Use of silicon and GaAs pixel detectors for digital autoradiography

Solid state detectors made of Si (4.8x8 mm(2)) and GaAs (6.4x8 mm(2)) pixel matrices bump-bonded to the Omega2 and Omega3 electronic read-out systems, developed at CERN for H.E.P. experiments, have been used to obtain autoradiographic images of clusters of human epithelial cells and DNA fragments separated via electrophoresis, both labeled with P-32. The system has shown a good minimum detectable activity per unit area of 2. 10(-4) cps mm(-2), and has proved linear for count rate in the range 0.2-20 cpa, typical of autoradiography. The pixel dimensions are 75x500 mu m(2) (Si-Omega2) and 50x500 mu m(2)(GaAs-Omega3), respectively. We are able to clearly localize clusters of cells which have incorporated the radioactive tracer and DNA fragments on an electrophoretic gel on paper (blots).