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J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking.

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Presentation on theme: "J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking."— Presentation transcript:

1 J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring…

2 Light tight, thermally insulating box Telescopes 180 GeV pion Beam Telescopes Scintillator Trigger Modules inside the beam test box. Setup 2 SCT Beam test results Typical SCT beam test setup with different types of modules J. E. Garcia RTN – December 03

3 Variation of efficiency and noise occupancy with comparator threshold. Horizontal lines are the ATLAS specifications. After 10 years the SCT will receive up to 2·10 14 n eq /cm 2. Radiation causes damage on the module. – Radiation creates defects – Type inversion – Electronics noise and leakage current increase Resolution is measured. SCT modules are almost single-strip. The detector pitch is 80  m in order to avoid charge sharing and preserve a good resolution. Beam test studies 3 SCT Beam test results  ~ 23  m J. E. Garcia RTN – December 03

4 The Lorentz angle has been measured using a 1.56 T magnet and different incidence angles. The most sensitive parameter to these changes is the cluster size  L = 3.3 º  0.3 º (at 150 V) Beam test… (II) 4 SCT Beam test results Signal to noise ratio for the SCT modules is  14. The median charge observed on binary SCT prototypes is around 3.4  0.2 fC S-Curve J. E. Garcia RTN – December 03 The pulse shape can be reconstructed from beam test data and compared with the theoretical response of the shaper

5 For reconstructing tracks only the position measurements of the irradiated SCT modules are used. The beam telescope is only read out for comparison. Example of a reconstructed event SCT Modules Telescope Tracking study 5 SCT Beam test results J. E. Garcia RTN – December 03 efficiency The tracking efficiency depends on threshold. The maximum efficiency is 97 % obtained at a threshold of 1.2 fC for a bias over 450 V. Fake rate is kept below 10 -3 independent of the bias voltage on the detector.

6 J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring… Little Higgs Searches: Capability of the ATLAS detector to find particles predicted by the Little Higgs Models. In particular new gauge bosons in the channels: W H  W H and Z H  Z H

7 Particle Spectrum Little Higgs Searches 7  0,  +,  ++ W H, Z H T AHAH 1 TeV Z,W h  t M scalar sector gauge sector top sector v’   ’ 1 new couplings J. E. Garcia RTN – December 03 Littlest Higgs model SU(5)  SO(5) Gauge sector  [SU 2  U 1 ] 2 Only 1 Higgs doublet Arkani-Hamed et al., JHEP 207 (2002) 34 Phenomenology Han et al., Phys. Rev. D67 (2003) 95004 Burdman, Perelstein, Pierce, hep-ph/0212228

8 Strategies at LHC 8 q W b T q’ q1q1 W+W+ q2q2 W+W+ 1 2  ++ q q ZHZH T ZHZH VBF mechanism   ( v’) 2 v’ should be small W + W +  ++  W + W + large SM bkg Wb fusion   ( 1 ) 2 1  1 but suppressed by b- quark PDF. bW, t Z T  bW, t Z clear signal qq annihilation   ( cot) 2 Wide range in cot  possible. e + e - Z H  e + e - clear signal Little Higgs Searches J. E. Garcia RTN – December 03

9 Z H Zh with h bb 9 h ZHZH Z l + l - b b 2 TeV h bb ZHZH Z l + l - 1 TeV Cuts Background: Z + jets Cuts |  | < 2.5 (jets and leptons) P T (Z) > 250 GeV P T (h) > 250 GeV b-tagging |  | < 2.5 (jets and leptons) P T (Z) > 500 GeV P T (h) > 500 GeV b-tagging Little Higgs Searches J. E. Garcia RTN – December 03

10 Signal and background 10 b-tag:  b = 40%, R u = 100 Inside mass window: S = 15 S B = 8  B = 5 b-tag:  b = 50%, R u = 100 Inside mass window: S = 195 S B = 16  B = 50 M(Z H ) (GeV) M Z = 1 TeV H M(Z H ) (GeV) M Z = 2 TeV H L = 3·10 5 pb -1 cot  = 0.5 L = 3·10 5 pb -1 cot  = 0.5 Events Little Higgs Searches J. E. Garcia RTN – December 03

11 Discovery region Z H  Zh 11 L = 3·10 5 pb -1 S/  B > 5 N > 10 h(120)  bb Z H  Zh  l + l - bb W H  Wh  l bb Little Higgs Searches J. E. Garcia RTN – December 03

12 J.E. Garcia RTN – December 03 PHD Work SCT beam test analysis: Tracking efficiency, noise occupancy, collected charge, S/N but also several studies: tracking with standalone SCT, dependencies on incidence angle, studies with LHC-like bunch structuring… Little Higgs Searches: Capability of the ATLAS detector to find particles predicted by the Little Higgs Models. In particular new gauge bosons in the channels: W H  W H and Z H  Z H b-tagging studies: b-tagging performance of the ATLAS detector for high p T jets applied to the Little searches and for the benchmark channels W H(120) and W H(400). Using the signed impact parameter b-tagging algorithms.

13 m h = 200 GeV BR(h W + W - ) = 74 % BR(hZZ) = 26 % Z H Zh 13 q q cot  cot 2    (cot  cot 2  ) 2  (cot  )  (cot  = 0.5) m h = 120 GeV BR(h bb) = 66 % BR(h) = 0.2 % ZHZH hZ Ratio 0.5 Little Higgs Searches J. E. Garcia RTN – December 03

14 b-tagging 14 = 220 GeV = 800 GeV 115 0.5 M Z = 1 TeV H M Z = 2 TeV H ~ 100 0.4 Little Higgs Searches J. E. Garcia RTN – December 03


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