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1.
2.
The total reaction cross sections for 11B + 9Be and 13C + 9Be have been measured by the total γ-ray yield method over the energy intervals Ec.m. = 1.4–4.4 MeV and Ec.m. = 2.0–5.2 MeV, respectively. The cross sections for the neutron transfer reactions 11B(9Be, 8Be)12B, leading to the 12B 0.953 and 1.674 MeV states, and 13C(9Be, 8Be)14C, leading to the 14C 6.094, 6.728 and 6.902 MeV states, have been obtained from the yields of the characteristic γ-rays. The α-transfer reaction 11B(9Be, 5He)15N, leading to many unresolved 15N states, has been observed with large cross section. There is, however, no evidence for the 13C(9Be, 5He)17O transfer process in the 17O + nα channels. This different behaviour of the 11B + 9Be and 13C + 9Be systems seems to indicate that the α-transfer reaction at sub-barrier energies is not a direct transfer process, and that it probably occurs via molecular state formation. 相似文献
3.
Proton polarization and differential cross section for the (3He,p) reaction on 6Li and 9Be at 14 MeV
Angular distributions of the proton polarization and the differential cross section have been measured for the reaction (3He, p) initiated by 14 MeV incident 3He particles and proceeding to the ground and the first excited states of the final nuclei 8Be and 11B. Large polarization values were observed, especially for the 9Be(3He, p)11B reaction leading to both the ground and the first excited states in 11B. The experimental results have been analysed in terms of a two-nucleon transfer spindependent distorted-waves theory using finite-range formalism and including corrections due to the non-locality of the optical potentials. A proper coherent summation over L and S, whenever necessary was included in the DWBA calculations of the polarization and the differential cross section as implied by the presence of the spin-orbit terms in the optical-model potentials used to generate the distorted waves. 相似文献
4.
K. Nakamura S. Hiramatsu T. Kamae H. Muramatsu N. Izutsu Y. Watase 《Nuclear Physics A》1978,296(3):431-443
The proton spectral functions of 6Li, 7Li, 9Be and 10B obtained from the (e, e′p) reactions at 700 MeV are presented. The results were analyzed in the distorted-wave impulse approximation, using the shell-model single-particle wave functions consistent with the elastic electron scattering results. The observed Ip proton momentum distributions for the nuclei 6Li, 7Li and 9Be show significant disagreement with the shell-model momentum distributions. The occupation probabilities of the proton single-particle states are around 0.7, with a few exceptions. 相似文献
5.
E. Aprile D. Besset Q.H. Do B. Favier R. Hausammann E. Heer R. Hess C. Lechanoine-Leluc W.R. Leo S. Morenzoni Y. Onel D. Rapin J.M. Cameron S. Jaccard S. Mango 《Nuclear Physics A》1982,379(3):369-380
The polarization asymmetries A0y and Ay0, and the spin correlation parameter Ayy have been measured at SIN at 515 and 578 MeV using a transversally polarized proton beam and target. The results are compared with various theoretical models. 相似文献
6.
R.E.L. Green D.H. Boal R.L. Helmer K.P. Jackson R.G. Korteling 《Nuclear Physics A》1983,405(3):463-496
A 9Be(p, 2p) coincidence experiment performed to further elucidate the reaction mechanism for the production of energetic wide-angle protons in intermediate-energy proton-induced reac- tions is reported. Detectors in a coplanar geometry were used to measure coincidences between trigger protons at 90° to the beam and forward-angle protons on the opposite side of the beam. The incident proton energy was 300 MeV. We report both the inclusive spectra for the trigger protons and the differential mean multiplicities for the coincidence events.The outgoing proton energies were measured using NaI detectors. Trigger protons were grouped into 10 MeV bins covering the kinetic energy range from 55 to 155 MeV. The forward protons were measured over a kinetic energy range of 65–280 MeV and an angular range of 14–60° with respect to the beam.The present results are compared with two previous experiments which covered a more restrictive kinematical range. Calculations are performed with both phase-space and direct knockout models, and compared with experiment. Observation of angle and energy correlation effects suggested by knockout models indicate that such direct mechanisms provide a significant contribution to energetic wide-angle inclusive proton spectra. 相似文献
7.
The polarization of protons from the 9Be(d,p)10Be reaction at Ed = 12.0 MeV was measured for the ground state and first excited state transitions. The results obtained are compared with the predictions of DWBA theory. It was found that better fits to the experimental data can be obtained using volume absorption in the distorting potential of the deuteron elastic channel. A comparison of the present polarization data with the vector analysing power for the same reaction and the same incident deuteron energy has also been made. 相似文献
8.
