1. The Super Large Hadron Collider: Tracking Particles with the Compact Muon Solenoid
By: John Hardin (UNC-CH) &
Kevin McDermott (Notre Dame) at
University of Notre Dame Physics REU
Advisers: Dr. Mike Hildreth and Dr. Kevin Lannon

2. CMS Overview

3. SLHC and Numbers
In 2020, the LHC will be upgraded to increase its luminosity by a factor of 10
This will overwhelm the current detectors readout rate
300Hz -> 20 MHz
1MB per readout
Therefore upgrade the Level-1 trigger and tracker.

4. Upgrading the Silicon Tracker
It will be broken by 2020, so it might as well be upgraded.
Tested Geometry: Long Barrel Straw Man

5. Algorithmic Plan
Each bunch crossing currently has 8 “pile up”, this will become 200 every 25ns
Goal: Add tracking information to the Level-1 trigger (hardware)
Allow for accurate pT measurements and effective filtering.
First try: Match “stub pT”
Unworkable precision
n.b. pT stands for transverse momentum (perpendicular to the beam)

6. Algorithm Cuts All Algorithms:
Start from the outside
Cut on z
Sort into pT bins by location. Linear bins for low, equal curvature for high

7. The Real World
Our algorithm looks for a series of stubs consistent with a specific pT, but even muons will rattle around some.
This is fixed by overlapping the bins with a value called slop.
Lower slop => less fakes, but less efficient.
0.5 slop is no overlap
Leads to oscillation in efficiency plot
We use 0.8 in the final iteration

8. Other Tweaks
To decrease the fake rate, we ignored all stubs reporting less than 2 GeV
We have the option of implementing a pT “plateau” to dynamically adjust slop based on bin number or to maintain a minimum bin width

9. Efficiencies

10. Efficiencies Continued

11. Fake Rate

12. Acknowledgements Our Advisors: NDCMS graduate students
Professor Michael Hildreth
Professor Kevin Lannon
NDCMS graduate students
Sean Antonelli
Jamie Lynch

13. References
The CMS Collaboration. “Technical Proposal for the Upgrade of the CMS Detector Through 2020.“ Spring2011. Web.
Everything you ever wanted to know (or didn’t) about CMS and the upgrade