Eur. Phys. J. C (2013) 73: 2365
https://doi.org/10.1140/epjc/s10052-013-2365-2

Special Article - Tools for Experiment and Theory

The MEG detector for μ ⁺→e⁺ γ decay search

¹ Paul Scherrer Institut PSI, 5232, Villigen, Switzerland
² Swiss Federal Institute of Technology ETH, 8093, Zurich, Switzerland
³ ICEPP, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
⁴ INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127, Pisa, Italy
⁵ Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, 56127, Pisa, Italy
⁶ University of California, Irvine, CA, 92697, USA
⁷ INFN Sezione di Pavia, Via Bassi 6, 27100, Pavia, Italy
⁸ Dipartimento di Fisica, Università di Pavia, Via Bassi 6, 27100, Pavia, Italy
⁹ INFN Sezione di Roma, Piazzale A. Moro, 00185, Rome, Italy
¹⁰ Dipartimento di Fisica, Università di Roma “Sapienza”, Piazzale A. Moro, 00185, Rome, Italy
¹¹ INFN Sezione di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
¹² Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146, Genoa, Italy
¹³ Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan
¹⁴ Budker Institute of Nuclear Physics of Siberian Branch of Russian Academy of Sciences, 630090, Novosibirsk, Russia
¹⁵ KEK, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan
¹⁶ Joint Institute for Nuclear Research, 141980, Dubna, Russia
¹⁷ INFN Sezione di Lecce, Via per Arnesano, 73100, Lecce, Italy
¹⁸ Dipartimento di Matematica e Fisica, Università del Salento, Via per Arnesano, 73100, Lecce, Italy
¹⁹ Novosibirsk State Technical University, 630092, Novosibirsk, Russia

^* e-mail: paolo.cattaneo@pv.infn.it

Received: 30 November 2012
Revised: 8 February 2013
Published online: 3 April 2013

Abstract

The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay μ ⁺→e⁺ γ by using one of the most intense continuous μ ⁺ beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.