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Timing Counter status @ july 2004

Explore the progress and key features of the Timing Counter project, including PM characteristics, integration with DC, and resolution achievements. Key focus on PM testing, gain measurements, and ongoing system tests. Discover implications for improved path length, geometric matching, and response uniformity. Follow the timeline of procurement procedures, PMT and APD evaluations, and detailed evaluations for system performance. Delve into the challenges and advancements in APD selection, testing, and dynamic parameters' impact on timing precision.

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Timing Counter status @ july 2004

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  1. Timing Counterstatus @ july 2004

  2. Timing Counter Activities • Timing resolution: 100 ps FWHM havebeen achieved. • PM’s characteristics in the COBRA magnet: gain and timing. • Full charactherisation of single TC’s counter is started • Final design and integration with DC is started • Ф-detector : APD directly from Hamamatsu

  3. From COBRA center 105 cm 25 cm 8.5º 30º 30º 10º B B TC key features PM active diameter Scintillator Cross Section 39x39 mm 70º *Note: data not corrected for time-walk effect PM section ☺Increase Positron Path-Length ~ 5 cm ☺Improve Geom. Matching Scint.-PMT ☺Tilt the PM @ ~30º respect Magn. Field →Rotated Scint. Slab improves response uniformity and timing performance due to coincidences. 0.75 T 1.05 T

  4. PM Drift Chamber assembly COBRA Magnet Scintillator slab Gain and TTS in the COBRA Magnet (April 04) Test of PM’s gain and timing resolution in the final operating conditions

  5. Gain vs Rate Zero field 1.05 T 27.5º The Gain vs Rate at 1500 V in zero field is fully recovered at 1.05 T and 27.5º at 2100 V. Unallowable increase of biasing voltage are needed at 0º.

  6. Gain Vs Bias at several angles +10º Max gain curve in magn. field Same gain +10º

  7. RMS timing resolution vs p.e. attenuator 60ps pulsed blue Laser 100um Fiber Laser beam illuminates the whole photocatode PM

  8. 50x39 mm • Conclusions: • 2” PMs allow to obtain the target resolution • At first order, the resolution is limited by the number of photoelectrons (light output from scintillator, quantum efficiency of PM, coupling scintillator-PM[2”], which has 39 mm dia. active area) • At second order, the slew rate could be used to improve the resolution in small signal regime: we have demonstrated that amplification recovers the timing resolution. • 2” PMs can supply 100uA -maximum- current ( 10uA for 1.5” PMs) • 2” PMs Lifetime=100uAx100h which correspond to 2.3 years at the event rate of 50kHz @ gain of 6x105. An increase of a factor 2 can be easily obtained. • To be done: • First systematic tests of single element of TC started in the run (May, 31 – June, 12) and will continue in the Frascati BTF • Finalize the design of TC and integration with DC 39x39 mm

  9. Single Counter Response Study

  10. BC408 Very Preliminary Time Resolution FWHM (ps) BC404 Position (mm) Single Counter Response Study • 39x39 slab in rotated configuration simulating a positron trajectory @ 40.5° along z and 70°in radial plane

  11. TC inside the COBRA

  12. 3D view of TC

  13. Scint. Fibers 5 x 10 mm APD Curved detector (triggering) • The design of the curved detectors has been modified in order to match the budget limits for procurement of virgin APD form Hamamatsu (159 Euro/each). • ~ 80 scintillating fibers and 160 APD per each TC. • Procurement preliminary procedure started

  14. 2002 2003 2004 2005 PMT Evaluation Beam Test PMT procur. APD Evaluation APD procur. APD test Design Procur & Manuf. Assembly PMT Evaluation Beam Test COBRA Test PMT procur. New APDs APD Evaluation APD procur. APD test APD procur. Design Procur & Manuf. Mechanical matching BG test Design Manufactoring Assembly Test Milestone Timing Counter Schedule Full installation

  15. - detector (triggering) • We found good APDs with high S/N ratio that we tested at PSI and LNF (Frascati) e- beam Pure e-beam

  16. - detector (triggering) • But, only about 10% of the selected APDs are good enough • Huge spread in dynamic parameters not predictable from static parameters [left figure] • The CMS selection and conditioning of the first batch of APDs is not applicable to MEG (we are working at few Volts from Vbkd – high gain- and we are interested to high slew rate and high S/N for timing purpose) • For comparison new APDs from Hamamatsu have similar response[right figure] • More work is needed to better understand the correlation between static and dynamic parameters of CMS APDs. from CMS selection From Hamamatsu

  17. Copper block APD Splitters Pulsed Laser Peltier Cell 1/1000 attenuator Integrating Calibrated Photometer Fast Photodiode Photomultiplier Status of test and procurements of APD APD test bench in Genoa About 10% can be accepted

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