Neutral-strange-particle production by 300-GeV protons

A neutral beam designed to transmit a high flux of ${\Lambda }^0$ hyperons with momenta above 50 GeV/c has been built and operated at Fermilab. Inclusive production cross sections per target nucleus have been measured for $p+A\to {\Lambda }^0+X$, $p+A\to K_S^0+X$, and $p+A\to {\overline{\Lambda }}^0+X$ with 300-GeV protons incident on solid targets $A=\mathrm{b}\mathrm{e}\mathrm{r}\mathrm{y}\mathrm{l}\mathrm{i}\mathrm{u}\mathrm{m},\mathrm{c}\mathrm{o}\mathrm{p}\mathrm{p}\mathrm{e}\mathrm{r},\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{l}\mathrm{e}\mathrm{a}\mathrm{d}$. The region of phase space covered is predominantly projectile fragmentation: $0.2<~x<~1$, $0<~p_{\perp }<~2$ GeV/c. The $A$ dependence of the inclusive cross sections is analyzed. The cross sections are compared to other work in $\mathrm{pp}$ collisions by extrapolating the $A$ dependence to $A=1\mathrm{}$. The results of measurements of ${\Lambda }^0$ and ${\overline{\Lambda }}^0$ polarization from the beryllium target are presented.