Contraction tests of lead-stainless steel composites from room temperature to 77 K using strain gauges

ALLEGRO is a proposed FCC-ee general-purpose detector concept with a noble-liquid electromagnetic calorimeter (ECAL) as one of its central detectors. Noble-liquid calorimetry is a strong option for future particle physics experiments – for both, hadron and lepton colliders. Such an ECAL is composed of a sandwich of 1536 multi-layer read-out electrodes realised as PCBs and the same number of absorbers immersed in a liquified noble gas at cryogenic temperatures. The absorbers are made of metallic composites using a lead core and stainless steel skin. The contraction of this material, from room temperature to 77 K, is studied by using analytical, simulation and testing techniques.