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1.
The reaction 40Ca(13C, 12C)41Ca leading to the ground and low-lying ? levels has been studied at bombarding energies of 18.5 and 19.0 MeV, close to the Coulomb barrier. The cross sections have been analysed using the DWBA with previously measured calibrations to obtain the rms radii of 1f and 2p orbits in the 41Ca levels. The rms radius of the 1f point neutron orbit in the ground state relative to the 40Ca core was determined to be 3.89 ± 0.12 fm. This is compared with various theoretical predictions based on Hartree-Fock theory. The 1f orbit radius gives the point neutron excess size to a good approximation for comparison with the value of 3.45 fm deduced from Coulomb energy differences. The consistency of the results with 40Ca(t, d)41Ca experiments using a (t/d), zero-range normalization of 3.26 × 104 MeV2 · fm3 is demonstrated, and trends in neutron size parameters through the Ca isotopes are discussed. 相似文献
2.
Angular distributions have been measured for transitions to low-lying states in 143Pm and 145Eu populated by the 142Nd(7Li, 6He)143 and the 144Sm(7Li, 6He)145Eu reactions at MeV. Elastic scattering of 7Li at 52 MeV on 142Nd and 144Sm, and 6Li at 46 MeV on 142Nd and at 45 MeV on 144Sm, were measured. Optical-model parameters extracted from fits to the scattering data were used in a finite-range DWBA analysis of the angular distributions for levels below 1.40 MeV excitation energy in 143Pm and 1.84 MeV in 145Eu. The reaction cross sections forward of 6° c.m. allow unambiguous distinction to be made between 2d and 2d final states. Final-state spins have been assigned to d-states in 143Pm at 1.40 MeV(+)and in 145Eu at 1.042 MeV (+). Existing assignments to other levels in both residual nuclei have been confirmed. 相似文献
3.
Highly excited 2P levels in alkali atoms were populated using a multi-step excitation, involving a tunable dye laser. The hyperfine structure of the 9 2P level in 87Rb and the 11, 12 2P levels in 133Cs was determined with optical double resonance. 相似文献
4.
The first six excited states of 17N have been studied by using the 18Ot, αγ)17N reaction at a bombarding energy of Et = 3.5 MeV. Alpha-gamma angular correlation measurements (method II) were used to determine spins, mixing ratios and branching ratios. The 1.37, 1.85, 1.91, 2.53, 3.13 and 3.20 MeV levels have been assigned the spins , , ?, +, and respectively. Excitation energies are also given. Most of the results are in good agreement with previous data or suggested values. Mixing ratios have been obtained for the first time. The level scheme of 17N is compared with some analogue states in 17O and 17F and with results of recent shell-model calculations. 相似文献
5.
S. Raman J.L. Foster O. Dietzsch D. Spalding L. Bimbot B.H. Wildenthal 《Nuclear Physics A》1973,201(1):21-40
The excited states of 142Nd were studied by means of the decay of 40 sec 142Pm and the 142Nd(p, p') reaction via isobaric analog resonances. Approximately sixty levels of 142Nd were observed below 5.3 MeV excitation, including several neutron particle-hole states excited strongly in (p, p') at f, p, p and f analog resonances. We have collected together all known energy levels in 142Nd and have proposed Jπ assignments for 22 excited states. We have also compared the experimental level spectrum (positive-parity states only) with a calculated one based on the shell model. 相似文献
6.
Levels of 66Cu have been studied using the (t, α) reaction on 67Zn at 18 MeV. Orbital and, in some cases, total angular momentum transfer were inferred from a comparison of differential cross sections with those measured for the same reaction on the even zinc isotopes. The quartet of levels corresponding to the p proton pick-up from the ? target was identified. In addition, a strong set of l = 3 transitions was found corresponding to pickup from the f proton shell. 相似文献
7.
The differential cross section and polarization for neutrons scattered from 10B have been measured at En = 2.63 MeV (Ex = 13.85 MeV). The results of this experiment and other available neutron scattering data in the range 1 < En < 4 MeV are interpreted through a single-level R-matrix calculation over the region 12 < Ex < 15 MeV. Based on this analysis the most probable Jπ assignment for the 14.0 MeV level in 11B is . The anomaly near Ex = 13.1 MeV can only be explained in terms of two overlapping levels having assignments of (, )? and (, , )+. 相似文献
8.
A. Baldacci S. Ghersetti S.C. Hurlock K. Narahari Rao 《Journal of Molecular Spectroscopy》1976,59(1):116-125
The rotational structure of about 40 bands of 12C2HD observed in the region 6000?600 cm?1 has been measured and interpreted with the purpose of determining a comprehensive set of molecular constants for this isotopic variety of acetylene. Combining these data with the results for 12C2H2 and 12C2D2, a reevaluation of the equilibrium internuclear distances for the acetylene molecule has been made: and were obtained. This paper presents all the molecular constants derived in this study. 相似文献
9.
