An Improved Shashlyk Calorimeter

TL;DR

This paper presents an improved design for a Shashlyk electromagnetic calorimeter with enhanced energy and time resolution, including detailed construction, material choices, and prototype testing results for photon detection efficiency.

Contribution

The paper introduces novel improvements in the mechanical design, fiber and photo-detector selection, and scintillator development for Shashlyk calorimeters, validated through prototype measurements.

Findings

Energy resolution of about 2%/sqrt{E} achieved

Time resolution of approximately 70 ps/sqrt{E} demonstrated

Photon detection inefficiency measured at 5*10^{-5} for angles >5 mrad

Abstract

Shashlyk electromagnetic calorimeter modules with an energy resolution of about 3%/sqrt{E (GeV)} for 50-1000 MeV photons has been developed, and a prototype tested. Details of these improved modules, including mechanical construction, selection of wave shifting fibers and photo-detectors, and development of a new scintillator with improved optical and mechanical properties are described. How the modules will perform in a large calorimeter was determined from prototype measurements. The experimentally determined characteristics of the calorimeter prototype show energy resolution of sigma_E/E=(1.96+-0.1)% \oplus (2.74+-0.05)%/sqrt{E}, time resolution of sigma_T = (72+-4)/sqrt{E} \oplus (14+-2)/E (ps), where photon energy E is given in GeV units and \oplus means a quadratic summation. A punch-through inefficiency of photon detection was measured to be \epsilon = 5*10^{-5} (\Theta >5 mrad).