共查询到20条相似文献,搜索用时 15 毫秒
1.
Melvin S. Freedman 《Nuclear Physics A》1975,249(1):182-184
It is argued that a recent claim that there is an error of a factor of two in the Law- Campbell theory of K-electron shake-off in β? decay is wrong. 相似文献
2.
D. Sinclair I. Paschopoulos H.S. Bradlow P.S. Fisher A.A. Pilt W.D.M. Rae 《Nuclear Physics A》1976,261(3):511-532
Reactions induced by 126 MeV 16O ions on 26Mg have been investigated in the angular range 5° to 12°. Optical model parameters were derived from the elastic scattering data and were used in a DWBA analysis of the inelastic scattering and single-nucleon transfer data. Satisfactory agreement was obtained for the angular distributions and for the spectroscopic factors. The two-nucleon transfer reactions appear to excite vibrational states. A DWBA analysis correctly describes the angular distributions for the two-proton transfer data. Most of the other few-nucleon transfer spectra exhibit little selective excitation but give a maximum at an energy consistent with the optimum Q-value predicte for direct transfer. Both the one- and twonucleon transfer data require that the 26Mg ground state contains considerable (λ, μ) = (4. 8) components and is not pure (10, 2) as predicted by simple SU(3) calculations. 相似文献
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4.
The transfer reactions 28Si(16O, α)40Ca and 16O(16O, α)28Si have been studied within the framework of the two-channel generator coordinate method. The geometry of the reactions has been discussed in terms of the cross-channel overlap kernels of the generating functions. A clear connection between maxima in the reaction rate and entrance channel resonances has been established. A two-step reaction mechanism involving quasimolecular resonances of inelastic 16O-16O channels is discussed as a possible explanation for narrow structures seen in the 16O(16O, α)28Si reaction cross section. 相似文献
5.
H. Spieler H. J. K?rner K. E. Rehm M. Richter H. P. Rother 《Zeitschrift für Physik A Hadrons and Nuclei》1976,53(5):241-250
The reactions120Sn+72 MeV18O and122Sn+74 MeV16O were investigated with time of-flightE-E-telescopes. Data are presented for all quasi-elastic reaction channels. The two neutron stripping and pickup reactions (18O,16O), (18O,20O) and (16O,18O) are analyzed in detail. It is shown that these heavy ion induced two neutron transfer reactions proceed with essentially the same type of selectivity as the corresponding light ion induced reactions. The differential cross sections for transfer reactions leaving the120, 122Sn nuclei in their 2+ first excited states are shown to be influenced by interference effects due to additional inelastic excitations. 相似文献
6.
The elastic scattering, inelastic scattering, single-neutron transfer reactions 13C(17O, 16O) 14C, 13C(17O, 18O)12C and 13C(17O, 18O2+, 1.98)12C, and seven other exit channels which involve 7Li, 9Be, 11B and 15N have been measured for the system 17O+13C at 12.9 and 14 MeV c.m. It is shown that all reactions mentioned above have significant contributions from compound nuclear decay, following fusion of projectile and target. 相似文献
7.
I. Tserruya W. Bohne P. Braun-Munzinger C.K. Gelbke W. Grochulski H.L. Harney J. Kuzminski 《Nuclear Physics A》1975,242(2):345-364
Angular distributions for one- and two-nucleon transfer reactions induced by 16O on 29, 30Si and for the elastic scattering of 16O on 28, 29, 30Si have been measured at 73.5 MeV bombarding energy. The results are analyzed with the DWBA code BRUNHILD that includes recoil effects. Spectroscopic factors extracted for all observed transitions in one-nucleon transfer reactions agree well with those derived from light panicle reactions. The effects of recoil on the Spectroscopic factors for transitions to final states with different spins are discussed. The transitions from smooth to oscillating angular distributions are examined. It is found that the shape of the angular distributions depends on both the matching conditions of the reaction and the localization of the S-matrix amplitudes in L-spacef. 相似文献
8.
The (α, 12C) reaction has been studied on a variety of nuclei, A = 16 to 40, at Eα = 90.3 MeV. The data indicate a rapid fall-off of cross sections with increasing target mass, approximately as At?5 ± 1. This and other systematics are used to estimate cross sections for multi-α-cluster transfer reactions in heavy nuclei and suggest σT < 10?34 cm2 consistent with present experimental limits. The data for 24Mg(α, 12C)16O has been studied in more detail and indicates a selective population of final states including 16O g.s., with oscillatory angular distributions in some instances. Finite-range distorted-wave Born approximation calculations for direct 8Be pickup have been performed utilizing cluster overlap amplitudes obtained with zero-order SU(3) wave functions. The calculations are in qualitative, and often quantitative, agreement with shapes and absolute magnitudes of the measured angular distributions although the cross sections for certain α-cluster states (2+, Ex ≈ 7 MeV; 4+, Ex ≈ 10.3 MeV) are greatly overestimated with this model. Other more complicated mechanisms, such as successive α-transfer, cannot be excluded. The systematics of the calculated 8Be cluster overlaps and the calculated and measured (α, 12C) cross sections are investigated, and implications for multi-α-cluster transfer reactions are discussed. 相似文献
9.
