1. Rafael Ballabriga Suñé Xavier Xirgu Aleixandre
Towards the automation of the test of photomultiplier tubes in Barcelona
Rafael Ballabriga Suñé
Xavier Xirgu Aleixandre

2. Introduction Measures performed Instruments and Automation Summary
Future Plans
Open Questions
Punts a tractar:
Laboratory equipment:
Ensenyar amb fotografies el setup que tenim al laboratori de la UB (2xPMTs, ADCs de càrrega, Oscil.loscopi, Taules mòvils i el seu control, Caixa negre i polsador de llum)
Measures results:
Quines mesures hem realitzat amb el setup.
Current Status:
Que estem preparats a realitzar, Estat del VME, Problema amb la font de llum.
Future plans
Dates de l’evolució del projecte.
Summary

3. Measures Performed

4. Measures performed Absolute Gain Linearity
Scintillation Pulses Analysis
Crosstalk

5. Gain Measurement Two Methods have been tested
Fitting the spectrum of large number of photoelectrons chosen
2 measures: spectrum/pedestal
Easy to compute:
Two methods have been chosen :
Fitting the spectrum of a large number of photoelectrons
Fitting the spectrum of few phe
Mathematical simplicity of 1st method 2
ped
sig
phe σ ) μ ( N - = 19 10
602 . 1 ) ( - =
phe
ped
sig N R G m

6. Gain Measurement (Setup)

7. Gain Measurement (Results)

8. Linearity measurement
Double pulse method has been used.
Deviation from linearity expressed as:
100
(%) h H D - =
Ample de banda de l’oscil.loscopi!!!! Comentar el problema actual!!!

9. Linearity Measurement (setup)

10. Linearity Measurement (results)

11. Linearity as a function of High Voltage
Linearity is a parameter dependent on the High Voltage
The aim of this measure is to study this dependence
Relative linearity has been found:
A small high frequency noise has been observed when the LED driver is pulsed (~400μV peak)

12. Linearity as a function of High Voltage

13. Linearity as a function of High Voltage

14. Scintillator Pulse Analysis
Objective: To study the performance of the system Scintillator-Fiber-PMT
A 12x12 pad has been used with 101 cmts WLS fiber
Aiming at:
Mean number of photoelectrons/MIP
Percentage of signal within 25 ns windows
Podem tenir altres centellejadors per testejar???
Mascares???? Nomes tenim 1!!!!!

15. Scintillator Pulse Analysis (Setup I)

16. Finding the fiber’s optimal position (setup)

17. Scintillator Pulse Analysis (results)
Histogram of the number
of photoelectrons per signal
Time response waveform

18. Scintillator Pulse Analysis (results)
Mean time waveform in lineal axis (time vs voltage)
Mean time waveform in logarithmical axis (time vs voltage)
Slope= E-1
Statistics=9568signals

19. Scintillator Pulse Analysis (results)

20. Scintillator Pulse Analysis (results)

21. Crosstalk Measurement
A measure of the system Scintillator-Fiber-PMT
A system to position automatically the fibers in the cathode has been designed
The mask used in this test places diagonally the fibers in the fired pixel

22. Crosstalk Crosstalk results of two studied channels.
2 diagonal WLS fibers are placed in close contact with each channel.
2.51
100
3.35
2.01
2.09 29 28 36 27 20 35 19 37 21
2.35
100
2.60
2.43
2.26 45 44 52 43 36 51 35 53 37

23. Crosstalk
2.02
100
2.84
1.62
2.43 21 20 28 19 12 27 11 29 13
4.24
4.08
7.18
5.8
In the upper figure the fibers are placed in close contact with the cathode. In the bottom the fibers are placed 0.5 mm from the pixel.

24. Instruments & automation

25. Instruments and automation
2x64 channels PMT H7546
2x1 channel PMT XP2262
Light source (mimics scintillator pulses)
4 channel High Voltage Source
2x32 channel charge ADC (CAEN V792)
PC with VME-MXI-2 interface (with LabVIEW software)
3 axis-motion stage ( X-Z motorized, Y manual)
Oscilloscope TDS 380
Timers, discriminators, logic units
Xp2262 used as a trigger PMT in test with cosmic rays.
Amplada de banda oscilloscope
The last ones are in a NIM standard
Funcionament de la font de llum

26. Some pictures of the setup

27. Some pictures of the setup

28. Some pictures of the setup

29. Some pictures of the setup
The LED pulser

30. Summary

31. Summary The setup in Barcelona has been shown
It is still under construction aiming at a fully automated system
Some measures have been made in order to test the performance of the PMT and calibrate the system

32. Future plans

33. Future plans Deadline: October 2003
Reduction of the noise of the LED pulse (1 month) in parallel with signals analysis
Which tests are to be performed on each PMT?
Absolute Gain of each channel
Tests to be performed on some PMTs?
Linearity
Scintillator pulse analysis (Crosstalk)
Deadline: means a massive test has to be designed and ready by October 2003
Fully Automated
Criteria to decide which channels of which PMTs must be tested
microVolt noise
Can we get a complete set of pads in order toe reproduce the system in our Lab?

34. Open questions

35. Open questions
Define the tests to be performed on each tube & criteria to decide which cannels
Base study status
Aging problem
Performance under magnetic field?
Possibility to test in the lab a complete set of Scintillators-fibres-PMT
I have been abroad (Aging problem)