Several people provided input ot this diagram : Eric^3 (Siskind, Grove, Charles) and Martin Kocian.
If there are mistakes they are mine and please point me to a better timing diagram and I will gladly update this one since I am not an expert (Eduardo)
Important Detector Register Settings for end-to-end runs (baseline data taking)
Values are coming mostly from LAT70X used for LAT Integration
Expected value for most important registers in DAC Counts or system clock ticks
CAL
- CAL Range Decision Time (GTEM/GCCC/GCRC/delay_1) : 31
- CAL Time After Range Decision Until ADC Readout Time (GTEM/GCCC/GCRC/delay_2) : 53
- CAL ADC Readout Time (GTEM/GCCC/GCRC/delay_3) : 133
- CAL Log Accept Discriminator (zero suppression) (GTEM/GCCC/GCRC/GCFE/log_acpt) : 20 to 50 for ~ 2 MeV settings at LE gain = 5
- CAL Low Energy Trigger Discriminator (GTEM/GCCC/GCRC/GCFE/fhe_dac) 85 to 95 for ~ 100 MeV settings at LE gain = 5
- CAL High Energy Trigger Discriminator (GTEM/GCCC/GCRC/GCFE/fle_dac) 15 to 25 for ~ 1000 MeV settings at HE gain = 15
- CAL Readout Range Select Discriminator (GTEM/GCCC/GCRC/GCFE/rng_uld_dac) : 120 = default; 105 to 120 for optimal settings
- CAL DAC for DC Reference (GTEM/GCCC/GCRC/GCFE/ref_dac) : 0
TKR
- TKR DAC (threshhold, range) (GTEM/GTCC/GTRC/GTFE/dac)) : (22 to 36, 0) for 1/3 of a MIP
ACD
- Note: if veto delay changes then change hitmap and hold delay by the same amount in the opposite direction so that the sum of veto_delay+ hitmap delay is constant and equal to 38 (with the current settings) and veto_delay + hold_delay is constant and equal to 40.
- Delay from ACD trigger discriminator to AEM trigger primitive formation (GAEM/GARC/veto_delay) : 16
- Stretch width of ACD trigger primitive (GAEM/GARC/veto_width): 5
- ADC acquisition time (GAEM/GARC/adc_tacq) : 0
- Delay from ACD trigger primitive to AEM hitmap data latch (GAEM/GARC/hitmap_delay): 22 (from Martin Kocian) and it does not add to the diagram at the bottom!
- Stretch width of ACD trigger primitive to AEMXS hitmap data latch (GAEM/GARC/hitmap_width) : 15 (for self-trigger or not from M. Kocian)
- Delay from trigger to hold (GAEM/GARC/hold_delay): 24
- Bias Dac (GAEM/GARC/GAFE/bias_dac): Set using AcdLeHeBiasCal script
- Zero suppresion threshold (GAEM/GARC/pha_threshold_xx): Set using AcdPedestal script
- Veto setting (GAEM/GARC/GAFE/veto_dac & veto_vernier): Set using Veto & Muon calibrations.
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- The veto setting is not essential to ACD perforamance, but could be interesting to study. Can be calibrated with a couple hours of muon runs.
Important Timing Settings for end-to-end runs (baseline data taking)
Recommended values from LAT integration in system clock ticks
- Width of trigger window in GEM : 12
- Delay from CAL trigger discriminator to TEM trigger primitive formation (GTEM/GCCC/trg_alignment:0-7) : 0
- Delay from TKR trigger discriminator to TEM trigger primitive formation (GTEM/GTCC/trg_alignment:0-7) : Default value is 5. Measurements range between 3 and 5.
- Stretch width of CAL trigger primitive (GTEM/GCCC/trg_alignment:8-15) : 15
- Hold trigger primitive for TEM diagnostic latching of CAL trigger primitive (GTEM/GCCC/trg_alignment:16-23) : 9
- Hold trigger primitive for TEM diagnostic latching of TKR trigger primitive (GTEM/GTCC/trg_alignment:16-23) : 15
- Delays from TKR trigger TACK to shaper hold : 0
- Delays from CAL trigger TACK to shaper hold : Default value is 45. Measurements range between 43 and 47.
The values shown below are based on the LAT Alignment and we will use these as default for CU tests. Note that this is for the flight configuration B2 that became LAT701 config. TEM diagnostics are not enabled and they will change these values.
Below is a timing diagram that explains how knobs are set to ensure charge is collected at the peak for all 3 detectors. Note that CAL beling the slowest its TREQ Delay is set to 0, while ACD being the fastest detector has more delays added.
Finally there are some plots from trigger jitter from Martin Kocian. Note that jitter is large when hit the CAL diodes (see figure)
