Electron Impact Ionization of H$_2$

Relative doubly-differential cross sections for the low energy electron impact ionization of H$_2$ have been measured at incident energies ranging from 17.6~eV to 40~eV and scattering angles of $20^\circ$ to $130^\circ$. The calibration of the electron analyzer during these measurements employed the recent doubly-differential cross section measurements of atomic hydrogen.\footnote{J.\ G.Childers, K.\ E.\ James, Jr., Igor Bray, M.\ Baertschy, and M.\ A.Khakoo, {\em Phys.\ Rev.\ A} {\bf 69}, 022709 (2004).} These measurements represent a new calibration standard useful in the determination of the transmission function of electron analyzers. This work is funded by the National Science Foundation under grant \# NSF-RUI-PHY-0096808.