FCal2 Mapping Problem P.Krieger, Toronto LAr Week, Munich, April 2011
Bad Channel / FCal Positioning Studies • Plot of <Ecell> vs. rT (transverse distance of FCal cell from beamspot) • Here using run 169045 (Pb-Pb collision data: lots of FCal energy FCal1A FCal1C
FCal2A rT < 180 mm i.e. FCal2A iϕ = 01, iη = 29 A2.01.29 A2.05.29 A2.09.29 A2.13.29 A2.02.29 A2.06.29 A2.10.29 A2.14.29
FCal2C rT < 180 mm C2.01.29 C2.05.29 C2.09.29 C2.13.29 C2.02.29 C2.06.29 C2.10.29 C2.14.29
Look at FCal2A Initial thought: A2.01.29 <--> A2.02.29 A2.05.29 <--> A2.06.29 A2.09.29 <--> A2.10.29 A2.13.29 <--> A2.14.29 since, according to mapping spreadsheet, or example, A2.06.29 has smaller rT than A2.05.29 But look more closely…..
Drawing close to 1/10 scale View is of readout side of FCal2A (so towards the IP since that is the rear face)
FCal2A Signal Endplate Drawing FCal2A Readout Tile Drawing Drawing close to 1/10 scale Note that these views are from the same side, so should match.
FCal2C Inner Edge Tiling FCal2A Inner Edge Tiling Location of downward pointing fish-shaped channel consistent with FCal2 Tiling drawings.
Summary • FCal2 channel mapping is OK (there is no mis-cabling). • FCal2 electrode mapping is wrong tube layout pattern for entire FCal2 (both sides) is the mirror image of what is should be (and layout is not mirror symmetric). • The tube layout assumed for a given channel (iϕ,iη) is that that actually belonging to the channel with the same iη value but reflected iϕ. • This affects the shape and position of every FCal2 channel, but the effect is rather small except for irregular-shaped channels which have rather different shapes on the -x and +x side of the detector: in practical terms this mean un-summed channels at the inner and out edge. • This problem is not present for either the FCal1 or FCal3 modules. • The mapping needs to be fixed. But this will take a bit of time. • This will also necessitate regeneration of the nearest neighbour map (Sven) as well as changes to the simulation.