Measurement of Differences between $\mathit{J}/\mathit{\psi }$ and ${\mathit{\psi }}^{\prime }$ Suppression in $\mathit{p}-\mathit{A}$ Collisions

Measurements of the suppression of the yield per nucleon of $J/\psi$ and ${\psi }^{\prime }$ production for 800 GeV/ $c$ protons incident on heavy nuclear targets, relative to light nuclear targets, have been made with very broad coverage in $x_F$ and $p_T$. The observed suppression is smallest at $x_F$ values of 0.25 and below, and increases at larger values of $x_F$. It is also strongest at small $p_T$. Substantial differences between ${\psi }^{\prime }$ and $J/\psi$ production are observed for the first time in $p-A$ collisions. The suppression for ${\psi }^{\prime }$ production is stronger than that for $J/\psi$ for $x_F$ near zero, but becomes comparable to that for $J/\psi$ for $x_F>0.6\mathrm{}$.