Characterization of large area proximity focused hybrid photo diodes

A study of the behaviour of hybrid photodiode detectors with respect to high magnetic field and to single photoelectron sensitivity has been performed. The response of several large area proximity focused HPDs in high magnetic field has been tested and results showing their substantial immunity to the magnetic field over a wide angular range are reported. area HPDs imply high diode capacitance and reverse current, which are important parameters limiting the signal to noise ratio. Tests with commercial charge preamplifiers have been performed and results showing a promising single photoelectron sensitivity are given.