The contribution of 2N photon absorption in C(γ,2N) reactions for Eγ = 150–400 MeV

The ¹²C(γ,pn) and ¹²C(γ,pp) reactions have been studied using tagged photons of energy E_γ = 150–400 MeV. Recoil momentum distributions are compared to the results of Monte Carlo calculations based on a two-nucleon photon absorption model and two different phase space models. The ¹²C(γ,pn) data at low missing energy are consistent with absorption on 1p² and 1s1p nucleon pairs.     

Proton polarization observables for the elastic and inelastic scattering of 500 MeV protons from Ca and Pb

Measurements for the elastic and inelastic scattering of 500 MeV protons from ⁴⁰Ca and ²⁰⁸Pb at small momentum transfers are reported. The induced proton polarization P and the spin rotation parameter Q were measured for the elastic scattering. The spin rotation parameters D_SS′, D_SL′, D_LL′, d_LS′ and the induced polarization P were measured for transitions to the 3⁻(3.37 MeV) and 5⁻(4.48 MeV) states in ⁴⁰Ca and the 3⁻(2.61 MeV) state in ²⁰⁸Pb. Comparisons of the data with the theoretical calculations were carried out in the framework of nonrelativistic and relativistic approaches. We extracted the spin-up and spin-down channels for the elastic scattering cross sections and found that predictions of the relativistic and nonrelativistic approaches agree well with the spin-up channel data and differ considerably in the spin-down channel.     

THE SYMMETRIC STRUCTURE OF EXCITED STATES OF 13ΛC AND INVESTIGATIONS OF THE ANGULAR DISTRIBUTIONS OF 13C(K-,π-)13ΛC*

Based on the meth SU₃ × SU₂ supermultiplet classification,we studied the symmetric compon-ents of 10.4 and 16.4 MeV configuration of the ¹³_ΛC hypernucleus by calculating the hypernucleus by calculating the angular distribution of ¹³C(K^-,π^-)¹³_ΛC^* in the framework of DWIA, and analysed the effects of varying the parameters on the angular distributions.     

High energy proton scattering by medium and heavy nuclei

The recent data on both elastic and inelastic scattering of 1 GeV protons by ⁴⁰Ca and ²⁰⁸Pb are analyzed by means of the first term of the multiple scattering series for the optical potential and the DWIA. Theory and experiment agree quite well. Coulomb effects are taken into account. Neutron and proton ground state densities given by Hartree-Fock calculations employing a density-dependent Hamiltonian and which provide a good fit to elastic electron scattering are used. The Tassie form factors, normalized by comparison with inelastic electron scattering, are employed in the DWIA.     

Analysis of the scattering of 46 MeV protons from Be and C

An analysis is made of the measurements of the elastic and inelastic scattering of 46 MeV protons by ³Be and ¹²C. The optical and collective models are used. There is considerable ambiguity in the optical parameters, and it was not found possible to obtain good fits to cross sections and polarizations simultaneously. Large quadrupole deformations were found for both ¹²C (β₂ ≈ 0.6) and ⁹Be(β₂ ≈ 1). The inelastic scattering from ¹²C agrees best with deformation of both real and imaginary parts of the optical potential, while ⁹Be shows a preference for real coupling. The 14.1 MeV level in ¹²C is interpreted as the 4⁺ rotational state, while the angular distribution for the 7.6 MeV 0⁺ level is well described by double quadrupole excitation via the lowest 2⁺. Interpretations are suggested for other inelastic transitions, including the excitation of spin and isospin oscillations.     

Spin alignment in resonant C+O inelastic scattering

The spin alignment of the 3⁻ state (6.13 MeV) of ¹⁶O from inelastic scattering of ¹²C+¹⁶O has been measured in the energy region of known resonances around E_cm=20 MeV. The result, that the population of the m=±3 magnetic substates is enhanced on four resonances at 19.7, 20.5, 22.0 and 22.6 MeV, indicates the dominance of the aligned configuration on these resonances.     

CDCC Approaches and Roles of Closed Channels in d-Nucleus Reactions

The effect of deuteron breakup in d-nucleus reaction is treated with the continuum discretized coupled channels (CDCC) approach, and the effects on the total reaction cross sections and elastic scattering angular distributions are studied by comparing the calculations of CDCC and spherical optical model with our global deuteron optical potential [Phys. Rev. C 73 (2006) 054605] below 200 MeV, for target nuclei ranging from ¹²C to ²⁰⁸Pb. The contributions from the closed channels to the total reaction and breakup cross sections, and angular distributions of elastic scattering are also seriously discussed.     

