1. CMS Feedback on the High pileup (PU) Fill
LSWG Meeting, Nov 29th, 2016
The CMS Collaboration
CMS Feedback on the High pileup (PU) Fill

2. Thank you, LHC!
High pileup fill 5412 gave CMS invaluable information to…
Tune the detector for 2017 operations
Understand the response of luminometers
Study L1 trigger algorithms to prioritize development
… a bit on these in the next slides 

3. High pileup: detector operation
Data collection was faultless, also triggering specifically on the isolated bunches with very high pileup
CMS doesn’t see limits for single events with pileup higher than what we are expecting to see before Phase II
Note that many detector pulses (e.g., ECAL) are sensitive to out of time PU, so data from trains are especially interesting
Crucial information obtained to tune detector configuration for operation (e.g., zero-suppression thresholds)
Matching simulation samples to be produced very soon…
Experts continue to analyze the data…

4. Regarding luminosity numbers
In the trains: values not far from “typical” 2016 numbers
For the single isolated bunches….
HF (Forward Hadronic calo  online #): likely underestimates lumi
Correction applied for trains
PLT (Pixel Luminosity Telescope): likely overestimates lumi
Values considerably higher than from lumi calculator…
Pixel Cluster Counting (nominal offline #): reconstruction just finished
Had to tune tracking thresholds for high PU in isolated bunches
Once we have pinned down these lumi numbers, we can start to make statements on rates and performance…

5. Level-1 Trigger: trains
Trains with pileup up to 50 are very useful for 2017 L1 menu development…
Comparison of rate with fills before and after the high PU fill        
Estimation of lumi for isolated bunches in progress...
~linear as expected
for single mu trigger
non-linearity as expected for MET