1. First data from TOTEM experiment at LHC
Fabrizio Ferro - INFN Genova
Diffraction 2010
Fabrizio Ferro – INFN Genova

2. Fabrizio Ferro – INFN Genova
TOTEM phyics
Total cross-section b
Elastic Scattering
Forward physics (with CMS)
Diffraction: soft and hard (with CMS)
Diffraction 2010
Fabrizio Ferro – INFN Genova

3. Fabrizio Ferro – INFN Genova
Total pp cross section
Current models predict for
14 TeV: 90 – 130 mb
Aim of TOTEM: ~ 1%
“First year” : ~5%
Luminosity independent method:
COMPETE Collaboration:
special optics
Diffraction 2010
Fabrizio Ferro – INFN Genova

4. Physics with high b* optics
log(|t|)/Gev2
-t = 4·
Total cross section measurement at ~5 % (~1%)
Elastic scattering: <|t|< 2.5 GeV2
Soft diffraction: all masses - 65 % of diffractive protons seen
Classification of inelastic events: rates & multiplicity
Diffraction 2010
Fabrizio Ferro – INFN Genova

5. Physics with low b* Single diffraction
Hits in RP220
Single diffraction
ds/dM : 0.025<x< < M < 3 TeV
s(M)/M ~ 2 - 5%
Acceptance
Hits in RP220
Central diffraction
ds/dM : 200 < M < 1000 GeV s(M)/M ~ 2 - 5%
Log M(GeV)
Elastic scattering
0.5< |t| < 5 GeV2 s(|t|) ~ 0.2√ |t|
Diffraction 2010
Fabrizio Ferro – INFN Genova

6. Fabrizio Ferro – INFN Genova
TOTEM detectors
Telescopes:
10.5 m
TAS
14 m
Roman Pot stations in the LHC tunnel
RP (147 m) RP (220m)
Diffraction 2010
Fabrizio Ferro – INFN Genova

7. T1 telescope (1)
2 arms of CSCs for track and vertex reconstruction
3.1<|h|< Df=2p
Both T1 arms on the test line. Ready for installation.
Diffraction 2010
Fabrizio Ferro – INFN Genova

8. CSC efficiencies with muons (triple coincidences)
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
Cu target
Beam monitor frame
Transverse vertex
Diffraction 2010
Fabrizio Ferro – INFN Genova

9. T2 telescope Both arms installed and taking data
2 arms of GEMs for tracks and vertex reconstruction
3.1<|h|< Df=2p
Both arms installed and taking data
Diffraction 2010
Fabrizio Ferro – INFN Genova

10. Fabrizio Ferro – INFN Genova
T2 event at 7 TeV
Diffraction 2010
Fabrizio Ferro – INFN Genova

11. Alignment and vertex reconstruction
Before
RMS=1.7cm
RMS=3.1m
RMS=1.4cm
After
RMS=0.8cm
RMS=1.0cm
RMS=2.3m
Diffraction 2010
Fabrizio Ferro – INFN Genova

12. Fabrizio Ferro – INFN Genova
h distribution
Tracks pointing to vertex
Statistical
error only
BeamPipe cone at h~5.53
Diffraction 2010
Fabrizio Ferro – INFN Genova

13. Fabrizio Ferro – INFN Genova
TOTEM Roman Pots
Diffraction 2010
Fabrizio Ferro – INFN Genova

14. Fabrizio Ferro – INFN Genova
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
Diffraction 2010
Fabrizio Ferro – INFN Genova

15. 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
Diffraction 2010
Fabrizio Ferro – INFN Genova

16. 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
Diffraction 2010
Fabrizio Ferro – INFN Genova

17. “Diffractive” protons at 7 TeV
preliminary
TOP
BOTTOM
Raw distributions, no selection:
Diffractive protons + background
Estimated Dp/p :
preliminary
Diffraction 2010
Fabrizio Ferro – INFN Genova

18. A first elastic scattering candidate
RPs at 25s
Run
Event 13682
Diffraction 2010
Fabrizio Ferro – INFN Genova

19. 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
Diffraction 2010
Fabrizio Ferro – INFN Genova

20. Fabrizio Ferro – INFN Genova
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 < |t| < 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 <|h |< 6.5
- Single and Central Diffraction at any mass
- Measurement of stot with a precision of ~ 5 % (1%)
Diffraction 2010
Fabrizio Ferro – INFN Genova