共查询到20条相似文献,搜索用时 46 毫秒
1.
K.W. Kemper R.L. White L.A. Charlton G.D. Gunn G.E. Moore 《Physics letters. [Part B]》1974,52(2):179-182
Angular distribution measurements for the reactions 24Mg(7Li, 6He)25 Al and 52Cr(7Li, 6He)53 Mn at MeV show that for angles less than 15°, the shapes of the measured angular distributions allow or , and or final-state configurations to be distinguished when compared with finite-range DWBA calculations. 相似文献
2.
F. Prats 《Nuclear Physics A》1974,227(3):469-484
The differential cross section for the quasi-elastic scattering of protons on 6Li is derived in the impulse approximation. The nucleus 5He is not treated as a bound nucleus in the derivation. Instead, the n-α interactions , , and in the final state are included. Fits to the unknown vertex functions appearing in the expression obtained for the momentum distribution at the “ground state” of 5He are given, showing that the n-α interaction is important at the “ground state” of 5He. The consistency between the observed momentum distribution and the 6Li form factor at low momentum transfers is shown utilizing Elton's model. 相似文献
3.
The nucleus 11B has been studied over the excitation energy range from 8.5 MeV to 21.5 MeV with the 9Be(3He, p)11B / reaction at / E3He = 38 MeV. The analogs of the parent states in 11Be have been located at 12.56, 12.92, 14.40, 16.44, 17.69, 18.0, 19.15 and 21.27 MeV. A complementary measurement with the 9Be(α, d)11B reaction at Eα = 48 MeV demonstrates that the 16.44, 17.69, 18.0 and 19.15 MeV resonances have rather pure isospin . The 14.40 MeV state is a strongly isospin-mixed analog of the state in 11Be. It is argued that spin S = 1 transfer is involved in the excitation of the 16.44 MeV state and its 3.887 MeV parent in 11Be in a two-step stripping process. The states and the lowest three states are compared with the predictions of DWBA utilizing shell-model form factors. It is concluded that the strength is more strongly fragmented than is implied by the calculations of Teeters and Kurath. 相似文献
4.
Koike Yasuro 《Nuclear Physics A》1980,337(1):23-39
The differential cross section and the polarization quantities (T11, T20, T21, T22, Pγ') in the deuteron breakup reaction by an α-particle are calculated in the framework of the recently developed three-body model. All values are discussed under the incomplete kinematical condition. All polarization quantities are caused by the difference of the potential between and waves of the N-α interaction. Results of the calculation are compared with the available measurement of (i) the differential cross section and the deuteron vector analysing power in the 4He(, p)n4He reaction and (ii) the differential cross section and neutron polarization in the 2H(α, )p4He reaction. The agreement with experiment is very satisfactory in each case. Among the tensor analysing powers of the deuteron the absolute value of T20 is very large. Observables at the FSI peak corresponding to 5Heg.s. are discussed systematically in the energy region of 5.4–20 MeV of the incident deuteron in the 4He(d, p)n4He reaction. Although the differential cross section is not sensitive to the energy of the three-body resonance, the polarization quantities T11, T20, Pγ' are quite sensitive to it. 相似文献
5.
D.J. Decman H. Grawe H. Kluge K.H. Maier A. Maj N. Roy Y.K. Agarwal K.P. Blume M. Guttormsen H. Hübel J. Recht 《Nuclear Physics A》1985,436(2):311-337
The nucleus 217Ac was studied using the 205Tl(16O, 4n), 206Pb(15N, 4n) and 209Bi(12C, 4n) reactions. The mesurements included αγ, γγ, α-ce and ce-ce coincidence experiments as well as γ-ray and α-particle perturbed angular distribution studies. Results are and , the shortest known α-decay of a ground state. 217mAc decays mainly by a γ-cascade, but also by α-emission to the single-particle states of 213Fr. Spins and parities of levels to the + isomer at 2013 keV with and g = + 0.347(5) are determined. The level scheme of 217Ac and the α-decay of N = 128 isotones are discussed. 相似文献
6.
