共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Ward H.R. Andrews A.J. Ferguson O. Häusser N. Rud P. Skensved J. Keinonen P. Taras 《Nuclear Physics A》1981,365(1):173-188
Inverse reactions of 63, 65Cu beams on 18, 16O targets have been used to populate states of 78Kr by fusion-evaporation reactions. The excited nuclei recoiled at high velocity v/c ≈ 7 % through a polarized iron (54Fe) layer and were stopped in a copper layer. During the period in iron, 0.05–0.65 ps, the nuclei were subjected to the intense transient magnetic field (initially ~ 3500 T). The resulting precession of the high-spin nuclear states populated during this time was determined by measuring the time integral rotation angle of the discrete γ-ray transitions at low spin.The average g-factor at low spin 2 ≦ J ≦ 8 compared to that at higher spin 8 ≦ J ≦ 12 in 78Kr was found to be identical within the experimental uncertainties of ~ 15 %. This result implies that either there are no rotational alignment effects at the backbend in 78Kr or more plausibly, proton (g ≈ 1) and neutron (g ≈ 0) aligned bands are equally competitive and both populated in the reaction. It is then likely that the resulting g-factor represents an average over many populated proton and neutron aligned bands. 相似文献
2.
M. Adachi T. Kohno A. Makishima S. Fukuda M. Fukuda M. Taya H. Taketani 《Nuclear Physics A》1985,442(2):361-368
The g-factors of two isomeric states at Ex = 3763 and 5170 keV in 216Ra have been measured to be 0.51 ± 0.03 and 0.63 ± 0.06, respectively, with a TDPAD method. Spin and parity assignments of 19? for the 3763 keV state and 25? or 24+ for the 5170 keV state are consistent with the measured g-factors. Proposed configurations for the 19? and 25? assignments are of the same type as those predicted by a deformed independent-particle model for 214Rn, which is an isotone of 216Ra. 相似文献
3.
H. Bertschat U. Leithäuser W. Leitz F. Pleiter E. Recknagel B. Spellmeyer 《Nuclear Physics A》1974,229(1):72-78
Short-lived isomeric states in 108Ag and 110Ag were populated by means of (p, n) and (d, p) reactions. The nuclear g-factors of these states were determined with the pulsed beam DPAD method to be . The results indicate a spin and parity Iπ = 2+ for 108Ag and Iπ = 3+ for 110Ag. 相似文献
4.
The gyromagnetic ratios of the first excited Jπ = 2+ states of 50,54Cr, 54Fe and 70Ge have been determined by the ion-implantation perturbed angular correlation technique (IMPAC) with ferromagnetic Gd as stopping material. The g-factors were extracted from the measured precession angles with use of known lifetimes, static hyperfine magnetic fields and transient hyperfine magnetic field data for fast ions traversing ferromagnetic lattices. The deduced values are 0.59 ± 0.10, 0.56 ± 0.10, 1.08±0.19 and 0.38±0.08, respectively. With the exception of 54Fe all g-factors are close to the collective value. A re-evaluation of earlier IMPAC data on 70, 72, 74, 76Ge with Fe as stopping material has been performed. The value obtained for 70Ge is in good agreement with the one measured in this work. 相似文献
5.
6.
Transient field precession measurements have been performed on the first excited Jπ = 2+ states of 28Si and 30Si with the IMPAC technique on recoil in magnetized iron. The results were analyzed with empirically adjusted Lindhard-Winther predictions. This yields g-factors of , respectively. In the present cases the influence of static hyperfine fields is negligible due to the very short mean lives for 28Si and 30Si of 0.68 and 0.35 ps, respectively. The results are compared with theoretical calculations. Previous results for 26Mg(21+) were reanalyzed with the more recent lifetime of τm = 0.72 ± 0.03 ps. The value of the g-factor becomes g = +0.82 ± 0.16. 相似文献
7.
G. Winter J. Döring W.D. Fromm L. Funke P. Kemnitz H. Prade E. Will 《Nuclear Physics A》1981,367(1):95-108
The excited states in 75Br have been studied via the reactions 74Se(p, γ), 74Se(d, n), 74Se(3He, pn) and 74Se(α, p2n) by using in-beam γ-ray spectroscopy. In addition to measurements of γ-γ coincidences, excitation functions and angular distributions of γ-rays, ns lifetime measurements have also been carried out. As a result 19 levels have been identified up to spin () and excitation energies up to 2.6 MeV. The B(E2) value of 88 W.u. derived for the 88.4 keV γ-ray indicates strong collectivity within a positive-parity band. A comparison of the excitation energies of the unique-parity states in 75Br and 77Br with those in 153Tb and 155Tb reveals that the average deformation increases when going from 77Br (N = 42) to 75Br (N = 40). 相似文献
8.
