The A - dependence of $K^0$ and $\Lambda$ neutrinoproduction on nuclei

Abstract

For the first time, the A- dependence of the production of $K^0$, $\Lambda$ and, for comparison, ${\pi }^{-}$ mesons is investigated in neutrinonuclear reactions, using the data obtained with SKAT bubble chamber. An exponential parametrization ($\sim A^{\beta }$) of the particle yields results in ${\beta }_{V^0}=0.20\pm 0.05$ for $V^0$ particles (combined $K^0$ and $\Lambda$), while for ${\pi }^{-}$ mesons the A- dependence is much weaker, ${\beta }_{{\pi }^{-}}=0.068\pm 0.007$. A nuclear enhancement of the ratio $K^0/{\pi }^{-}$ is found; this ratio increases from $0.055\pm 0.013$ for $\nu N$- interactions up to $0.070\pm 0.011$ at $A\approx 21$ and $0.099\pm 0.011$ at $A\approx 45$. It is observed, that the multiplicity rise of $V^0$'s occures predominantely in the backward hemisphere of the hadronic c.m.s. It is shown, that the A- dependence of the nuclear enhancement of the ${\Lambda }^0$ and ${\pi }^{-}$ yields can be reproduced in the framework of a model, incorporating the secondary intranuclear interactions of pions originating from the primary $\nu N$- interactions, while only (29$\pm$9)% of that for $K^0$ at $A\approx 45$ can be attributed to intranuclear interactions.

18 pages, 8 figures