The Heidelberg shape-effect model for heavy-ion tensor interactions is reformulated and generalized using the Hooton-Johnson formulation. The generalized semiclassical model (the turning-point model) predicts that the components of the tensor analysing power have certain relations with each other for each type of tensor interaction (TR, TP and TL types). The predicted relations between the are very simple and have a direct connection with the properties of the tensor interaction at the turning point. The model predictions are satisfied in quantum-mechanical calculations for 7Li and 23Na elastic scattering from 58Ni in the Fresnel-diffraction energy region. As a consequence of this model, it becomes possible to single out effects from a TP? or TL-type tensor interaction in polarized heavy-ion scattering. The presence of a TP-type tensor interaction is suggested by measured ratios for 7Li+58Ni scattering. In the turning-point model the three types of tensor operator are not independent, and this is found to be true also in a quantum-mechanical calculation. The model also predicts relations between the components of higher-rank tensor analysing power in the presence of a higher-rank tensor interaction. The rank-3 tensor case is discussed in detail. 相似文献
7.
8.
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
9.
At 57 MeV bombarding energy the (α, 2He) reaction has been investigated on targets of 54,56Fe, 58,60,62,64Ni, 64,66Zn, and 70Ge. Selective excitation of the 2n configurations , , and was observed in all final nuclei. A linear A and T dependence of the binding energies of these states was observed. This systematic behaviour is well described by the Bansal-French model. The values obtained for the strength of the isoscalar and the isovector parts of the particle-hole interaction are consistent with the average of the values describing the corresponding single-particle states. 相似文献
10.
The specific heat of liquid 3He has been measured from 4 to 300 mK. Even at very low temperature, it deviates from a pure γT behavior. The effective mass is in good agreement with previous results, but disagrees with recent measurements around TA. 相似文献
11.
L.K. Kostov H. Rotter C. Heiser H. Prade F. Stary W. Andrejtscheff 《Nuclear Physics A》1982,376(3):451-462
Applying the generalized centroid shift method in (α, 2n) reactions, the half-lives of the 3080 keV 15+ state in 176Hf and of the 1637 keV 5? state in 178Hf have been measured as and , respectively. B(El) values of K-allowed E1 transitions are derived, and together with other data on similar transitions in odd-A nuclei, compared with predictions of the Nilsson plus pairing model. In 176Hf, the 15+ and 14? states at 3080 and 2866 keV, respectively, appear as quite pure deformed 4QP configurations. In the 2QP state at 1637 keV in 178Hf, possible strong mixing of vibrational components is discussed coupled via 2QP K-admixtures arising from the partial alignment of the neutron. 相似文献
12.
The spectrum seen in single neutron pickup leading to the doubly odd nucleus 84Rb is remarkably clean, with only five levels populated by l = 4 and six by l = 1 transitions. A simple 2J+1 weighting for the l = 4 data, combined with previous information on 84Rb, allowed the Jπ = 2?–7? states of the () multiplet to be identified. These data are used to determine the two-hole interaction matrix elements. 相似文献
13.
M. Langevin C. Détraz D. Guillemaud F. Naulin M. Epherre R. Klapisch S.K.T. Mark M. De Saint Simon C. Thibault F. Touchard 《Nuclear Physics A》1981,366(3):449-460
β-delayed emission of α-particles from 9Li and of both α and 6He particles from 11Li is observed. Singles energy spectra and two-dimensional energy spectra of coincident particles are measured. A time-of-flight versus energy measurement is used to identify the mass of the particle. New β-branches are observed which populate high-energy levels in the daughter nuclei. The branching ratios are measured and the β-delayed neutron emission probabilities are deduced. 相似文献
14.
The reactions 17O(d, t) 16O and 17O(d, τ)16N have been investigated at Ed = 52 MeV. Energy spectra of tritons and τ-particles have been measured simultaneously up to excitation energies of 22 MeV in 16O and 10 MeV in 16N, respectively. Spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From the comparison of the t- and τ-spectra analog (T = 1) states in 16O could be identified and the distribution of T = 0 and T = 1 spectroscopic strengths could be deduced. Nearly the total and hole strengths have been found and the particle-hole multiplets could be located both for T = 0 and T = 1. The average residual interactions in both shell-model configurations turned out to be strikingly different. 相似文献
15.
