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## FCal2 Mapping Problem

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**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.