Spectroscopy of the α- and τ-particles from 40 MeV proton bombardment of 11B reveals transitions to 8Be states up to 19 MeV. The ratio of excitation of the 16.6 MeV state to the 16.9 MeV state is 2.3 ± 0.4. The 8Be(4+) state is found at 12.5 MeV with a width of 4.0 ± 0.5 MeV. 相似文献
9.
J.L. Ullmann F.P. Brady D.H. Fitzgerald G.A. Needham J.L. Romero C.M. Castaneda N.S.P. King 《Nuclear Physics A》1982,386(1):179-188
The parent analog of the giant dipole resonance in 28Si is studied by means of the (n, p) reaction. The continuum contribution to the giant dipole region was estimated by a phenomenological parameterization. The observed cross section exhausts 31% of the SJ sum rule; 88% of the GT sum rule or 67% of the Myers-Swiatecki prediction. A comparison is made to the giant resonance region observed in the 28Si(p, p') reaction which was recently used, via comparison to 28Si(α, α'), to infer that the GDR in 28Si is not excited or at least not seen in (p, p'). 相似文献
10.
A study of the (3He, 7Be) reaction has been undertaken using a 70 MeV 3He beam. By surveying a wide range of target nuclides, namely 12, 13C, 16O, 24, 26Mg, 40, 42, 44Ca, 58, 60, 62, 64Ni, 90Zr, 120, 124Sn, 144Sm and 206Pb, systematics of the α-clustering phenomenon were investigated. In addition, masses and energy levels of 60Fe and 120Cd were measured. The 7Be particles were detected in a single wire proportional counter backed by a plastic scintillator in the focal plane of an Enge spectrometer to ensure adequate particle identification. Total energy resolution as small as 140 keV full width at half maximum was obtained, although in most cases the target thickness limited the energy resolution to larger values. Differential cross sections as low as 20 nb/sr were measured. The finite range programs LOLA and LOLITA were used to calculate differential cross sections for comparison to data, assuming the reaction to proceed by a direct α-transfer. The spectroscopic factors which were extracted show a marked decrease with increasing atomic mass number, implying a decrease in surface α-clustering for heavier nuclei. 相似文献
11.
Time-of-flight techniques were used to measure the analyzing power for the scattering of neutrons from 9Be at energies from 9 to 17 MeV. Because of the high nuclear density of beryllium, particular attention was paid to finite-geometry and multiple-scattering effects. For representing the data, an unusual method of Legendre-coefficient analysis was used to establish the smooth energy dependence of both the cross section σ(θ) and the analyzing power Ay(θ). Spherical optical-model calculations were able to describe the σ(θ) and Ay(θ) data simultaneously, but only after the introduction of an imaginary spin-orbit potential Ws.o.(r). The geometry of the Ws.o.(r) term was found to be the same as that of the surface-peaked imaginary central potential. Coupledchannels calculations using a quadrupole-deformed rotational model built on the ground state were able to describe inelastic scattering to the and excited states, but also required a Ws.o.r potential. 相似文献
12.
Elastic and inelastic scattering data extending to θc.m ≈ 175° are reported for 6Li + 28Si at 27 and 34 MeV. Optical model analyses of the elastic data were made using a variety of real potential forms. The large-angle data cannot be fitted with a Woods-Saxon real potential, but are well described by Woods-Saxon squared, double-folded or Fourier-Bessel potentials. The real potential is the same at both energies, but the imaginary potential is weaker at 27 MeV. The inelastic data were analyzed using the DWBA and coupled channels techniques with folded real form factors and deformed Woods-Saxon imaginary potentials, with the deformations taken from electron scattering. The 2+ state was fitted well at both energies with the DWBA, while the prediction decreased too rapidly at large angles for the 4+ state. The large-angle 4+ data were better described when two-step excitations were included in the coupled-channels calculations. The forward-angle 2+ data are sensitive to the interference between Coulomb and nuclear scattering and show that the nuclear and Coulomb deformation parameters β2 are equal for this transition. 相似文献
13.
B. Ramstein R. Tamisier L.H. Rosier P. Avignon J.P. Delaroche 《Nuclear Physics A》1983,411(2):231-247
The 76Ge(p, p′) inelastic scattering has been studied at 22 MeV with an overall resolution of 10 keV using a tandem Van de Graaff and a split-pole magnetic spectrometer. Angular distributions have been obtained for about 40 levels in 76Ge. Vibrational and asymmetric rotor model CC calculations and DWBA calculations have been made. Spin and parity assignments have been deduced. 相似文献
14.
R. F. Casten 《Nuclear Physics A》1973,210(3)
The 182W(t, p)184W reaction has been studied at 20 MeV. The outgoing protons were detected in an Elbek broad range magnetic spectrograph. Absolute cross sections and angular distributions were measured. Evidence for inelastic effects in the reaction mechanism was observed for the first excited 2+ state, the 3− level at 1221 keV and the 5+ state at 1295 keV. The 0+ level at 1002 keV was populated with ≈ 2% the ground state cross section. A 4+ level at 1536 keV was observed with ≈ 50% the ground state cross section. Calculations of the absolute (t, p) cross sections to this and other states with known structure resulted in excellent agreement with the measured values. 相似文献
15.
