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1.
The intrinsic structure of 168Tm has been studied using the (3He, d) and (α, t) proton stripping reactions as well as the (d, t) and (3He, α) neutron pick-up reactions. The beams of 24 MeV 3He particles, 25 MeV α-particles and 12 MeV deuterons were obtained from the McMaster tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The spectra have been interpreted in terms of the coupling of an odd proton and an odd neutron, each moving independently in a spheroidal potential, which gives rise to intrinsic two-quasiparticle states with . The identification of the intrinsic states was made by comparing the experimental cross-section patterns with those predicted with the aid of Coriolis coupling and distorted-wave Born approximation (DWBA) calculations. Rotational bands superimposed on the Kπ = 3+ and configurations, the first of which is the ground state, ha been observed in the spectra of all four reactions. New assignments have been made for configurations resulting from coupling the ? [541], + [404], + [402] and ? [530] p to the + [633] neutron state. The neutron pick-up measurements confirmed the earlier assignments based on (d, t) reaction studies and suggested tentative assignments for the {+ [400]n±+ [411]p} and {+ [402]n±+ [411]p} 相似文献
2.
Angular distributions of the vector analyzing power and the absolute cross section were measured for the 58Ni(d, p)59Ni reaction at a deuteron energy of 10 MeV. The observed j-dependence of the vector analyzing power allowed unambiguous spin assignments for the following states in 59Ni with excitation energies in ; ; . The data are well reproduced by DWBA calculations employing deuteron and proton optical model parameters obtained from analyses of elastic scattering cross sections and polarizations. A tentative spin assignment of is made for the level at 3.061 MeV. A assignment to the level at 3.538 MeV is suggested on the basis of the empirical behavior of the j-dependence of the vector analyzing power for l = 2 transitions. Measurements of the vector analyzing power for the four low-lying 59Ni states formed by l = 1 transfer were made for angles from 2.5° to 15° using a magnetic spectrograph. A very strong j-dependence was observed for these far-forward-angle measurements in agreement with DWBA predictions. 相似文献
3.
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 , if and , respectively. The previously known level at 2524 keV was assigned to have . These together with the known (1224 keV) and (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
4.
The electron capture decay schemes of 245Bk and 246Bk have been investigated by measuring the γ-ray and conversion-electron spectra of mass-separated 245Bk and 246Bk samples. The γ-ray spectra were measured with a 25 cm3 Ge(Li) spectrometer and the conversion-electron spectra were measured with a cooled Si (Li) detector. Multipolarities of most of the transitions in 245Cm and 246Cm were deduced. The half-lives of 245Bk and 246Bk were determined by following the decay of the 252.85 and 798.7 keV photopeaks and were found to be 4.90 ± 0.03 d and 1.80 ± 0.02 d, respectively. The α/(α+EC) ratio for the 245Bk decay was measured to be (1.2 ± 0.1) × 10?3. On the basis of the present investigation the following non-rotational states were identified in 245Cm: [624], 0; [622], 252.85; 355.95; vibrational, 633.65; and [620], 740.95 keV. The state at 633.65 keV is int as a Kπ = 2? phonon coupled to the i[624] single-particle state. Our measurements of 246Bk γ-ray and conversion-electron energies and intensities confirm previous level assignments in 246Cm. 相似文献
5.
L.K. Fifield T.J.M. Symons C.H. Zimmerman M.J. Hurst F. Watt K.W. Allen 《Physics letters. [Part B]》1977,68(2):125-128
Levels at 7.17, 8.29, 8.96 and 9.88 MeV in 19F have been assigned spin and parity , , and , respectively, from resonance strength and γ-ray angular distribution measurements employing the 15N(α,γ) 19F reaction. An earlier assignment of to the 8.96 MeV level is incorrect. The measured properties of the states are compared with the results of both SU (3) shell model and cluster model calculations. 相似文献
6.
