Recombination of electron-ion pairs in liquid argon and liquid xenon

We have measured the electric field dependence of electron-ion recombination in liquid argon and xenon. The observed relationship is incompatible with Onsager's geminate theory [Phys. Rev. 54, 554 (1938)] of recombination so we have developed a new, single-parameter model to describe the data. The model is based on realistic assumptions about liquid argon and xenon and yields a simple, analytic result. This work is part of a program to build a high-resolution liquid-xenon detector.