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1.
Gamma-ray spectra following the 165Ho(α, 2n)167Tm reaction have been studied using different semiconductor detector systems including a Compton suppression spectrometer. Approxi- mately 400 transitions have been observed in the energy range 60 to 1250 keV and 4 × 107 γγ coincidence events have been recorded. The angular distributions of the more intense γ-rays have been determined. The level scheme of 167Tm has been extended in several respects: The four previously known rotational bands based on the Nilsson orbitais , , an have been extended up to spin values , , , respective based on the and orbitals have been established for which only few levels were known previously. Finally two hitherto unknown rotational bands have been found for which we propose the assignments and . Coriolis coup calculations are presented. The value of was determined for three bands from branching ratios and from angular distributions. 相似文献
2.
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
3.
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
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I. Adam M. Honusek Z. Hons V.V. Kuznetsov T.M. Muminov R.R. Usmanov A. Budziak 《Nuclear Physics A》1981,356(1):129-145
The decay of 161Yb () has been investigated with Ge(Li) and Si(Li) detectors and a toroidal β-spectrometer. Isobarically separated samples produced by the YASNAPP facility at Dubna Institute were used. The singles γ-ray spectrum, the conversion electron spectrum, γ-γ-τ and e-γ coincidences have been measured. In all, 67 γ-ray transitions have been observed. A decay scheme for 161Yb is proposed involving 12 excited states in 161Tm. The +[404], ?[523] and +[402] levels have been identified. The interpretation of the high-lying levels is discussed. The Q-value of 161Yb decay has been determined to be 3850 ± 250 keV. The A-dependence of the energies of the one-quasiparticle states in odd-A Tm isotopes is demonstrated. 相似文献
6.
The 225Ac level scheme, populated by the α-branching (0.25%) of 229Pa, was investigated with an α-spectrograph and a two-dimensional α-γ coincidence device. The proposed level scheme was interpreted in terms of rotational bands and we tried to describe it in terms of the Nilsson configurations . The perturbation bands due to the Coriolis coupling were also discussed. 相似文献
7.
Rotational bands up to high-spin members in odd-neutron Hf nucleides are studied by in-beam spectroscopy using (α, xn) reactions on isotopically enriched Yb targets. The [521], [512], and the mixed positive-parity (mainly [633]) bands were observed in 173Hf and 175Hf while the [514], (mainly [624]), and the +) bands were studied in 177Hf. The analysis of the band structure within the Nilsson model is extended to also include adjacent odd Hf nuclei making it possible to follow these bands through five isotopes of Hf. 相似文献
8.
The odd-mass nuclei 191–197Tl have been formed in a variety of (HI, xn) reactions and studied by in-beam spectroscopic techniques. The decay of the high-spin Pb isomers, also formed in (HI, xn) reactions, leading to 193–197Tl has also been investigated. Evidence is presented for the existence of levels of the previously proposed rotational bands in the nuclei. Tentative evidence is given for the existence of oblate rotational bands, based on the state, in 191–195Tl. 相似文献
9.
The reaction has been studied using 17 MeV tritons with a polarization of ≈ 0.78 from the Los Alamos tandem Van de Graaff accelerator facility. The reaction products were momentum analyzed with a Q3D magnetic spectrometer and detected with a helical-cathode position-sensitive proportional counter. No nuclear structure information is available in the literature for the neutron-rich 175Tm isotope. A comparison of the measured angular distribution for the reaction with DWBA predictions permitted spin and parity assignments for many levels. Rotational bands have been assigned for the orbitals, and tentative suggestions are given for the location of the Nilsson states. For the weakly populated band members the assignments rest strongly on the Nilsson model and are based mostly on energy relations and comparison with experimental population patterns observed in neighbouring nuclei for the same orbitals. 相似文献
10.
