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1.
In-beamγ-ray and conversion electron measurements with (α, xn) reactions have established the145Sm highspin states up toI π=25/2+ at 3.5 MeV excitation. A shell model analysis using empirical two- and one-body energies from neighbouring nuclei classifies the low-lying odd-parity levels as 3-quasiparticle states formed by the144Sm two-proton-hole excitations and thef 7/2 valence neutron. The higher-lying positive-parity states involve particle-hole core excitations with one proton inh 11/2.  相似文献   

2.
Time-integral measurements have been made of the vacuum deorientation of the 2+ and 4+ states in 150Sm and the 6+ and 8+ states in 156Gd Coulomb-excited by 133 MeV 35Cl ions. The 150Sm results were deduced from γ-ray angular distributions measured in coincidence with backscattered 35Cl ions. In the 156Gd measurements, a fixed counter array and a sandwich target were used to measure directly the differences between the γ-ray angular distributions from nuclei recoiling in vacuum and the unperturbed γ-ray angular distributions from nuclei stopped in a thick 156Gd target. The measured deorientation time constants in ps are τ2(2+) = 27±4; τ2(4+) = 14±4; τ2(6+) = 24±3; τ2(8+) = 23+10?6; τ4(2+) = 12±2; τ4(4+) = 5±3; τ4(6+) = 7.6±2.5. The 8+ data were analyzed assuming τ24 = 103 as predicted by the Abragam-Pound theory for I ≧ 4 essentially independently of the degree of quadrupole admixture. The other results are consistent with this except for the 2+ level which shows some quadrupole effect. The present results, which show strong deorientation of high spin levels, are in contrast to earlier work on neutron deficient Er isotopes. In light of our findings we suggest that the failure to observe deorientation in the high spin states in Er is primarily due to anomalously low g-factors associated with the backbending observed in these nuclei.  相似文献   

3.
For single-closed shell nuclei with a large number of extra-protons, outside theZ=50,N=82 double-closed shell nucleus, a standard shell-model calculation yields dimensions of the Hamiltonian matrices beyond the scope of present computer technology. A quasi-particle (QP) calculation however, is able to describe the most important proton-excitations in a much restricted configuration space. Extended BCS+TDA calculations are performed on the single-closed shell144Sm and146Gd nuclei with a Gaussian force as effective two-body interaction. The influence of the nonconservation of the exact number of extra-protons in the BCS-approach is studied by performing a projection onto the states with an exact number of extra-protons (BCS+P). The first excited 2+, 4+ and 6+ states in146Gd are described mainly by the (1g7/2) 0 8 (2d5/2) 0 4 \((1h11/2)_{J^\pi }^2 \) configuration.  相似文献   

4.
赵洪英  戴长建  关锋 《物理学报》2009,58(1):215-222
采用两步激发共振光电离技术研究了Sm原子的偶宇称高激发态光谱.实验采用了两条激发路线:1)第一束激光的波长固定在478.44nm以便将Sm原子从4f66s27F1]态激发至4f66s6p[7D1]态,再用第二束激光使其波长从480nm扫描至530nm,将Sm原子进一步激发至待测的高激发态;2)第一束激光的波长固定在574.8 关键词: Sm原子 光谱 分步激发 共振电离  相似文献   

5.
Two novel complexes of Sm(III) and Dy(III) with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands were synthesized and their structure and luminescence properties were characterized. The complexes of [Ln(ODA)(phen)·4H2O]Cl·5H2O [Ln=Sm and Dy] crystallize in the monoclinic space group P21/n with Sm: a=12.3401(14) Å, b=16.821(2), c=12.6847(11) Å, β=107.939(10)°, V=2505.0(5) Å3, Z=4 and ρ=1.841 mg/m3, and with Dy: a=12.289(7) Å, b=16.805(6) Å, c=12.705(4) Å, β=108.144(18)°, V=2493.4(19) Å3, Z=4 and ρ=1.786 mg/m3. The complexes of [Sm(ODA)(phen)·4H2O]+ and [Dy(ODA)(phen)·4H2O]+ excited by UV light produce orange red and lightly white emissions, respectively, via the nonradiative energy transfer from phen to the metals. The quantum yield of the sensitized luminescence of [Dy(ODA)(phen)·4H2O]+ (Q=19%) is much greater than that of [Sm(ODA)(phen)·4H2O]+ (Q=1.4%). The luminescence decay times of the complexes were in a few microsecond range and independent of temperature.  相似文献   

