• Description of (as far as we understood) the VFAT calibration procedure

• Software/firmware activities

• people

• Set first approx threshold– random triggers / no cal pulse– -Set default DVt– Reduce DVt until noise limit– Set DVt to noise limit + n.sigma

• Use it to guess delay– Scan for delay (approximate) by setting the threshold

and using a large amplitude CalPulse• Further adjust delay

– scan latency with cal pulse– look latency value +/- 1 --> adjust CalPhase to have

all hits in the same time slot

• Do the real threshold scan– Do the precise (high statistics) S-curve– optionally scan dac respose via DCU to know

number of e- corresponding to chosen DVt (via I2C). One VFAT at a time (they are in a chain). Or do a look-up table at the beginning and store it.

– extract Qth and noise.

• Then trim the DACs to equalize the thresholds– do the high-statistics S-curve on every channel

(analysis of the channels one by one)– Do with TrimDACs=00000 and =11111 (min and max)– Adjust DACrange– cycle until Qth distributions overlap– in a channel-by-channel base, set Qth to be in the

middle of the value found for 00000 and 11111 (middle of the 2 histograms) (assume it is linear)

• Final timing– re-do the timing with the CalPulse with more

accuracy.– time the external trigger

• Then: ready to run.• How long will it take to do all this with the

complete TOTEM? – Nobody knows now, will learn it the hard way.– Too early now (and too busy on other matters) to start

worrying

• Paul– Reference knowledge, Q&A parties

• Juha, Rauno– FEC software + extension (hard+soft) to send

calibration / random triggers• Jan, Hubert

– Sync monitoring to FEC config files, develop algorithms to extract threshold/noise

• Giovanni, Gianfranco under Gueorgui’s supervision– VFAT emulator as bridge, fix Opto-rx firmware

• We are now dealing with the first step: first rough evaluation of threshold

• Need– FEC software in a loop– Monitoring able to read FEC configuration + extract

threshold + noise values– Triggering the system from the PC– Working VFAT hybrid + VFAT emulator bridge– Working Opto-rx

• 3 activities in parallel• … it’s a long, long way …

Set D_Vt

Write configfile

Send T1

n.T1 = N?

n.D_Vt = M?

• First step: do initial S-curve with random triggers

• Choose number M of threshold (D_Vt) values to scan– Defines plot granularity

• Choose number N of T1 triggers– Defines statistics

• Hardware– I2C to program D_Vt– I/O register (or equivalent) send

triggers– Opto-RX to receive data

• Software– FEC in a loop + write config file– Monitoring must read config file