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Warren Clarida

Warren Clarida. Design and Testing of a Quartz Plate Cherenkov Calorimeter Prototype & Search for a Right Handed Majorana Mass Neutrino Using the CMS Detector. Outline. High Energy Experimental Particle Physics

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Warren Clarida

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  1. Warren Clarida Design and Testing of a Quartz Plate Cherenkov Calorimeter Prototype & Search for a Right Handed Majorana Mass Neutrino Using the CMS Detector

  2. Outline • High Energy Experimental Particle Physics • Introduction to the Large Hadron Collider (LHC) and Compact Muon Solenoid (CMS) Detector • Design and Testing of the 1st Phase Quartz Plate Calorimeter (QPC) Prototype • Motivation of design • Test Beam Results • Heavy Majorana Mass Neutrino Search with the CMS Detector at the (LHC) • Introduction • Signal Studies • Backgrounds • 2011 Data Results • Plans for 2012 Data W. Clarida

  3. High Energy Experimental Particle Physics (HEP) • Evolution of the last 100 years of physics. • Begin with discovery of quantum mechanics in early 20th century • The natural extension of nuclear physics • Study of fundamental particles and dynamics. • Lead to the formulation of The Standard Model of physics. • These studies are primarily done using the data coming from collisions of sub-atomic particles. • Fixed target experiments: with particle beams hitting a stationary target. • Particle collider: Accelerated particle beams colliding with each other. • In both cases detectors a constructed around the collision points to observed post collision results. • My work concerns the Compact Muon Solenoid (CMS) detector, a general purpose detector at the Large Hadron Collider (LHC). W. Clarida

  4. The Standard Model • Current understanding of the fundamental nature of the universe. • Very successful at explaining the fundamental forces of nature and its constituents. • Still open questions, gravity, mass, dark matter. • Future HEP studies will attempt to understand these questions. • This is the goal of experiments such as the LHC. W. Clarida

  5. Large Hadron Collider “Discovery Machine” designed as the next step in HEP research. Search for new physics, including the Higgs Boson, Supersymmetry, and more. Designed for 7 times more energy than the Tevatron Collider. Has already produced spectacular results including a new particle in the 2012 data that is probably the Higgs. W. Clarida

  6. LHC built in the old LEP tunnel. 4 detectors built for the LHC’s collisions. CMS and ATLAS built as general purpose detectors. There goal is the discovery of new physics. W. Clarida

  7. W. Clarida

  8. Tracker • Innermost CMS subdetector. • Purpose is to identify the momentum, and charge of particles. • Output is the track of charged particles. • These can be used in conjunction with other subdetectors to reconstruct electrons, photons, and muons. W. Clarida

  9. Calorimeters • Absorb and stop most of the particles coming from the collisions. • Signal proportional to particle energy measured. • Quark showers “jets”, electrons, and photons reconstructed from these energy deposits. W. Clarida

  10. Muon System • Final layer of the detector. • Similar to tracker observes the passage of particles. • Almost no particles that are not muons make it to the muon system. • Muon system tracks combined with tracker tracks to reconstruct muons. W. Clarida

  11. Quartz Plate Calorimeter Prototype I W. Clarida

  12. Why Quartz Cerenkov Calorimeter • Increasing beam energy and luminosities brings increased radiation levels in HEP detectors. • Conventional calorimeters relying upon scintillating materials that are not sufficiently rad hard in these new types of environments. • Proposed upgrades to the LHC will mean the CMS Hadronic Endcap Calorimeter will face this exact problem. • This type of problem was solved for the forward region of the CMS detector by a Cerenkovbased Hadronic Forward Calorimter (HF) • This experience lead to the design of a sampling Cerenkov Quartz Calorimeter Prototype. W. Clarida

  13. CMS Calorimeter CMS Calorimeter (ECAL+HCAL) - Very hermetic (>10λ in all η, no projective gap) HO-2 HO-1 HO0 HO+1 HO+2 HB- HB+ HE- HE+ HF- HF+ Tracker EE- EE+ EB- EB+ Super conducting coil Return yoke Muon chambers HB Brass Absorber (5cm) + Scintillator Tiles (3.7mm) Photo Detector (HPD) |h| 0.0 ~ 1.4 HE Brass Absorber (8cm) + Scintillator Tiles (3.7mm) Photo Detector (HPD) |h| 1.3 ~ 3.0 HO Scintillator Tile (10mm) outside of solenoid Photo Detector (HPD) |h| 0.0 ~ 1.3 HF Iron Absorber + Quartz Fibers Photo Detector (PMT) |h| 2.9 ~ 5.2

