Diffraction dissociation and Coulomb dissociation of high-energy neutrons by nuclei

Abstract

We present the results of a spark chamber experiment in which we studied the reaction n + A --> (p + [pi]-) + A', where the (p[pi]-) pair is coherently produced off carbon, copper, and lead nuclei. Between 5 000 and 55 000 good events were collected with each target. Incident neutrons in the momentum range 10 to 28 GeV/c were used. Forward-going (p[pi]-) pairs from the above reaction were detected in a wire spark chamber spectrometer which measured the momentum and angles of each particle. The observation of a sharp forward peak (of width appropriate to the nuclear radius) indicated that a large fraction of the events were coherently produced. There is no evidence for any appreciable production of the well-established nucleon isobars; our limits appear to be inconsistent with estimates based on a straightforward extrapolation of pp data. The lead data show evidence for coulomb production of the [Delta] (1236). The carbon data indicate a spin for the coherently produced (p[pi]-) states with pure possible. We cannot draw any firm conclusions about helicity conservation. The Drell-Hiida-Deck model does not adequately fit the data, nor is the double-Regge-pole model completely satisfactory.