No abstract

The total scattering cross section for e+ in He has been measured through two energy intervals, 1 to 4 eV and 17 to 26 eV. Through the lower elastic-scattering interval our results are consistent with the calculations of Drachman. From below the positronium formation threshold, at 17.8 eV to above the He ionization threshold, our results agree qualitatively with the calculations of Kraidy, who includes in his model virtual positronium and positronium polarization. Just below 17.8 eV the cross section is 0.35 ± 0.04 πa02. In these experiments a high-current linac has been used as a source of positrons and total beam attenuation has been used to determine the cross section.

The momentum spectrum of the alpha particles from the Be 9 (p,a)Li* reaction has been measured in a magnetic spectrometer at 30° with 10-MeV incident proton energy. The discrete alpha-particle groups observed correspond to states in Li 6 at 0-, 2.19-, 3.55-, 4.40-, and 5.32-MeV excitation energy. Higher excited states are obscured at all angles of observation by the continuous alpha spectrum from the breakup in flight of Be 8 , Li 6 *, Be 9 *, and B 9 .

No abstract

No abstract