Relative differential cross sections for the reaction 208 P(7Li, 8Li) leading to the predominantly single-hole states in 207Pb have been analysed using the DWBA to determine the rms radius of the 1h neutron orbital in 208Pb by comparison with known sizes of the 3p and 2f orbits. The experiment was performed at a beam energy of 52 MeV. The insensitivity of the technique to unknown input parameters to the DWBA analysis is demonstrated and a value of 5.94±0.11 fm for the rms radius of the 1h orbit obtained assuming 70% of the hole strength is concentrated on the , 3.41 MeV state in 207Pb. Effects due to fragmentation of the different hole strengths are examined and a value of 6.00 ± 0.11 fm is extracted as the best value for the rms radius of the neutron excess in 208Pb. The relevance of these data to mean-field calculations of nuclei is discussed. 相似文献
10.
L. Funke P. Kemnitz G. Winter S.A. Hjorth A. Johnson Th. Lindblad 《Physics letters. [Part B]》1975,55(5):436-438
Levels with spins up to 18 (20) in the ground-state bands of 190Pt and 192Pt have been observed. The very small energy spacing between the 12+ and 10+ levels in both nuclides is interpreted as a sudden decoupling of two i neutrons from the collective core. 相似文献
11.
E. Hammarén E. Liukkonen M. Piiparinen J. Kownacki Z. Sujkowski Th. Lindblad H. Ryde 《Nuclear Physics A》1979,321(1):71-108
The 146, 148Nd(α, χn) and 148, 150Nd(3He, χn) reactions at Eα = 20–43 MeV and E3He = 19–27 MeV, are used to study excited states in the 149Sm86 and 149Sm87 nucleides and consequently the low-spin odd-parity excitation. The mixing ratios and multipolarities of the most prominent transitions are deduced from the combined evidence of angular distribution and electron conversion data. The spin-parity assignments for most of the levels observed are established. In 148Sm the ground state band extending to Iπ = 10+ is predominantly populated. A negative-parity odd-spin band extending from Iπ = 3?through 11? is also observed. The bands in 148Sm are interpreted within the framework of the interacting boson approximation model. In 149Sm positive-parity levels with spin up to and negative-parity levels with spins up to are observed. The predominant γ-decay proceeds via transitions associated with , , and intrinsic configurations. The branching ratios B(E1)/B(E2) are calculated and compared in both 148Sm and 149Sm nucleides. The B(E1)/B(E2) dependence on the value of Z for some N = 86 (as well as 88 and 84) isotones showing a minimum of Z = 64 was noted. A 4 ns high-spin isomer mainly decaying into the positive-parity band based on the state in 149Sm is found. Experimental evidence is presented to interprete the , , … and , , …, ΔI = 2, sequences in 149Sm as arising from the coupling of an neutron to the octupole and quadrupole modes of the 148Sm core nucleus. The absolute reaction cross sections for the 146, 148, 150Nd(3He, χn) reactions have been determined for different bombarding energies. The mixing of the and shells is discussed in the framework of an axial-particle-rotor model calculation. 相似文献
12.
R. Julin J. Kantele M. Luontama T. Poikolainen V. Rahkonen 《Physics letters. [Part B]》1976,65(4):337-338
Half-lives of O2+ states in 206Pb and 208Po, 770±40 and 465±20ps, respectively, are determined using direct-timing techniques. The corresponding monopole strength parameter values, and , indicate that the O2+ states in both nuclei are mainly of similar two-neutron-hole character. 相似文献
13.
The energy levels of 74As have been studied using the 73Ge(3He, d)74As reaction at an incident energy of 17 MeV. The overall energy resolution was 30 keV. Twenty-five levels in 74As were identified up to 2.2 MeV excitation energy and angular distributions were measured in the interval to . Spectroscopic strengths and lp values have been extracted for many of the transitions by means of a distorted-wave analysis of the differential cross sections. A comparison with the 75As(p, d) data suggests the presence of several unresolved doublets in 74As. 相似文献
14.
W. Bohne H. Fuchs K. Grabisch H. Kluge H. Morgenstern H. Oeschler W. Schlegel 《Nuclear Physics A》1975,240(1):171-188
The proton transfer on 40K has been studied with the 40K(3He, d)41Ca reaction at 13 and 21 MeV bombarding energy and with the 40K(d, n)41Ca reaction at 6.5 MeV bombarding energy. The energy and angular distribution of outgoing particles have been measured. For transitions to 62 levels in 41Ca the l-values and spectroscopic factors have been derived with DWBA. The excitation energies of levels populated with l = 3 and the qualitative distribution of transfer strength strongly suggest their interpretation as 2p-1h states of the f2d?1 configuration with weak coupling between the particle pair and the hole. The high-spin states of this configuration (with Jπ up to ) are preferentially excited. 相似文献
15.
