J. B. McClelland

Proton polarization observables for the elastic and inelastic scattering of 500 MeV protons from 40Ca and 208Pb

Abstract Measurements for the elastic and inelastic scattering of 500 MeV protons from 40 Ca and 208 Pb 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 40 Ca and the 3 − (2.61 MeV) state in 208 Pb. 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.

Cross sections and analyzing powers in the (p,d) reaction around 500 MeV

Abstract Cross sections and analyzing powers for the (p,d) reaction on 12 C, 13 C and 28 Si are measured around 500 MeV. DWBA calculations are found to reproduce the main features of the (p,d) data, when proton potentials are used which give strong oscillations in the (p,p) analyzing powers as required by the elastic data. Damping of the nuclear interior contribution is unimportant at this energy.

Spin-longitudinal and spin-transverse cross sections for Δ production in the 12C(p, n) reaction

Abstract We present ( p , n ) spin observable measurements in the delta region of excitation taken on the targets 2H and 12C at 0° and 795 MeV proton energy. These observables have been used to form the spin-longitudinal and spin-transverse cross sections. Good agreement is found between experiment and theory in the spin-longitudinal channel.

Cross section and analyzing power for quasifree (p, n) reactions

Abstract Cross sections and analyzing powers have been measured for 12C(p, n) at 494 MeV and 795 MeV and for Pb(p, n) at 795 MeV. The data span an energy loss range of at least 200 MeV, vhich is sufficient to clearly reveal the large peak associated with quasifree neutron knockout. The kinematics, cross section and analyzing power for this peak are compared to the corresponding observables for free nucleon-nucleon scattering and to the observables calculated with a relativistic Fermi-gas model.

Spin observables in small-angle elastic pd → pd scattering with an L-type deuteron target at 800 MeV

Abstract 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 A SL , A LL and A NLL and the proton spin-transfer coefficients C 0L,S , C 0L,L , C SL,N , C NL,S , C NL,L and C LL,N . The results are compared with single-scattering predictions based on different phase-shift solutions for the nucleon-nucleon scattering matrix.

Inclusive quasielastic spin observables for p+2H, 12C at 500 Me V☆

Abstract Analyzing powers (Ay) and spin-rotation-depolarization parameters (DSS, DSL, DLS, DLL, DNN) were determined for 500 MeV p + 2 H and p + 12 C inclusive quasielastic scattering at 10°, 15°, and 20° laboratory scattering angles. The p + 2 H data are consistent with the isospin-average of the proton-proton and proton-neutron scattering observables; the p + 12 C data are not. A relativistic plane wave impulse approximation calculation leads to better agreement with the p + 12 C spin-observables.

A study of the Fermi (0+) transition in 14C(p↘,n)14N at 495 MeV

Differential cross sections and analyzing powers have been measured for the 14C(p↘,n)14N*(IAS) reaction at a proton energy of 495 MeV. The data were obtained at the LAMPF Neutron Time‐of‐Flight Facility (NTOF) using a flight path of 400 meters over an angular distribution of θlab=0° to 10° (q=0.0 to 0.956fm−1). Previous Ay results for targets with mixed Fermi (ΔJπ=0+) and Gamow‐Teller (ΔJπ=1+) transitions are not reproduced with either DWIA or RIA calculations. The 14C target offers the best opportunity to study a pure Fermi transition (2.31 MeV) resolved from the nearest Gamow‐Teller (GT) strength (3.95 MeV). The results compare favorably with DWIA and RIA calculations. Thus the discrepancies for mixed Fermi and GT states most likely arise from either failure to understand nuclear structure effects or the nuclear distortion factors.

Summary of low‐energy aspects of QCD and medium‐energy hadron parallel sessions

Two sessions were organized dealing with low energy aspects of QCD. The first dealt with the issue of QCD dibaryons. The second session centered on mostly low-energy tests of QCD. This report discusses experiments dealing with these sessions.

Spin transfer measurements in the quasifree (p↘,n↘) reactions at 500 MeV

Complete sets of polarization transfer observables in the quasifree (p↘,n↘) reactions have been measured for the first time. Experiments were performed using the newly calibrated neutron polarimeter and newly developed Neutron Time‐of‐Flight Facility (NTOF) at LAMPF. Measurements were made at 18° and over a broad excitation energy range. The resulting energy‐loss spectra of the spin‐longitudinal and spin‐transverse response functions are presented and discussed for Ca, C, and 2H at 500 MeV, and for a momentum transfer of 350 MeV/c.

Evidence for pionic enhancement in quasifree Δ production in the 12C(p↘,n↘) reaction

We present (p↘,n↘) spin observable measurements in the quasielastic and quasifree delta region of excitation taken on the targets 2H and 12C at 0° and 795 MeV proton energy. These observables have been used to form the spin–longitudinal (σ⋅q) and spin–transverse (σ×q) cross sections. Good agreement is found between experiment and theory in the spin–longitudinal channel.