Primary scintillation yield and α/β ratio in liquid xenon

Abstract

Scintillation of liquid xenon due to 5.49 MeV /spl alpha/-particles and 59.6 keV /spl gamma/-rays, both emitted by a /sup 241/Am source, was observed. By measuring the amplitudes, A/sub /spl alpha// and A/sub /spl gamma//, corresponding to the peaks due to /spl alpha/-particles and /spl gamma/-rays on the same spectrum, respectively, the specific light yield ratio (A/sub /spl alpha///E/sub /spl alpha//)/(A/sub /spl gamma///E/sub /spl gamma//) (in short, /spl alpha///spl beta/ ratio) was found to be /spl alpha///spl beta/=1.01/spl plusmn/0.05 at zero electric field. In order to compare with experimental values and theoretical calculations from other authors, usually obtained for 1 MeV electrons, the specific light yield measured for 59.6 keV /spl gamma/-rays was corrected taking into account its dependence on the /spl gamma/-ray energy known from the literature. This results in /spl alpha///spl beta/=1.33/spl plusmn/0.08 for fast electrons. From our measurements, we estimated the mean energy expended per scintillation photon, i.e., W/sub s/, in liquid xenon as W/sub s/=16.4/spl plusmn/1.6 eV for /spl alpha/-particles and 59.6 keV /spl gamma/-rays and W/sub s/=21.7/spl plusmn/2.2 eV for 1 MeV electrons. Our results are compared with those existing in the literature and an analysis of the better precision that can be expected for measurements of the absolute value of the light yield is done.