Particle Discrimination by Time-of-Flight Methods

A time-of-flight technique has been used to discriminate between particles of differing masses which are emitted from nuclear reactions. The particles are detected with a silicon junction counter. A two-parameter pulse-height analyzer is used to record both the energy and the flight time of each particle detected. The Argonne tandem Van de Graaff provides a chopped and bunched incident beam. Pulses from the silicon detector are fed into both a fast (200-Mc/sec band width) amplifier and into a conventional charge-sensitive preamplifier with a slower response. The fast side of the circuit feeds into a time-to-pulse-height converter giving a pulse which is a measure of flight time. An energy pulse is provided by the slower circuitry. The experimental data show a time resolution of 2 nsec and an energy resolution of 50 keV for particles with energies between 400 keV and 10 MeV.