Transcript Panel hit

Veto Wall Test
Hyupwoo Lee
MINERvA/Jupiter Group Meeting
Oct, 3, 2007
From the last presentation
to now
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The FEB which was a little modified by Paul was
returned to me after collaboration meeting.
Have been struggled with huge signal and got some
solutions. => It’s time to make a decision about it. I
need your comments about it.
Have been looking for proper setup to fix the timing
problem of trigger hit
Made an order for a pulse generator
2
Setup – 1
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Trigger hit
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Blue
- Positive logic
Orange
- NIM logic
Red
- PMT signal
Panel hit
Trigger input
3
Setup – 2
(TriP-t register setting)
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Basic TriP-t register setting
R egister #
1
2
3
4
5
6
7
8
9
10
11
11
12
13
Trip R egister
IB P
IB B N Foll
IFF
IB P P IFF1R E F
IB P O P A M P
IB P Fol2
IFFP 2
IB C O M P
VR E F
VTH
G A IN
P IP E D E LA Y
IR S E L
IW S E L
Trip0
100
120
0
160
138
24
42
8
160
100
11
7
3
3
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I followed Paul’s suggestions and
Jesse’s note only but VTH and
GAIN.
I set relatively very high threshold
for big signal and big noise but it
should be calibrated and cut more
down in later time.
Recently, Paul suggest again to
change IBPOPAMP(=60) and
VREF(=200) but I couldn’t have
tried with this value yet
4
Huge signal...
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Using attenuator
Splitting signal
Attaching a AC coupling circuit on board?
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Need a decision for following steps
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5
Attenuator 1
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I tried to use an attenuator( ~6db : ~1/2 cut-down
the signal size) again.
Seems that there still exist lost charge problem.
Impedance mismatching? ( Paul pointed out ) => I
agree but I’m not sure about lost charge.
Paul says that data seems OK with attenuator and I
can use attenuator.
6
Attenuator 2
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Splitting signal
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Using wire divider => split the signal and feed
them into several channels
Paul agree with this method except but not using
too many channels (OK with 2 or 3 channels)
because of noise. => I tried with 3 channels
Still saturated with GAIN=11, so I tried to adjust
gain. => The results will be shown in next 4 slides
8
Gain adjust 1
9
Gain adjust 2
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Relative ratio to GAIN=11 is 3/4
10
Gain adjust 3
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Relative ratio to GAIN=11 is 1/2
11
Gain adjust 4
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Relative ratio to GAIN=11 is 1/4
Minimum board gain
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Huge signal - conclusion
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My preference is splitting method with
GAIN=8 (lowest gain).
Is there any problem with this solution?
13
Trigger hit timing
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I am using trigger hit signal as an indicator
of reference position in time dimension.
Paul modified FEB a little but timing
problem of trigger hit (delaying maybe
caused by impedance mismatch) still
remains.
I tried to fix it.
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Using pulse generator 1
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Main idea : Make a pulse signal from 50 Ohm
NIM logic signal => to confirm it can be fixable
with another pulse generator
Use a function generator (from student lab) for
Gate signal => I did not make veto signal for
coincidence
Make trigger hit signal with the pulse generator
which originally used for gate.
It might be fixable with new pulse generator.
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Using pulse generator 2
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Using pulse generator : ch9 [trigger hit]
I think it is caused by
generator’s big internal
delay => signal goes
away from the time
window for counting
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Using 50-Ohm termination
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I attached 50-Ohm resistor in parallel at the board
side end of signal cable.
From this the impedance can be matched with.
(The input resistor of FEB is 1M)
Almost all charges passing through the 50-Ohm
resistor. So very small portion of charge comes
into the board. => need to change cut condition for
event selection.
Shows exact the same timing as scope.
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Trigger hit -2
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Using 50 Ohms : ch6 [trigger hit w/ 50 Ohms], ch2 [trigger hit
w/o 50 Ohms]
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Plan for Future
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Before getting new generator, I will do
pedestal studies
There will be lots of things to do…
Finding the proper threshold and the ratio of
charge/ADC counts, taking real(?) data, and
analysis the data.
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Using trigger hit for timing test
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Two kind of time information in output data file
- Board clock counts for the fastest hit between the
channels (It has random reference position in time
dimension. One count matches with ~9.4ns)
- Time difference from above time to the time of
firing discriminator in ¼ clock count units for each
channels (If there were no fire, it shows 0. The
minimum quantized value is ~2.5ns)
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There are no information about timing for trigger
input in data output file!
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Use trigger hit signal as an indicator of reference
position in time dimension. (I have lots of unused
channel!)
More over, it can give a good cut condition for
event selection. (During a triggered gate, 4 events
can be taken. If there were only one real event, the
rooms for the others are filled with meaningless
data.
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3.9*9.4ns =
~40ns
~3.5ns
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Problem with trigger hit -1
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Actual time difference( panel hit to trigger hit) is ~20ns but output data tells ~40ns (?)
I used NIM logic (need 50 ohm termination) for trigger hit signal but the input
impedance of the FEB is not 50 ohm. ( So, impedance mismatching can make reflections,
interferences, oscillations, and long discharging tail. )
I need one more pulse generator in order to solve this problem.
However, I will assume that the signal patterns of trigger hit with the NIM logic are the
same and I will do rough analysis for timing resolution.
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Problem with trigger hit - 2
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During I tried to change VREF( Trip register ), I got a data set that the cross
talk( of trigger hit ) fires discriminator.
The data show that cross talk seems to be an early walker than trigger hit.
The time difference from panel hit to cross talk is roughly matched with
scope result => Something goes wrong with trigger hit and it shows more
clear evident
~20ns
~40ns
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