6.
TheE4 transition matrix element from the ground state to the 4+ state has been measured in152Sm and154Sm, by comparing relative thick targetγ-ray intensities following Coulomb excitation with 12 MeV4He, 24–30 MeV16O, and 35–40 MeV32S projectiles. Values for 〈0+∥?(E4)∥4+〉 of (+0.31 ?0.20 +0.12 ) barn in152Sm and (+0.50 ?0.12 +0.09 ) barn in154Sm are found.  相似文献   

7.
Asymmetries and differential cross sections have been measured for elastic and inelastic scattering of 24.5 MeV polarized protons from the spherical nucleus 148Sm. The comparison with the results of an asymmetry measurement at the same proton energy on the rotational nucleus 152Sm shows significant differences for the first 2+ states. A coupled-channels analysis for the first 2+ and 3 states in 148Sm and for the 2+ and 4+ states of the ground-state rotational band in 152Sm fits the experimental data very well.  相似文献   

8.
The branching ratios of E0 and E2 transitions depopulating the 0+2 and 0+3 states in 70Ge have been studied using conversion-electron and γ-ray spectroscopy, as well as a new internal-pair measurement technique. A value of 3.7 (2) ns has been obtained in a remeasurement of the half-life of the 0+2 state. Two new E0 transitions, 0+3 → 0+2 and 0+3 → 0+1, have been observed. A comparison of the measured X(E0/E2), ρ2(E0) and B(E2) values for the excited 0+ states in 70Ge with the corresponding 150Sm data supports a recent shape-coexistence interpretation of the even-mass Ge isotopes.  相似文献   

9.
赵艳红  戴长建  野仕伟 《中国物理 B》2013,22(2):23203-023203
Spectra of autoionizing states of the Sm atom in an energy region between 45948.9 cm-1 and 46943.6 cm-1 are systematically investigated by a three-color multi-step resonant excitation scheme with three different excitation paths.The three intermediate states,4f 66s7s 7F3,4f 66s7s 7F4,and 4f 66s7s 9F5 are employed for the three paths,respectively.Based on precise calibration of wavelength,the level energies of 112 autoionizing states are determined with the line widths and the relative line intensities of the related transitions.The possible influence of configuration interaction on the line shape of autoionizing state is also discussed.In addition,a unique value of J,the total angular momentum,is assigned to all detected states by comparing the three spectra obtained with the different excitation paths.  相似文献   

10.
Two-color stepwise excitation and photoionization schemes are adopted to study the spectra of bound even-parity high-lying states of the Sm atom with three different excitation paths via the 4f66s6p 7DJ (J=1, 2 and 3) intermediate states. In order to obtain the information of these high-lying states, the Sm atom in these high-lying states is photoionized with an extra photon. Among 231 states detected in the energy region between 35,545 and 44,225 cm−1, 108 states are newly discovered, while the rest can be identified as the same with the literature. In most cases, comparisons of the spectra corresponding to the three different excitation paths may partially determine the total angular momentum of the observed peaks with the selection rules. In addition, the relative intensities of all related transition lines are given.  相似文献   

11.
《Physics letters. [Part B]》1988,206(3):404-407
The g-factors of the two 10+ states in 140Sm at 3172 and 3210 keV have been measured by means of the TDPAD method. The obtained values are g = −0.176(20) and g = 1.27(9), respectively. The reaction 116Cd (28Si, 4n)140Sm, at incident beam energy of 125 MeV, has been used. The measured values clearly show that these states can be described as rather pure (νh11/2)−2 and (πh11/2)2 configurations.  相似文献   

