共查询到20条相似文献,搜索用时 15 毫秒
1.
The (n, 2n) cross sections at neutron energies between 14.9 and 17.0 MeV have been measured for 85Rb, 87Rb and 144Sm by the mixed-powder method and γ-ray detection by a Ge(Li) spectrometer. Using the 27Al(n, α)24Na reaction for monitoring, the measured cross sections were (in mb): . The measured values are compared with the statistical model calculations of Pearlstein. 相似文献
2.
W.K. Dagenhart P.H. Stelson F.K. Mcgowan R.L. Robinson W.T. Milner S. Raman W.K. Tuttle 《Nuclear Physics A》1977,284(3):484-500
Coulomb excitation of the nucleus 115Sn was studied with beams of 4He and 16O. Level energies, spins, mean-lives and B(E2) and B(M1) transition probabilities were obtained. Spin + states were observed at 497.35 and 1280.08 keV and spin + states were observed at 986.54 and 1416.78 keV. A state of 612.79 keV was observed to be indirectly excited by decay of the Coulomb excited states. Eleven B(E2) values and nine B(M1) values were obtained for the transitions between the low-lying states. In contrast to previous particle transfer results which suggested a clear distinction between shell-model and collective + and + states, our results suggest the collective strength is shared by the two + and two + states. 相似文献
3.
The static quadrupole moment of the first excited Jπ = 2+ state in 24Mg and the reduced electric quadrupole transition probability between this state and the ground state were measured via projectile Coulomb excitation. The quadrupole moment was deduced from the shapes of γ-ray angular distributions. The result is . The transition strength was deduced from yield measurements and by comparison with the yields of target γ-rays, The result is . The experimental measurements are compared with theoretical predictions and previous measurements and a detailed discussion is given of corrections to this type of reorientation experiment. 相似文献
4.
L. Hulstman H.P. Blok J. Verburg J.G. Hoogteyling C.B. Nederveen H.T. Vijlbrief E.J. Kaptein S.W.L. Milo J. Blok 《Nuclear Physics A》1975,251(2):269-288
The (p, p′) reaction on 89Y at incident energies of 20.51 MeV and 14.33 MeV and on 87Rb at 20.89 MeV has been studied. In 89Y 28 levels with Eex between 2 and 4.2 MeV and 79 levels with Eex between 4.2 and 6 MeV have been identified. In 87Rb 45 levels with Eex up to 4.2 MeV have been found. Transferred orbital angular momenta and deformation parameters have been deduced from a macroscopic DWBA analysis of the differential cross sections. The experimental results are not consistent with the interpretation of states in 89Y and 87Rb as resulting from the weak-coupling of a proton or proton-hole to excited states of the 88Sr core. Simple shell model arguments are able to yield at least a qualitative agreement with the level scheme as found for 89Y. 相似文献
5.
E. Drǎgulescu M. Ivaşcu R. Mihu D. Popescu G. Semenescu V. Paar D. Vretenar 《Nuclear Physics A》1984,419(1):148-162
The low-lying states of 143Nd and 154Nd have been studied by means of Coulomb excitation with 16O and α-particles. Angular distribution measurements were carried out for some transitions in 145Nd with 11.2 MeV α-particles. Level energy decay schemes and B(E2)↑ values were measured for two states in 143Nd and for six states in 145Nd. Some spin assignments have been established for the 145Nd nucleus. 143Nd and 145Nd have been theoretically described by coupling one and three particles, respectively, to quadrupole vibrations, and rather good agreement with experiment was achieved. 相似文献
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7.
Elastic scattering of 16O on 148, 150, 152Sm isotopes and inelastic scattering leading to the first 2+ state for the three isotopes and the 4+ state for 152Sm have been measured at several energies in the vicinity of the Coulomb barrier. The whole set of data was reproduced at forward angles with an effective potential taking into account Coulomb excitation and in the full angular range by CCBA calculations including separate nuclear and Coulomb deformations. 相似文献
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9.
