jános sziklai wigner rcp on behalf of the totem collaboration:
DESCRIPTION
Elastic scattering, total cross-section and charged particle pseudorapidity density in 7 TeV pp reactions measured by the TOTEM Experiment at the LHC. János Sziklai WIGNER RCP On behalf of the TOTEM Collaboration: - PowerPoint PPT PresentationTRANSCRIPT
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic scattering, total cross-section and charged particle pseudorapidity density in 7 TeV
pp reactions measured by the TOTEM Experiment at the LHC
János Sziklai WIGNER RCP
On behalf of the TOTEM Collaboration:Bari, Budapest, Case Western Reserve, CERN, Genova, Helsinki,
Penn State, Pisa/Siena, Prague, Tallin (~ 80 physicists)
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
TOTEM Physics Overview TOTEM Detector Setup in LHC IP5 Measurement of the Elastic pp Cross Section Inelastic Cross Section
direct T1 and T2 measurement Total Cross Section Measurement of the forward charged particle
pseudorapidity density in T2 Data taking in 2012 at √s = 8 TeV TOTEM Running Strategy for 2011 and
Conclusions
OUTLINE
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
TOTEM Physics Overview:
jetjet
b
Total cross-section Elastic scattering
Forward physics
Soft and hard diffraction
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
TOTEM Detector Setup in LHC IP5(together with CMS)
Inelastic detector configurations on both sides of IP5: all capable for tracking and triggering
24 Roman Pots on both sides of CMS: measuring the elastic & inelastic protons closed to the beam
Purpose: Identifying charged particles in inelastic events & vertex reconstruction
IP5
RP147 RP220
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
TOTEM inelastic telescopesT1 telescope CSC (Chatode Strip Chambers)
T2 Telescope GEM (Gas Electron Multiplier)
charged particle detection vertex reconstruction trigger
3.1 < < 4.7
5.3 < < 6.5
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Roman Pot detectors
detect protons scattered at Interaction Point 5 near-beam movable devices equipped with edgeless silicon mycrostrip detectors resolution of 16μm trigger capability with FPGA processing
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Measurement of the Elastic pp Cross Section
710-3 GeV2 < |t| < 3.5 GeV2
Roman Pots
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Data samplesWide range of |t| measured with various LHC configurations
2.3106
6.8103
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic pp scattering in Roman Pots
β*=3.5m (7σ) β*=90m (10σ) β*=90m (5σ)
Aperture limitation, tmax Beamhalo
Diagonals analysed independentlyty = -p2y
2
ξ=p/p
Sect
or
45
S
ect
or
56
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
LHC optics in brief
Proton position at a given RP (x, y) is a function of position (x*, y*) and angle (x*, y
*) at IP5:
• Scattering angle reconstructed in both projections• High Θ*-reconstruction resolution available
σ(Θy*)=1.7 μrad for β*=90 m and low t-range
σ(Θy*)=12.5 μrad for β*=3.5 m and high t-range
Elastic proton reconstruction:
RP IP5
measuredin Roman
Potsreconstructed
Proton transport matrix
0 ,
/
/
**
*,
*
p
p
Lyvyds
dLx
ds
dv
yyRPy
xxRPxx
Excellent optics calibration and alignment required
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Calibrations per beam fillOptics determination Special TOTEM runs, optics can change from fill to fill !!
– Analysis of transport matrix sensitivity to LHC imperfections (MADX optics model)– Machine tolerances and measured errors combined
• magnet currents• magnet conversion curves, field imperfections• magnet displacements
– Measured optics constraints from RP proton tracks distributions
– Optics matched with MADX– Procedure verified with MC studiesN
ovel
met
hod
of T
OTE
M
m90 for %6.2%8.0 %1
%1*
'
'
tt
LL
dLdL
y
y
x
x
Optics related systematic errors
H. Niewiadomski, Roman Pots for beam diagnostic, OMCM, CERN, 20-23.06.2011H. Niewiadomski, F. Nemes, LHC Optics Determination with Proton Tracks, IPAC'12, Louisiana, USA, 20-25.05.2012
Alignment of Roman Pots ->Movable devices by definition !!– internal components : metrology, tracks– with respect to LHC beams : beam touching exercise (<200 μm)– relative between RPs with overlapping tracks (a few μm)– physics based : exploits coinearity of elastically scattered protons,
constraints especially the 2 sides of IP5 (a few μm)
Final overall precision of 10 μm achieved!Track based alignment
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic pp scattering : analysis highlights IProton selection cuts
+ collinearity cuts (left-right) Θ*
x,45 Θ*x,56
Θ*y,45 Θ*
y,56
+ low ξ cuts + vertex cuts+ optics related cuts
Background subtraction
Acceptancecorrection
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic pp scattering : analysis highlights II
Resolution unfolding
divergenceuncertainty
Extrapolation limit
β*=90mσ(Θ*)=1.7µrad
β*=3.5m
Normalization Reconstruction efficiency – intrinsic detector inefficiency: 1-2% / pot – elastic proton loss due to interaction: 1.5%/pot – event lost due to overlap with beam halo (depends on dataset and diagonal) 4% - 8% (β*=90m); 30% (β*=3.5m)
Luminosity from CMS systematic error of 4%u
nfo
ldin
g co
rrec
tion
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic scattering cross-section
