Helmut W. Baer

/sup 3/He(. pi. /sup -/,. pi. /sup 0/) reaction at T/sub. pi. / = 200 MeV

Energy and angle differential cross sections for the /sup 3/He(..pi../sup -/,..pi../sup 0/) reaction at T/sub ..pi../ = 200 MeV have been measured. Angular distributions for the isobaric analog state and the energy integrated continuum have been obtained from 0 to 90/sup 0/. The excitation of the analog state seems to be best represented by Glauber model calculations with nuclear wave functions suitable to explain electron scattering, but all model calculations underestimate the forward angles by 1.5 standard errors. The continuum angular distribution has the same shape as the free p(..pi../sup -/,..pi../sup 0/)n reaction except at forward angles, where the cross section is suppressed by Pauli blocking of the final state. The total isobaric analog state cross section is 6.29 +- 0.94 mb and the total charge exchange cross section from 0 to 90/sup 0/ is 28.4 +- 3.8 mb. The latter is one-half the plane wave impulse approximation value.

PHOTON SPECTRA FROM PION ABSORPTION ON 3He AND 6Li

Publisher Summary This chapter discusses the photon spectra from pion absorption on 3He and 6Li+ and the preliminary results of a high-resolution study of the photon spectra in the 50–150 MeV regions associated with stopped п− absorption on 3He and 6Li. The measurements are performed at the Berkeley l84-in. cyclotron. The principal modifications have been to replace the optical spark chambers of the pair spectrometer with a set of three wire spark chambers and to increase the solid angle by a factor of 2. A liquid hydrogen target was employed in the calibration. The branching ratio for the direct transition to 6He(g.s.) was determined by fitting the instrumental line shape, obtained from the hydrogen spectrum, to the high energy region of the observed peak.