S.T. Thornton T.C. Schweizer D.E. Gustafson J.L.C. FORD M.J. Levine 《Nuclear Physics A》1976,270(2):428-436
Nuclear and Coulomb deformation parameters have been deduced from DWBA analyses of angular distributions of 67.5 MeV 13C ions inelastically scattered from 142Nd. Optical model parameters from fits of measured elastic scattering data were used with previously measured B(EL) values to determine initial deformation parameters. Comparison With the experimental data indicates that DWBA calculations can be used to understand the inelastic scattering from the nearly spherical nucleus 142Nd. 相似文献
10.
M. Behar A. Filevich G.García Bermudez M.A.J. Mariscotti L. Szybisz 《Nuclear Physics A》1980,337(2):253-260
Nuclear states of 82Rb were studied through the 81Br(α, 3n) reaction at various bombarding energies between 30 and 55 MeV. Excitation functions, γ-ray angular distributions, γ-γ coincidences and γ-time distributions with respect to the beam bursts were determined. Levels at 123.2, 187.7, 233.6, 796.3, 1214.1 keV and tentatively at 1835.5 keV were observed. It was not possible to establish whether the lowest state of the proposed level scheme corresponds to the ground state or to the isomeric state. The 45.9 and 64.5 keV γ-rays do not exhibit any measurable lifetime and a limit has been determined. The situation is similar for the 123.2 keV γ-ray, although in this case the presence of a long-lived component cannot be ruled out. 相似文献
11.
Coupled-channels study of projectile and target excitation in the scattering of 6Li from 12C and 16O
J. Cook 《Nuclear Physics A》1985,445(2):350-366
Coupled-channels calculations are presented tor elastic and inelastic 6Li + 12C scattering at Ec.m. = 16 MeV and 20 MeV, and for 6Li + 16O at 18.7 MeV. Excitation of states within 6Li, 12C and 16O are treated with rotational, rotation-vibration and vibrational models only. The 3+6Li and 2+12C states are strongly coupled to the elastic scattering and reduce the strengths of both the real and imaginary potentials. The 3?16O state reduces only the strength of the imaginary potential. All other states are weakly coupled and have little effect on each other or the potential. The data are reasonably well described, with there being some preference for the 3? state in 12C to be K = 0. Excitation of the 02+ state in 12C requires a combination of β-vibration and monopole breathing-mode form factors. The deformation lengths found are in poor agreement with those deduced from electron or proton scattering. 相似文献
12.
A. Weidinger K.A. Eberhard E. Mathiak J. Stettmeier W. Trombik L.N. Wüstefeld 《Nuclear Physics A》1976,257(1):144-164
An array of eight detectors has been developed for identifying the particle unstable 8Be nucleus from nuclear reactions with high detection efficiency. Absolute cross sections have been measured for the reaction 12C(12C, 8Beg.s.)16O to the ground state and to several excited states in 16O. Excitation functions at seven angles from 15° to 45° (lab) in 5° steps have been measured for bombarding energies between E12C(lab) = 35 and 69 MeV. Excitation functions were obtained for the following states in the residual nucleus 16O which were found to be strongly populated: g.s.(0+); 6.1 MeV (0+, 3?); 6.9 MeV (2+); 10.4 MeV (4+); 11.1 MeV (4+); 14.7 MeV (6+,…) and 16.3 MeV (6+,…). The energy range is covered in 250 keV (c.m.) steps; at certain energy ranges in 125 keV or 50keV steps. All excitation functions exhibit a strong energy dependence of the cross section; pronounced gross structures with superimposed fine structures, similar to those observed for 12C+12C elastic and inelastic scattering at these energies, are observed. At 19.3 MeV, where resonant structures were observed in the reactions 12C(12C, p)23Na, 12C(12C, n)23Mg and 12C(12C, d)22Na, no resonance is found for the reaction studied here. At 60, 61 and 63 MeV angular distributions have been measured in 1° and 2.5°(lab) angular steps. The excitation functions have been analyzed in terms of Ericson fluctuations and cross-correlation functions. 相似文献
13.
