1. Efficiency of the CMS Level-1 Trigger to Selected Physics Channels by: Corey Sulkko Faculty Mentor: prof. Darin Acosta Funded by: National Science Foundation

2. Presentation overview zOverview of CMS experiment zThe importance of the Level-1 Trigger to CMS zMethods of calculating the efficiency of the Level-1 Trigger zResults zFuture Research

3. Overview of the CMS Experiment zThe Standard Model predicts a particle not yet found, the Higgs Boson zthe Higgs is expected to be very massive, and because, it needs high energy collisions to be created z Currently the Tevatron collides particles at 2 trillion electron volts, which may not be enough energy to create the Higgs, which leads us to the Large Hadron Collider at CERN

4. the Large Hadron Collider

5. the LHC zthe Large Hadron Collider will be used to collide protons at 14 TeV, which we think may be enough energy to create many Higgs particles for study zTo find the Higgs, we will try to reconsruct the particles that it decays into, by using the momenta of these reconstructed particles we can calculate the mass of the Higgs zSince a couple of Higgs decays modes go into muons, we will use a muon detector...

6. the Compact Muon Solenoid zCompact Muon Solenoid detector zSolenoid provides magnetic field to measure momentum of particles, which can be used to calculate their masses zUF works with the endcap detectors and Trigger system

7. zEndcap detectors use Cathode Strip Chamber(CSC) detectors zThe CSC’s are trapezoidal and each contain six layers of detection, they are arranged overlapping each other to form a circular disc zEach endcap consists of four discs zCSC contains gas mixture which ionizes when a muon passes through, electrons are collected on high voltage wires, signals induced on perpendicular cathode strips endcap detectors

8. Using reconstructed paths to calculate transverse momentum of muon zBy knowing where the muon hit on each of the four CSC’s, we can reconstruct the path that the muon took  Knowing the change in the angle  the transverse momentum(Pt, the momentum in the direction of the change in the angle  the mass can be calculated

9. the Level-1 Muon Trigger zSince the LHC will be colliding p’s at 40,000,000 per second, something is needed to filter out muons with low Pt’s, because they couldn’t have possibly come from the massive Higgs particle, otherwise there would be too much data to analyze(1 megabyte per collision) zThe CSC detectors create electronic signals, something is needed to reconstruct the tracks and calculate the Pt of the muons zthe Level-1 Muon Trigger(L1T), under design at UF, does these two things

10. Efficiency of the Level-1 Trigger zThe efficiency of the L1T is the fraction of time that the trigger reconstructs a particle in the endcap region that was produced in that region. To select is to allow the particle to be stored for future analysis zThe L1T is the first of a 3 level trigger system being designed for the CMS endcaps zBecause the Higgs is expected to be created less than once every trillion collisions, we want the efficiency for these particles to be as high as possible. zPhysicists will set the Trigger so that it selects all events that generate muons above a certain Pt

11. Calculating the Efficiency of the Trigger zrun simulations of the collisions, the detectors, and the Trigger zcalculate the efficiency

12. Signal Zebra files with HITS ORCA Digitization (merge signal and MB) Objectivity Database HEPEVT ntuples CMSIM HLT Algorithms New Reconstructed Objects MC Prod. ORCA Prod. HLT Grp Databases ORCA ooHit Formatter Objectivity Database MB Objectivity Database Catalog import Objectivity Database Objectivity Database ytivitcejbOesabataD Mirrored Db’s (CERN, US, Italy,…) Detection Collisions Simulating the Experiment Triggering

13. Simulate the Collisions zUse an event generator program to simulate the particle collisions. yPythia simulates particle collisions and decays based on the rules of quantum mechanics zSet the generator to produce only the decays you are interested in ypp -> H -> ZZ -> µµµµ, pp -> H -> WW -> µµ  B -> J/  -> µµ zGenerate many events

14. Simulate the detection and the Level-1 Trigger behavior zSimulated detection using the program CMSIM ysimulates the behavior of the particles as they move through the material of the CMS detector zUsed ORCA to simulate the response of the detectors and to simulate the behavior of the L1T in response to the digitized data from the detectors zORCA stores the information about the particles produced by the collision, the generated data, and the results as interpreted by the L1T all in a binary file zThis file can then be analyzed using the graphical analysis program ROOT

15. Results zROOT was used to calculate the efficiency of the L1T to select 1, 2 and 3 muon events for three different Pt Thresholds: Pt > 0, Pt > 10, and Pt > 25 GeV/c zThis was done for all three decays zFor the Higgs decays this was done for 6 different Higgs masses between 125 and 250 GeV zFor J/Psi we simulated minbias proton collisions zThe probability of generating 1 or more, 2 or more, and 3 or more muons was also calculated for the three diffirent Pt thresholds and six diffirent masses

16. Efficiency of the L1T to select 1 and 2 muon events as a function of Higgs mass for select Higgs decays

17. Efficiency of the L1T to select 1 or 2 muon events for minbias B -> J/  -> µµ decays  The efficiency of the L1T to select muons from B -> J/  - > µµ decays was found to be much lower zThis is because the Higgs boson has a higher mass then the j/Psi, and is therefore easier to detect at higher Pt’s

18. Probability of generating 1, 2, or 3 or more muons in the endcaps as a function of mass for H  Z o Z o  u + u - u + u z About 80% of all H  Z o Z o  u + u - u + u events had at least 1 muon go into the endcap

19. Probability of generating 1, 2, or 3 or more muons in the endcaps as a function of mass for H  W + W -  u + u - z About 50% of all H  W + W -  u + u - events had at least 1 muon go into the endcap

20. Probability of B -> J/  -> µµ generating one or two muons in the endcap  The probability if B -> J/y -> µµ producing 1 or more muons in the endcaps was found to be about 27%

21. Future Research zThe L1T is the first in a series of three triggers for the CMS endcap detectors, efficiency analysis should be done for the other triggers as well zTry to calculate the Higgs mass the data obtained from the L1T

22. Acknowledgements zThanks to NSF, Kevin Ingersent, and Alan Dorsey for the REU program zThanks to Prof. Darin Acosta for guiding my research