Measurement ofJψ(3100)Photoproduction in Deuterium at a Mean Energy of 55 GeV

Abstract

We report the result of a brief experiment to measure the cross section for photoproduction of $\frac{J}{\psi }\mathrm{}\left(3100\right)\mathrm{}$. At a mean energy of 55 GeV we find this cross section per nucleon to be 37.5 ± 8.2 (statistical) ± 4 (systematic) nb. The result establishes the previously indicated rise in $\frac{J}{\psi }$ photoproduction on protons above 20 GeV and suggests that the rise has occurred by 55 GeV.