A Dedicated Calibration Tool For The Meg And Meg Ii Positron Spectrometer

The MEG experiment has set the latest limit of 5.7 x 10(-13)(90 % C.L.) on the branching ratio of the charged lepton flavor violating decay mu(+) -> e(+)gamma, making use of the most intense continuous surface muon beam in the world at the Paul Scherrer Institut (PSI), Villigen, Switzerland. High resolutions in terms of energy, timing and relative opening angle are needed in the detection of the e(+) and gamma, requiring careful calibration and monitoring of the experimental apparatus. A dedicated calibration method involving Mott scattering of a monochromatic positron beam at energies close to the MEG signal energy is presented. (C) 2015 Elsevier B.V. All rights reserved.