identified. In the ν7/2 −[503] and ν11/2 +[615] rotational structures, a signal of an admixture of an octupole-vibrational structure has been observed in their in-band B(M1)/ B(E2) ratios and gK factors. In the Kπ=19 − rotational band, a Coriolis effect on the ν1/2 −[510] neutron has been identified. In all, 17 K-forbidden transitions have been observed. Energies of intrinsic states below 4 MeV have been calculated based on the Blocked BCS theory, and they are used in support of the configuration assignments. 相似文献
7.
Thermal quenching of 5 d-4 f luminescence from Nd 3+, Er 3+ and Tm 3+ ions doped into KYF 4 crystals has been investigated in the temperature range up to ∼750 K where this luminescence is completely quenched. The obtained temperatures of thermal quenching ( Tq) are ∼270, 495, 450 K for Nd 3+, Er 3+, Tm 3+, respectively. At high temperatures, thermal quenching of 5 d-4 f luminescence from Nd 3+ and Er 3+ is accompanied by the appearance of 4 f-4 f luminescence from the lower-energy 4 f levels. It has been shown that the dominating mechanism of thermal quenching for Nd 3+ and Er 3+ ions is thermally stimulated non-radiative transitions (intersystem crossing) from the 5 d states to lower-energy 4 f levels, namely 2G(2) 9/2 and 2F(2) 7/2, respectively, whereas for the Tm 3+ ion, thermally stimulated ionization of 5 d electrons to the conduction band states is responsible for thermal quenching of 5 d-4 f luminescence. The energy gap between the lowest Tm 3+ 5 d level and the bottom of the KYF 4 conduction band has been estimated to be 0.66 eV. 相似文献
8.
Time-resolved Fourier transform spectroscopy (TR-FTS) is reviewed, with emphasis on synchronous FTS using continuously scanning interferometers. By using a high-resolution Bruker IFS 120 HR, a TR-FTS method has been developed with the help of a microcontroller SX, where a maximum of 64 time-resolved data are recorded with a preset time interval in a single scan of the interferometer. The time resolution is 1 μs, limited by the response time of the detector system used. This method has been applied to a pulsed discharge in an Ar and H 2 mixture to observe time profiles of ArH + and ArH emission spectra. Electronic transitions of He 2 have been observed in the infrared region with this method, and from the time profiles, He 2 in Rydberg states with higher energy than the b3Π state is found to be produced efficiently in afterglow plasma. Fifteen bands in the 2300-8000 cm −1 region have been assigned by using previously reported data from the optical region. A new band from the 5 f state has been assigned for the first time through the 5 f-4 d band in the 2600 cm −1 region. 相似文献
9.
Lu 3(Al,Ga) 5O 12 and (Y,Lu) 3(Al,Mg,Si) 5O 12 samples doped with 1% Pr 3+ were prepared by two aqueous sol-gel chemistry approaches, such as citrate and glycolate methods. All samples were characterised by powder X-ray diffraction (XRD), thermal quenching (TQ), fluorescence lifetime measurements and photoluminescence (PL) techniques. It turned out that the Pr 3+ emission is very sensitive to the composition of the garnet host lattice. Lu 3Al 5O 12:Pr 3+ samples showed mainly [Xe]4f 15d 1→[Xe]4f 2 broad band emission in UV-blue region, whereas [Xe]4f 2-[Xe]4f 2 line emission of Pr 3+ dominated in Lu 3Ga 5O 12 samples. Modification of garnet crystals with Mg 2+-Si 4+ pair has led to generation of strong crystal field strength resulting in energy transfer from 5d to 4f orbitals. Y 3AlMg 2Si 2O 12 composition generated the strongest crystal field splitting out of all synthesised samples and showed practically only Pr 3+ [Xe]4f 2-[Xe]4f 2 line emission in the red spectral region. 相似文献
10.
High-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2+[642], 3/2−[521], and 11/2−[505] configurations have been extended up to high-spin states, and particularly, the α = −1/2 branch of the ground state 3/2−[521] band has been revised significantly. It is found that signature inversion occurs in the 3/2−[521] band after the band crossing in 161Er. The systematics of the signature inversion associated with the 3/2−[521] configuration in the rare-earth region is discussed. The band properties are analyzed within the framework of a triaxial particle-rotor model, and a triaxial deformation is proposed to the 3/2−[521] band. 相似文献
11.
Information on energy levels and on E 2 and M 1 matrix elements in 231Pa has been obtained using conversion-electron and gamma-ray spectroscopy following the 232Th( p, 2n) 231Pa reaction and Coulomb excitation of the radioactive target 231Pa by 4He and 32S ions. The results are analyzed in the framework of the rotational model, applied to the rotational band built on the 1/2 ?[530] Nilsson state whose 3/2 ? member forms the ground state of this nucleus. The deviations of the level energies from the rigid-rotor values can be described by Coriolis couplings. The analysis of the Coulomb-excitation process shows that a constant set of rotational parameters Q 0, g R, g K, and b can fairly well account for the measured line intensities. 相似文献
12.
The half-lives of the following intrinsic states in deformed odd-mass nuclei has been measured by delayed coincidences with a time-to-amplitude converter: - 5/2 5/2+[642] at 86.5 keV in155Gd:T 1/2=6.7±0.3 ns, which results in the determination of theE1,ΔK=1 transition probability to the ground state 3/2 3/2?[521] and first rotational state 5/2 3/2?[521], yielding hindrance factors ofF N ≈5.5 and ≈1.8 (F W =3.1×104 and 2.3×104) respectively.
