The Timing Counter of the MEG experiment: calibration and performance

TL;DR

The paper details the design, calibration, and performance of the Timing Counter in the MEG experiment, crucial for precise timing measurements to detect rare muon decays and suppress background noise.

Contribution

It introduces the design and calibration procedures of the MEG detector's Timing Counter, highlighting its performance in precise timing measurements for rare decay detection.

Findings

Achieved high timing resolution for positron detection.

Validated the Timing Counter's effectiveness in background suppression.

Demonstrated reliable operation of scintillating bars and fibers.

Abstract

The MEG detector is designed to test Lepton Flavor Violation in the $\mu^+\rightarrow e^+\gamma$ decay down to a Branching Ratio of a few $10^{-13}$. The decay topology consists in the coincident emission of a monochromatic photon in direction opposite to a monochromatic positron. A precise measurement of the relative time $t_{e^+\gamma}$ is crucial to suppress the background. The Timing Counter (TC) is designed to precisely measure the time of arrival of the $e^+$ and to provide information to the trigger system. It consists of two sectors up and down stream the decay target, each consisting of two layers. The outer one made of scintillating bars and the inner one of scintillating fibers. Their design criteria and performances are described.