R.F. Curl 《Journal of Molecular Spectroscopy》1973,48(1):165-173
The and transitions of the J = 7 levels of the ground state of CH4 have been observed by infrared-radio frequency double resonance using the 3.39 μ HeNe laser line. The transition frequencies are 423.02 ± 0.02 MHz and 1246.55 ± 0.02 MHz, respectively. Using these frequencies and the splitting of the E and F2 levels of the J = 2 state calculated from the molecular beam magnetic resonance spectra of Ozier, the centrifugal distortion constants are derived to be Dt = 132933 ± 10 Hz, H4t = ? 16.65 ± 0.2 Hz, and H6t = 10 ± 1 Hz. The J = 15 E(1) → E(2) microwave transition is predicted as 14150 ± 9 MHz. 相似文献
16.
A. Filevich A. Ceballos M.A.J. Mariscotti P. Thieberger E. Der Mateosian 《Nuclear Physics A》1978,295(3):513-524
The 6? and 7? isomeric states in 66Ga and 68Ga at 1440.9 and 1229.6 keV, respectively, have been populated with the (13C, 2np) and (15N, n2p) reactions on natural Fe. The half-lives of these states have been measured to be and . Using previous data on the hyperfine field of Ga in Fe, the g-factors of these states have been determined by means of the TDPAD method. The results are and . These values are in very good agreement with the independent particle model if one assumes the and configurations and uses the empirical proton and neutron g-factors from odd-A neighboring nuclei instead of the Schmidt values. The large disagreements with experiment when Schmidt values are used show that core polarization effects are important in these nuclei. 相似文献
17.
The 58Ni(τ, α)57Ni reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 50° with a split-pole spectrometer up to 13.5 MeV excitation energy. A local zero-range DWBA analysis has been carried out, allowing l-assignments for about eighty levels, most of them previously unknown. An isospin-dependent potential has been used in the calculation of the neutron form factor for both T<and T> states, and the C2S values deduced using this procedure are compared to those obtained with the usual separation energy method. Analog states of eleven 57Co levels have been identified and the eventuality for isospin mixing in 57Ni has been discussed. A sum rule analysis has been carried out and energy centroids of hole states have been determined. About 60% of the strengths and the full and hole strengths are observed. It is shown that the two excess neutrons in the 58Ni ground state mainly populate the orbitals, whereas the occupancy number of the subshell is found to be smaller than 0.1%. Some non-pickup angular distributions have also been observed and a CRC analysis assuming two-step processes in the (τ, α) reaction and weak-coupling wave functions for final states has been attempted. Assignments of Jπ values are proposed for four 57Ni levels, based on this analysis. 相似文献
18.
The analyzing powers iT11, T20, T21 and T22 have been measured for the reaction 3He(d, p)4He at laboratory energies of 344, 465 and 727 keV. A polarized deuteron beam was used with quantization axis oriented perpendicular to and at 54.7° to the incident beam direction. With semi-conductor proton detectors in two perpendicular planes all four analyzing powers could be determined. The beam polarization was determined using the 3H(d, n)4He reaction at a mean energy of 130 keV. The uncertainty in this analyzing power and the effect on the results is discussed. The analyzing powers have been fitted to a Legendre polynomial expansion to four or five terms and the resulting coefficients tabulated. The results indicate that d-waves contribute to the reaction only through the entrance channel and their contribution falls off both above and below the resonance at 430 keV. 相似文献
19.
A shell-model calculation of the N = 51, 39 ≦ Z ≦ 42 nuclei is presented. The 88Sr nucleus is assumed to be an inert closed core. The extra-core protons are restricted to the (, ) configurations, and the active neutron is allowed to occupy the , , and orbits. The proton-proton effective interaction is directly taken from the previous analysis on the energy levels for N = 50 isotones by Ball et al. The proton-neutron effective interaction is assumed to be of the form of the surface δ-interaction. The energy spectra are calculated from a least-squares fit to the experimental data, varying the T = 0 and T = 1 strengths of the surface δ-interaction. Spectroscopic factors, E2 transition rates and two-body matrix elements are also calculated and compared with the observed values and the previous theoretical results. 相似文献
20.
Spin lattice relaxation T1 of naturally abundant 13C nuclei in squaric acid was measured close to the antiferroelectric-paraelectric phase transition temperature Tc = 373 K. A rapid increase in is observed close to Tc coming from above, which follows the power law where . This behaviour is explained on the basis of the two-dimensional character of the fluctuations. 相似文献