The study of excited 55Mn levels with the 52Cr(α, pγ) reaction was extended to levels up to 3161 keV. With a Ge(Li) detector, DSA measurements in gold-backed targets were made, as well as angular correlations; both of these experiments were done in coincidence with protons detected near 180°. A multiple-detector NaI(Tl) array was also used in the same reaction geometry for better γ-ray detection efficiency. Mean lifetimes of 12 levels from 2727 to 3161 keV are reported. Spins and sometimes parities of the following levels were deduced from the angular-correlation analyses and lifetime results: 1885 keV, ?; 2199 keV, (?); 2311 keV, (); 2366keV, ?; 2727 keV, ; 2823 keV, . Multipole mixing ratios and M1 and E2 transition rates of the radiations from these and from the 1292 keV level are presented. The similarity of the low-lying level structure and of interlevel transitions in 55Mn to those in certain other f3 nuclei is examined. 相似文献
16.
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
17.
M.A. Van Driel H.H. Eggenhuisen J.A.J. Hermans D. Bucurescu H.A. Van Rinsvelt G.A.P. Engelbertink 《Nuclear Physics A》1974,226(2):326-346
The τ = 22 μs isomeric level of 38K at an excitation energy of 3458.0 ± 0.2keVf is strongly populated in the 24Mg(16O, pnγ)38K reaction. Delayed γ-rays are studied with Ge(Li), Si(Li), and NaI detectors. Accurate excitation energies, branching ratios and lifetimes of levels involved in the decay of the isomeric state are determined. The isomeric level predominantly decays by a dipole transition of 38.03±0.03 keV with a total conversion coefficient of αT = 0.42 ± 0.15. Mean lives of 38K levels are measured with the recoil-distance method. The results are τm = 10.1 ± 0.9 ps, 1.41 ± 0.14 ns and 101 ± 15 ps for the levels at excitation energies of 0.46, 2.65 and 3.42 MeV, respectively. It is suggested that the (1f)2 structure of a low-lying Jπ = 7+ state in combination with the selection rules for γ-decay in a self-conjugate nucleus is responsible for the isomerism. 相似文献
18.
C.P. Swann 《Nuclear Physics A》1973,201(3):534-540
The Doppler-broadened 7.117 MeV line from the 19F(p, αγ)16O reaction has been used to resonantly excite levels in 208Pb at 7071±2 and 7091±2 keV, in 207Pb at 7186±5 and 7206±5 keV and in 209Bi at 7179±5 and 7202±5 keV. On the basis of angular distribution measurements the 7071 and 7091 keV levels of 208Pb are assigned spins of 1 and assuming 100% ground state branching the widths are calculated to be 31±3 and 17±2 eV respectively. It is suggested that the states in 207Pb and 209Bi arise from the weak coupling of a neutron hole and an proton respectively to one or the other of the 208Pb levels. The widths obtained in terms of gΓo2/Γ are 15±4 and 25±5 eV for the 7186 and 7206 keV levels of 207Pb and 24±5 and 30±5 for the levels of 209Bi respectively. These values are consistent with the weak-coupling suggestion. 相似文献
19.
S. Galés E. Hourani S. Fortier H. Laurent J.M. Maison J.P. Schapira 《Nuclear Physics A》1977,288(2):201-220
The 96Zr(τ, α)95Zr reaction at 39 MeV incident energy was used to populate both the low-lying and highly excited (up to an excitation energy of 18 MeV) analog states in 95Zr and some low-lying levels in other Zr isotopes. The main components of the 2d. and 1g. hole strengths and the analogs of the 2p., 2p. and 1f. proton hole states in 95Y have been observed in this work. Angular distributions of transitions to 27 levels in 95Zr have been extracted and analysed with DWBA calculations to yield spectroscopic factors. Between the excitation energies of 1 and 3 MeV in 95Zr a number of levels with l = 2, 4 and 5 angular distributions have been identified. These are associated with the 2d, 1g and 1h components already observed in the previous study of the 94Zr(d, p) and (α, τ) reactions. The total strength and center of gravity for levels assigned to the (1g)?1 configurations in 95Zr are presented and compared to the results obtained from the studies of neutron pick-up reaction on 91Zr and 98Mo. For the isobaric analog states observed between the excitation energies of 15 and 17 MeV, total widths, Coulomb displacement energies and spectroscopic factors are also determined from this experiment and the results compared with the properties of the low-lying proton hole states in the 95Y parent nucleus. 相似文献
20.
Measurements of γ-ray yield functions, γ-γ coincidence spectra and y-ray angular distributions following the 64Ni(α, n) and (α, 2n) reactions have been made. Beam energies of 17 to 25 MeV were used. Among the new levels observed, with their proposed spin-parity assignments, are: in 66Zn, 3708 keV, (5)+; 3896 keV, 5?; 4812 keV, (7?); 5110 keV, (8?); 6417 keV; (10?); 7516 keV, (12+); and in 67Zn, 2937 keV, ; 3491 keV, or ; 3492 keV, ((si+)); 4221 keV, (?); 4631 keV, (); 4685 keV, (?). Comparison between the ground-state sequence, 0+ to 6+, in 66Zn and the first + to + levels in 67Zn strongly suggests that the latter be described as a g neutron orbital weakly coupled to the 66Zn core. Other sequences of high-spin 66Zn states are proposed to be formed from two-quasiparticle states containing the g excitation, coupled to the same ground-state sequence. 相似文献