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

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M. Bonesini INFN Milano

PMTs tests in Milano (M. Bonesini, M. Rayner, S. Terzo)

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

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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

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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 ($$$)

Ghislain “TOF1/2 cage”

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

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PMTs tests: conventional PMTs tests: conventional PMTs shieldingPMTs shielding

TOF0 PMTs requires no shielding, aside 1 mm -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

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Problem: R4998 can bare Bperp but not B//

B//< 50 Gauss fine; B_|_ < 100-120 Gauss fine eventually additional

-metal or soft iron

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

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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

Background infos

MIB test magnet: coil with 5 windings for fields up to 600-650 G

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

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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

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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

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R. Bertoni, M. Bonesini, M. Rayner, S.Trezzo

INFN MIBChanged 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

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• 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

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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

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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

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TOF PMTs: only 1 mm mu metal

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

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Timing measurements:

1. START laser sync out

2. STOP PMT signal after LE PLS 707 discriminator + PLS inverter

• MCA + Silena 7422 QVT

• Measure t=start-stop

STARTSTOP

LE PLS707

discr

Silena QVT

PMT

Delay+inverter

Laser sync

AVTECH pulser

MCA

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

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FE360 shielding 5x5 cm2 + 1mm mu-metal : 0 cm extension

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

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

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Fe360 5x5 cm2 shielding + 1mm mu-metal : 1cm extension

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

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

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Fe360 5x5 cm2 shielding + 1mm mu-metal: 2 cm extension

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

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

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0 cm

Extending the Fe box beyond the mu-metal shielding makes it much more effective

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

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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

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Local shielding of TOF2Assuming 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

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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

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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 teamsProposal: 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)