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M. Bonesini INFN Milano

PMTs tests in Milano (M. Bonesini, M. Rayner, S. Terzo). M. Bonesini INFN Milano. Outline. Hot topics TOF2 PMTs shielding TOF/KL PMTs magnetic tests: new power supply (up to 600 G), more PMTs under test TOF2 frame with local PMTs shielding Conclusions. Ghislain “TOF1/2 cage”.

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M. Bonesini INFN Milano

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  1. PMTs tests in Milano (M. Bonesini, M. Rayner, S. Terzo) M. Bonesini INFN Milano M. Bonesini - MICE CM19 RAL 07/10/07

  2. Outline • Hot topics • TOF2 PMTs shielding • TOF/KL PMTs magnetic tests: new power supply (up to 600 G), more PMTs under test • TOF2 frame with local PMTs shielding • Conclusions M. Bonesini - MICE CM19 RAL 07/10/07

  3. Ghislain “TOF1/2 cage” • Problems: • cabling (HV, signal, calibration fibers …) • checks with 3-D calculations: TOF PMTs with mu-metal shielding only can bare B// up to ~ 60 G • cost issue ($$$) M. Bonesini - MICE CM19 RAL 07/10/07

  4. PMTs tests: conventional PMTs shielding • TOF0 PMTs requires no shielding, aside 1 mm m-metal due to small B field (B << 50 Gauss, Kevin private communication) • TOF1/2 even after the 100 mm global iron shielding needs some additional shielding to use conventional PMTs (as B// ~ 200-300 G, B _|_ ~ 1000 G) M. Bonesini - MICE CM19 RAL 07/10/07

  5. Problem: R4998 can bare Bperp but not B// B//< 50 Gauss fine; B_|_ < 100-120 Gauss fineeventually additional m-metal or soft iron M. Bonesini - MICE CM19 RAL 07/10/07

  6. Background infos • B field is ~ 200-300 G //; ~ 1000 G _|_ at r=30-35 cm (PMTs position) • It seems that single PMTs may be individually shielded preserving good timing properties • the design of the final shielding may be optimized, using our test facility at MIB MIB test magnet: coil with 5 windings for fields up to 600-650 G M. Bonesini - MICE CM19 RAL 07/10/07

  7. Advocated solutions: • Solution A (“Ghislain cage”): extra shield connected with joints to first shield (100 mm) • Solution B: no-extra shield but heavy local shielding of PMTs a la D0 (test magnet at Milano Bicocca) M. Bonesini - MICE CM19 RAL 07/10/07

  8. D0 tests (note # 2706) • Problems: • It will work for R4998 1” PMTs? • Tests to be done for Gain + timing See some results later M. Bonesini - MICE CM19 RAL 07/10/07

  9. R. Bertoni, M. Bonesini, M. Rayner, S.Trezzo INFN MIB Changed with a big 200A (30 V) power supply from Eutron (on loan) -> B up to 600 G M. Bonesini - MICE CM19 RAL 07/10/07

  10. Laser source (Nichia Blue laser diode + up to 1MHz Avtec fast pulser: signals 100 ps- 2 ns) • field was up to 470 G (40A power), now up to 600 G with new power supply (on loan) • signal comparable to BTF (~ 200-700 mV) • Use of different shieldings: mu-metal only, additional Fe shielding, … M. Bonesini - MICE CM19 RAL 07/10/07

  11. B field calibration • B is uniform to some % in a region +- 5 cm from solenoid center • calibration with a Hirst GM404 Hall probe M. Bonesini - MICE CM19 RAL 07/10/07

  12. KL PMTs tests More than fine !!! and in addition Ludovico has put thicker shielding (7.6 cm x 7.6 cm) and connected shields M. Bonesini - MICE CM19 RAL 07/10/07

  13. TOF PMTs: only 1 mm mu metal M. Bonesini - MICE CM19 RAL 07/10/07

  14. AVTECH pulser PMT • Timing measurements: • START laser sync out • STOP PMT signal after LE PLS 707 discriminator + PLS inverter • MCA + Silena 7422 QVT • Measure Dt=start-stop Laser sync LE PLS 707 discr Delay+inverter START STOP MCA Silena QVT M. Bonesini - MICE CM19 RAL 07/10/07

  15. FE360 shielding 5x5 cm2 + 1mm mu-metal : 0 cm extension M. Bonesini - MICE CM19 RAL 07/10/07

  16. M. Bonesini - MICE CM19 RAL 07/10/07

  17. Fe360 5x5 cm2 shielding + 1mm mu-metal : 1cm extension M. Bonesini - MICE CM19 RAL 07/10/07

  18. M. Bonesini - MICE CM19 RAL 07/10/07

  19. Fe360 5x5 cm2 shielding + 1mm mu-metal: 2 cm extension M. Bonesini - MICE CM19 RAL 07/10/07

  20. M. Bonesini - MICE CM19 RAL 07/10/07

  21. 0 cm Extending the Fe box beyond the mu-metal shielding makes it much more effective M. Bonesini - MICE CM19 RAL 07/10/07

  22. Preliminary conclusions: • System tests have been extended from 400 G to 600 G (thanks loan of a new power supply of CNR IFP “Thorello”) • more statistics needed, some syst. must be reduced, the best design of local shielding must be worked out • BUT it seems that local shielding may work well for R4998 PMTs (we may also go from 5x5 cm2 to 6x6 cm2 in a bar-connected structure : more shielding !!!) M. Bonesini - MICE CM19 RAL 07/10/07

  23. Local shielding of TOF2 • Assuming local PMT shield will work for TOF2 • CAD design for TOF2 frame+local bar PMT shielding+ support • structure is not much more complicate and expensive than not shielded TOF2 ~30 Kg M. Bonesini - MICE CM19 RAL 07/10/07

  24. Local shielding of TOF2 • Some details: Inventor CAD for hanging of metal shielding blocks • If funded, all may be done at MIB M. Bonesini - MICE CM19 RAL 07/10/07

  25. Conclusions • TOF2 local shielding is a valuable (cost-effective) solution • requires some extra work from MIB mechanics shop (no extra funding required, if what promised for TOF0/1/2 will arrive) • some tests to be finalized, to be completely sure (but I am confident) • Preferred solution (if feasible) by TOF+KL teams • Proposal: NOT decide now, taking also into account delays arising from experiment (6 months beamline delay), NTA INFN funding still pending [up to now we are at 0 E or $ as you like]: continue with tests to optimize local shielding design) M. Bonesini - MICE CM19 RAL 07/10/07

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