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Measurements of the lifetime of conduction electrons in liquid xenon

1991; Elsevier BV; Volume: 300; Issue: 2 Linguagem: Inglês

10.1016/0168-9002(91)90446-w

1872-9576

E. Aprile, R. Mukherjee, Mamoru Suzuki,

Dark Matter and Cosmic Phenomena

A gridded ionization chamber with a gap of 5.9 cm was used to study the drift of conduction electrons in liquid xenon. Electrons were generated by cosmic rays traversing the active volume of 0.6 liter. To be sensitive to the effect of electron attachment by electronegative impurities, long drift distances, or equivalently, long drift times, were achieved by reducing the electric field strength. Data were recorded for the range 7 V/cm ≤ E < 500 V/cm. From the waveform analysis of the measured ionization pulses, we find that the average electron lifetime before capture by impurities is longer than 220 μs, corresponding to an average attenuation length of at least 44 cm, at a field of 500 V/cm. These results indicate that an impurity concentration below 1 ppb of oxygen equivalent can be achieved in liquid xenon with a fairly simple and reliable purification system. From the measured drift times the electric field dependence of the electron drift velocity in liquid xenon at T = 195 K is also obtained. The extrapolated zero field electron mobility at this temperature is 4230 ± 400 cm2V−s−1, much higher than the corresponding value measured at liquid xenon temperature the triple point.