Leading Edge Timing Circuit for Ge-Li Detectors

A circuit for producing a timing signal from the leading edge of slow rising Ge-Li detector output signals is described. In order to preserve the system resolution, the input signal is taken from the output of the charge sensitive preamplifier. An internal discriminator strobes the tunnel diode pick-off to reduce the noise triggering rate. The effects of multiple low-pass time constants on the walk is analyzed and found to be in agreement with the measured results. For input signals having a rise-time of 100 ns, the walk is less than 3 ns and the FWHM time jitter less than 1 ns over the range of l to 10 MeV. A temperature compensated delayed output circuit, adjustable over the range of 50 to 750 ns, is also included for use in conjunction with cross-over timing.