Checking trigger timing

The trigger timing is measured with the digital scope at the paddle cards (spy cards) at the upper two headers of the LB 500 "Mix".

The trigger timing is essential for the experiment and needs to be checked whenever something gets changed in the trigger logic, like the prescaling factors in the LB 500 Prescaler. Following table gives the signals to check.

Example signals were taken on August 2nd, 1999, at 160k PiStop rate. Channel one sees Signal1, channel 2 sees Signal 2. All times are Full Width Tenth Maximum.

ItemSignal 1 Signal 2 CommentExample
1 Pi-Beta Hi CsI Hi Width 8.5-9ns
Trailing edges aligned
2 Pi-Beta Lo CsI Lo Width 8.5-9ns
Jitter larger than for Hi signals
2.5 beam Pi-Beta Lo Pibeta Lo stops ~1ns before beam
note all above four triggers should be compared with beam veto
3 Beam CsI Hi Beam Width 15ns
CsI Hi starts ~3ns after beam
and stops ~1ns before beam
4 Pi-Stop CsI Hi Pi-Stop width 8.5-9ns
CsI Hi starts ~2ns after Pi-Stop
5 CsI Hi
Pi-Beta Hi
CsI Lo
Pi-Beta Lo
Lo and Hi signals aligned trailing edge
Same width as Hi
6 Three Beam Veto Tigger three is well contained inside the beam veto.
7 Pi-Stop PS
Pi-Stop Pi-Stop PS width 9.5ns
Pi-Beam width 13ns
Trailing edges aligned if possible
8 Pi-Stop Pi-Gate Pi-Gate width 180ns
Pi-Gate opens 30ns before Pi-Stop
9 Pi-Gate Pi-Gate PS(Hi,PB,Lo) Prescaled gates same timing as unprescaled one
10 Sum PV CsI Hi Width 20ns
PV Starts ~7ns before CsI Hi
11 CMV Pi-Beta Hi CMV width 60ns
CMV comes ~23ns before Pi-Beta Hi
12 CMV PS CMV CMV PS Width 44ns
CMV PS comes 6ns after CMV
13 Random Width 25ns
14 Any CsI at splitter output FB ADC gate at fan-out Gate width 100ns
CsI signal comes 52ns after gate
15 Any BADC input
switch trigger to prompt (16)
BADC gate Gate width 25ns
beam signal comes 2ns after gate due
to internal delay in LRS2248
16 e+ Beam
switch trigger to eBeam (256)
eBeam trigger width 9ns
Timed only at BADC (CAMAC)
B0/B1 comes 10ns after gate
others come 2ns after gate

S. Ritt, August 2nd, 1999
last update H.P. Wirtz, November 4th, 1999