Particle detection through the quantum counter concept in YAG:Er3+

Abstract

We report on a scheme for particle detection based on the infrared quantum counter concept. Its operation consists of a two-step excitation process of a four level system, which can be realized in rare earth-doped crystals when a cw pump laser is tuned to the transition from the second to the fourth level. The incident particle raises the atoms of the active material into a low lying, metastable energy state, triggering the absorption of the pump laser to a higher level. Following a rapid non-radiative decay to a fluorescent level, an optical signal is observed with a conventional detector. In order to demonstrate the feasibility of such a scheme, we have investigated the emission from the fluorescent level 4S3∕2 (540 nm band) in an Er3+-doped YAG crystal pumped by a tunable titanium sapphire laser when it is irradiated with 60 keV electrons delivered by an electron gun. We have obtained a clear signature that this excitation increases the 4I13∕2 metastable level population that can efficiently be exploited to generate a detectable optical signal.