  14. Motivation Coming From The (S)LHC Time-line Start of LHC 2009 Run 1: 7 TeV centre of mass energy, luminosity ramping up to few 1033 cm-2 s-1, few fb-1 delivered LHC shut-down to prepare machine for design energy and nominal luminosity 2013/14 Run 2: Ramp up luminosity to nominal (1034 cm-2 s-1), ~50 to 100 fb-1 Injector and LHC Phase-I upgrades to go to ultimate luminosity ~5x1034 2017 or 18 Run 3: Ramp up luminosity to 2.2 x nominal, reaching ~100 fb-1 / year accumulate few hundred fb-1 Phase-II: High-luminosity LHC. New focussing magnets and CRAB cavities for very high luminosity with levelling Radiation Increase ~2021/22 Run 4: Collect data until > 3000 fb-1 ILC, High energy LHC, ... ? 2030 From T1.00002: The LHC and Beyond April 2011 APS

  15. SLHC -> CMS Calorimeter Upgrade • Current HE not sufficiently radiation hard • Plastic scintillator tiles and wavelength shifting fiber is only moderatlyradiationresistantup to 25 kGy while at SLHC, expect up to 30kGy in some areas of HE. • R&D new scintillators and waveshifters in liquids, paints, and solids, and Cerenkov radiation emitting materials e.g. Quartz • Quartz plates will not be affected by high radiation. • Quartz in the form of fiber was irradiated in Argonne IPNS for 313 hours. • The fibers were tested for optical degradation before and after 17.6 Mrad of neutron and 73.5 Mrad of gamma radiation. • Quartz plates could be used to replace plastic scintillators. W. Clarida, DPF 2009

  16. Quartz Plate Prototype I • A single “tower” calorimeter prototype was simulated and developed for testing. • Quartz plates with imbedded fibers were layered between iron blocks. W. Clarida

  17. 2006 Test Beam • The QPC1 was test at both Fermilab’s meson test beam facility and CERN’s H2 beam line facility. • Energy scans and surface scans were done at both locations. • Both electromagnetic and hadronic responses were tested. • The calorimeter was also simulated using GEANT4. The uniformity of response by QPC1 for 100 GeV electrons. W. Clarida

  18. Hadronic Calorimeter Setup Hadronic Response Linearity within 0.1% Hadronic Resolution • Hadronic setup mimicked HE with 5cm steel absorber between each layer. • A 20 layer single “tower” was measured at with 7 differing energy pion beams. • The red shows the GEANT4 simulations, while the black is the data. • Fitting the data to the standard response function, the stochastic term (A) is 235 ± 4% negligible noise and a constant of 10.9± 0.4% (C). W. Clarida

  19. Electromagnetic Setup Electromagnetic Response Linearity within 1% Electromagnetic Resolution • With the absorber depth reduced to 2cm the QPC1 can act as an Ecal. • ACerenkov calorimeter is a radiation hard option for future calorimetersathigh energyneeding high radiation detectors. • 4 different energy electron beams where tested again using a 20 layer “tower.” • The electromagnetic resolution gave fit values: A = 31±2 %, B = 7.5±0.5%, and C = 6.7±0.2%. W. Clarida

  20. Future of the QPC • This initial design served to show that a sampling Cerenkov calorimeter would work for HEP studies. • As Cernkov light yield is much lower than scintillation the efficiency of collection must be higher, or more light must be produced. • The fiber layout used in this study increased efficiency, but required the use of WLS fibers that are not radiation hard. • Work is being done here at Iowa to develop radiation hard WLS fiber options. • Other studies have been done to increase the light production by depositing radiation hard scintillators on the quartz plate. • The subsequent versions of the QPC have used these deposited plates, and have shown significant improvements. W. Clarida

