L. Hugon

Scattering of negative pions on carbon

Abstract Data are presented on elastic and inelastic differential cross sections as well as on total cross sections for negative pions on carbon in the energy range 120 MeV to 280 MeV.

Scattering of Negative Pions on Helium

Abstract Differential cross sections for negative pion scattering on 4 He have been measured at five pion kinetic energies between 110 and 260 MeV in the angular range from 5° to 180°. Total cross sections have also been measured at eleven energies between 67 and 285 MeV. The differential cross sections have been fitted with a phenomenological expression for the nuclear scattering amplitude. Conventional phase shifts have been reconstructed starting from the parameters of the fits.

Coulomb-nuclear interference in π−-12C elastic scattering

Abstract The π − - 12 C elatic differential cross sections have beenmeasured at three kinetic energies around the ( 3 2 , 3 2 ) pion-nucleon resonance, namely 120, 180 and 260 MeV, in the small-angle region [ t ≤ 18 000 (MeV/ c ) 2 ] where the interference between Coulomb and nuclear amplitudes is most pronounced. An expression for the relative phase between Coulomb and nuclear amplitudes has been derived which takes into account a variation linear in t of the nuclear phase. Using this formula, the real part of the forward nuclear amplitude has been deduced from the data at each energy. The results are in good agreement with the predictions of pion-nucleus forward dispersion relations. The nuclear phase seems to vary significantly at 260 MeV.Abstract The π−-12C elatic differential cross sections have beenmeasured at three kinetic energies around the ( 3 2 , 3 2 ) pion-nucleon resonance, namely 120, 180 and 260 MeV, in the small-angle region [t ≤ 18 000 (MeV/c)2] where the interference between Coulomb and nuclear amplitudes is most pronounced. An expression for the relative phase between Coulomb and nuclear amplitudes has been derived which takes into account a variation linear in t of the nuclear phase. Using this formula, the real part of the forward nuclear amplitude has been deduced from the data at each energy. The results are in good agreement with the predictions of pion-nucleus forward dispersion relations. The nuclear phase seems to vary significantly at 260 MeV.

Low pressure multiwire proportional chambers with high time resolution for strongly ionizing particles

Abstract Multiwire proportional chambers have been tested in the range of pressures from 3 to 30 mm Hg of isobutane, pentane and heptane. With 5.5 MeV α particles, a time resolution of 2.5 nsec was obtained at 100% efficiency.