The half-lives of the first and second excited states at 43.9 and 66.3 keV in 66Ga were determined by measuring the time dependence of the 43.9 and 22.4 keV γ-transition intensities. The levels in 66Ga were populated by the 66Za(p, n)66Ga and 63Cu(α, n)66Ga reactions. The results are T(43.9 keV) = 16(4) ns and T(66.3 keV) = 23(2) ns. A g-factor measurement reported in the literature is reanalysed. 相似文献
9.
The reorientation effect in Coulomb excitation has been used to measure the following static quadrupole moments: . Interference effects from higher excited states have been included in the analysis, with the signs of the E2 matrix elements taken from an anharmonic model. The value obtained for is in disagreement with two previous measurements. We attribute the discrepancy to the smaller internucleon separation distances involved in the previous experiments, which can cause deviations from Coulomb excitation cross sections. The other quadrupole moments have not been measured previously. The B (E2: 0+ → 2+) measured were: . From the angular distribution of the de-excitation γ-rays of the Pb nuclei following recoil into vacuum, we have determined the following (two standard deviations), . Our value of is in agreement with a previous measurement. 相似文献
10.
N. Bräuer A. Goldmann J. Hadijuana M. Von Hartrott K. Nishiyama D. Quitmann D. Riegel W. Zeitz H. Schweickert 《Nuclear Physics A》1973,206(3):452-458
The isomeric levels in 204Po and 206Po have been measured with the stroboscopic method. The results obtained are: . These and other known states in the 208Pb region are compared with theoretical predictions in order to analyze the dependence of the proton g-value on the core constitution. The variation of the g-values is systematically smaller than expected from first-order configuration mixing theory, if pure shell-model wave functions are assumed. 相似文献
11.
M. Ivaşcu D. Popescu E. Drăgulescu V. Avrigeanu C. Beşliu N. Martalogu 《Nuclear Physics A》1974,218(1):104-108
Mean lives and excitation energies of the lowest levels in64Ni,66Zn and68Zn were measured with the aid of the (α, α′γ) and (α, pγ) reactions. The γ-rays were detected in coincidence with the outgoing particles. The following mean lives were determined from DSA measurements: 400 ± 150 fs for the level at Ex = 1.35 MeV in 64Ni; 270 ± 100, 210 ± 110, 330 ± 200, 80 ± 70 fs for the levels at Ex = 1.87, 2.45, 2.83, 2.94 MeV in 66Zn, and 1300 ± 300, > 160, 600 ± 200 fs for the levels at Ex = 1.08, 1.89 and 2.76 MeV in 68Zn, respectively. 相似文献
12.
The reaction 12C(α, α')12C1(3α) is observed by using 90 MeV a-particles in ionographic matter. The energies of the three α-particles from the break-up of 12C1 are plotted in Dalitz diagrams. The density distributions for the three α-particles in the diagrams are calculated by assuming the spins and parities for the states in 12C1(3α). The spin-parities for the states are assigned by comparing the observed density distributions with those calculated. 相似文献
13.
E. Bożek B. Haas B. Ingarden-Dutkiewicz K. Królas J.C. Merdinger J. Styczeń J.P. Vivien 《Nuclear Physics A》1976,266(2):457-460
The rotation of the angular distribution pattern of the 524 keV γ-radiation from the 6+, 3200 keV state in 50Ti was measured in an external magnetic field using the 48Ca(α, 2n) reaction. The IPAD method was applied. From the experimental precession angle, the value of the g-factor, g = 1.57 ± 0.17, has been derived. 相似文献
14.
Integrated cross sections up to 28 MeV have been measured to excited residual states in 21Si, 27Al and 24Mg, following the photodisintegration of 28Si. From comparisons with spectroscopic factors of nucleon pickup reactions on 28Si, leading to the same residual states, it is concluded that the photonucleon emission process is predominantly single particle in nature. Estimates of isospin mixing in the 28Si giant dipole resonance are also given. 相似文献
15.
