Correlations in Signals Generated by Runaway Electrons in the GOLEM Tokamak measured using the Timepix3 Detection Modules

An application study of modern pixel semiconductor detectors for characterization of runaway electron events in a tokamak is presented. This study is based on comparative techniques utilizing spectroscopy and timing measurements of X-rays produced by the runaway electrons. The measurements were performed on the tokamak Golem using three Advapix detection modules. The first two modules were based on a Timepix3 R/O chip with a 1 mm thick silicon sensor. The last module was based also on the Timepix3 R/O chip but with a 2 mm thick CdTe sensor. The modules were placed at different positions around the tokamak chamber and were triggered by a common trigger signal. We have observed that energy spectra measured by the two identical modules in the same place are identical. The spectra measured in different places show variations which can be used for runaway electron characterization. The time evolution of the signals from the detection modules are well correlated. Comparison of the time evolutions measured by the same two detection modules can be used for estimation of places where the runaway electrons interact with the tokamak matter.