B.K. Park

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.

Asymmetries for elastic scattering ofπ±from polarized3He atΔresonance energies

Asymmetries A{sub y} for {pi}{sup +} and {pi}{sup {minus}} elastic scattering from polarized {sup 3}He were measured at incident energies passing through the {pi} nucleon P{sub 33}, or {Delta}(1232), resonance. The data were taken at the Clinton P. Anderson Meson Physics Facility using the high-energy pion channel P{sup 3} and a large acceptance spectrometer to detect the scattered pions. The polarized {sup 3}He target, originally developed at TRIUMF, was modified for these experiments by the addition of diode lasers. Completely unexpected negative asymmetries were observed at and below the resonance in {pi}{sup +} scattering near 50{degree}{endash}60{degree}, which cannot be reproduced by multiple scattering theory and Faddeev wave functions. A hybrid model, which adds a {Delta}-neutron spin-spin interaction term to the conventional calculations, provides a good description of the {pi}{sup +} data. For {pi}{sup {minus}} scattering this term predicts a negligible effect on A{sub y} and the data do not show the anomalous A{sub y} seen with {pi}{sup +}. {copyright} {ital 1997} {ital The American Physical Society}

Coherent pion production in 12C(p, nπ) at 800 MeV

Abstract Studies of the production of the Δ resonance in hadronic charge exchange reactions show a shift in the Δ peak position. Measurements looking also at the Δ decay products give some evidence for coherent pion production. We have recently completed a new measurement of the 12 C ( p , n ) reaction leading to the Δ resonance, including a higher resolution coincidence measurement of decay πs in the forward direction. We describe the experiment and some aspects of the preliminary analysis.

Asymmetries for elastic scattering of pi+- from polarized He-3 at Delta resonance energies

Asymmetries A{sub y} for {pi}{sup +} and {pi}{sup {minus}} elastic scattering from polarized {sup 3}He were measured at incident energies passing through the {pi} nucleon P{sub 33}, or {Delta}(1232), resonance. The data were taken at the Clinton P. Anderson Meson Physics Facility using the high-energy pion channel P{sup 3} and a large acceptance spectrometer to detect the scattered pions. The polarized {sup 3}He target, originally developed at TRIUMF, was modified for these experiments by the addition of diode lasers. Completely unexpected negative asymmetries were observed at and below the resonance in {pi}{sup +} scattering near 50{degree}{endash}60{degree}, which cannot be reproduced by multiple scattering theory and Faddeev wave functions. A hybrid model, which adds a {Delta}-neutron spin-spin interaction term to the conventional calculations, provides a good description of the {pi}{sup +} data. For {pi}{sup {minus}} scattering this term predicts a negligible effect on A{sub y} and the data do not show the anomalous A{sub y} seen with {pi}{sup +}. {copyright} {ital 1997} {ital The American Physical Society}

Asymmetries for elastic scattering of {pi}{sup {plus_minus}} from polarized {sup 3}He at {Delta} resonance energies

Asymmetries A{sub y} for {pi}{sup +} and {pi}{sup {minus}} elastic scattering from polarized {sup 3}He were measured at incident energies passing through the {pi} nucleon P{sub 33}, or {Delta}(1232), resonance. The data were taken at the Clinton P. Anderson Meson Physics Facility using the high-energy pion channel P{sup 3} and a large acceptance spectrometer to detect the scattered pions. The polarized {sup 3}He target, originally developed at TRIUMF, was modified for these experiments by the addition of diode lasers. Completely unexpected negative asymmetries were observed at and below the resonance in {pi}{sup +} scattering near 50{degree}{endash}60{degree}, which cannot be reproduced by multiple scattering theory and Faddeev wave functions. A hybrid model, which adds a {Delta}-neutron spin-spin interaction term to the conventional calculations, provides a good description of the {pi}{sup +} data. For {pi}{sup {minus}} scattering this term predicts a negligible effect on A{sub y} and the data do not show the anomalous A{sub y} seen with {pi}{sup +}. {copyright} {ital 1997} {ital The American Physical Society}

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.