Optimizing Endcap Navigation Rick Wilkinson

Endcap Compatibility Checks: Old method, CSC & RPC Propagate to best-matching chamber Propagate to center of layer Keep bouncing until a neighbor is incompatible Propagate back to check neighbors Rick Wilkinson

Endcap Compatibility Checks: Old method, CSC & RPC Propagate to center of layer Propagate to best-match chamber Check left neighbor Check right neighbor Propagate back up to test neighbor’s neighbor Rick Wilkinson

New Technique Make a DetLayer consisting of two internal DetLayers. Class’s methods go to the nearer of the two layers first. No external code changes needed In CSC, # of propagations per layer goes from 3.8 to 1.2 class MuRingForwardDoubleLayer : public RingedForwardLayer { MuRingForwardLayer theFrontLayer; MuRingForwardLayer theBackLayer; }; Rick Wilkinson

Results, Standalone Muons Endcaps now have half as many propagations Overlaps still bad, because of 3 seeds Barrel-barrel, barrel-endcap, and endcap-endcap Overall Standalone Speedup: ~5% Half of CPU time spent in propagation ~1/3 of propagation time “short-distance” (2-30 cm) ~1/3 of short propagations eliminated Rick Wilkinson

Conclusions Factored CSC and RPC overlapping DetLayers into front and back layers. Eliminates many propagations. Speeds up Standalone Muons by ~5%. Rick Wilkinson