Warren Clarida

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 • 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 • Monte Carlo Studies • Backgrounds • 2010 Data Results • Still To Be Done W. Clarida

3. Large Hadron Collider • IP1- ATLAS (general purpose) • IP5-CMS (general purpose) • IP2-ALICE (Heavy Ion, p-ion) • IP8-LHCb (pp B-Physics) • Design: 2808x2 bunches protons, 1011 protons/bunch, 14 TeVcenter of mass energy • 2011: 7 TeVcenter of mass energy, 930/1400 bunches > 1033cm-2s-1 • Expect more than 1 fb-1 W. Clarida

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5. 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. • This problem was solved for the forward region of the CMS detector by a Cerenkov detection based Hadronic Forward Calorimter (HF) • This experience lead to the design of a sampling Cerenkov Quartz Calorimeter Prototype. W. Clarida

6. 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

7. 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

8. SLHC -> CMS Calorimeter Upgrade • Current HE not sufficiently radiation hard • Plastic scintillator tiles and wavelength shifting fiber is radiation hard up to 2.5 MRad while at SLHC, expect 25MRad in 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

9. 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

10. 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 uniformity of response by QPC1 for 100 GeV electrons. W. Clarida

11. Hadronic Calorimeter Setup Hadronic Response Linearity Hadronic Resolution • Hadronic setup mimicked HE with 5cm steel absorber between each layer. • 20 layers were read out. • Proof of concept but light yield not sufficient for HE needs. W. Clarida

12. Electromagnetic Setup Electromagnetic Resolution • With the absorber depth reduced to 2cm the QPC1 can act as an Ecal. • We wee a Cerenkov calorimeter is a radiation hard option for future calorimeters at high energy high radiation detectors. • Light yield probably needs to be increased. • Future QPC prototypes with the use of scintillating coatings on plates. W. Clarida

13. Majorana Neutrino Search W. Clarida

14. Introduction To 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 • The simplest method of adding a Dirac mass term in the SM requires right handed neutrinos, which haven’t been observed. • With the addition of Majorana mass terms1 the left handed nature of the 3 known neutrinos can be preserved. They would have a mass scale given so called “seesaw” relationship: mMmν ~ mD2 where the Majorana mass and neutrino mass must balance each other and the dirac mass is on the order of a standard quark or lepton mass. • There would be an addition of new heavy Majorana mass neutrinos with a mass mN ~ mM • We are searching for such a massive neutrino at the LHC. • There have been two recent papers which discuss the potential of finding a heavy Neutrino between the masses of 100 and 200 GeV at the LHC • The Search for Heavy Majorana Neutrinos1 • The Little Review on Leptongenesis2 1) A. Atre, T. Han, S. Pascoli, B. Shang, 0901.3589 [hep-ph] 2) A. Pilaftsis, 0904.1182 [hep-ph] W. Clarida

15. Signature • The Majorana nature of the heavy neutrino allows for lepton number violating final states. • In order to still be within the SM, we only look at decays with SM gauge bosons. • Our primary signature is chosen to be two same sign muons with no ETmiss and 2 jets from a W. • We will look first for decay into muons • 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. 15 W. Clarida

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

17. Current Limits & CMS Contribution • In 2009, the mass range of 100 GeV – 200 GeV was studied, there are no current limits set from direct searches. • The full mass range was expected to be excluded with 100 pb-1 at 10 TeV. (Sμμ=1 & Sμμ≅VNμ). • For our search we use a parameterization of the cross section. • The equation relating the S value and the cross section is below[1]. • The other parameter, σ0(N4), is the “bare” cross section depending only upon the neutrino mass and the collision energy. W. Clarida 1) arXiv:0901.3589v2

18. 7TeV Signal Generation • A program based upon matrix element calculation is used to generate weightedMajorana neutrino events with pp collision properties. (written by T. Han U. Wisconsin) • The output from the 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 datasets for the masses: 50, 60, 70, 80, 90, 100, 110, and 120 GeV. W. Clarida

19. 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

20. 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.

