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The LArIAT supercycle

A description of the system as implemented on July 26, 2014. Notice a weakness described at the bottom of the page.

$00

  • Start of the super-cycle
  • Enters CR from ACNET and sent into a logic fanout in the LArIAT NIM-bin
  • Outputs do the following:
    • RESET WUT and RESET 1495
    • Start DIGITIZERS ENABLED. DIGITIZERS ENABLED is implemented with a gate-delay generator in the LArIAT NIM-bin in the CR.
  • Also, used within ACNET to derive the delayed $00+T signal

$21

  • Enters CR from ACNET and sent into a logic fanout in the LArIAT NIM-bin.
  • Used to START BEAMON. This signal is high from $21 to $36 and is implemented with a gate-delay generator in the LArIAT NIM-bin in the CR. The actual beam spill seems to begin a second later than $21, more like at $39. We don't want to cut it close.

$36

  • End of the spill
  • Stops BEAMON
  • Starts COSMICON. COSMICON is implemented using a gate-delay generator in the LArIAT NIM-bin in the CR.
    • Started from the DEL output of the gate/delay generator which implements BEAMON.

$00+T

  • Signal delayed from $00 by T. This is done within ACNET with T specified in ms.
  • This signal is taken from the ACNET rack to a logic fanout in the LArIAT rack.
  • Ends COSMICON
  • Used to send END OF READOUT pulse to channel 0 of the v2718 crate controller.

Weakness of this scheme: it relies on $36 to change state from BEAMON to COSMICON. When $36 isn't present you would might like to take cosmic data, but COSMICON never comes on. Therefore, if it's required by the trigger, you have a problem. A possible solution is to go into the v1495.config and change the trigger requirements. Another solution, would be to start COSMIC-ON according to another delayed signal from $00.