A Optical Model Calculation of Proton and K Meson Scattering from HELIUM-3.

A study is made of proton and K meson scattering from the ('3)He using a microscopic optical potential derived from multiple scattering theory. The theory includes target and projectile spin, internal nucleon recoil and binding, a Lorentz invariant angle transformation (relation of off -energy-shell momenta in different reference frames), and realistic (electron scattering) form factors describing the distribution of neutron and proton matter and spin within the nucleus. The two-body (KN or pN) amplitudes are calculated from empirical KN or pN phase shifts and extrapolated off the energy shell with separable potentials. Scattering from the resulting nonlocal, energy dependent optical potential is calculated in momentum space by using and extending the computer code LPOTT. The kaon calculations are the first ever performed for the helium isotopes/isotones, ('3)He,('4)He,('3)H and examine the effects of nuclear structure for elastic scattering and the charge exchange reaction, ('3)H(K('+),K('0))('3) He, in the energy rage 40-1000 MeV. Although at present there are no He data with which to compare the calculations, the charge exchange reaction does exhibit a high sensitivity to the nuclear form factors for appropriate kinematical conditions. Comparison of theoretical predictions and data for K('+)-('12)C elastic scattering at 446 MeV indicates a mysterious factor of 2 discrepancy at small angles. Since the publication of this finding another group has confirmed our results. The proton-('3)He work develops the theory for the spin 1/2 (CRTIMES) 1/2 optical potential and then develops and tests new numerical techniques needed to solve the resulting coupled integral equations. It appears to be the first microscopic calculation of p('3)He elastic scattering with the full 1/2 (CRTIMES) 1/2 spin structure, and is equivalent to an optical potential with a central, spin orbit and three tensor terms. Although a full phenomenological study of data is not attempted, the trial runs do indicate a high sensitivity to the p and n spin distributions within ('3)He.