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

22. 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

23. 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 < 0.2 mm • 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 > 20 GeV, eta < 3.0 Pt Cuts Isolation Cuts Quality Cuts Z veto W. Clarida

24. 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

25. Real Backgrounds For the 2010 date the contributions from the real backgrounds are insignificant. We also considered Z/γ+Jets. The contribution from this background was negligible. W. Clarida

26. Muon Selection Criteria Efficiencies

27. Selection Cut Efficiencies W. Clarida

28. 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. • Events with a fakeable object are weighted by a factor determined by the fake rate (f) of f/(1-f) • 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 • Currently there is no correction for signal contamination as we see no excess. • Thefis a function of muon pT and η. W. Clarida

29. Muon Fake Rate Cuts • We look for events with a well separated “opposite side” jet. ΔR>1.0 from the muon. • Fake rate dependence on jet pT. • Prediction from 40 GeV cut compared to actual results for 20,40,60 GeV cuts in QCD MC. • There is an over prediction for events with high pTjets • Accounted for in our final systematics. • Muons: • pT > 10 GeV • η < 2.4 • RelIso < 0.1 (0.4 for loose) • Χ2/ndof < 10 • Transvers IP < 0.2 mm • Jets: • pT > 40 GeV • η < 3.0 • Trigger • HLT_Mu9 W. Clarida

30. T/L Ratio • Single Fake Prediction: • 3.089 ± 0.247 events (Ns) • Double Fake Prediction: • 2.082 ± 0.323 events (ND) • Total Fake Prediction • 1.007 ± 0.735 (NF) • Wait 3+1 ≠ 1 • The single prediction over counts by including double fake events where one muon passed the tight criteria. • NF = NS - ND W. Clarida

31. Closure Test & Systematic Error • Predict the dimuon rate in ttbar with FR obtained from QCD MC • In the ttbar sample we find 63 fake muons. • The FR prediction is 104.79 ± 3.79 • This gives us a ratio of predicted/observed 1.66 • The over prediction seems to come from a high jet PT tail present in ttbar, not in QCD. • This leads us to assign a 50% systematic error on our fake rate result. W. Clarida

32. 95% Preliminary Exclusion 2010 This is preliminary. It does not contain all systematic errors. Much of the 2011 sensitive mass region has not been studied. 2010 results above 100 GeV are not competitive with precision electroweak measurements. Already 7 times more data in 2011. W. Clarida

33. To Be Done • Redo Analysis with 2011 Data • Understand pile up • Understand Trigger efficiencies for signal • Not in current MC • Include systematics in exclusion result • JES and muon reconstruction not expected to have significant affect – must confirm. • Use Alpgen (another generator) to understand systematics from signal MC • Include pile up systematics • Systematic on expected “real” backgrounds • Extend search up to ~200 GeV • Investigate use of MET significance cut. W. Clarida

34. Backup W. Clarida

35. Fake Rate Calc. Details • Define some variables: • f: ratio of muons passing tight cuts to those passing loose cuts • NL: Events with 2 muons passing loose cuts • Nmu: Events with 2 real muons • NS: Events with 1 real and 1 fake muon • ND: Events with 2 fake muons • N2t,1t,0t: Events where 2, 1, or 0 muons pass tight cuts • NL can be written in terms of measurable N2t,1t,0t or in terms of truth Nmu,S,D • NL = Nmu + NS + ND = N2t + N1t + N0t • The measurable can be written in terms of the truth • N0t = (1-f)2ND • N1t = (1-f)NS + 2f(1-f)ND • N2t = Nmu + fNS + f2ND • Work out the algebra and get: • N2t = Nmu + f/(1-f)N1t – 2f2/(1-f)2N0t + f2/(1-f)2N0t W. Clarida