Elastic scattering of B on B in the energy range from 4 to 15 MeV

Angular distributions (at E_c.m. = 4, 6.5 and 10.5 MeV) and excitation functions (at 30°, 60° and 90°) are given for the elastic scattering of ¹⁰B on ¹⁰B. The results of an optical model (OM) analysis are presented and discussed. In the energy range covered the Sommerfeld parameter η varies from 4.4 to 2.3.     

Elastic scattering of polarized deuterons from Al, Si and Ni between 7 and 11 MeV

Polarization parameters have been determined for deuteron elastic scattering from ²⁷Al, Si and ⁶⁰Ni at energies between 7 and 11 MeV and laboratory scattering angles from 30° to 135°. The vector polarization, iT₁₁, and two tensor parameters T₂₀ and T₂₂, were measured by scattering polarized and unpolarized deuterons which were obtained from a tandem accelerator. The largest polarization was |iT₁₁| ≈ 0.3 and |T₂₀| ≈ 0.2 for ²⁷Al at 11 MeV. For ⁶⁰Ni, the observed polarizations were substantially smaller. Angular distributions of the unpolarized cross section were also measured for ²⁷Al and Si. An optical-model analysis of the polarization and cross-section data was performed. The vector polarization was reproduced reasonably well by a vector spin-orbit coupling of similar strength as found for nucleon scattering. A tensor interaction appears to be needed to account for the observed tensor polarizations.     

Polarization of protons from the Be(d, p)Be reaction

The polarization of protons from the ⁹Be(d, p)¹⁰Be reaction has been measured for deuteron energies between 1 and 6 MeV. Angular distributions of the polarization for the ground state proton group (Q=4.59 MeV) have been measured for laboratory angles 10° and 135° at 2.5, 4.0 and 5.5 MeV. The polarization at a laboratory angle of 30° was measured in 0.2 MeV steps between 1 and 6 MeV. In addition the polarization of protons leaving ¹⁰Be in its first excited state (Q=1.22 MeV) was measured between 10° and 90° for a deuteron bombarding energy of 5.5 MeV. Measurements were made by conventional double-scattering techniques using elastic scattering from helium at 45° as the analyser. The results show a strong energy dependence contrary to what one might expect on the basis of the lack of structure in the cross section. The maximum polarization observed at each energy is about 0.35.     

Nuclear structure studies in the Te isotopes: The Te(d, p)Te reaction

The reaction ¹²⁵Te(d, p)¹²⁶Te has been studied at a bombarding energy of 7.5 MeV in order to get information about the ¹²⁶Te nuclear level scheme. Forty-two levels were observed below an excitation energy of 5.1 MeV. The angular distributions of 25 of the emitted proton groups were compared with DWBA calculations to determine the angular momentum of the captured neutrons. Contributions from more than one l_n value were observed for two of the transitions. Transition strengths were extracted and compared to pairing-theory calculations.     

Isobar doorway approach to pion scattering on open shell nuclei

Delta-hole approach developed for the pion scattering on closed shell nuclei is extended to be applied to the case of open shell nuclei. The doorway space is spanned by the states of the form |Ψ^(A−1)ψ^(Δ) which correspond to |Δ h states in the usual delta-hole approach for closed shell nuclei. In this approach, the effects of the couplings between elastic and inelastic channels are incorporated in a natural way. As a first application of this approach, some numerical calculations have been done for the elastic and inelastic pion scattering on ¹²C and the elastic scattering on ¹⁴N and ¹⁴C. The effects of the nuclear structure and the coupling between elastic and inelastic channels are discussed.     

Elastic scattering of positive pions by O between 80 and 340 MeV

Angular distributions of cross sections for π⁺ elastic scattering by ¹⁶O have been measured between 14° and 138° at five energies (79, 114, 163, 240 and 343 MeV). They are compared to calculations using a first-order static model and an isobar doorway model. Phase-shift analyses have been done using the theoretical inputs as guidelines. The validity of these models is discussed.     

A complete measurement of spin-observables for intermediate-energy inclusive quasielastic polarized proton scattering from C

The complete set of Wolfenstein parameters, the polarization, the asymmetry of scattering and the unpolarized double-differential cross section are presented for inclusive quasielastic proton scattering from ¹²C at a central momentum transfer of q = 1.9 fm⁻¹ and incident energies of 290 and 420 MeV. The spin observables D₀, D_x, D_y and D_z as well as the longitudinal-to-transverse ratio of spin-flip probabilities are extracted from the data. Across the quasielastic continuum, the experimental data is compared to the variations expected from a single-scattering Fermi-gas approximation using the free NN amplitudes. Medium effects are evident in the pronounced quenching of the polarization parameter relative to the free value.     

