ToF -LR HV upgrade

Faculty of Physics, University of Belgrade

Collaboration meeting, Dubna 8th of April, 2014.

ToF-LR Upgrade

Jovan Puzović,Faculty of Physics, Belgrade


Collaboration meeting, Dubna, 8.4.2014. out of 24Jovan Puzović, Belgrade SHINE team

ToF-LR HV upgrade- Current status:

1) 2 Caen crates (right 1 and 2) replaced with BG crates

2) Both crates connected via RS485 link to computer in counting room

3) Connection established, beta version of monitoring program working well



ToF-LR HV upgrade

All hardware finished!



ToF-LR HV upgrade

- Crate R3 already in CERN, wait to be installed, Crate R4 still in Belgrade

- All distributors (HV readout) have to be calibrated!

- Finishing of the work foreseen for August this year



Pixels repair

- ToF (especially ToF-L) performance decreases with time,too many pixels on ToF-L out of order, repair needed

- Currently, 98 pixels on ToF-L don't work, and 24 on ToF-R (our analysis, based on ToF online monitoring program)

- Szymon analysis (pp80, more sophisticated) and our new analysis (pp158, 2009) show even worst situation!



ToF-LR pixel efficiency



Pixels statistic

February 2013, Be @ 30 GeV



Pixels statistic

Left side: 81 dead pixels (9.1%) (~70 PMT!)17 almost dead (1.9%)-------------------------------98 not working (11.0%)

Right side: 20 dead pixels (2.2%) (~16 PMT!) 4 almost dead (0.5%)-------------------------------24 not working (2.7%)



Cassette inspection



Broken PMT



Spare parts

• We found some spare PMTs with scintilators

6 cm – 1 pcs (needed ~30)7 cm – 17 pcs (needed ~30)8 cm – 25 pcs (needed ~30)

-------------- 43 pcs (needed ~90)

• Replacing foreseen for middle of August (13.8 - 23.8)



New parts

- FEU-87 doesn’t produce any more

- No leftovers in Dubna!

- Replacement: Hammamatsu R3478 from Buda wall (~400 pieces with HV voltage dividers, optical coupled with grease, can be use again)

- Smaller then FEU, mechanically can be adapted to fit in existing cassette (photocatode 15mm instead of 22!)



New parts



Hammamatsu PMT- Wavelength (Peak): 420nm- Dynode Stages: 8

(FEU-87 11!)- Anode to Cathode Supply Voltage: 1700V- Max Anode to Cathode Voltage: 1800V- Gain Typ.: 1.7 x 106 - Rise Time Typ.: 1.3 ns

- Assembled with our ToF-LR scintilators an tested (cosmic)- Nominal HV (1700V) too high (gain too high)! Use ~1000V- More current consumption (~30%) compared to FEU-87!



Hammamatsu PMT



PMT from the right wall



Pulse shape



Amplitude spectra



Conclusion

- Hammamatsu PMTs performed very well during testing (in spite of their smaller photocatode)

- Seems that its possible to produce replacement for broken pixels on the ToF left wall based on Hammamatsu PMTs

- However, lots of problems are foreseen!



Conclusion

- A lot of mechanical work needed!- new cassettes have to be produced (12 of them)- new scintilators wanted- electrical cables have to be extended- mechanical support for (smaller) PMTs for tight fit to existing space in cassette- light guides for laser calibration system needed- replacing the old cassette with the new one, then use good FEU-87 pixels as spare part for the rest of the wall- HV calibration needed! - Current consumption?



Conclusion

- Price (in CHF and man power) cannot be estimate at the moment – mostly for traveling expenses and men work!

- Further study needed – how to mechanically adapt smaller PMTs to tight fit in existing cassette space?

- Cost-benefit analysis needed: what we will get and how much does it cost!



Thank you!

ToF -LR HV upgrade

Documents

Transcript of ToF -LR HV upgrade