We have measured the ratio of cross sections for double to single ioni
zation of helium by Compton scattering, R(C) = sigma(C)(++)/sigma(C)(), at a photon energy of 58 keV using cold target recoil ion momentum
spectroscopy. We find a value R(C) = (0.84(-0.11)(+0.08))% that is in
agreement with the asymptotic limits predicted by Andersson and Burgdo
rfer [Phys. Rev. A 50, R2810 (1944)] and Suric et al. [Phys. Rev. Lett
. 73, 790 (1994)].