1 stony brook update: what a long strange trip its been t.k. hemmick for the tent crew
DESCRIPTION
3 What causes the differences in trips? We spent an afternoon making various trips and trying to find a pattern as to which works which way. Few real patterns emerged. The Ghost –The ghost is the only one that reproduced regularly. This one comes from having a DC current and changing the allowed setting below the level. Does not occur under physical trips. The Stubborn –This one is the only one that we fear. It seems to occur more frequently when using the slow trip current. We are now setting BOTH the slow and fast trip currents to +1.5%. The Standard –This one is the most often observance and the “slow reset” feature of Greg’s circuit refuses to reset the relay during the brief HV pulse. The ideal –Rare, but happens! The LeCroy trips correctly on rare occasions. This can be made to occur more often if your spark is like a switch closure (i.e. not like a spark).TRANSCRIPT
1
Stony Brook Update:What a long STRANGE TRIP its been
T.K. Hemmick for the Tent Crew
2
LeCroy 1471 Trip Relay Works• The trip circuit works as designed:
– Monostable multi-vibrator set for 92 kHZ(don’t know where 800 kHz came from…).
– Fast trip, slow reset via RC with diode in parallel with R.– Works like we expect, except LeCroy is funny…
• LeCroy Trip Types:– The ideal: freq goes away, stay gone.– The standard: freq goes away, reappears ~0.5 sec later,
then quickly goes away forever.– The stubborn: freq goes away, reappears ~0.5 sec later,
and STAYS (output low but not off).– The ghost: Goes away for ~0.1 sec, comes back for 2 sec,
then followed by ideal, standard, or stubborn.• BNL is working to develop same circuit but tripping
both mesh and GEM.– Are we sure that we want this? LeCroy does not always
work in the expected manner and can defeat trip circuit.
3
What causes the differences in trips?• We spent an afternoon making various trips and trying to find
a pattern as to which works which way.• Few real patterns emerged.• The Ghost
– The ghost is the only one that reproduced regularly. This one comes from having a DC current and changing the allowed setting below the level. Does not occur under physical trips.
• The Stubborn– This one is the only one that we fear. It seems to occur more
frequently when using the slow trip current. We are now setting BOTH the slow and fast trip currents to +1.5%.
• The Standard– This one is the most often observance and the “slow reset”
feature of Greg’s circuit refuses to reset the relay during the brief HV pulse.
• The ideal– Rare, but happens! The LeCroy trips correctly on rare occasions.
This can be made to occur more often if your spark is like a switch closure (i.e. not like a spark).
4
Failed shot.• We had one failed shot.• A lead popped off of one GEM and landed in
a way that the lid would not seal when lifted. We removed the GEMs, washed them, pumped over the holiday weekend and are ready for the next shot.
5
Overnight conditioning.• We have long term experience on a
GEMstack. This one gets better with time.• Presently the GEMstack operates at 5000
gain for day-long periods at V=3600.• We will have soon a LabVIEW software to
run overnight conditioning.