m. bonesini , f. strati infn milano
DESCRIPTION
Tests at LASA for MICE Tof PMTs. M. Bonesini , F. Strati INFN Milano. Considerations for PMT choice. Rate capability (up to some MHz) Good timing properties (TTS) Sustain magnetic field ( about 100-200 gauss for TOF0, about .2 T for TOF2). - PowerPoint PPT PresentationTRANSCRIPT
M. Bonesini - Osaka coll. meeting
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M. Bonesini, F. Strati INFN Milano
Tests at LASA for MICE Tof PMTs
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Considerations for PMT choice
1. Rate capability (up to some MHz)2. Good timing properties (TTS)3. Sustain magnetic field ( about 100-200
gauss for TOF0, about .2 T for TOF2)
Tests at Lasa magnet test facility (end July 04, for 15 days) with Pavia MEG group to optimize choice.
Now preliminary report, more detailed report later.
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Tests done at LASA
Laser source to simulate MIP signal (about 200-300 p.e.) Laser sync out triggers VME based acquisition (TDC + QADC) 5000 events for each data point : different PMTs (fine-mesh vs mod R4998), different B-field, different inclination vs B field axis (), diff laser rate to simulate incoming particle rates
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Rate capabilities of PMTs
To have a linear signal the max ouput current must be 1/20 of the divider current (16 A for R4998, 10 A for R7761 or R5505 fine-mesh PMTs)This gives a theoretical rate capability of:
267 KHZ with R4998 167 KHZ with R7761,R5505BUT !!! Divider can be modified only for
R4998 (going up to 1.67 MHZ)
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Test magnet at LASA (B up to 1.2T)
PMT under test
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Used laser light sourceLight source: Hamamatsu fast laser ( 405 nm, FWHM 60 ps, 250 mW peak power) PLP-10Optical system: x,y,z flexure movement to inject light into a CERAM/OPTEC multimode fiber (spread 14 ps/m) PMT under test
Laser light Signal ~ 200 p.e.to reproduce a MIP as
measured with a powermeter
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Fine-mesh phototube Properties
Under test: 1” (R5005), 1.5” (R7761), 2” (R5946).Results for G,TTS, rate efects in B-fields availablesoon
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PMT rate studies R4998 with modified
divider circuit: booste for last dynodes
Lab rate tests done with mod R4998,
R7761 and R5946 in/outB-field
Nominal: up to 1.5 MHz
R 4998 R 5505 Structure Linear Focused Fine Mesh
Stages 10 15 Gain 5.7 106 5 105 B=0
1.8 104 B=1 T Rise Time 0.7 ns 1.5 ns
Transit Time 10 ns 5.6 ns Transit Time
Jitter 0.16 ns 0.35 ns
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R4998 with modified divider (booster for last dynodes) + mu-metal
shielding
One specimen on loan in June 2004 for tests
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Gain in magnetic field for R4998
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Timimg properties of R4998
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Rate effects studies for R4998
• done with available R4998 with modified divider from Hamamatsu (booster on last dynodes) on loan
•Light signal corresponds to ~ 200 p.e.
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Conclusions
Only some results on R4998 mod have been shown (we finished data taking for tests last Friday)A lot of results on fine-mesh PMTs (1”, 1.5”, 2”) have been obtainedAll will be shown later