Post on 01-Jan-2016
description
J.E. Garcia RTN – December 03
PHD WorkPHD 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…
Light tight, thermally insulating box
Telescopes
180 GeV pion Beam
Telescopes
Scintillator Trigger
Modules inside the beam test box.
SetupSetup 2
SCT Beam test results
Typical SCT beam test setup with different types of modules
J. E. Garcia RTN – December 03
Variation of efficiency and noise occupancy with comparator threshold. Horizontal lines are the ATLAS specifications.
• After 10 years the SCT will receive up to 2·1014 neq/cm2. 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 studiesBeam test studies 3
SCT Beam test results
~ 23 m
J. E. Garcia RTN – December 03
• 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)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
• 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 ModulesTelescope
Tracking studyTracking study 5
SCT Beam test resultsJ. E. Garcia RTN – December 03
effic
ienc
y• 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.
J.E. Garcia RTN – December 03
PHD WorkPHD 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: WH W H and ZH Z H
Particle SpectrumParticle Spectrum
Little Higgs Searches
7
0,+,++
WH , ZH
T
AH1 TeV
Z ,Wh
t
M
scalar sector gauge sector
topsector
v’ ’ 1
new couplings
J. E. Garcia RTN – December 03
Littlest Higgs modelSU(5) SO(5)Gauge sector [SU2U1]2
Only 1 Higgs doubletOnly 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
Strategies at LHC 8
q
W
b T
q’
q’
q1
W+
q2
q’
W+
1
2
++q
q
ZH
++++ TT ZH
VBF mechanismVBF mechanism (v’)2
v’ should be small ++ WW++WW++
large SM bkglarge SM bkg
Wb fusionWb fusion (1)2
1 1 but
suppressed by b-quark PDF.
T bW, bW, ttZZ clear signalclear signal
qq annihilationqq annihilation (cot)2
Wide range in cot possible.ZH
ee++ee--
clear signal
Little Higgs SearchesJ. E. Garcia RTN – December 03
ZH Zh with h bb 9
hh
ZH
ZZ
l +
l -
bbbb
2 TeVhh
bb
bbZH
ZZ
l +
l -
1 TeV
Cuts
Background: Z + jets
Cuts
|| < 2.5 (jets and leptons)
PT(Z) > 250 GeVPT(h) > 250 GeVb-tagging
|| < 2.5 (jets and leptons)
PT(Z) > 500 GeV PT(h) > 500 GeV b-tagging
Little Higgs SearchesJ. E. Garcia RTN – December 03
Signal and background 10
b-tag: b = 40%, Ru = 100 Inside mass window:S = 15 SB = 8 B
= 5
b-tag: b = 50%, Ru = 100 Inside mass window:S = 195 SB = 16 B
= 50
M(ZH) (GeV)
MZ = 1 TeVH
M(ZH) (GeV)
MZ = 2 TeV
H
L = 3·105 pb-1
cot = 0.5L = 3·105 pb-1
cot = 0.5
Eve
nts
Eve
nts
Little Higgs SearchesJ. E. Garcia RTN – December 03
Discovery region ZDiscovery region ZH H Zh Zh 11
L = 3·105 pb-1
S/B > 5 N > 10
h(120) bb
ZH Zh l +l - bbWH Wh l bb
Little Higgs SearchesJ. E. Garcia RTN – December 03
J.E. Garcia RTN – December 03
PHD WorkPHD 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: WH W H and ZH Z H
b-tagging studies:b-tagging performance of the ATLAS detector for high pT 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.
mh = 200 GeV
BR(h W+W-) =
74 %BR(h ZZ) = 26
%
ZH Zh 13
q
q
cot cot 2
(cot cot 2) 2
(cot )
(cot = 0.5) mh = 120 GeV
BR(h bb) = 66
%BR(h ) = 0.2
%
ZH
hh
ZZ
Rat
io
0.5
Little Higgs SearchesJ. E. Garcia RTN – December 03