A measurement of the differential cross section for the reaction $γn \to π^{-} p$ from deuterium

Abstract

We report a measurement of the differential cross section for the $γn \to π^- p$ process from the CLAS detector at Jefferson Lab in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles ($θ_{c.m.}$) between 50$^\circ$ and 115$^\circ$. We confirm a previous indication of a broad enhancement around a c.m. energy ($\sqrt{s}$) of 2.2 GeV at $θ_{c.m.}=90^\circ$ in the scaled differential cross section, $s^7 {\frac{dσ}{dt}}$. Our data show the angular dependence of this enhancement as the scaling region is approached in the kinematic region from 70$^\circ$ to 105$^\circ$.