Veto Wall Test

1. Veto Wall Test Hyupwoo Lee MINERvA/Jupiter Group Meeting July 18, 2007

2. From the last presentation to now • Timing test with NIM modules and scope : in order to reduce errors from DAQ board ( 24ns for one clock count ) • Have been troubled with lots of problem in using the FEB. ( about electronics, DAQ software, setting, and etc.) • A few days ago, I could get first reasonable data. • Wrote a program for data analysis with PAW.

3. Previous result of timing test • Standard deviation of timing (signal’s falling edge to trigger’s falling edge) is ~10ns • Time characteristics are almost the same with analysis method : just use scope calculation

4. Timing test without FEB • Standard deviation of timing (signal’s falling edge to trigger’s falling edge) is ~4ns

5. Setup with FEB - 1 • Blue - Positive logic • Orange - NIM logic • Red - PMT signal Trigger hit Panel hit kHz Trigger input 1Mohm, 1Mohm

6. Setup with FEB - 2 Panel hit • Trip register setting Trigger hit Large cross talk • I followed Paul’s suggestion and Jesse’s note only but VTH. • I set relatively very high threshold for big signal and big noise but it should be calibrated and cut more down in later time.

7. 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

8. 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.

9. 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 ~40ns ~20ns

10. Timing resolution summary • With DAQ board ( being used for PARTICLE program) and scope : ~10ns • With NIM modules and scope : ~4ns • With FEB : ~4ns ( rough result with an assumption ) • The last two are roughly matched with

11. Attenuator - 1 • I tried to use an attenuator( ~6db ) for panel hit

12. Attenuator - 2 • The signal looks like to be a little distorted and delayed Delayed Distorted

13. Plan for Future • Now Bob carries the master FEB to Fermilab for modifying input AC coupling to use directly for big signal. => Need ADC calibration and check linearity after change • Determine the proper threshold setup of FEB for veto wall • Use both side PMTs to do hit position related study