The Phase 2 Upgrade of the LHCb Calorimeter system

The purpose of the Phase 2 LHCb Upgrade is to make it able to work at luminosity of (1. . . 2); 10$^{34}$ cm $^{-2}$ s $^{-1}$ Upgrade will require a major revision of the LHCb Calorimeter system. The plan is to collect ∼300 fb$^{-1}$ of data during 3–5 years. The Phase 2 Upgrade will require a major revision of the LHCb Calorimeter system. The increased instantaneous and integrated luminosity will result in very high particle density and radiation doses in the central area of the detector. In these conditions, ECAL has to provide high quality energy and position measurement for electromagnetic showers, as well as separation of two closely lying showers. The choice for the central part of ECAL can be a sampling scintillation calorimeter with dense tungsten-based converter. The radiation hard crystal scintillators, like GAGG:Ce, can be used as active elements. The peripheral areas with moderate radiation doses can be instrumented with calorimeter modules based on plastic scintillator. Another requirement for the LHCb Phase 2 Upgrade ECAL is the ability to measure the time of arrival of the photon or electron with an accuracy of few tens of picosecond. At high luminosity, such time measurement is a powerful tool helping to correctly assign electromagnetic showers to primary vertices. A dedicated timing layer in front of ECAL can be used for time measurements; another option is to use the “intrinsic” time resolution of the ECAL modules. An R&D; campaign was started to optimize the Upgrade 2 ECAL structure. It includes studies of scintillating materials, in particular irradiation measurements, beam test studies of the performance of various ECAL module prototypes, both for central and peripheral areas, and simulation studies to find the optimal detector layout. Here we are presenting the current status and the first R&D; results of the LHCb Calorimeter upgrade Phase 2.