Angular distribution of charge exchange and inelastic neutrons in π--p interactions at 313 and 371 MeV

Abstract

Neutron angular distributions from the charge-exchange (π0n) and inelastic modes (π0π0n,π+π-n) of the π--p interaction have been investigated at 313 and 371 MeV incident-pion kinetic energy. The data were obtained with an electronic counter system. Elastic and inelastic neutrons were separated in the all-neutral final states by time of flight. At both energies the charge-exchange differential cross section at the forward neutron angles differs from that determined by Caris et al. from measurements of the π0-decay gamma distributions, but generally agrees with the phase-shift-analysis calculations of Roper. The distribution of inelastic neutrons from both modes shows a strong preference for low center-of-mass neutron energies. The distribution of these neutrons does not correspond to that expected from the I=0, π-π interaction (ABC effect) suggested to account for the anomaly in p-d collisions observed by Abashian et al. Finally, all available charge-exchange differential-cross-section data from this and other experiments were combined by at least-squares fit to a Legendre expansion of the form dσ/dΩ*(cosθπ0*)=Σl=0NalPl(cosθπ0*) with the following results (in mb/sr): Tπ- a0 a1 a2 a3 313 1.21±0.03 1.88±0.06 1.61±0.06 0.45±0.06 371 0.89±0.02 1.57±0.04 1.13±0.04 0.38±0.03.

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