Study of the contrast resolution of Timepix detector with a semi-insulating GaAs sensor

This work reports on a prototype of a semi-insulating GaAs Timepix imaging detector. The statistical noise of the detector was investigated under uniform X-ray illumination and compared with theoretical predictions. The results show that the detector operated close to the theoretical predictions. Further investigations were done using an aluminum testing object fabricated by single point diamond nanomachining. The testing object consisted of several steps with different heights. With precise beam hardening corrections, we were able to determine the height of each step and the thickness of the testing object. The average error in the thickness determination was about 10.8 mu m. This corresponds to a relative value below 1% of the maximum thickness of the object.