sPHENIX tracking discussion

["Michael P. McCumber" <mccumber AT bnl.gov>]

Hello all,

Marzia asked me after the meeting to check the performance of a 4 layer MAPS tracker (3 inner vertex plus one outer layer). Of course such a long projection length (~few cm to 65 cm) starting with a small lever arm can not be done without fakes and the tracking is often picking the wrong outer cluster at higher pt---the ghost rejection should probably be turned off as it starts killing correct matches in favor of better false matches.

Here are those plots:

However the purities in central heavy ion collisions (bottom row, 3rd plot) aren't really that match worse than the ganged strip design, but since the momentum comes from only the single outer cluster it has more immediate impact on the track performance.

If we were to move this single outer layer inward the fake rate would drop, but there would be a tradeoff in correct match momentum resolution.

Mike

PS: I know from previous work that removing a single intermediate layer from the ITS doesn't impact the performance so I a 5-layer design with a single intermediate layer in-between should be a big improvement over this.

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Michael P. McCumber, PhD
Los Alamos National Laboratory
505-709-8161