Two-pronged events inHe4-pcollisions at 8.56 GeV/cHe4incident momentum

We have studied $^{4}\mathrm{He}$-$p$ collisions at a $^{4}\mathrm{He}$ incident momentum of 8.56 GeV/c using the 1 m Dubna bubble chamber. The $p$--- $^{4}\mathrm{He}$ elastic scattering, the coherent $p+^{4}\mathrm{He}\ensuremath{\rightarrow}N+^{4}\mathrm{He}+\ensuremath{\pi}$ production and the breakup reaction $p+^{4}\mathrm{He}\ensuremath{\rightarrow}p+^{3}\mathrm{He}+n$ have been investigated. Cross sections and production features are presented. From the breakup reaction, subsamples of events in which a $^{3}\mathrm{He}$ or a $n$ appear as spectators were selected. These events were used to study the virtual $\mathrm{pn}\ensuremath{\rightarrow}\mathrm{pn}$ and $p+^{3}\mathrm{He}\ensuremath{\rightarrow}p+^{3}\mathrm{He}$ scattering.NUCLEAR REACTIONS $^{4}\mathrm{He}(p, p)$, ($p, p{\ensuremath{\pi}}^{0}$), ($p, n{\ensuremath{\pi}}^{+}$), ($p, \mathrm{pn}$), $E=1.41$ GeV; bubble chamber; measured $\ensuremath{\sigma}$; deduced $n(p, p)$, $^{3}\mathrm{He}(p, p)$.