Polarization of neutrons from the O(d, n)F reaction

The polarizations of neutrons from the ¹⁶O(d, n₀)¹⁷F and ¹⁶O(d, n₁ ¹⁷F reactions have been measured at 30° (lab) in steps of approximately 0.15 MeV from E_d = 3.96 to 5.35 MeV. Polarization angular distributions have been obtained at 3.96 and 5.35 MeV. It is determined that the random phase approximation for the scattering amplitudes is not appropriate for the compound nucleus contributions. The analysis indicates probable interference between the compound nucleus and direct interaction reaction mechanisms.     

Spectroscopy of C

The ¹⁴C(t, p)¹⁶C reaction locates five new states in ¹⁶C, at excitation energies of 3120 ± 15, 3983 ± 10, 4136 ± 10 and 6109 ± 15 keV, in addition to the g.s. and 1.76 MeV states. The 3.02 and 3.98 MeV states appear to be the second 0⁺ and 2⁺ 2p-2h states, respectively. The 4.14 MeV state has J^π = 4⁺ and the 6.11 MeV state has J^π = 2⁺, 3⁻, or 4⁺.     

The elastic scattering of protons by deuterium

Proton-deuteron elastic scattering was investigated with a gas target. Excitation curves were taken at 45.28°, 90.26°, and 118.92° c.m. for lab proton energies from 4.5 to 11.5 MeV. Angular distribution were taken at 4.45, 5.45, 6.50, 7.46, 8.47, 9.47, 10.47 and 11.47 MeV from 30° to 140° c.m. Differential cross sections were measured with an absolute error of less than ±3%. The scattering data were compared with predictions derived from the scattering amplitudes of Aaron, Amado and Yam ¹⁰). No evidence for the existence of ³He excited states was found in this energy range.     

The elastic and inelastic scattering of intermediate energy protons on deuterium at small momentum transfer

The differential cross sections for the elastic and inelastic scattering of protons on deuterium have been measured for scattering angles less than 14° at 198.5, 297.6 and 456.6 MeV. These quantities were determined relative to dσ / dΩ for pp elastic scattering with a precision of typically 2%. The range of excitation energies for the (p, p') reaction was chosen to emphasize the region near the np threshold dominated by the final-state interaction in the ¹S₀ channel. Particular attention was given to the dependence on excitation energy of the spectra at 198.5 MeV to examine the sensitivity to the ¹S₀ scattering length, a_np In this paper all data are compared with a new, detailed formulation of a simple model of the reaction mechanism based on the impulse approximation. The experimental results differ from the predictions by typically 10% and the differential cross sections exhibit a sensitivity to the intermediate-energy nucleon-nucleon amplitudes. If the impulse approximation is used to estimate a_np from the data at 198.5 MeV a value of − 24.7 ± 0.4 fm is obtained.     

Investigation of the S(d, p)S reaction at Ed = 10 MeV

Angular distributions of proton groups, corresponding to fifteen levels observed in the reaction ³⁴S(d, p)³⁵S at E_d = 10 MeV have been measured with a split-pole spectrograph equipped with position-sensitive detectors. For the levels at E_x = 0, 1.58, 1.99, 2.34, 2.73, 3.68, 3.80 and 4.20 MeV, l_n = 2, 0, 3, 1, (2, 3), (1), 1 and 1, respectively, has been found from a DWBA analysis. Experimental spectroscopic factors and those following from many-particle shell-model calculations for the lowest four states are in satisfactory agreement. The ground state Q-value has been measured as Q = 4757 ± 5 keV.     

Intermediate Energy Pion-20Ne Elastic Scattering in the α+16O Model of 20Ne

We present an analysis of π-²⁰Ne elastic scattering at intermediate energy basing on the α+¹⁶O model of the ²⁰Ne nucleus and in the framework of Glauber multiple scattering theory. Satisfactory agreement with the general features of the experimental data of pion elastic scattering on the neighboring 4N-type nuclei is obtained without any free parameters. Compared with the experimental angular distributions of pion elastic scattering on ¹²C, ¹⁶O, ²⁴Mg, and ²⁸Si nuclei, the diffractive patterns and the positions of the dips and peaks in the angular distributions of π-²⁰Ne elastic scattering are reasonably predicted by the calculations.