A Single Valued Time to Pulse Height System Using Tunnel Diodes

Several aspects of interest in a new delayed coincidence apparatus are described. A tunnel diode time to pulse height converter has been built having an inherently single-valued response, rather than the usual double-valued one. The circuit built has an inherent time resolution (full width at half maximum) of 40 psec. The method used to obtain an accurate time calibration and detect small non-linearities in the system response is discussed. A pile-up detector, consisting of a univibrator, an integrator, and a biased diode discriminator is also discussed. Using Naton 136 plastic scintillators, RCA 7850 photomultipliers, zero-crossing triggers and pulse height compensation, Co60 resolution curves having a f.w.h.m. of 250 psec and covering more than four decades are obtained.