Nanosecond lifetimes of several states in 147Nd have been studied using the reaction 146Nd(d, pγ)147Nd with 10 MeV deuterons. The following lifetimes were observed: the level at 49.9 keV, 2.5±0.5 ns; the level at 127.9 keV, ≦ 0.8 ns; the level at 190.3 keV, 1.1±0.3 ns and the level at 214.6 keV, 5.8±0.8 ns. The wave functions of the states were constructed using an axial particle-plus-rotor model. The free parameters used are compared to the systematics observed in the neighbouring heavier N = 87 isotones as well as in the N = 89 and 91 isotones. Transition rates within the and based excitations, separately, are reasonably well reproduced, but the connecting transitions indicate too strong a mixing of the shells in the calculation. 相似文献
7.
A new isomeric state with 125 ± 20 ns half-life has been found in a 235U(d, pγ)236U experiments. Of the 12 observed delayed λ-lines, 11 have been fitted into a tentative decay scheme. The isomeric level is deduced to be the K, Jπ = 4,4? two-quasineutron state at 1052 keV with configuration ; that is also seen in (d, p) experiments. 相似文献
8.
Levels of 184W populated in the decay of 8.7 h 184Ta have been studied by a variety of experimental techniques. As a result of β and γ-ray energy and intensity determinations and extensive β-γ and γ-γ coincidence measurements, a detailed 184Ta decay scheme accommodating more than 99.5% of the decay intensity has been established. Intense β-ray groups of end-point energies 1165±26 and 1123±26 keV populate levels in 184W at 1699 and 1746 keV, which de-excite predominantly to the 8.3 μs isomeric level at 1285 keV, recently identified as the band origin. The 1699 keV level also de-excites to members of a band based at 1425 keV. New information about the properties of the γ-vibrational and K = 2 octupole bands in 184W is presented and the possible configurations of the levels directly populated in the β? decay are discussed. The configuration is indicated for the 184Ta ground state. 相似文献
9.
The one-quasiparticle bands in the N = 99 nucleus 171Hf have been identified to spins of about using (heavy ion, xn) reactions. The moments of inertia of these bands are consistent with the absence of backbending in the N = 98 core nucleus. The half-life of the intrinsic state was measured as 63.6 ns. The strength of the transition is discussed. Two three-quasiparticle isomers with spins and parities have been identified and their suggested configurations are a neutron added to the 6+ and 8? two-quasiproton states of the core. The moment of inertia of a rotational band based on the isomer supports this suggestion, and shows the effect of partial rotation alignment of the neutron. 相似文献
10.
Electromagnetic studies have established that the ground state doublet in 7Li is well described by the LS coupling shell model, provided quadrupole effective charge is introduced. The results of microscopic calculations for the excitation of the level in inelastic proton scattering shown within indicate that an equivalent renormalization of the 7Li quadrupole neutron transition densities is also necessary. This verifies the assumption which was made in a previous calculation of the cross section for the excitation of the level in the 7Li+24Mg reaction. 相似文献
11.
12.
In the 48Ca (τ,α)47Ca reaction at 25 MeV, some angular distributions are well reproduced by CCBA calculations, assumping double-step excitation of states. Unambigous Jπ assignments are extracted from the analysis. 相似文献
13.
S. André J. Boutet J. Rivier J. Treherne J. Jastrzebski J. Łukasiak Z. Sujkowski C. Sebille-Schück 《Nuclear Physics A》1975,243(2):229-259
Enriched targets of 187Re and 185Re were bombarded with α-particles of energy between 23.0 and 42.8 MeV. The levels characteristic of 189Ir and 187Ir produced by the (α, 2n) reaction were studied. The positive parity bands built on the ground state and on the first excited state in both nuclei were observed and interpreted as bands built on the +[402] and [400] Nilsson states. The negative parity levels form two independent systems: the first one possesses characteristics typical of a rotation-aligned band and is interpreted as belonging to the h orbital; the second one is connected with the isomeric state which originates from the h orbital. The possibility of a triaxial shape for this h. level system is discussed. In 189Ir a 3.2 ms isomeric state of 2333 keV excitation energy has been found and, as a by-product, some information has been gathered on the 4.1 ms isomer in 188Ir. 相似文献
14.
