Elastic Scattering ofαParticles and the Phase of the Nucleon-Nucleon Scattering Amplitude

Glauber theory can describe elastic scattering of $\alpha$ particles by ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, and 1H at 7 GeV/c if the phase of the nucleon-nucleon elastic-scattering amplitude varies with momentum transfer. The phase variation leads to diffraction patterns differing markedly from those typical of constant-phase calculations and greatly affects the magnitudes of the intensities. These changes are mainly due to changes in the interference between amplitudes for different orders of multiple scattering and to a decrease in their moduli.