Measurement of single and double radiative low-Q2 Bhabha scattering at Ec.m.=29 GeV

The process e/sup +/e/sup -/..-->..e/sup +/e/sup -/..gamma..(..gamma..), where one electron scatters at a small angle, is studied with data from the Mark II detector at the SLAC storage ring PEP. The data are in excellent agreement with a Monte Carlo calculation and include a large contribution from order ..cap alpha../sup 4/. The ratio of measured to calculated cross sections is R = 0.993 +- 0.017 +- 0.015, where the first error is statistical and the second systematic. This is a sensitive test of the calculation of the dominant background for neutrino-counting experiments.