821 LeCroy Quad Discriminator

The Teledyne / Lecroy 821 Quad 100 MHz Discriminator is a high performance Quad Discriminator incorporating the features requested by experimenters throughout the world. The reliability designed into the 821 is based upon Teledyne / LeCroy's experience with its last three generations of quad discriminators. Its advanced hybrid front ends afford high sensitivity and greater than 100 MHz counting rate capability. Output pulse width stability is excellent even at threshold. Each channel has its own threshold and width controls, 5 NIM outputs, 1 ANTI-NIM output and a Rate Lite. Threshold may be monitored at a front-panel test point.

The output duration of the 821 may be adjusted over the range 5 nsec to 1 usec. In the updating mode, a threshold crossing extends the output pulse duration by a time equal to the selected pulse width. If the second threshold crossing occurs within the 9 nsec double-pulse resolution, the unit will not respond.

If, in a train of input pulses to a discriminator, the pulses are separated by less than the resolving time, the discriminator output will be extended until the falling edge of the last pulse in the burst. This is a particularly important feature in veto applications.

Rate Lite is an indicator LED. It produces a flash for each discriminator firing. A stretching circuit allows single firings to be discerned.

Common Veto provides the option of inhibiting all channels simultaneously, by application of a NIM fast pulse. This is an effective means of eliminating unwanted background early in the logic system.