A Si-PAD and Tungsten Based Electromagnetic Calorimeter for the Forward Direct Photon Measurement at LHC

For the forward direct photon measurement at LHC-ALICE, we propose to construct a Forward Calorimeter (FoCal). FoCal-E is a silicon and tungsten calorimeter design, consists of low granularity Si-Pad layers (LGL) for precise measurement of photon energy and a few high granularity layers (HGL) with pixel readout to achieve an excellent position resolution to separate two photons from $\pi ^0$ . We performed R&D; of LGL prototype since 2014. From results of past three years tests (2014 $\sim $ 2016) at CERN PS and SPS, LGL prototype has a good linearity and the energy resolution is about $10\%$ . In addition, good agreement with theoretical values and simulation were observed about longitudinal shower profile.