LHCb CALO beam test programme Three tasks for

LHCb CALO beam test programme Three tasks for the October 2018 beam test period: 1. time resolution measurements with present ECAL modules (shashlik + PMT) • important for Upgrade Ib/II • measurements done 2. studies of a Upgrade-Ib/II ECAL prototype (W/crystal) • commissioning of the prototype done • took data with muons • studies with electrons will start this Saturday 3. studies of performance of the Upgrade-I electronics (with present ECAL modules) • a part of combined tests of the LHCb Upgrade I • ongoing 2018 -09 -21

Beam • The quality of electron beam in 2018 is not as good as before • At the standard T 4 wobbling settings: 20 Ge. V positrons with ~15% purity • The best beam can be obtained at the 80 Ge. V wobbling settings • Many thanks to Alexander and Johannes for their efforts to provide us with best possible beam! • And many thanks to the SPS users which allowed us to keep the 80 Ge. V wobbling at T 4 for so long 2018 -08 -17 2

Timing measurements for present LHCb ECAL Studied: a (spare) LHCb ECAL module, made by Shashlik technology (lead + plastic scintillator) Time reference for the beam particle: two 6 mm thick Cerenkov radiators (plexiglas) read out by MCP PMTs (kindly given to us by our Novosibirsk colleagues) Time measurement: using a CAEN DT 5742 digitizer @ 5 GS/s (200 ps/count) the time reference is (t. MCP 1+t. MCP 2)/2 the uncertainty is 22. 5 ps 30 Ge. V electrons: ~60 ps uncertainty Data were taken at a few different energies and few PMT gains. To be analyzed. 2018 -08 -17 3

The W/crystals prototype for LHCb ECAL Upgrade Ib/II • Dense radiator (W: Cu) • radiation hard crystal scintillator • longitudinal segmentation: front and rear sections • the commissioning of the prototype is done • the data with muons are taken • To do: studies with electrons: resolution at different energies and incident angles 2018 -08 -17 4

The LHCb Upgrade I combined test CALO Purpose: test new electronics and readout with real detectors. Many detector groups participate. Ongoing since yesterday. 2018 -08 -17 5