R4998 tests in B field M. Bonesini - MICE CM20 RAL INFN Milano M. - - PDF document

• M. Bonesini - MICE CM20 RAL

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• M. Bonesini

INFN Milano

R4998 tests in B field

• M. Bonesini - MICE CM20 RAL

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Conventional Conventional PMTs PMTs shielding shielding

TOF0 PMTs requires no shielding, aside 1

mm µ-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 CM20 RAL

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Advocated solutions:

Solution A (“Ghislain cage”): extra shield (50

mm) connected with joints to first shield (100 mm) and local shielding of PMTs (µ-metal only if 420 mm hole)

Solution B: no-extra shield

but heavy local shielding of PMTs a la D0 (test results reported in MICE-NOTE-DET-201)

• M. Bonesini - MICE CM20 RAL

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B field with one 100 mm iron shield (current design)

Figure 4: B at the position of TOF2 with the 100 mm iron shield.

Figure 5: B⊥ at the position of TOF2 with the 100 mm iron shield.

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Figure 6: Radial and longitudinal field components at TOF2 (z=664 cm) as a func- tion of r with 100 mm thick iron shield.

B field is ~ 200-300 G / / ; ~ 1000 G _| _ at r= 30-35 cm (PMTs position)

• I doubt it can be shielded

with individual PMTs shields, preserving good timing properties

• this point to 2nd shield, but

we will try to test PMTs “exotic shieldings” by building a 400 G lab solenoid

My old transparency at RAL CM16 BUILT: coil with 5 windings for fields up to 700-800 G

• M. Bonesini - MICE CM20 RAL

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Used test solenoid

• Laser source (Nichia Blue laser diode + up to 1MHz

Avtec fast pulser: signals 100 ps- 2 ns)

• field up to 600 G
• Use of different shieldings: mu-metal only, additional Fe

shielding, …

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PMT test system

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1 mm µ-metal shielding

B/ / < 60 Gauss fine; B_| _ < 150 Gauss fine eventually additional µ-metal or soft iron

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[Gauss]

solenoid

B 10 20 30 40 50 60 70 80 90

(0)

(B)/V

V

0.2 0.4 0.6 0.8 1 1.2 1.4

• nly muMetal, B field parallel

[Gauss]

solenoid

B 10 20 30 40 50 60 70 80 90

FWHM(B)/FWHM(0)

0.5 1 1.5 2 2.5 3 3.5

• nly muMetal, B field parallel

[Gauss]

solenoid

B 20 40 60 80 100 120 140 160 180 200

(0)

(B)/V

V

0.2 0.4 0.6 0.8 1 1.2 1.4

• nly muMetal, B field orthogonal

[Gauss]

solenoid

B 20 40 60 80 100 120 140 160 180 200

FWHM(B)/FWHM(0)

0.5 1 1.5 2 2.5 3 3.5 4

• nly muMetal, B field orthogonal

average of 10 PMTs

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D0 tests (note # 2706) (brought

to our attention by Ludovico)

Questions:

• It will work for R4998 1” PMTs?
• Tests to be done for Gain + timing

Box shielding

See results later

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R4998 PMTs: Fe-360 box shielding

From 5x5 to 6x6 cm2

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Pure steel ARMCO

[Gauss]

solenoid

B 100 200 300 400 500 600

(0)

(B)/V

V

0.2 0.4 0.6 0.8 1 1.2 1.4 feARMCO, 5x5 no extension [Gauss]

solenoid

B 100 200 300 400 500 600

FWHM(B)/FWHM(0)

0.2 0.4 0.6 0.8 1 1.2 1.4 feARMCO, 5x5 no extension [Gauss]

B 100 200 300 400 500 600

(0)

(B)/V

V

0.2 0.4 0.6 0.8 1 1.2 1.4

feARMCO, 6x6 no extension

[Gauss]

B 100 200 300 400 500 600

FWHM(B)/FWHM(0)

0.2 0.4 0.6 0.8 1 1.2 1.4

feARMCO, 6x6 no extension

5x5 cm2 6x6 cm2

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Comparison between shields

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Sketch of TOF2 local shielding

• 1. Final design to be

dictated by shielding + mechanics

• 2. A final single PMT

shielding will be tested before production of local shielding

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Conclusions

PMTs shielding with massive Fe blocks

• f pure steel ARMCO seems adequate

some extra work needed for mechanics

• f TOF2 (work together with Roma3

mechanics shop)