T. Tanabe K. Haga M. Yasue K. Sato K. Ogino Y. Kadota M. Tochi K. Makino T. Kitahara T. Shiba 《Nuclear Physics A》1983,399(1):241-258
The 24, 26Mg(6Li, d)28, 30Si reactions have been studied at 73 MeV bombarding energy. The angular distributions were analyzed with exact finite-range distorted wave Born approximation calculations assuming a direct α-cluster transfer. Extracted spectroscopic strengths leading to low-lying levels of 28Si and relative spectroscopic strengths between transitions to 28Si and 30Si ground states are consistent with those previously obtained by several α-transfer reactions. Many strongly populated levels have been observed at Ex ? 10 MeV for 28Si. A marked similarity was found between the deuteron spectrum and the 24Mg(α, α)24Mg excitation function in this excitation energy region. A brief comparison of the present α-transfer results with previous two-nucleon transfer data leading to 28,30Si is also presented. 相似文献
10.
C.K. Gelbke G. Baur R. Bock P. Braun-Munzinger W. Grochulski H.L. Harney R. Stock 《Nuclear Physics A》1974,219(2):253-265
Angular distributions and an excitation function of the reaction 17O(16O, 16O)17O1 () have been measured. The observed fine structure of the angular distributions cannot be explained by the dominating transfer process alone. An explanation is given in terms of interference between one-neutron transfer and inelastic scattering. 相似文献
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12.
Angular distributions have been measured for the elastic and inelastic scattering of 64 MeV 16O ions on 116Sn targets and analysed through coupled-equation calculations. The one-proton transfer has also been studied and the DWBA analysis gives results consistent with those derived from (3He, d). The two-proton transfer has been analysed in the framework of both DWBA and CCBA; theoretical wave functions for Te isotopes have been tested and the importance of multistep processes is discussed. 相似文献
13.
Levels in 26Mg and 26Al were excited with the 23Na + α reaction, and the recoil-distance method was used to determine the mean lives of the following levels: 26Mg, 3.59 MeV (9.6 ± 1.2ps) and 3.94 MeV (1.38 ± 0.11 ps); 26Al, 1.76 MeV (6.4 ± 0.4 ps) and 2.072 MeV (1.00 ± 0.10ps). The deduced values are compared to previous measurements by the Doppler-shift attenuation method. 相似文献
14.
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
15.
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
16.
G. Proudfoot H.S. Bradlow P.S. Fisher N.S. Godwin J. King D. Sinclair W.D.M. Rae 《Nuclear Physics A》1980,345(1):278-301
11B and 13C induced two-nucleon transfer data on 14N, 15N and 16O are compared with exact finite-range sequential transfer calculations. The data appear to be consistent with this reaction model and the assumed shell-model structure of the states populated. Single-nucleon transfer data on these targets is also analyzed using the DWBA. Modifications to the exit channel optical potential are required to obtain agreement with shell-model spectroscopic factors. 相似文献
17.
K.G. Bernhardt H. Bohn K.A. Eberhard R. Sielemann R. Vandenbosch M.P. Webb 《Nuclear Physics A》1981,365(1):157-172
Excitation functions for α-emission leading to the ground and first excited states of 26Mg and 8Be emission leading to the ground and first and second excited states of 22Ne have been measured at several forward angles for Ec.m. = 15 to 22.4 MeV. There is little evidence for correlated structure. The angular distribution at 16.5 MeV for the α + 26Mg(g.s.) channel is rather structureless while that for the 8Be+22Ne(g.s.) channel appears to be dominated by a J = 13 contribution. Statistical model calculations indicate that much of the yield for both the α and 8Be exit channel is compound nuclear in origin, with some indication of a larger direct contribution for the 8Be channel at the lower end of the bombarding energy range. 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.
利用时间相关Hartree-Fock 理论和完整Skyrme 有效相互作用研究了16O+16O 碰撞在库仑位垒附近的熔合动力学。数值计算是在没有任何对称性约束的三维笛卡尔基下完成。将时间相关Hartree-Fock 理论和冻结密度近似下的能量密度泛函方法给出的库仑位垒与实验结果进行了比较,发现同位旋标量的张量项能降低自旋饱和体系16O+16O的库仑位垒,而库仑位垒高度随着同位旋矢量的张量项的耦合常数减小而降低。并计算了包含和不包含张量力的16O+16O熔合截面,发现张量力对16O+16O碰撞在库仑位垒附近的熔合动力学影响较小。The fusion dynamics of 16O+16O around Coulomb barrier has been studied in the timedependent Hartree-Fock (TDHF) theory with the full Skyrme effective interaction. The calculations have been carried out in three-dimensional Cartesian basis without any symmetry restrictions. We have included the full tensor force and all the time-odd terms in Skyrme energy density functional (EDF). The Coulomb barrier obtained from the dynamical TDHF calculations and EDF with frozen density approximation has been compared with the available experimental data. The isoscalar tensor terms and the rearrangement of other terms are found to decrease the barrier height in the spin-saturated system 16O+16O, while the energy of Coulomb barrier tends to decrease as the isovector coupling constant decreases. The fusion cross section for 16O+16O collision has been calculated with and without the tensor force. We found that the tensor force has minor effect on the fusion dynamics of 16O+16O at the energies around Coulomb barrier. 相似文献
20.
J.P. Bondorf 《Nuclear Physics A》1973,202(1):30-36
The difference between the observed fluctuations in the elastic excitation functions for carbon-carbon and oxygen-oxygen scattering, just above the Coulomb barrier, is interpreted in terms of the compound nucleus model. 相似文献