Quasi-band structures in 74Se, 78, 80Kr and 84Sr have been investigated using (p, 2nγ) reactions. The members of the quasi-γ band have been observed up to 5+ in 74Se, 78, 80Kr and up to 3+ in84Sr. The analyses of the energy systematics of the quasi-γ bands studied in this mass region as well as in other regions make clear the evolution of the quasi-γ band to the γ-band in well-deformed nuclei. In addition to these positive-parity bands, negative-parity levels were observed in 74Se, 80Kr and 84Sr. 相似文献
16.
R.E. Horstman J.L. Eberhardt H.A. Doubt C.M.E. Otten G. Van Middelkoop 《Nuclear Physics A》1975,248(2):291-316
Time-differential recoil-into-vacuum measurements have been performed with a plunger on the first-excited Iπ = 2+ states of 24Mg and 20Ne. The states were populated by the reactions 12C(16O, α)24Mg and 12C(12C, α)20Ne. The measured anisotropy of the α-γ angular correlation was greatly increased by means of a vertical slit on the annular particle detector. Values of have been deduced for the 24Mg and 20Ne g-factors, respectively. The mean lives of these states have been determined as τm = 2.09 ± 0.13 ps and 0.8 ± 0.2 ps, respectively. Various theoretical calculations are discussed and compared with the measured g-factors.The analysis of the measurement also yields values for the populations of electronic states contributing to the hyperfine interaction. For 20Ne the populations of the different electronic configurations are compared with the results of a separate time-integral measurement, in which the correlations were measured for each ionic state separately. Large fractions of two-electron excited states are found to contribute. 相似文献
17.
M.T. Esat M.P. Fewell R.H. Spear T.H. Zabel A.M. Baxter S. Hinds 《Nuclear Physics A》1981,362(1):227-240
The static electric quadrupole moment Q2+ and the B(E2; 0+ → 2+) value of the 2+ first excited state of 204Hg have been determined using the reorientation effect in Coulomb excitation. An annular Si surface-barrier detector was used to detect back-scattered 4He, 12C and 16O projectiles. In a subsidiary experiment, spectra were obtained from 204Hg(p, p')204Hg using Si surface-barrier detectors, and the results were used in conjunction with previously existing data to provide information on higher states of 204Hg which might participate in the Coulomb excitation of the 2+ state. From a 3-level analysis, we find Q2+ = +0.40 ± 0.20 e · b and B(E2; 0+ → 2+) = 0.423 ± 0.005 e2 · b2. These results are in good agreement with the predictions of particle-vibrational coupling calculations. The value obtained for is substantially smaller in magnitude than values of Q2+ previously determined for 198, 200, 202Hg. 相似文献
18.
The static quadrupole moment Q2+ and the B(E2; 0+ → 2+) value of the first excited state of 18O at ex = 1.982 MeV have been determined using the reorientation effect in Coulomb excitation. Surface-barrier detectors at laboratory angles of 90° and 174° were used to detect 18O ions elastically and inelastically scattered from 208Pb. At both angles, we determined experimentally the maximum bombarding energies at which nuclear interference effects were negligible. It is found that Q+ = ?0.023 ± 0.021 e · b (?0.052 ± 0.021 e · b) for destructive (constructive) interference from higher states. This result is in good agreement with theoretical expectation. For the transition moment we find B(E2; 0+ → 2+) = 0.00390 ± 0.00018 e2 · b2 (0.00371 ± 0.00018 e2 · b2) for destructive (constructive) interference. 相似文献
19.
The static quadrupole moment and B(E2; 0+ → 2+) value for the first excited state of 32S were measured using the reorientation effect in Coulomb excitation of 32S projectiles. Silicon surface barrier detectors were used to detect 32S ions scattered from 208Pb at mean laboratory angles of 90° and 174°, for bombarding energies in the range 122 to 160 MeV. The results for constructive (destructive) interference from the second 2+ state in 32S are QP2+ = ?16.0±2.2 (?13.3±2.2) e·fd2 and B(E2; 0+ → 2+) = 292±17 (307±17) e2·fm4 相似文献
20.
L.D. Wood H.H. Bolotin I. Morrison R.A. Bark H. Yamada A.E. Stuchbery 《Nuclear Physics A》1984,427(3):639-649
The gyromagnetic ratios of the lowest excited states in 107, 109Ag were simultaneously measured relative to that of the 21+ level in 108Pd. The thin-foil, perturbed γ-ray angular distribution technique was employed utilizing the transient hyperfine magnetic field present at the nuclei of these ions as they swiftly recoiled through a thin magnetized Co foil. The states of interest were Coulomb-excited using beams of 100 MeV 32S ions. The present measurements yielded . These findings are compared with weak-coupling and other appropriate model calculations. 相似文献