12.
The low-spin excitations of the nucleus 146Sm which is just two neutrons and two protons away from the N = 82 shell and Z = 64 subshell closures have been investigated by means of the 143Nd (??, n) and 144Nd (??, 2n) fusion-evaporation reactions. We established 47 hitherto unknown energy levels up to 4.7MeV and 75 new transitions. In addition, 7 spin assignments were possible from the ??-?? angular correlation analysis. The structure of the possible candidates for a 2+ ? 3? quadrupole-octupole multiplet are first discussed in terms of the harmonic vibrational model. A comparison of these states with the corresponding ones in the neighboring N = 84 isotones is also presented. Finally, the structure of the 146Sm nucleus is interpreted in terms of the IBA-spdf model. It is shown that the model is able to reproduce the experimental relative transition strengths of the 2+ ? 3? quadrupole-octupole multiplet and also a series of collective properties such as the proposed double-octupole excitations.  相似文献   

13.
A new approach to the study of width distributions is developed. The approach makes use of level-level interference effects in (n,γ) reactions to produce a set of radiative width amplitudes. This set is compared to the width distribution and to the hypothesis of Porter and Thomas for the case of 149Sm(n, γ)150Sm. Both width and amplitude distributions show small but significant deviations from the hypothesis for transitions to low-lying 3+ and 4+ states in 150Sm. No significant width correlations are observed, nor is there apparent any violation of the assumption of random phases for the amplitudes.  相似文献   

14.
Tensor polarizabilities of the levels 4f146s6p3P1 in Yb and (4f66s6p+4f55d6s2)7D1,7F1,7G1 in Sm were deduced for the even isotopes from the modulation frequency of quantum beat signals.  相似文献   

15.
A recoil distance method was used to measure half-lives of the excited states of 145Sm. The reaction used was 139La(10B, 4n)145Sm. A plunger system was used. Half-lives were determined for two excited states for the first time. The yrast 27/2+ state was found to have a half-life of 1.1 ± 0.2 ns corresponding to the retardation of 3.1 × 10−4 comparing with the single particle estimate of M1. The excitation energy of this state was well reproduced by the shell model calculation having a mixed configuration of [π{h11/2(g7/2)−2 (d5/2)−1}10−, νf7/2] + [π{h11/2(g7/2)−1}9−,νh9/2]. Another retarded E1 transition was also found in a decay of a 21/2+ state. Its retardation was 1.6 × 10−4 comparing with the single particle value. Received: 9 September 1997 / Revised version: 12 June 1998  相似文献   

16.
Boro-tellurite glasses with the composition (69-x)H3BO3+xTeO2+15MgCO3+15K2CO3+1Sm2O3 (where x=0, 10, 20, 30 and 40 wt%) doped with trivalent samarium have been prepared and their structural and spectroscopic behavior were studied and reported. The FTIR spectra reveal the presence of BO3 and BO4 non-bridging oxygen as well as strong OH bonds in the prepared glasses. Through the optical absorption spectra, Judd-Ofelt intensity parameters (Ωλ, λ=2, 4 and 6) have been evaluated and the same is in turn used to predict radiative properties such as radiative transition probability (A), stimulated emission cross-section () and branching ratios (βR) for the excited levels of Sm3+ ions corresponding to 4G5/26H5/2, 4G5/26H7/2, 4G5/26H9/2 and 4G5/26H11/2 transitions. Structural and spectral dependence of the Sm3+ ions due to the compositional changes have been examined and reported. The lifetime of the 4G5/2 level is found to be non-exponential for all the prepared glasses indicating a cross-relaxation among the Sm3+ ions. The structural and spectroscopic results corresponding to compositional changes have been compared with the similar studies and reported.  相似文献   

