Potential of non-linear optical phenomena for fast timing in detectors of ionizing radiation

Abstract

After the discovery of the Higgs boson at CERN, the development of new experiments at future colliders remains the main stream in experimental high energy physics. Since pile up shows significant increase with the increase of collider luminosity, timing becomes the key issue for the future detection of rare events. Unfortunately, the time resolution of the detectors currently used in high energy physics experiments is limited to 50–70 ps. That occurs due to the spontaneous processes involved in the development of the light response signal, which is generated after the relaxation of carriers, created during the interaction. In this study, we consider a possibility to exploit some phenomena for ionizing radiation detection which are carried on in parallel with relaxation of carriers in the very first few ps while ionization starts. One is the elastic polarization due to local lattice distortion as the electrons are displaced and holes generated at ionization. The key feature of the elastic polarization is its short response time, which makes it promising to use as an optically detectable time mark. Nonlinear optical absorption of femtosecond light pulses of appropriate wavelength is considered to be a tool to generate time mark. The study was targeting at searching of the inorganic scintillating materials combining scintillation properties and non-linear absorption of ultra-short laser pulses. The nonlinear pump-and-probe optical absorption technique with of 200 fs laser pulses was used to study the effects in lead tungstate and garnet type scintillator crystals.