Low noise charge sensitive preamplifier for fast pulse counting

A charge-sensitive preamplifier has been developed for use with photomultipliers in fast photon-counting applications. The device has the following characteristics: linear response of 1.04 x 10 to the 15th mV/C between 10 to the -15th and 10 to the -12th C; input noise not less than 660 rms electrons, and pulse repetition rate not greater than 3 x 10 to the 6th pps. It was specifically designed for a rocket-borne astronomical application, in which amplification of single photoelectrons from a photomultiplier cathode permitted detection of single X-ray photons by a phosphorus-photocathode sensor. The spaceflight environment required optimization of the design to achieve low weight (12 g), small size (25 x 45 x 13 mm) and high reliability under rugged conditions. A circuit diagram is presented along with a figure illustrating the basic parameters of the device.