Direct Position and Time Digitizer for Position-Sensitive Proportional Counters

A circuit for directly digitizing the location and flight time of neutrons detected in a 2-dimensional position-sensitive proportional counter has been constructed and is now in use here in diffraction experiments with the pulsed neutron source. The position along each coordinate is digitized directly by counting pulses from a 250 MHz clock during the time interval corresponding to the difference in rise times of pulses from the opposite ends of a resistive cathode. In addition, a slower time base is included for digitizing the neutron time-of-flightlight. The circuits, on a single CAMAC board, provide 8 binary bits of x position, 8 bits of y position and 12 bits of time without adding to the system deadtime. All-digital circuitry assures linearity, stability and reliability.