  21. Majorana Neutrino Search W. Clarida

  22. Why Search For Heavy Majorana Neutrinos • We know that neutrinos must be massive particles. • 1.9 × 10−3 eV2 < ∆m2atm < 3.0 × 10−3 eV2 • 7 × 10−5 eV2 < ∆m2sol < 9 × 10−5 eV2 • Adding a standard Dirac mass term in the SM requires right handed neutrinos, which haven’t been observed. • The leading theoretical candidate for accommodating neutrino masses is the so-called “seesaw” mechanism • New right hand neutrinos and a very large mass scale (N) are introduced. • This leads to terms that look like mυ≅yυ2 v2/mN, where yυ2 is the yukawa coupling of υ to the higgs field. • The lightest new heavy Majorana mass neutrinos would have an approximate mass mN. • This study follows a model independent phenomenological approach allowing the new massive neutrino state’s mass (mN) and the mixing between the heavy Majorana neutrino and the SM neutrino (VlN) to be free parameters. W. Clarida

  23. Signature • Owing to theheavy neutrino’s Majorana nature, it is its own antiparticle, which allows for processes that violate lepton-number conservation by two units. • Minimizing the extension to the Standard ModelonlydecaysintoSM gauge bosons are considered. • The primary signature isthen2same sign leptons, nomissing energy (energy unmeasured by the detector),and 2 jets from the W decay. • Dimuons signatures where the first signal studied. • non-observation of neutrinoless double-β decay puts a very low bound on the mixing element for electrons: • Also this takes advantage of the excellent muon detection of CMS. 23 W. Clarida

  24. CMS Muon Reconstruction Muon are reconstructed combining information from the central tracker and the muon system. Achieving a momentum resolution of ~3% for muon pT< 300 GeV. Charge mis-ID for this range is ~ 10-5 The acceptance region is:

  25. Current Limits & CMS Contribution • The L3 and DELPHI collaboration have searched for Z->νlN decays. • They have set limits on Sμμ(~|VμN|2) up to a mN of 90 GeV • 2009 MC studies indicated that the the 2011 CMS data should be able to extend these limits to above 200 GeV. • There are additional indirect limits from precision electroweak measurement. (90% CL of |VμN|2 < 0.0060) W. Clarida

  26. 7TeV Signal Generation • The heavy Majorana neutrino production and decay process is simulated using an event generator implemented in ALPGEN. • The output from this first step is is in unweighted Les Houches format. • These events are interfaced with CMSSW to include parton showering with pythia. Full detector simulation, digitization and reconstruction are then performed. • We produced 50k datasets for the masses: 50, 70, 75, 80, 85, 90, 95, 100, 105, 110, 130, 150, 170, 190, and 210 GeV. • A similar process was used to create Monte Carlo simulations of the various backgrounds to the signal. W. Clarida

  27. Generated Data Sets W. Clarida

  28. Selection Cuts • Muons • Mu pt > 20, 10 (1st muon, 2nd muon) • Eta < 2.4 • Ecal Isolation < 4 GeV • Hcal Isolation < 6 GeV • Relative Isolation < 0.1 • Normalized Chi2 < 10 • D0 < 0.1 mm, Dz < 0.1 cm • 11 hits in tracker, at least one muon system hit • Global and tracker Muon • Dimuon mass > 5 GeV • No event with 3rd muon in Z mass window • Jets • 2 Jets with pt > 30 GeV, eta <2.5 • MET < 50 GeV Pt Cuts Isolation Cuts Quality Cuts Z veto W. Clarida

  29. Tag and Probe Method • The muons in simulation and data may be compared using the tag and probe method. • Z bosons (or any other strong resonance) are reconstructed using two muons, one called the tag and the other the probe. • The tag muon is a high quality muon passing stringent tests. • The probe muons passes lest stringent tests. • Tag probe pairs within whose invariant mass is within a Z mass window are be kept. • The probe muon can then be tested to pass the tighter selection cuts. • An efficiency for real muons to pass these cuts can then be established. Eff = TP/(TP + TF) • TP is the number of passing pairs • TF is the number of failing pairs • These values can be found in the simplest case by simply counting • Alternatively a fit of the invariant mass can be made, and in data a background can be then considered. W. Clarida

  30. MC/Data Scaling • To correct for difference between the detector simulation and the actual detector performance in muon reconstruction simulated events where scaled. • The scaling factors where found for isolation and ID cuts for 2 different transverse momentum ranges. W. Clarida

  31. Muon Selection Criteria Efficiencies

  32. Selection Cut Efficiencies (% Events Passing Cuts) W. Clarida

  33. Backgrounds • “Real” backgrounds WW, WZ, ZZ, tW • These are backgrounds than can produce 2 same sign muons. • Take contribution from Monte Carlo. • “Fake” backgrounds QCD, tt, W+jets • Processes where one or both muons are faked from jets. • Used loose/tight method to get muon fake rate from data • Closure check with ttbar and QCD MC. Assign systematic. W. Clarida

