TileCal Trigger Signals

The TileCal LVL1 trigger signals are produced by analog adders located in the electronics drawers. The inputs to the adders are shaped analog signals from the the 3-in-1 cards associated with each PMT. The signal amplitudes are proportional to the charge from the PMT and the timing is set with fixed delay cables to obtain a coincidence of all signals in the tower.

The output timing from each tower varies because of time-of-flight effects and the location of the adder circuit. The signals represent energy sums not E_T sums.

Trigger tower output signals

• unipolar, 50 ns FWHM
• calibration, ± 4 mV/GeV
• differential, ± 2 V full scale (500 GeV)
• outputs are capable of driving 50 ohm loads with respect to ground
• noise < ± 1 mV RMS
• fast overload recovery

Input signals to trigger tower adders

• unipolar, 50 ns FWHM
• shaped pulses derived from PMT signals
• coincident in time to ± 1.5 ns
• calibration, ± 0.5 mV/GeV
• differential, ± 0.5 V full scale (1000 GeV)
• enable/disable for each signal via 3-in-1 control