Deuteron production in alpha -nucleus collisions from 200 to 800 MeV per nucleon.

Abstract

Deuteron spectra at laboratory angles from 30\ifmmode^\circ\else\textdegree\fi{} to 90\ifmmode^\circ\else\textdegree\fi{} were measured in \ensuremath{\alpha}+(Pb, Cu, and C) collisions at 800, 600, and 200 MeV/nucleon, and \ensuremath{\alpha}+(Pb and C) collisions at 400 MeV/nucleon. The coalescence relation between protons and deuterons was examined for the inclusive part of the spectra. The size of the interacting region was evaluated from the observed coalescence coefficients. The rms radius is typically 4--5 fm, depending of the target mass. The proton and deuteron energy spectra corresponding to central collisions were fitted assuming emission from a single source moving with a velocity intermediate between that of the projectile and the target. The extracted ``temperatures'' are independent of the nature of the emitted particle, indicating that the fragments have a common source. The best fits were achieved for 200- and 400-MeV/nucleon reactions. Spectra of deuteron-like pairs, including real deuterons and neutron-proton pairs that may be contained in a larger nuclear cluster, are compared to the prediction of an intranuclear cascade model incorporating a clustering algorithm based on a classical coalescence prescription. Best agreements between experimental and predicted deuteron-like spectra occur for 800- and 600-MeV/nucleon collisions.