Total pion cross section measurements. Annual progress report, January 1, 1976--December 31, 1976

Pion-nucleus cross section measurements were made using essentially a ''good geometry'' transmission method. The final data gathering run ended at LAMPF in June. Data were obtained for both π+ and π- mesons. The energy range covered for 4He was 25 → 90 MeV, for 12C was 25 → 240 MeV, for 6Li, 7Li, 9Be, 10B, 11B, 13C, 16O, 18O, 27Al, 40Ca, 44Ca, 48Ca, 45Sc, 51V, Cu, Sn, 165Ho, and Pb was approximately 45 → 240 MeV. In general, data were taken in 15 MeV steps below 90 MeV and 25 MeV steps above 90 MeV. Statistical accuracies of approximately 1 percent were obtained for targets of approximately 1 gram/cm2 thickness. Time-of-flight counters identified the incident pions for energies below 70 MeV and a DISC counter identified the pions for higher energies. Data analysis for the determination of neutron radii differences for the carbon and calcium isotopes has been completed first. For 13C-12C, Δr/sub n/ = 0.08 +- 0.03 fm, for 44Ca-40Ca, Δr/sub n/ = 0.01 +- 0.05 fm and for 48Ca-40C, Δr/sub n/ = 0.11 +- 0.04 fm. The 48Ca-40Ca neutron radii difference agrees with recent alpha particle and proton scattering experiments