Measurements of charmed-meson production in interactions between 350 GeV/c $\pi^-$ particles and nuclei

Charmed-meson production by $350$~GeV/$c$ {$\pi^-$} particles incident on copper and tungsten targets has been studied in the WA$92$ experiment, performed at the CERN $\Omega^\prime$ spectrometer. Results obtained are reported and discussed. Reconstruction of decays from the set ${\rm D}^0 \rightarrow {\rm K}^- \pi^+$, ${\rm D}^0 \rightarrow {\rm K}^- \pi^- \pi^+ \pi^+$, ${\rm D}^+ \rightarrow {\rm K}^- \pi^+ \pi^+$, ${{\rm D}_{\rm s}}^+ \rightarrow \phi \pi^+$ and charge conjugates has yielded a sample of $7280 \pm 108$ charmed mesons, produced with $\xf > 0$, $\langle \xf \rangle = 0.18$ and $\langle {\pt}^2 \rangle = 1.86~{\rm (GeV/}c{\rm )}^2$. Assuming a relationship $\sigma = \sigma_0 A^\alpha$ between the cross-section, $\sigma$, per nucleus of mass $A$ and the nucleonic cross-section, $\sigma_0$, the $\alpha$ value found for the detected charmed particles is $0.95 \pm 0.06 \pm 0.03$. Taking $\alpha = 1$, the measured cross-sections per nucleon for $\xf > 0$ production are $7.78 \pm 0.14 \pm 0.52$~$\mu$barn for ${\rm D}^0$/$\bar{\rm D}^0$, $3.28 \pm 0.08 \pm 0.29$~$\mu$barn for ${\rm D}^+$/${\rm D}^-$ and $1.29 \pm 0.16 \pm 0.33$~$\mu$barn for ${{\rm D}_{\rm s}}^+$/${{\rm D}_{\rm s}}^-$. Differential cross-sections with respect to $\xf$ and ${\pt}^2$ have been determined for the various types of charmed meson, and particle-antiparticle asymmetries have been analysed.