Neutral-strange-particle production in 200-Gev/c pπ+K+ interactions on Au, Ag, and Mg

Le résumé fourni par la source

We have used the Fermilab 30-in. bubble-chamber-hybrid spectrometer to study neutral-strange-particle production in the interactions of 200-GeV/c protons and ${\ensuremath{\pi}}^{+}$ and ${K}^{+}$ mesons with nuclei of gold, silver, and magnesium. Average multiplicities and inclusive cross sections for ${K}^{0}$ and $\ensuremath{\Lambda}$ are measured, and a power law is found to give a good description of their $A$ dependence. The exponent characterizing the $A$ dependence is consistent with being the same for ${K}^{0}$ and $\ensuremath{\Lambda}$ production, and also the same for proton and ${\ensuremath{\pi}}^{+}$ beams. Average ${K}^{0}$ and $\ensuremath{\Lambda}$ multiplicities, as well as their ratio, have been measured as functions of the numbers of projectile collisions ${\ensuremath{\nu}}_{p}$ and secondary collisions ${\ensuremath{\nu}}_{s}$ in the nucleus, and indicate that rescattering contributes significantly to enhancement of $\ensuremath{\Lambda}$ production but not to ${K}^{0}$ production. The properties of events with multiple ${K}^{0}'\mathrm{s}$ or $\ensuremath{\Lambda}'\mathrm{s}$ also corroborate this conclusion. ${K}^{0}$ rapidities are in the central region and decrease gently with increasing ${\ensuremath{\nu}}_{p}$, while $\ensuremath{\Lambda}$ rapidities are in the target-fragmentation region and are independent of ${\ensuremath{\nu}}_{p}$. ${K}^{0}$ and $\ensuremath{\Lambda}$ multiplicities increase with the rapidity loss of the projectile, but their rapidities do not.

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