Neutrons produced by 1.22 GeV antiproton interactions with nuclei

Inclusive neutron energy spectra were measured by time of flight using 1.22 GeV antiprotons from LEAR, CERN, as projectiles and targets from natural Al, Cu, Ag, Ho, Ta, Au, Pb, Bi, and U. The sum of two Maxwellian distributions was fitted to the spectra d/sup 2/ sigma /(d Omega dE) obtained at several forward and backward angles yielding neutron multiplicities M/sub i/ and slope or temperature parameters T/sub i/ for the low-energy (evaporative, i=1) and high- energy (pre-equilibrium, i=2) parts, respectively. M/sub 1/ increases with A, proportional to the nuclear volume, and M/sub 2/ is growing with A/sup 1/3/, proportional to the nuclear radius. The T parameters are nearly independent of A. The results are compared with previous multiplicity measurements with a 4 pi neutron detector, intranuclear cascade calculations and neutron spectra from stopped antiproton annihilation on nuclei. With the measured proton spectra also the ratio of emitted neutrons to protons was determined for Au. (26 refs) .