Target fragmentation in pp, ep and gamma p collisions at high energies

We calculate target fragmentation in pp --> nX and gamma p --> nX reactions in the meson cloud picture of the nucleon. The pp --> nX reaction is used to fix the pn pi(+) form factor for three different models. We take into account the possible destruction of the residual neutron by the projectile. Using the form factor from the hadronic reaction we calculate photoproduction and, small x(Bj) electroproduction of forward neutrons at HERA. Here the q-qbar dipoles in the photon can rescatter on the residual neutron. In photoproduction we observe slightly less absorption than in the hadronic reaction. For deep inelastic events (Q(2) > 10 GeV2) screening is weaker but still present at large Q2. The signature for this absorptive rescattering: is a shift of the d sigma/dE(n) distribution to higher neutron energies for photofragmentation.