The 16O + 9Be reactions have been studied from Ec.m. = 2.0 MeV to 5.1 MeV, an energy near the top of the Coulomb barrier. The cross section for the neutron transfer reaction 9Be(16O,17O1 (0.87 MeV))8Be has been measured over this range by detecting the prompt 0.87 MeV γ-rays. The total fusion cross section has been determined from Ec.m. = 2.8 to 5.1 MeV by observing individual γ-ray transitions in the evaporation residues with a Ge(Li) detector, and then summing the separate yields. Direct processes are found to dominate the reaction yield below Ec.m. = 4 MeV. A comparison of the energy dependence of the fusion cross section for this reaction and the 12C + 13C reaction, which proceeds via the formation of the same compound nucleus, 25Mg, reveals differences at sub-barrier energies. Optical model and incoming-wave boundary condition calculations are presented. Data have also been obtained for the near optimum Q-value neutron-transfer reactions 9Be(12C, 13C1)8Be and 9Be(19F, 20F)8Be, and these are discussed in terms of a simple model of sub-barrier direct reactions. 相似文献
16.
D. L. Adams B. Aas E. Bleszynski M. Bleszynski G. Igo C. Newsom Y. Ohashi G. Pauletta F. Sperisen C. A. Whitten Jr. H. Fujisawa M. GazzalyS. J. Greene K. Jones J. B. McClelland N. TanakaH. Hasai K. IwataniS. Ishimoto S. IsagawaA. MasaikeA. OkihanaS. Okumi 《Nuclear Physics A》1988,480(3-4)
We have measured spin correlation parameters that describe the elastic scattering of 800 MeV polarized protons from an L-type polarized deuteron target at laboratory angles below 20°. The measured parameters include the correlated analyzing powers ASL, ALL and ANLL and the proton spin-transfer coefficients C0L,S, C0L,L, CSL,N, CNL,S, CNL,L and CLL,N. The results are compared with single-scattering predictions based on different phase-shift solutions for the nucleon-nucleon scattering matrix. 相似文献
17.
D.L. Shannon W. Breunlich Ivo S̆laus J.W. Sunier G. Anzelon E. Tin W.T.H. Van Oers M.B. Epstein W. Ebenhöh 《Nuclear Physics A》1974,218(2):381-395
The differential cross section for the 2H(p, 2p)n reaction at Einc = 44.9 MeV is measured in noncoplanar geometry. The Amado model in general gives a good fit to the absolute cross section. The dependence of the cross section on the momentum of the undetected particle Q5, on the scattering angle θ34, as well as on the angle of the undetected particle is investigated. 相似文献
18.
A magnetic spectrometer was used for the momentum analysis of pions produced by 185 MeV protons on a 9Be target. The obtained energy resolution (0.55 MeV FWHM) made it possible to resolve a number of discrete final states in 10Be and 10C. Energy spectra were measured in the angular region 15°–130° (lab). Angular distributions for six peaks in 10Be and four peaks in 10C are presented in tables and graphs. A peak corresponding to a not previously reported level in 10Be was observed at 11.75 ±0.11 MeV excitation energy. The measured ratio for the ground state analogues was found to be angular dependent and varied from 30 at 35° (lab) to 2 at 125° (lab). The results are compared with theoretical predictions and discussed in terms of one- and two-nucleon models. 相似文献
19.
The polarization in the scattering of neutrons from protons has been measured at a lab neutron energy of 16.2 MeV for the three c.m. angles 70°, 100° and 130°, at which the measured polarizations were (+2.95 ± 0.86) %, (+1.84 ± 0.91)% and (+1.62 ± 0.99) % respectively. 相似文献
20.
S. F. Collins G. G. Shute B. M. Spicer V. C. Officer I. Morrison K. A. Amos 《Nuclear Physics A》1982,380(3):445-464
A relativistic mean field approach is used to determine and compare the single-particle Dirac potentials for nuclei and hypernuclei (Λ, Σ, Ξ). A simple model is used and the Dirac-Hartree-Fock equations are reduced to a Schrödinger-like equation. The subsequent central and spin-orbit shell-model potentials are compared to those of phenomenological approach and other recent microscopic approaches. In the case of hypernuclei the Hartree approximation works already quite well without any need of taking into account the strangeness exchange part coming from strange mesons. The influence of the anomalous magnetic moment of the baryon on the spin-orbit term is found to be rather important for both Λ- and Σ-hyperons. 相似文献