- (3) 5/2 5/2?[512] at 191.4 keV in169Yb:T 1/2=3.35±0.15 ns and at 122.39 keV in171Yb:T 1/2=265±20 ns which results in the determination of the transition probabilities of theE1,ΔK=1 transitions to the ground states 7/2 7/2+[633], of theK-forbiddenM1 transitions to the 5/2 and 3/2 1/2?[521] and of theE2 transitions to the 5/2, 3/2 and 1/2 1/2?[521] states in both nuclei.
The E1 transition probabilities are compared to the transitions between the same Nilsson states in 173Yb and 175Hf discussing the influence of the position of the Fermi surface — obtained from recent stripping and pick-up reactions — on these transition probabilities. Additional information on the decay scheme of 171Lu→ 171Yb is obtained by delayed coincidence measurements. For testing the used time-to-amplitude converter the well known half-lives of the 482 keV level in 181Ta ( T 1/2=10.4±0.3 ns) and of the 279 keV level in 203Tl ( T 1/2=0.285 ±0.015 ns) were measured, in good agreement with other measurements. 相似文献
13.
Level in 159Tm have been excited in the 150Sm( 14N,5n reaction. The yrast band 7/2 ?[ 523] observed up to spin 45/2 ? is built on a isomeric state at 166 keV ( T 1/2=37±5ns). Connections between the 7/2 ?[523] and 7/2 + [404] bands fix the band-head energies. 相似文献
14.
Three new bands in 174Ta have been identified by using the 160Gd( 19F,5n) reaction at beam energies of 87 MeV and 96 MeV. Nilsson configurations are assigned to these bands. In the 9/2 −[514] p+5/2 −[512] n band, the AB neutron crossing occurs at a rotational frequency of 0.30 MeV. This is indicative of the disappearance of the
evidence for a reduction in neutron pair correlations.
Received: 30 March 1998 相似文献
15.
The 233Th( 3He, d) 233Pa and 233Th( α, t) 233Pa reactions were studied with 28.5-MeV 3He and 30-MeV α-particles, respectively. The reaction results are interpreted in terms of a distorted-wave Born-approximation analysis. Transferred angular momenta are deduced from ( α, t) and ( 3He, d) cross-section ratios, R=dσ(α, t)/d σ( 3He, d). Theoretical cross sections, calculated in the framework of the Nilsson model with pairing and Coriolis interactions included, are in reasonable agreement with experiment. Rotational bands built on the following Nilsson proton configurations are identified in 233Pa: 1/2 ?[530↑], 3/2 +[651↑], 1/2 +[660↑], 5/2 +[642↑], 5/2 ?[5231↓], and 3/2 ?[521↑]. 相似文献
16.
Ultraviolet fluorescence of Nd 3+ ions induced by triphotonic excitation process was studied in Nd-doped LiYF 4, LiLuF 4 and BaY 2F 8 crystals using a technique of time-resolved spectroscopy. The observed ultraviolet luminescence was due to transitions between the bottom of 4 f25 d configuration and 4 f3 states of Nd 3+ ions. Narrow emission lines superposed to the broadband emissions were observed. A detailed analysis of luminescence spectrum revealed that the narrow emissions are due to parity and spin allowed radiative transitions from the Stark levels of 4K 11/2(5 d) state created by the electrostatic interaction between the 5 d electron and the two electrons of the 4 f2 configuration. The narrow emissions are related to the high spin state ( S=3/2) which gives f- f characteristics to the f- d broadband emissions. The narrow emissions superposed to the wide emission correspond to 18%, 34% and 43% of the integrated broadband emission at 262 nm observed in LiYF 4, LiLuF 4 and BaY 2F 8 crystals, respectively. Although the 5 d-4 f2 interaction is observed to be weaker than 5 d-crystal field interaction, it is stronger enough to select only the radiative transitions from 4 f25 d configuration to 4 f3 states that preserves the total spin S=3/2. 相似文献
17.
Behavior of the excitation cross sections of the perturbed 6 s[3/2] n°? np[1/2] 0 spectral series of the xenon atom is experimentally studied. By using the methods of extended electron beam and optical spectroscopy, the cross sections are measured and the optical excitation functions are recorded for the transitions of this series with n=6–13. A deviation of the dependence Q= f( n) from a power-law function is revealed, as well as changes in the form of optical excitation functions and in the nature of the branching caused by perturbation of the 7 p[1/2] 0 level by levels of the 5 p 5( 2 P 1/2°)6 p configuration. 相似文献
18.
The decay of the T
1/2 = 420 ns isomer in 151Er has been reinvestigated. The multipolarities of the decaying transitions have been established by measuring the electron
conversion coefficients. An I
π
= 67/2 − assignment is proposed for this isomer with a π[ h
112/4
d
32/1
d
52/−1]⊗ ν[ f
7/2
h
9/2
h
112/−1] configuration. 相似文献
20.
The nonstationary behavior of Eu 2+ and Sm 2+ photoluminescence in continuously optically pumped CaF 2:RE 2+-CdF 2superlattices was considered. The transient character of the photoluminescence is due to spontaneous electron tunneling from the excited 4 f5 d states into the conduction band of the adjacent CdF 2 layer. Coupled balance equations were constructed and numerically analyzed. It is shown that photoionization energies of the 4 f5 d states can be derived from the experimentally measured variation of the photoluminescence intensity in superlattices with CaF 2 and CdF 2 layers 10 to 20 monolayers thick. 相似文献
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