1 R4998 tests in B field M. Bonesini - MICE CM20 RAL INFN Milano M. Bonesini
Conventional PMTs PMTs shielding shielding Conventional � 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 2
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 3
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. M. Bonesini - MICE CM20 RAL 4
My old transparency at RAL CM16 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 Figure 6: Radial and longitudinal field components at TOF2 ( z =664 cm) as a func- • this point to 2 nd shield, but tion of r with 100 mm thick iron shield. we will try to test PMTs “exotic shieldings” by BUILT : coil with 5 building a 400 G lab solenoid windings for fields up to 700-800 G M. Bonesini - MICE CM20 RAL 5
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, … M. Bonesini - MICE CM20 RAL 6
7 M. Bonesini - MICE CM20 RAL PMT test system
1 mm µ -metal shielding B / / < 60 Gauss fine; B _| _ < 150 Gauss fine eventually additional µ -metal or soft iron M. Bonesini - MICE CM20 RAL 8
only muMetal, B field parallel only muMetal, B field orthogonal (0) (0) PMT 1.4 PMT 1.4 (B)/V (B)/V 1.2 1.2 PMT PMT V V 1 1 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 0 10 20 30 40 50 60 70 80 90 0 20 40 60 80 100 120 140 160 180 200 B [Gauss] solenoid B [Gauss] solenoid only muMetal, B field parallel only muMetal, B field orthogonal 3.5 FWHM(B)/FWHM(0) 4 FWHM(B)/FWHM(0) 3 3.5 3 2.5 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 10 20 30 40 50 60 70 80 90 0 0 20 40 60 80 100 120 140 160 180 200 B [Gauss] solenoid B [Gauss] solenoid average of 10 PMTs M. Bonesini - MICE CM20 RAL 9
Box shielding 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 See results later M. Bonesini - MICE CM20 RAL 10
R4998 PMTs: Fe-360 box shielding From 5x5 to 6x6 cm2 M. Bonesini - MICE CM20 RAL 11
Pure steel ARMCO feARMCO, 5x5 no extension feARMCO, 6x6 no extension (0) PMT 1.4 (0) (B)/V PMT 1.4 (B)/V 1.2 PMT V 1.2 PMT 1 V 5x5 cm 2 1 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 100 200 300 400 500 600 0 B [Gauss] 0 100 200 300 400 500 600 solenoid B [Gauss] solenoid feARMCO, 5x5 no extension feARMCO, 6x6 no extension FWHM(B)/FWHM(0) FWHM(B)/FWHM(0) 1.4 1.4 1.2 1.2 1 1 0.8 0.8 0.6 0.6 0.4 0.4 6x6 cm 2 0.2 0.2 0 0 0 100 200 300 400 500 600 0 100 200 300 400 500 600 B [Gauss] B [Gauss] solenoid solenoid M. Bonesini - MICE CM20 RAL 12
Comparison between shields M. Bonesini - MICE CM20 RAL 13
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 M. Bonesini - MICE CM20 RAL 14
Conclusions PMTs shielding with massive Fe blocks of pure steel ARMCO seems adequate some extra work needed for mechanics of TOF2 (work together with Roma3 mechanics shop) M. Bonesini - MICE CM20 RAL 15
Recommend
More recommend
