Coherent scattering of $\pi$ mesons from helium at high energies : 4 papers

[Article I: A measurement of the differential cross section for elastic pion-helium scattering at 7.76 GeV/c] Results are presented for the region of squared four-momentum transfers between −0.05 and −0.5 (GeV/c)2. The directions of the scattered pions and alpha particles were measured with spark chambers and the momentum of the alphas as obtained from pulse-height and time-of-flight measurements. The results are compared with calculations from the Glauber theory, showing good agreement over the whole momentum-transfer range including the interference-dip region. [Article II:A helium-recoil spectrometer] The instrument described is intended for the detection and measurement of particles from coherent interactions of high-energy particles with 4He nuclei. It allows the determination of the magnitude and the direction of the momenta of the helium recoils from interactions in a pressurized gas target. The measurements are carried out with spark chambers and scintillation counters. Recoils emitted at angles greater than 65° with respect to the beam direction are accepted and the range of azimuth angles covered is 294°.