Target fragmentation in pp, ep and γp collisions at high energies

We calculate target fragmentation in pp→nX and γp→nX reactions in the meson cloud picture of the nucleon. The pp→nX reaction is used to fix the pnπ+ 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 xBj electroproduction of forward neutrons at HERA. Here the anti qq 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 (Q2>10 GeV2) screening is weaker but still present at large Q2. The signature for this absorptive rescattering is a shift of the dσ/dEn distribution to higher neutron energies for photofragmentation. (orig.)