The reaction was studied using 17 MeV polarized tritons from the tandem Van de Graaff accelerator at the Los Alamos Scientific Laboratory. The α-particles were analyzed using a Q3D magnetic spectrometer and detected with a helical-cathode position-sensitive counter. The overall resolution was ~ 18 keV FWHM. Measurements of the 150Nd(3He, d)151Pm reaction were made using 24 MeV 3He beams from the McMaster University tandem accelerator. The deuteron spectra were analyzed with a magnetic spectrograph using photographic emulsions for detectors, yielding a resolution of ~ 13 keV FWHM. By comparing the measured angular distributions of () and (3He, d) cross sections and () analyzing powers with DWBA predictions it was possible to assign spins and parities to many levels. The present results confirm earlier assignments of rotational bands based on the low-lying orbitals. In addition, states at higher excitation have now been assigned to the orbitals, and members of the bands are tentatively proposed. The spectroscopic strengths can be explained reasonably well by the Nilsson model when pairing and Coriolis mixing effects are included. 相似文献
15.
Compound nucleus states in and have been investigated with the and three-particle reactions. The observed states (EX≈20 MeV) can be understood, in analogy to the ground states of the A=5 system, by coupling a nucleon to the first 0+ excited state of . 相似文献
16.
Several rotational bands in 163,165,167Yb are observed in (HI,xnγe?) experiments. The and bands do not backbend, whereas the bands do, indicating additional processes besides the rotational alignment of one neutron pair that are responsible for the backbending. 相似文献
17.
R. Davis R. Ammar W. Kropac H. Yarger B. Werner Y. Cho D. Johnson B. Musgrave T. Wangler 《Nuclear Physics B》1975,96(3):426-434
A search has been made for exotic states produced in K?d interactions at 5.5 GeV/c. The reactions investigated were: K?d→X??pp, and K?d→ M??Σ+p. Upper limits are set for the production cross sections. 相似文献
18.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
19.
D.G. Burke W.F. Davidson J.A. Cizewski Ronald E. Brown J.W. Sunier 《Nuclear Physics A》1985,445(1):70-92
The reaction has been studied using 17 MeV polarized tritons from the Los Alamos National Laboratory tandem Van de Graaff accelerator. The α-spectra were analyzed with a Q3D magnetic spectrometer. The overall energy resolution was typically ~ 15 keV (FHWM) and angular distributions of cross sections and analyzing powers were obtained for levels up to ~ 2.7 MeV. The fact that spins and parities for all levels up to ? 2 MeV were previously known from an extensive series of (n, γ) studies made it possible to determine specific two-quasiproton structures for many bands from the present results. The Kπ = 2+ γ-vibrational band was found to have a large admixture, consistent with the predicted microscopic composition of this phonon, but no component was observed. The Kπ = 04+ band at 1833 keV has ~ 25% of the two-quasiproton strength. This is in excellent agreement with the Soloviev model but is inconsistent with the interacting boson model, in which the Kπ = 04+ band is composed almost completely of multiphonon configurations that should not be populated in a single-nucleon transfer reaction. The two-quasiproton and the two-quasineutron states are mixed strongly with each other, but the two Kπ = 3? bands composed of antiparallel couplings of the same particles are not. A good qualitative explanation of this mixing pattern is provided in terms of the effective neutron-proton interaction. 相似文献
20.
Robert W. Field Richard A. Gottscho E. Miescher 《Journal of Molecular Spectroscopy》1975,58(3):394-413
No perturbation between two valence states of NO has ever been identified, although many valence-Rydberg and several Rydberg-Rydberg perturbations have been extensively studied. The first valence-valence crossing to be experimentally documented for NO is reported here and occurs between the 15N18O B2Π (v = 18) and B′2Δ (v = 1) levels. No level shifts larger than the detection limit of 0.1 cm?1 are observed at the crossings near and ; two crossings involving higher rotational levels could not be examined. Semi-empirical calculations of spin-orbit and Coriolis perturbation matrix elements indicate that although the electronic part of the interaction is large, a small vibrational factor renders the 15N18O B (v = 18) ? B′ (v = 1) perturbation unobservable. Semi-empirical estimates are given for all perturbation matrix elements of the operators and which connect states belonging to the configurations , , and . 相似文献