Production ofVParticles by 3-Bev Protons

With a well-collimated beam of 3-Bev protons and a hydrogen-filled diffusion cloud chamber a search has been made for $V$ particles from $p-p$ collisions. The rarity of such events leads to the conclusion that the $V$-production cross section is probably less than 0.2 mb. This value is significantly smaller than the ∼1 mb $V$-production cross section observed for ${\pi }^{-}-p$ collisions at comparable center-of-mass energies. At the same time a cross section of 7.4±1.5 mb is obtained for iron (per nucleus). A direct comparison of $p-p$ and $p$-Fe interactions under essentially similar conditions allows us to conclude that an interaction with an iron nucleus is at least 4 times more effective in producing $V\text{'}\mathrm{s}$ than is an interaction with a free proton.