17.
Valence and deep-lying neutron-hole strengths corresponding to orbits near and well below the Fermi surface have been observed in high-resolution studies of the 144, 148, 152Sm(3He, α) and of the 144, 148, 150, 152, 154Sm(p, d) reactions at 70 and 42 MeV bombarding energy, respectively. The explored excitation energy range was 28 MeV for the (3He, α) experiment and about 12 MeV in the (p, d) study. Complete angular distributions have been measured in both cases and the data was analyzed within the framework of the distorted waves Born approximation theory of direct reactions.For the neutron closed shell target (144Sm), in addition to the well-known fragmentation of the 2d52 and 1g72 valence-hole strength, a new bump observed around 7.6 MeV excitation energy is excited in both reactions. This structure corresponds to the 1g92 inner-hole strength in 143Sm and the analysis of the (3He, α) data suggests that more than 50% of the l = 4 strength can be found between 6 and 12 MeV. When one goes to the heavier Sm isotopes, the energy spacing between valence-hole states located above and just below the N = 82 shell decreases strongly and disappears in 151Sm as a result of increasing deformation.Combining good energy resolution and detailed analysis of the two reactions, rather complete spectroscopic information is obtained for the valence-hole strength distributions. With regard to inner-hole states, the energy spectra exhibit a narrow structure whose centroid energy decreases from 4.4 to 2.9 MeV when the mass number increases from A = 147 to A = 153. The main peak displays an asymmetric shape with an extremely large high-energy tail. The 1h112 hole strength is split into the Nilsson Orbitals. The narrow bumps are found to carry a large fraction of the l = 5 and l = 2 hole strengths in 147,149,151,152Sm isotopes. In the high-energy tail of the structures one observes overlapping and increasing spreading of the g72, 2d52 and possibly 1g92 inner-hole strengths due to the disappearance of the N = 82 shell gap between N = 83 and N = 89 neutron numbers. The experimental hole strengths distributions are compared where possible to the predictions of the quasiparticle-phonon nuclear model or to the simple Nilsson model.  相似文献   

18.
Isotope shifts have been measured in Sm II from which the shifts between pure configurations 4f 6 s and 4f 65d can be determined. The specific mass shift for such a “transition” was estimated to be (?1±2)mK for a change of two neutrons. The values derived for the change in the nuclear charge distribution,δr 2〉, are in good agreement with the results obtained from isotope shift measurements in Sm I (H. Brand et al.: J. Phys. B11, L99, 1978). The weighted mean values representing the best information onδr 2〉 presently available are in fm2: [144, 148] 0.488(23); [148, 150] 0.285(14); [150, 152] 0.400(19); [152, 154] 0.217(11).  相似文献   

19.
The three proton-hole states ?2d5/2, 1g7/2 and 1g9/2 are found to be fragmented as a result of coupling of these states with the 3?, 5?, 2+, 4+ and 6+ collective states of208Pb. The excited states in208Pb (t,α) reaction can be quantitatively explained in terms of altered 2d5/2, 1g7/2 and 1g9/2 states with the hole-core coupling model.  相似文献   

20.
李鸣  戴长建  谢军 《中国物理 B》2011,20(6):63204-063204
Two-colour stepwise excitation and photoionization schemes are adopted to study the spectra of high-lying states of the Sm atom. These bound even-parity states are excited with three different excitation paths from the 4f66s6p7DJ (J = 1, 2, 3) intermediate states, respectively. They are probed by photoionization process with an extra photon driving them to the continuum states. In this experiment, 270 states are detected in an energy range from 36160 cm-1 to 42250 cm-1, 109 of which are newly discovered, while the rest of them are confirmed to be the energy levels reported previously. Furthermore, based on the J-momentum selection rules of three excitation paths, a unique assignment of J-momentum for all observed states is determined, eliminating all remaining ambiguities in the literature. Finally, 53 single-colour transitions originating from the scanning laser are also identified. For all the relevant transitions, the information about their relative intensities is also given in the paper.  相似文献   

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