  34. Muon Fake Rate Determination • To estimate the number of events we should expect from fake muons we determine the fake rate using a loose/tight method. • The rate is a ratio of the number of muons passing a set of tight and loose cuts. • Essentially events with a fakeable object are weighted by a factor determined by the fake rate (FR) of fFR/(1-FR) • Nexp = Nw/ttbar + NQCD • Nw/ttbar is obtained from the number events with one loose muon not passing the tight cuts • NQCD is obtained from the number of events with two loose muons not passing the tight cuts. • Nw/ttbar must be corrected for double counting events where there are two fakes but one pass the full selection criteria • The FRis a function of muon pT and η. W. Clarida

  35. Closure Tests • As the fake rate is the dominate background some time was taken to study the fake rate prediction. • 1) Compare MC prediction to MC truth. • 2) Observe the fake rate sensitivity prediction to changes in definition. • 3) Compare high met prediction to data • 1) Fake rate obtained from QCD sample. Prediction made on QCD, W+jets, ttbar. The values agreed within 35% • 2) Vary the “loose” cut value for the muon relIso: 23%. Vary the jet pt cut: 18% • Based upon 1 and 2 a 35% systematic is applied. • 3) Compare the observed events in high MET to the prediction. 48 observed 55 ± 2.03 (stat) ± 15.80 (syst) predicted. W. Clarida

  36. Backgrounds And Observed Data After the full selection is applied 65 events are observed. 70 events were predicted. 8% difference is well within the 35% systematic. W. Clarida

  37. Typical Event in Data Rho-Phi Rho-Z Lego 3D Tower W. Clarida

  38. Systematic Error • Integrated luminosity: 2.2% • PDF and Q2 Scale: 1% each • Muon Trigger and Selection: 2% per muon each for trigger and selection efficiency. • Jet Energy Scale: 3.3-14% depending on mN • Jet Energy Resolution: 0.1%-1% depending on mN • Pile Up model: 1% from varying the number of interactions by 0.6. • Background Estimate: dominated by fake rate 35% • Muon resolution: The error on the muon momentum is between 1.3-6%, this had a negligible affect on the overall signal efficiency. W. Clarida

  39. 95% Exclusion 2011 As no excess is observed an exclusion on the mixing can be made. The 95% C.L. upper limit on the cross section is obtained. From this a limit on the mixing element squared can be obtained using the bare cross section (defined as the cross section where the mixing is 1.0) 95% CL upper limits on the cross section time acceptance times efficiency can also be calculated. (σAε)obs=5.39fb and (σAε)exp = 5.26fb W. Clarida

  40. Plans For 2012 Data • Redo Analysis with 2012 Data • Higher luminosity -> higher trigger thresholds • Some evidence in 2011 data that higher pt cuts would reduce our background. • More data in 2012 already. • The studied mass range will be extended to 700 GeV. • Possibly include additional channels (trilepton channels, emu channel, tau channels). • Use mass distribution to improve signal sensitivity. • May improve upon the precision electroweak limits in the 100-200 GeV range. W. Clarida

  41. Thank you! W. Clarida

  42. Backup W. Clarida

  43. Muon Distribution At low mass the muon pt distribution is split. As the neutrino mass increases the muon pt distributions converges and then begins to increase. The eta and phi distributions are all flat across the mass range. W. Clarida

  44. Muon Isolation The Ecal and Hcal isolation is the sum of deposits within an dR cone of 0.3. The relative isolation is the sum of the deposits/max(20, mu pt) All three of the isolations distributions we use don’t change as the neutrino mass increases.

  45. JetMET MET, Jet Multiplicity and Jet Pt all increase with Majorana Mass W. Clarida

  46. 2nd Jet/Muon Pt Cuts • Our event signature is 2 jets + 2 muons, however at the lower masses the 2nd objects can be difficult to identify. • Our efficiency when requiring two jets is very low for the much of the studied mass range. • We use asymmetrical cuts for the muon pt so this effect isn’t as significant. W. Clarida

  47. Fake Rate W. Clarida

  48. Closure Tests W. Clarida

  49. “Bare” Cross Section W. Clarida

  50. Majorana Neutrino Gauge Interactions From F. del Aguila, J. A. Aguilar-Saavedra, R. Pittau hep-ph/0703261 W. Clarida

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