Speaker
Description
The upgrade of the MEG experiment, MEGII, has started physics data taking
in fall 2021, collecting ~ 8x10^13 mu on target during 34 days of DAQ live
time, searching for the Standard Model violating Lepton Flavor Violating
Decay mu->e gamma with sensitivity improved by an order of magnitude.
During this period the pixelated Timing Counter (pTC), a time of flight
detector devoted to extrapolating the muon decay time on target by
measuring the positron hit time, has been fully readout and has
operated stably.
The detector consists of 512 fast plastic scintillator pixels
(120x50(40)x5 mm^3) readout by two arrays of 6 SiPM each connected in series
glued on opposite sides.
Its goal is to achieve a resolution on positron hit time of about 40 ps by
exploiting multiple-hits events.
This contribution will show how the detector achieved the design performance
during the 2021 run reaching ~39 ps for events with 8 hits corresponding to the average number of hits expected from MC simulation for mu->e gamma events.
This result was obtained in spite of a suboptimal performance of electronic
noise and of a slow degradation in dark current due to irradiation damage
on SiPMs.
Instrumental in achieving this performance was a full set of hardware and
software calibration tools developed to align precisely in time and space
the counters relative to each other and to the rest of the MEG II detector.
| Collaboration | MEGII |
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