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Published April 2016 | public
Journal Article

Characterization of a 5 x 5 LYSO Matrix Calorimeter Prototype


In this paper, we present measurements of the energy and the time resolution of the Lutetium-Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The prototype calorimeter matrix consisted of 25, 3 × 3 × 130 mm^3, LYSO crystals readout by 10 × 10 mm^2 Hamamatsu APDs. The prototype has been tested both with the tagged photon beam at MAMI, Mainz, Germany, and with the e-beam of BTF, Frascati. The energy of particles used ranges between 61.3 and 187.1 MeV (80-130 MeV) for photon (electron) beams. While the MAMI data shows a negligible beam energy spread, we observe a 3%-5% contribution related to the beam in BTF sample. After correcting this effect, we obtain a global energy dependence of the energy resolution described by the formula σE/E_(dep) = a/√(E_(dep)/GeV) ⊕ b, with a = (0.59 ± 0.12)% and b = (3.63 ± 0.21)%. The simulation is in good agreement with data if we add an additional contribution due to the intrinsic LYSO fluctuation of 2.6%. We present also the measurements of the time resolution. The measurements have been performed using the e- beam BTF in the energy range from 100 to 400 MeV. A resolution of (161 ± 3) ps at 100 MeV has been achieved. The energy dependence of the resolution has been fitted with following parametrization: σ_t(E) = a/ √E/GeV ⊕ b, where the stochastic term and the constant term are determined to be a = (50 ± 1) ps and b = (40 ± 3) ps, respectively.

Additional Information

© 2016 IEEE. Manuscript received July 21, 2015; revised December 04, 2015; accepted January 25, 2016. Date of current version April 15, 2016. The authors are grateful to many people for the successful realization of the matrix. In particular, they thank all the LNF mechanical shop for the realization of the support and the APD boxes. They also thank the whole MAMI and BTF staff for providing the beam time and helping them in getting a smooth running period. They express their warmest thanks to A. Thomas and L. Foggetta for adjusting and tuning the beam to their detector needs.

Additional details

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