Using spectroscopic information gained by earlier measurements of the proton bound states populated by stripping reactions, (3He, d) reactions on 58, 60Ni and 56Fe targets are studied at energies near the Coulomb barrier and evaluation is made of the vertex function . This value is then used to determine spectroscopic factors for low-lying states in 57Co. 相似文献
14.
J. Wilczynski K. Siwek-Wilczynska J.S. Larsen J.C. Acquadro P.R. Christensen 《Nuclear Physics A》1975,244(1):147-156
The reaction 58Ni(16O, 12C) has been studied at three incident energies, 60, 72 and 81 MeV, for a wide range of scattering angles. The angular and energy dependence of the optimum Q-value has been determined from the data. A simple optimum Q-value model which combines the recoil model of Siemens et al. with a concept of nuclear friction is proposed. 相似文献
15.
Angular distributions, a 0° excitation function and Doppler-broadened γ-ray profiles for the reaction 15N(p, α1γ), and angular distributions for the 15N(p, α0) reaction, have been measured for proton energies from about 900 to 1250 keV. These data, together with analysing powers from the , α0) reaction, have been satisfactorily fitted by means of R-matrix theory in terms of the known levels of 16O in the 13 MeV region together with background contributions. 相似文献
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17.
W. Mittig P. Charles S.M. Lee I. Badawy B. Berthier B. Fernandez J. Gastebois 《Nuclear Physics A》1974,233(1):48-54
Excitation functions of 24Mg(16O, 16O)24Mg were studied between 25 and 64 MeV incident energy. A strongly resonant behaviour was observed for inelastic scattering at backward angles. The data were analysed in terms of coupled channel calculations. While agreement was good at forward angles, at backward angles the calculated cross sections are an order of magnitude too low suggesting that another reaction mechanism or neglected terms in the heavy ion interaction potential are important. 相似文献
18.
A.F. Zeller G.T. Hickey D.C. Weisser D.F. Hebbard B.A. Robson 《Nuclear Physics A》1978,301(1):130-140
Reactions induced by 14N on 26Mg at bombarding energies of 60–95 MeV have been studied. Angular distributions for states populated in 29Si by the (14N, 11B) reaction and in 30Si by the (14N, 10B) reaction have been compared with Hauser-Feshbach and DWBA calculations to determine the reaction mechanism and to deduce spectroscopic information. The cross sections for the states populated in 29Si and 30Si are in poor agreement with statistical model calculations, indicating a non-compound nucleus mechanism. 相似文献
19.
Reactions of 40Ar ions with targets of 159Tb, 142Nd, and 144Sm have been studied at energies below 300 MeV with a helium gas-jet system. Excitation functions for (Ar, xn) reactions, where x = 5–10, were obtained for the radioactive products that decay by α-emission. Based on the characteristics of these excitation functions and on the systematics of α-decay, evidence is presented for the existence of the nuclides 189Bi with α-particle energy Eα = 6.67±0.01 MeV and half-life < 1.5 sec, and 173Pt with Eα = 6.19±0.01 MeV; and for the emission from 177Au of an α-particle with Eα = 6.15±0.01 MeV. 相似文献
20.
F. Hinterberger P.v. Rossen E. Lebsanft P. Lütticken J. Bisping R. Jahn B. Schüller 《Nuclear Physics A》1976,259(3):385-398
In a high resolution study of the 4He + α initiated excitation functions in the region of the 8Be first T = 2 state, weak resonance excursions have been observed in some reaction channels yielding the total width Γ = 14.7 ± 4.0 keV. No resonance excursion has been observed in the 4He + α elastic scattering yielding the branching ratio Γα/Γ ≦ 0.003 for the decay of the 8Be first T = 2 state into two α-particles. For the decay to the low-lying states of 6Li and 7Li lower limits of the branching ratio are given. The reinvestigation of the 7Li+p initiated excitation functions revealed no resonance anomaly in the region of the 8Be first T = 2 state. The upper limit Γp/Γ ≦ 0.023 has been derived for the proton decay to the 7Lig.s.. The results are compared with previous measurements and with shell-model calculations. 相似文献