NLC Timing System Triggering Capabilities

(Proposed Requirements)

For the normal trigger unit, triggering would occur in steps of 1.4nsec (1/714MHz). A veneer device for fine time resolution could be constructed.

The following triggering output would be provided, (counted in cycles of 714MHz):

• Pulse would start Tstart cycles after the fiducial.
• Pulse would stop Tlength cycles after Tstart.
• Pulse would repeat after Tperiod cycles.
• Repetition would continue for Npulses number of repetitions.

The above actions are well defined for pulse train durations which do not span more than one fiducial. It is suggested that longer trains be allowed, with re-triggering if a new command is received the next fiducial. A continuous mode (infinite duration or number of pulses) should also be allowed.

The triggers should have the following set of default actions:

• No new pattern received: Select either repeat previous output, or disable output.
• No fiducial received: Select either continue previous output (at a locally determined fiducial time), or disable output.

Possible options:

• Possible adjustable output types: ECL, NIM, TTL? (different module variants?)
• Possible direct optical trigger output (system variant)

Page by  Josef Frisch frisch@slac.stanford.edu updated 04/22/2002

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