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
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V.A. Ionescu Jean Kern R.F. Casten W.R. Kane I. Ahmad J. Erskine A.M. Friedman K. Katori 《Nuclear Physics A》1979,313(3):283-306
Low and high energy spectra from thermal neutron capture in 237Np have been studied over the energy ranges 25 to 650 keV and 2600 to 5500 keV. Primary transitions from neutron capture in four resonances have been observed between about 4800 and 5400 keV. Using 12 MeV deuterons, (d, p) spectra at three angles have been observed with a magnetic spectrograph. A nuclear level scheme for 238Np has been constructed by combining the results of the above measurements with previous data from a study of the 242mAm α-decay. The Nilsson model has been used to interpret the level structure. Including results from the previous α-decay study, nine rotational bands can be assigned. The Nilsson configurations (Kπ [Nn3ΛΣ]) and band-head energies are: 2+π[642↑]?ν[631↓], 0.0 keV; 3+π[642↑]+ν[631↓], 86.6 keV; 3?π[523↓]+ν[631↓], 136.0 keV; 2?π[523↓]?ν[631↓], 182.8 keV; 5+π[642↑]+ν[622↑], 278.1 keV; 0+π[642↑]?ν[622↑], 332.5 keV; 5?π[523↓]+ν[622↑], 342.6 keV; 0?π[523↓]?ν[622↑], 286.0 keV; 6?π[642↑]+ν[743↑], 301 keV. The measured (d, p) reaction cross sections are compared with theoretical calculations based on these assignments. The Gallagher-Moszkowski rule is found to be valid in the four cases where we have observed both parallel and antiparallel coupled bands with and . The lowest levels of the two K = 0 bands have spin I = 1; Newby odd-even shifts can be determined in both cases. 相似文献
13.
The absorption spectrum of the 2491 Å NO2 bands () has been observed in neon and argon matrices at 6 K. Evidence for two distinct matrix sites is confirmed by the doubling of the electronic origin. The bands are shifted slightly to the blue (~ + 60 cm?1) in neon and to the red (~ ?64 cm?1) in argon. The excited state vibrational frequencies are reported. 相似文献
14.
R.G. Lanier R.K. Sheline G.L. Struble L.G. Mann J.A. Cizewski 《Nuclear Physics A》1984,413(2):236-246
A radioactive target of 154Eu(8.3y) has been used to study the 154Eu(t, p)156Eu reaction at an incident energy of 17 MeV. The bandhead and one rotational state of the configuration have been identified in 156Eu. The excitation energy of the 3? bandhead is determined to be 448 ± 15 keV. The angular distribution of the first excited rotational state is anamolous and may indicate evidence for a strong two-step component in the reaction mechanism. The energy systematics of the Eu-Sm transition region are also investigated. We find that the systematics of suggest that at N = 87 the 150Eu excited configurations has a significantly more stable deformed structure than the corresponding one-quasiparticle structure in 149Sm. 相似文献
15.
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
16.
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
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18.
R.M. Lieder A. Neskakis M. Müller-Veggian Y. Gono C. Mayer-Böricke S. Beshai K. Fransson C.G. Linden Th. Lindblad 《Nuclear Physics A》1978,299(2):255-284
High-spin states in 195, 197Tl have been populated with (α, xn) reactions and studied by means of in-beam γ-ray and e? spectroscopic methods. Complementary studies of the decay of 195, 197Pb to 195, 197Tl have been carried out. Several new features have been observed in these nuclei. The bands of 195, 197T1. extended to and , respectively, show a quenching of energy spacings between the , , and states. This has been interpreted as resulting from the coupling of a proton to the ( configurations in the core nuclei 194, 196Hg. Furthermore, positive-parity bands based on states were established up to the and states in 195, 197Tl respectively. Probably these bands originate from the coupling of a h proton to a broken neutron pair. This pair consists of a rotation-aligned neutron and a low-j neutron in the , or shell. It is known to constitute the 5? bands in 194, 196Hg. 相似文献
19.
M.R. Beitins N.D. Kramer P.T. Prokofjev J.J. Tambergs L. Jacobs G. Vandenput J.M. van den Cruyce P.H.M. van Assche D. Breitig H.A. Baader H.R. Koch 《Nuclear Physics A》1976,262(2):273-300
The excited levels of 179Hf are investigated using the thermal neutron capture γ-ray and conversion electron spectra measured with the bent crystal diffraction spectrometer in Risø and the β-spectrograph in Riga. The level scheme contains the odd parity rotational bands and . The energies of these levels and the intensity ratios of the transitions between them are calculated taking into account the rotation-particle coupling (RPC). The following even parity levels are proposed: 859.0 and 942.2 keV ; 1004.1 and 1079.2 keV ; 1186.0, 1199.2 and 1296.4 keV . The levels at 1249.8, 1269.7, 1432.9, 1482.2 and 1755.5 keV, supported by the analysis of the γγ coincidence spectrum and Ge(Li) singles data, are discussed. 相似文献
20.
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