We Present detailed measurements of the electron-avalanche process in liquid xenon. The measurements were made by using liquid-xenon-filled proportional chambers with anode diameters of 2.9, 3.5, and 5.0 μ to detect 279-keV $\gamma$ rays and measure the photopeak pulse height as a function of applied voltage. The use of uniform pulses of electrons enabled us to discriminate against secondary Townsend processes. We present a table of the first Townsend coefficient $\alpha$ as a function of electric field $E$; a typical value is $\alpha =(4.5\mathrm{}\pm 0.3)\times {10}^4$ ${\mathrm{cm}}^{-1\mathrm{}}$ at $E=2\mathrm{}\times {10}^6$ V/cm. The electron avalanche occurs in liquid xenon at electric fields 27 ± 3 times smaller than would be predicted using measurements made in gaseous xenon and $\frac{E}{\rho }$ density scaling.

• Received 10 August 1973

DOI:https://doi.org/10.1103/PhysRevA.9.2582