Michael A. Greene, Massachusetts Institute of Technology / LANSCE
Title:
Authors: M.A. Greene, T. Akdogan, J. Da Graca, L. Kwok, J.L. Matthews,
Y. Safkan, W.M. Schmitt, V.V. Zelevinsky, (MIT); P.A.M. Gram, T.N. Taddeucci,
S.A. Wender (LANL) S.F. Pate, (New Mexico State University)
Abstract: The differential cross sections for the pion production
reactions, np -> np_pi0 and np -> pp_pi-, have been measured at the WNR
facility of the Los Alamos Neutron Science Center (LANSCE) for incident
neutron energies between 300 and 600 MeV. The pion production cross
section in this energy region is dominated by the isospin I=3/2 Delta(1232)
resonance. Since the neutron-proton
system can exist in both I=0 and I=1 states, study of pion production
in this system can elucidate the non-resonant as well as the resonant amplitudes.
Our data, together with existing data for pp -> pp_pi0, will allow a complete
determination of the isospin decomposition of the NN -> NN_pi cross sections
sigma_01, sigma_10, and sigma_11. In this experiment, nucleons from
a liquid hydrogen target were detected in coincidence on opposite sides
of the beam using CsI and organic scintillators at angles of 20, 28, and
36 degrees. The energies of the particles were determined from time
of flight and pulse height information. The presence of a pion in the final
state is determined by calculating the missing mass from the measured four-momenta
of the initial and final nucleons.