Tritium digital autoradiography with a Medipix2 hybrid silicon pixel detector

We report on the first measurements of 3 H beta autoradiography obtained using a room temperature hybrid pixel detector, consisting of the Medipix2 single particle counting read-out chip bump-bonded to a 300 pm thick silicon pixel detector. This system has 256 x 256 square pixels of 55 mum pitch for a total sensitive area of 14 x 14 mm(2). Each pixel contains a double threshold discriminator and a 13-bit counter. Using a detection threshold equivalent to less than 6 keV and a background count rate of 5 x 10(-3) counts mm(-2) s(-1), with exposures up to several hours, real-time images have been obtained of tritium-labeled solution drops spotted on a thin mylar foil placed in contact with the continuous top electrode of the silicon detector, in open air condition. (C) 2003 Elsevier B.V. All rights reserved.