Spin excitations in the40Ca(p→,p′)reaction revisited

Physics Letters B, 2013

The transverse spin correlations Ax,x and Ay,y in the n p → dπ 0 reaction have been measured for the first time in quasi-free kinematics at the COSY-ANKE facility using a polarised deuteron beam incident on a polarised hydrogen cell target. The results obtained for neutron energies close to 353 MeV and 600 MeV are in good agreement with the partial wave analysis of data on the isospin-related pp → dπ + reaction, though the present results cover also the small-angle region, which was largely absent from these data.

Physical Review C, 1997

We measured the spin observables A y , P, and S NN Ј for the 208 Pb(p,n) 208 Bi reaction at 135 MeV at laboratory angles of 0°, 3°, 6°, and 9°. The overall energy resolution was about 1 MeV. Data for S NN Ј are compared with distorted-wave impulse-approximation calculations that use random-phase approximation wave functions. Comparisons are also made for the 48 Ca(p,n) 48 Sc reaction. The agreement between these calculations and the data is generally good, after adjustment of the nucleon-nucleon interaction in the random-phase approximation calculations to place the 0 ϩ isobaric-analog states at the correct excitation energies. A single adjustment of the nucleon-nucleon force works for both target nuclei. ͓S0556-2813͑97͒03107-5͔

Nuclear Physics A

The reactions a8Si(p, d)97Si and 4®Ca(p, d)39Ca have been studied using a 30.5 MeV polarized proton beam. For the ground state transitions, polarization analysing powers and differential cross sections have been measured over a wide angular range. These data are compared with DWBA calculations for which optical-model parameters were obtained from analyses of deuteron elastic scattering data for 9'Al and "Ca. Agreement between the theoretical and experimental (p, d) differential cross sections and analysing powers for 2BSi(p, d)a'Si is good. For the 4°Ca(p, d)39Ca reaction, reasonable agreement is obtained only by using a deuteron optical potential derived from a coupled-channels analysis of the (d, d) and (d, p) reactions on 4°C a. NUCLEAR REACTIONS s8Si, "Ca (polarized p, d), E = 30.5 MeV; measured ß(8), polarization analysing power. Natural targets .

Physical Review C, 2012

The angular dependence of proton-proton correlation functions is studied in central 40 Ca+ 40 Ca and 48 Ca+ 48 Ca nuclear reactions at E = 80 MeV/A. Measurements were performed with the HiRA detector complemented by the 4π Array at NSCL. A striking angular dependence in the laboratory frame is found within p-p correlation functions for both systems that greatly exceeds the measured and expected isospin dependent difference between the neutron-rich and neutron-deficient systems. Sources measured at backward angles reflect the participant zone of the reaction, while much larger sources observed at forward angles reflect the expanding, fragmenting and evaporating projectile remnants. The decrease of the size of the source with increasing momentum is observed at backward angles while a weaker trend in the opposite direction is observed at forward angles. The results are compared to the theoretical calculations using the BUU transport model.

Physics of Atomic Nuclei

The polarization of the secondary protons in the inelastic (p, p') reaction on the 40 Ca and 12 C nuclei at the initial proton energy 1 GeV was measured in a wide range of the scattered proton momenta at a laboratory angle Θ=21 •. The cross sections of the reaction were measured as well. The outgoing protons from the reaction were detected using a magnetic spectrometer equipped with a multiwire-proportional chambers polarimeter. A structure in the polarization and cross section data, related probably to scattering off the nucleon correlations in the nuclei, was observed.

Physical Review Letters, 1996

The first ͑ p, n͒ polarization-transfer measurements for delta production on a nuclear target are presented for the 12 C͑ p, n͒ reaction at 0 ± and 795 MeV. Polarization observables are used to extract the spin-longitudinal, spin-transverse, and spin-independent partial cross sections. In the spin-longitudinal channel, fair agreement is found between experiment and a model which includes a strongly attractive residual interaction. A large unexpected enhancement in the spin-transverse cross section is observed. [S0031-9007(96)

Progress of Theoretical and Experimental Physics

We have measured the differential cross-sections and analyzing powers for ($p,2p$) reactions at an incident energy of 392 MeV on $^{12}$C, $^{16}$O, $^{40}$Ca, and $^{208}$Pb nuclei, leading to discrete states of the residual nuclei. The data are compared with two kinds of distorted-wave impulse approximation (DWIA) calculations, a standard calculation using a global optical potential and a calculation using wave functions generated in a relativistic Hartree model. The spectroscopic factors deduced from these two calculations agree with those determined in ($e,e'p$) studies mostly within 15% in the case of the lighter three target nuclei. However, those for the $^{208}$Pb target are overestimated compared with the ($e,e'p$) results. In the heavy target case, the DWIA results are very sensitive to the radius parameter of the bound-state potential and thus a careful treatment is required. Regarding the analyzing powers of the present measurement, we confirmed that the $j$-depe...

Physical Review C, 1983

Coupled channel calculations were carried out for the inelastic scattering of ' C on Mg using form factors generated in a single folding model. We studied the population probability P~for Mg in the 1.37 MeV 2+ level with~m~=1 and ' C in its ground state. Using spin-independent potentials the excitation of various states in "C gave rise to a maximum P~(6') of 0.2%. This increased to 0.3% when spin-dependence was allowed for in an approximate manner. At 10' the calculations fell significantly short of the experimental data. Large polarizations were found when excited states of ' C were populated; these effects are discussed. NUCLEAR REACTIONS "C+ Mg inelastic scattering, E =35 MeV; coupled channel study of~m~=1 population probability for the Mg 1.37 MeV 2+ level and polarization phenomena.

Nuclear Physics A - NUCL PHYS A, 1994

Hadronic spin-excitations in nuclei are investigated by studying inelastic proton-nucleus scattering. The Random-Phase-Approximation (RPA) and the Distorted-Wave-Impulse-Approximation (DWIA) are used to describe the nuclear structure and reaction, respectively. To study spin-excitations in (p,p')-reactions, the double differential cross section and the spin-flip probability Snn' are investigated for forward angles. The longitudinal and transverse spin-flip probabilities SL and ST give information about the pi and rho-exchange in the nuclear medium. These spin observables depend sensitively on the distortions of the projectile wave.

Physical Review C, 1997

Spin-polarization response functions are examined for high-energy (− → e , e − → p) reaction by computing the full 18 response functions for the proton kinetic energy T p = 0.515 GeV and 3.179 GeV with an 16 O target. The Dirac eikonal formalism is applied to account for the final-state interactions. The formalism is found to yield the response functions in good agreement with those calculated by the partial-wave expansion method at 0.515 GeV. We identify the response functions that depend on the spin-orbital potential in the final-state interactions, but not on the central potential. Dependence on the Dirac-or Pauli-type current of the nucleon is investigated in the helicitydependent response functions, and the normal-component polarization of the knocked-out proton, P n , is computed.