veto wall test
DESCRIPTION
Veto Wall Test. Hyupwoo Lee MINER v A/Jupiter Group Meeting Oct, 3, 2007. From the last presentation to now. The FEB which was a little modified by Paul was returned to me after collaboration meeting. - PowerPoint PPT PresentationTRANSCRIPT
Veto Wall Test
Hyupwoo Lee
MINERvA/Jupiter Group MeetingOct, 3, 2007
2
From the last presentation to now
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
3
Setup – 1
Trigger hit
Trigger input
Blue - Positive logic Orange - NIM logic Red - PMT signal
Panel hit
4
Setup – 2 (TriP-t register setting)
Register # Trip Register Trip01 IBP 1002 IBBNFoll 1203 IFF 04 IBPPIFF1REF 1605 IBPOPAMP 1386 IBPFol2 247 IFFP2 428 IBCOMP 89 VREF 160
10 VTH 10011 GAIN 1111 PIPEDELAY 712 IRSEL 313 IWSEL 3
Basic TriP-t register setting
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
5
Huge signal...
Using attenuator Splitting signal Attaching a AC coupling circuit on board?
Need a decision for following steps
6
Attenuator 1
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.
7
Attenuator 2
8
Splitting signal
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
9
Gain adjust 1
10
Gain adjust 2 Relative ratio to GAIN=11 is 3/4
11
Gain adjust 3 Relative ratio to GAIN=11 is 1/2
12
Gain adjust 4 Relative ratio to GAIN=11 is 1/4 Minimum board gain
13
Huge signal - conclusion
My preference is splitting method with GAIN=8 (lowest gain).
Is there any problem with this solution?
14
Trigger hit timing
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.
15
Using pulse generator 1
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.
16
Using pulse generator 2 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
17
Using 50-Ohm termination
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.
18
Trigger hit -2 Using 50 Ohms : ch6 [trigger hit w/ 50 Ohms], ch2 [trigger hit w/o 50 Ohms]
19
Plan for Future
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.
20
Using trigger hit for timing test
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)
There are no information about timing for trigger input in data output file!
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.
3.9*9.4ns = ~40ns
~3.5ns
21
Problem with trigger hit -1
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.
22
Problem with trigger hit - 2 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