Speaker
Description
The Search for Hidden Particles (SHiP) experiment is a planned general-purpose facility at the CERN Beam Dump Facility designed to explore the hidden sector at the intensity frontier. A primary physics goal of SHiP is the search for long-lived, weakly interacting particles, such as Axion-Like Particles (ALPs) decaying into a diphoton final state ($a \to \gamma\gamma$). Because these decays occur at a displaced vertex without associated charged tracks, the electromagnetic calorimeter (ECAL) must be able to provide the missing tracking information by reconstructing the shower directions.
We have developed a high-granularity sampling calorimeter concept based on plastic scintillator strips. The detector employs a unique "split" architecture, where longitudinal modules are separated to provide a significant lever arm for the 3D reconstruction of the shower axis.
This talk presents the comprehensive R&D path for the SHiP ECAL. We discuss the physics-driven requirements for pointing calorimetry and detail the detector's 3D segmentation strategy. Performance results are presented from a recent test beam at CERN SPS using a full depth conceptual prototype, including the corresponding GEANT4 simulations. These studies demonstrate an angular resolution of $\mathcal{O}(\text{few mrad})$ for GeV-scale showers and robust Particle Identification (PID). Finally, we report on the current optimisation of the final detector setup, aiming at a technological prototype.