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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.

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Veto wall test

Veto Wall Test

Hyupwoo Lee

MINERvA/Jupiter Group Meeting

Oct, 3, 2007

From the last presentation to now
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

Setup 1
Setup – 1

  • Blue

    - Positive logic

  • Orange

    - NIM logic

  • Red

    - PMT signal

Trigger hit

Panel hit

Trigger input

Setup 2 trip t register setting
Setup – 2 (TriP-t register setting)

  • 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

Huge signal
Huge signal...

  • Using attenuator

  • Splitting signal

  • Attaching a AC coupling circuit on board?

  • Need a decision for following steps

Attenuator 1
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.

Splitting signal
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

Gain adjust 2
Gain adjust 2

  • Relative ratio to GAIN=11 is 3/4

Gain adjust 3
Gain adjust 3

  • Relative ratio to GAIN=11 is 1/2

Gain adjust 4
Gain adjust 4

  • Relative ratio to GAIN=11 is 1/4

  • Minimum board gain

Huge signal conclusion
Huge signal - conclusion

  • My preference is splitting method with GAIN=8 (lowest gain).

  • Is there any problem with this solution?

Trigger hit timing
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.

Using pulse generator 1
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.

Using pulse generator 2
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

Using 50 ohm termination
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.

Trigger hit 2
Trigger hit -2

  • Using 50 Ohms : ch6 [trigger hit w/ 50 Ohms], ch2 [trigger hit w/o 50 Ohms]

Plan for future
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.

Using trigger hit for timing test
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 =



Problem with trigger hit 1
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.

Problem with trigger hit 2
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