Speaker
Description
A new type of SiW electromagnetic calorimeter is being developed using digital pixel sensors. The R&D is performed in the context of the FoCal upgrade within the ALICE experiment and is related to studies of imaging in proton CT; it is applicable to other future collider projects such as EIC, ILC, CLIC or FCC. Based on a proof of principle with a first digital calorimeter prototype, we have constructed an advanced second prototype, EPICAL-2, using ALPIDE MAPS sensors. Binary readout is possible due to the pixel size of $\approx 30 \times 30 \, \mu \mathrm{m}^2$. The prototype consists of alternating W absorber and Si sensor layers, with a total thickness of ~20$X_0$, an area of $\mathrm{30mm\times30mm}$, and ~25 million pixels. It has been successfully tested with cosmic muons and with test beams at DESY and the CERN SPS. First results have been published in [1], showing good energy resolution and linearity.
We will report on recent updates of performance results and comparisons to detailed MC simulations. The spatial precision of event-by-event measurements of the showers allows unprecedented studies of the shower shape, providing unique feedback to GEANT developers. The detector also features two-shower separation capabilities at extremely small distances. Further studies include a three-dimensional parameterisation of showers and electron/photon discrimination from hadrons. We will also discuss the limitations of the currently used sensor technology and perspectives for future development of digital calorimetry.
[1] J.Alme et al 2023 JINST 18 P01038
