Speaker
Description
"The LHCb Upgrade II will operate at instantaneous luminosities up to 1.5×10³⁴ cm⁻²s⁻¹ and collect about 300 fb⁻¹ during the HL-LHC era. In the central region of the electromagnetic calorimeter this means MGy-level accumulated dose, more than 50 pile-up interactions per bunch crossing, and the need to keep an energy resolution of about 10%/√E ⊕ 1% while adding timing at the level of O(10 ps). The PicoCal concept proposed for Upgrade II addresses this with spaghetti-calorimeter (SpaCal) modules made of tungsten absorber and garnet scintillating fibres, and the key material for the innermost modules is an ultra-fast, radiation-tolerant GAGG:Ce crystal.
This talk summarises the GAGG R&D carried out by the Peking University group together with the LHCb ECAL Upgrade II R&D group and the 26th Research Institute of CETC (SIPAT). Czochralski-grown GAGG:Ce with heavy Mg/Ce co-doping has reached an effective decay time of about 10 ns in ingots of Ø45 mm × 100 mm; the remaining issues are residual slow components around 20 and 50 ns, top-to-tail non-uniformity along the ingot, and the radiation hardness of heavily doped material, which is still being characterised."