|t|-7.8
||tBEL Aedt
d
EPL 95 (2011) 41001EPL 96 (2011) 21002To be published
|t|dip= 0.53 GeV2
B = 19.9 GeV-2
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Elastic scattering cross-section
EPL 96 (2011) 21002
To be published
A = 506 ±22.7syst±1.0stat mb/GeV2
A = 503±26.7syst±1.5stat mb/GeV2
B = 19.9±0.26syst±0.04stat GeV-2
Elastic cross-section25.4±1.0lumi±0.3syst±0.03stat mb (90% directly measured) 24.8±1.0lumi±0.2syst±0.2stat mb (50% directly measured)
Extrapolation to t=0
0
t
EL
dt
dA
||/ tBEL Aedtd
dσE
L/d
t [
mb/
GeV
2 ]
-t [GeV2]
0t
EL
dt
d
measELextrapolELEL ,.,
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Inelastic Cross Sectiondirect T1 and T2 measurement
T2
η
tracks
T2
η
η
Inelastic events in T2: classificationtracks in both hemispheresnon-diffractive minimum biasdouble diffraction
tracks in a single hemispheremainly single diffractionMX > 3.4 GeV/c2
Corrections to the T2 visible events
σinelastic, T2 visible = 69.7 ± 0.1 stat ± 0.7 syst ± 2.8 lumi mb
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Total Cross Section: 4 approaches
1. CMS Luminosity (small bunches) + Elastic Scattering+ Optical Theorem depends on CMS luminosity for low-L bunches & elastic efficiencies & ρ
σTOT = 98.3 mb ± 2.0 mb EPL 96 (2011) 21002
2. CMS Luminosity (large bunches) + Elastic Scattering + Optical Theorem compare the CMS luminosity measurement for high-L vs. low-L bunches
σTOT = 98.6 mb ± 2.3 mb
3. CMS Luminosity (large bunches) + Elastic Scattering + Inelastic Scattering minimizes dependence on elastic efficiencies and no dependence on ρ
σTOT = 99.1 mb ± 4.4 mb
4. (L-independent) + Elastic Scattering + Inelastic Scattering+ Optical Theorem eliminates dependence on luminosity
σTOT = 98.1 mb ± 2.4 mb
=0.14±0.09 (Compete)
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Total Cross Sections: Summary
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Measurement of the forward charged particle
pseudorapidity density in T2 dNch/d in 5.3 < < 6.5 range at s = 7 GeVData sample: events at low luminosity and low pile-up, triggered with T2Selection: at least one track reconstructed Primary particle definition: charged particle with t > 0.310-10 s & pt > 40 MeV/c
Primary particle selection: - primary/secondary discrimination with primary vertex reconstruction
Primary track reconstruction efficiency - evaluated as a function of the track and the multiplicity - efficiency of 80% - fraction of primary tracks within the cuts of 75% – 90% ( dependent)
primary
secondary
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
dNch/dh in T2 : results
TOTEM measurements combined with the other LHC experiments
TOTEM measurements compared to MC predictions
Published: EPL 98 (2012) 31002
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Data taking foreseen (done) in 2012 at √s = 8 TeVβ*=90m, 2 bunches (done)
elastic scattering and cross-sections
β*=90m, 156 bunches (done together with CMS)test for diffractive 2 jet events hard diffraction, 2 jets (pt > 20 GeV) plus protonsproton coverage : full range in ξ , -t > 0.02 GeV2integrated luminosity: 6nb-1/h, 10 hours of data takingseveral million events
β*=0.6m, ~1400 bunches, full luminosity (also some runs with CMS)tests for diffractive 2 jet events at high lumnositiesproton coverage : ξ > 2-3%, full range of timportant test for the futurehard diffraction, 2 jets (pt > 50 GeV) plus protons
β*~1000mt > 5 10 -4 GeV2 measurement of
p A runs planned at the beginning of 2013
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Questions ?
Thank you!
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Backup Slides
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
TOTEM capabilities
• Unique possibility of detecting charged particles with high pseudorapidity
• Ideal tool for studying forward phenomena (elastic & diffractive scattering)
• In case of inelastic events the energy flow and the multiplicity increases in forward angles CMS +TOTEM = The largest acceptance detector ever built at a hadron collider:
90% (65%) of all diffractive protons are detected for * = 1540 (90) m
CMS central
T1
HCal
T2 CASTOR
=90m=90m
RPss
=1540m=1540m
ZDC
Rom
an Pots
T1,T2 T1,T2
Rom
an Pots
Charged particles
Energyflux
dNdNchch
/d/d
dE/d
dE/d
CMS
CMS
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
The Roman Pot System
• Special movable detector assembly in a separate vacuum space • Roman Pot pairs at a distance of 4 meters at 147 és 220 m from IP
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
T2 Telescope GEM (Gas Elecron Multiplier)
Castor
Collar
Castor
T2 GEM
10 tripple GEM layers on both sides of the IP to tolerate high particle fluxes in 5.3 < || < 6.6pseudorapidity range
Design & installation together with CMS
Final GEM chamber
Beam
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
T2 events reconstruction
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Hit profile in T2:
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Single diffraction low = p/p
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Double POMERON exchange
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Single diffraction large
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09/20/2012 Kielce ISMD 2012 J. Sziklai WIGNER RCP
Double POMERON exchange