Angular distributions of light projectile fragments in deep inelastic Pb + Em interactions at 160 A GeV

摘要

The nuclear emulsion was exposed at CERN by the lead projectile at 160 A GeV. The angles between any pair of fragments with Z = 2 - 4 have been measured in the emulsion plane for the events which did not contain heavy fragments. The constant characterizing the normal angle (#phi#) distribution of the fragment momentum projection onto the emulsion plane with respect to initial projectile momentum po is found to be #sigma#_#phi# = (0.37 +- 0.02) mrad. Corresponding value #sigma#_0 = (121 +- 6) MeV/c of nucleon momentum distribution in the lead nucleus coincides with that expected from Fermi momentum distribution for this nucleus. The peak in the pair-angle distribution of double-charged fragments, ~8Be -> 2#alpha#, is presented for the region of small angles (< 0.1 mrad). The fraction of #alpha#-particles coming from the decay of the ground state ~8Be is found to be (13 +- 2)% of their whole number.