CMS Muon and SLHC Trigger

1. CMS Muon and SLHC Trigger http://www.physics.purdue.edu/~mjones/talks/mjones_cms_Aug19_2009.ppt Paid by NSF award Matthew Jones (Associate Professor) David Silvers (Graduate student, M. Jones) • Overview • Absolute tracking efficiency • Plans for SLHC trigger work • Summary 2009 DOE site visit

2. Overview • Competing goals: • Analysis of early data • Design of tracker/trigger upgrades for SLHC • SLHC trigger projections based on assumed, simulated detector response • Adopted strategy: • Understand tracking/muon performance with early collision data • Derive/validate projections where possible using these constraints • Important to have short term analysis applications 2009 DOE site visit

3. Measuring Muon Efficiency • High pT muons (eg, from Zμ+μ-): • Muons with pT below about 4 GeV might not be identified as StandAloneMuons – introduces an intrinsic bias. • Need another strategy for measuring trigger and reconstruction efficiencies of low pT muons. High pT single muon from trigger (biased) Unbiased leg found in tracker Unbiased leg found in muon chambers 2009 DOE site visit

4. Low pT Muon Efficiency • Use low mass di-muon resonances: • requires a low pT single muon trigger, prescaled to control rate • Identify J/ψμ+μ-, possibly ϒμ+μ-using triggered muon and a reconstructed track • Measure efficiency of muon selection imposed on unbiased track • Efficiencies measured relative to absolute track finding efficiency, which needs to be measured in data. 2009 DOE site visit

5. Hit Embedding Strategy • Measure absolute track finding efficiency in data using hit embedding • Tracking can be inefficient because of • Limited acceptance (physical coverage, cracks) • Failed pattern recognition (algorithms) • Embed hits from simulated, fiducial tracks into collision data • Can’t find it anymore? tracking inefficiency 2009 DOE site visit

6. Hit Embedding Procedure 2009 DOE site visit

7. Results • Embedding 10 GeV muons: • Next, calculate efficiency as function of local hit density, proximity to jets • Easily extended to hadrons, electrons. • Preparing for application to collision data. • Also need to study properties of “fake” muon triggers. (Presented in Monday’s Tracking Meeting) 2009 DOE site visit

8. SLHC Trigger Upgrades • Goal is to confront trigger constraints as early as possible. • Natural opportunity: Pixel double-column multiplicity trigger in Phase-I upgrade. • Probably enough fibers for trigger data • Develop and model a design to combine with calorimeter jet data • Significant interest in μTCA as hardware platform for future trigger electronics development. • SLHC tracker upgrade with L1 trigger capabilities is much longer term... 2009 DOE site visit

9. Next Steps • Parameterize response of PSI ROC to give Σdouble-column and Σclusters • Study parameter space to optimize identification of jets • Bin jet production point along z axis correlate with phi from calorimeter • Concept studied in 2003 (Universität Basel) • Preliminary studies at UNL • Important to initially determine requirements on data volume and bandwidth. 2009 DOE site visit

10. Summary • Current work important for understanding tracking in early data • Necessary part of the ϒ and J/ψ cross-section measurement. • Closely connected with tracker/trigger performance. • Connects with trigger upgrade path • Initially focus on short-term opportunities. 2009 DOE site visit