This is test dataset taken by a CERN@school Timepix detector. It consists of the frame data for three 256x256 pixel frames (data), the detector settings file (data.dsc) and the data index file (data.idx).
The data themselves are the readings from the pixels (X, Y, number of counts) caused by particles incident on the Timepix detector's silicon sensor element when exposed to a potassium chloride source. Three frames were taken with an acquisition time of 60 seconds.
Further information may be found on the CERN@school website. A frame-reading tool may be found in the Github repository linked to below.