Tentative trigger alignment procedure:
Initial settings:
Module | trg_alignment | tack_delay |
---|---|---|
CAL FM 109 | 0x80f00 | 0x2d |
CAL FM 101 | 0x90f00 | 0x2c |
CAL FM 119 | 0x80f00 | 0x2e |
TKR FM 16 | 0x900005 | 0x0 |
TKR FM 8 | 0x900005 | 0x0 |
namely nominal SLAC settings (CAL treq delay = 0, TKR treq delay = 5, CAL tack delay ~ 45, TKR tack delay = 0). Also the delay_ext_trig is set to 0x0, at the beginning.
With these setting the trigger panel in RunControl (run 700000799) shows that, within the trigger window:
- TKR peaks at 10 ticks.
- CAL peaks at 7 ticks.
Also note that the CAL_LO and EXT trigger rates are almost identical, while the TKR is lower by ~ 40%.
Then next try is the following:
Module | trg_alignment | tack_delay |
---|---|---|
CAL FM 109 | 0x80f00 | 0x2d |
CAL FM 101 | 0x90f00 | 0x2c |
CAL FM 119 | 0x80f00 | 0x2e |
TKR FM 16 | 0x900002 | 0x0 |
TKR FM 8 | 0x900002 | 0x0 |
with delay_ext_trig set to 0x5. With these settings:
- TKR peaks at 3 ticks.
- CAL also peaks at 3 ticks.
the two primitives being perfectly aligned. The TKR trigger rate is still ~30% lower that CAL_LO and EXT, though. Following figure refers to a run taken immediately after with a different ext_delay; sorry for the confusion, but it shows how the primitives are aligned.
Need to understand why:
- The TKR trigger rate is lower than the others (maybe worth mentioning that the beam is 5 GeV electrons, 90 Hz average rate, 500 Hz istantaneous).
- The (apparently) optimal setting for the TKR treq_delay is 2 and *not* 5 as expected from SLAC. Does the particle energy makes a difference?
So here is the proposal for the data taking during the beam test:
- CAL treq_delay = 0x0 (nominal)
- TKR treq_delay = 0x2
- CAL tack_delay ~ 0x2d-0x2e (nominal)
- TKR tack_delay = 0x0 (nominal)
- delay_ext_trig = 0x8
With these settings the trigger primitives within the trigger window look like this: