Study of Si-W sampling calorimeter for ALICE upgrade through simulation and prototype tests

In this abstract we focus on the development of a Si-W type sampling electromagnetic calorimeter to be placed in the forward rapidity region in the ALICE experiment at CERN as a suggested upgrade (Forward Calorimeter; FoCal). The FoCal consists of 20 alternating layers of tungsten (~1 X₀) absorbers and finely segmented Si sensors. The main physics goal of this detector is to elucidate partonic structure of the initial state, where gluon saturation a.k.a. the Color Glass Condensate could occur. FoCal is planned to be installed after the Long Shutdown (2024-2026) in the ALICE detector at Z≈7m from the interaction point (3.3<η<5.3) in order to measure EM particles in the forward rapidity region. The key purpose of the detector is to differentiate direct photons from the decay-photon background coming mostly from neutral pions. For this it requires very good two-shower separation. FoCal is designed to meet such a requirement using two types of Si sensors: very high- and low-granularity (30µm and 1cm square). The current design performance will be presented using GEANT4 simulations. In addition, the results from the low-granularity prototype tests will also be presented in this talk.