Miami University

Instrumentation Laboratory Project Page

Project: Fast-Slow Coincidence Module

Department: Physics

Primary Investigator: Dr. Herbert Jaeger

Purpose of Project: The fast-slow coincidence module is part of an experiment that determines the angular correlation of two gamma rays emitted from a source at the center of four gamma-ray detectors. Each detector emits two pulses when it "sees" a gamma ray. One pulse is very fast (duration of about 10-20 ns) and serves as a time signal, i.e. this pulse tell us when a gamma ray was detected. The other pulse is slower (a few ms long) and is used to determine the energy of the gamma ray. Since we are looking for correlations of two gamma rays, we have to watch the outputs of all detectors and decide when one detector gives us a signal of the correct energy, followed by another detector within a time of a few 100 ns. Since the pulse processing involves different time scales (ns for the fast pulses and ms for the slow pulses), the fast pulses must be delayed in order to see if they did happen simultaneously. This is what the fast-slow coincidence module does.

More details about the spectrometer can be found at

IL Comment: Custom circuit using fast (<2 ns) comparators and ECL (emitter coupled logic) was designed and implemented on two printed circuit boards which were laid out and fabricated in the IL. The circuit boards had to fit within the size and power constraints of the NIM standard package. This was the first use of ECL technology by the IL.

Cost to researcher: $229.93

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