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M. Bonesini , F. Strati INFN Milano

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).

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M. Bonesini , F. Strati INFN Milano

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  1. Tests at LASA for MICE Tof PMTs M. Bonesini, F. Strati INFN Milano M. Bonesini - Osaka coll. meeting

  2. 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) 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. M. Bonesini - Osaka coll. meeting

  3. 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 M. Bonesini - Osaka coll. meeting

  4. 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,R5505 BUT !!! Divider can be modified only for R4998 (going up to 1.67 MHZ) M. Bonesini - Osaka coll. meeting

  5. Test magnet at LASA (Bup to 1.2T) PMT under test M. Bonesini - Osaka coll. meeting

  6. Used laser light source • Light source: Hamamatsu fast laser ( 405 nm, FWHM 60 ps, 250 mW peak power) PLP-10 • Optical 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 M. Bonesini - Osaka coll. meeting

  7. Fine-mesh phototube Properties Under test: 1” (R5005), 1.5” (R7761), 2” (R5946). Results for G, TTS, rate efects in B-fields available soon M. Bonesini - Osaka coll. meeting

  8. Lab rate tests done with mod R4998, R7761 and R5946 in/out B-field R4998 with modified divider circuit: booste for last dynodes Nominal: up to 1.5 MHz PMT rate studies M. Bonesini - Osaka coll. meeting

  9. R4998 with modified divider (booster for last dynodes) + mu-metal shielding One specimen on loan in June 2004 for tests M. Bonesini - Osaka coll. meeting

  10. Gain in magnetic field for R4998 M. Bonesini - Osaka coll. meeting

  11. Timimg properties of R4998 M. Bonesini - Osaka coll. meeting

  12. 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. M. Bonesini - Osaka coll. meeting

  13. 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 obtained • All will be shown later M. Bonesini - Osaka coll. meeting

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