First data from TOTEM experiment at LHC

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First data from TOTEM experiment at LHC

• Fabrizio Ferro - INFN Genova

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TOTEM phyics
Diffraction soft and hard (with CMS)
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Total pp cross section
Current models predict for 14 TeV 90 130
mb Aim of TOTEM 1 First year 5
Luminosity independent method
special optics
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Physics with high b optics
log(t)/Gev2
-t 410-4 0.012
0.3 2.5

• Total cross section measurement at 5 (1)
• Elastic scattering 0.0004lttlt 2.5 GeV2
• Soft diffraction all masses - 65 of
  diffractive protons seen
• Classification of inelastic events rates
  multiplicity

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Physics with low b
Single diffraction
ds/dM 0.025ltxlt0.15 1 lt M lt 3 TeV s(M)/M
2 - 5
Acceptance
Central diffraction
ds/dM 200 lt M lt 1000 GeV s(M)/M 2 - 5

Log M(GeV)
Elastic scattering
0.5lt t lt 5 GeV2 s(t) 0.2v t
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TOTEM detectors
Telescopes
10.5 m
TAS
14 m
Roman Pot stations in the LHC tunnel
RP (147 m)
RP (220m)
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T1 telescope (1)
2 arms of CSCs for track and vertex
reconstruction 3.1lthlt4.7 - Df2p

• Both T1 arms on the test line. Ready for
  installation.

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T1 telescope (2)
Both arms successfully tested with pion and muon
beams Pions on copper target to get many-tracks
events
? reconstructed hits
efficiency
CSC efficiencies with muons ?(triple coincidences)
Longitudinal vertex
Transverse vertex
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T2 telescope
2 arms of GEMs for tracks and vertex
reconstruction
3.1lthlt4.7 - Df2p
Both arms installed and taking data
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T2 event at 7 TeV
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Alignment and vertex reconstruction
Before
RMS1.7cm
RMS3.1m
RMS1.4cm
After
RMS0.8cm
RMS1.0cm
RMS2.3m
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h distribution
Tracks pointing to vertex Statistical error
only
BeamPipe cone at h5.53
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TOTEM Roman Pots
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Roman pot alignment

• Critical and fundamental for any physics
  measurement

• To align proton detectors means
• Resolve misalignments within detector assembly
  ? methods local track
• Resolve relative positions of the pot
  
  
  principal information source motor control (?
  calibration, reliability, )
• ? method local track based (detector
  overlap)
• Resolve position of beam (uncertainties and
  variations of optics)
• ? method profiles from physics events,
  Beam Halo
  Cross-check
  Beam Position Monitors Alignment with
  collimators
• Resolve left-right position
• ? method global (elastic) track based

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Roman Pot alignment (at 20s)
Vertical alignment
sectors 5-6 (IP5 minus side)
sectors 4-5 (IP5 plus side)
Tracks in horizontal pot
Tracks in horizontal pot
preliminary
preliminary
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Roman Pot alignment (at 20s)
Horizontal alignment
sectors 5-6 (IP5 minus side)
sectors 4-5 (IP5 plus side)
preliminary
preliminary
Halo protons
Tracks in horizontal pot
Tracks in vertical pot
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Diffractive protons at 7 TeV
preliminary
TOP BOTTOM
Raw distributions, no selection Diffractive
protons background Estimated Dp/p 0.06 -
0.12
preliminary
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A first elastic scattering candidate
RPs at 25s
Run 1964.004 Event 13682
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Analysis and data taking still in progress
Data taking with RP at 25s collected 3 M
events with RP only
5 M
RP T2 Data taking with RP at 20s
collected 6 M RP T2 Data taking with
RP at 15s under investigation with the machine
Full set of systematics sources under
investigation - Alignment - Beam position
- Beam divergence - Background from the machine
(halo, beam gas,.....) - Multiple scattering and
material interaction - Optics uncertainty on
the optical functions, crossing angle,
vertex.... and in addition - Estimate
Efficiencies (trigger, track reconstruction....)
- Luminosity - Physics Background Pile-up
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Summary

• The TOTEM Detectors installed in the LHC (RP220m
  and T2) have completed the commissioning and are
  presently taking data
• Once that the 220m RPs will be inserted at their
  nominal position, TOTEM can move on to its physic
  program at low b
• - high mass Single Central Diffraction
• - large t elastic scattering (0.65 lt t
  lt 5 GeV2)
• - forward density of charged particles
• Precise measurements of elastic, diffractive and
  total cross sections
• require high b optics and the installation of T1
  and of RP147m
• - Elastic scattering in a wider t range
• - Diffractive physics over a larger
  rapidity range 3.1 lth lt 6.5
• - Single and Central Diffraction at any
  mass
• - Measurement of stot with a precision of
  5 (1)