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First data from TOTEM experiment at LHC

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First data from TOTEM experiment at LHC Powered By Docstoc
					             First data from TOTEM
               experiment at LHC
               Fabrizio Ferro - INFN Genova




Diffraction 2010       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
                        Total pp cross section
Current models predict for
  14 TeV: 90 – 130 mb                               COMPETE
                                                    Collaboration:
Aim of TOTEM: ~ 1%
                         special optics
“First year”   : ~5%


  Luminosity independent method:




  Diffraction 2010              Fabrizio Ferro – INFN Genova
                          Physics with high b* optics




                                  log(|t|)/Gev2
-t = 4·10-4       0.012     0.3         2.5


              Total cross section measurement at ~5 % (~1%)
              Elastic scattering: 0.0004<|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
                           Physics with low b*
                                 Hits in RP220

      Single diffraction
   ds/dM : 0.025<x<0.15
       1 < 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
                     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
               T1 telescope (1)
  2 arms of CSCs for track and vertex
             reconstruction
        3.1<|h|<4.7 - Df=2p
• Both T1 arms on the test
  line. Ready for installation.




 Diffraction 2010        Fabrizio Ferro – INFN Genova
                                      T1 telescope (2)
               Both arms successfully tested with pion and muon beams
               Pions on copper target to get many-tracks events
efficiency




                                                                                p reconstructed hits



                    CSC efficiencies with muons
                       (triple coincidences)



                Longitudinal vertex
                                 Cu                                        Transverse vertex
                                 target



                                          Beam
                                          monitor
                                          frame



             Diffraction 2010               Fabrizio Ferro – INFN Genova
                            T2 telescope
 2 arms of GEMs for tracks and vertex reconstruction

   3.1<|h|<4.7 - Df=2p


Both arms installed and
      taking data




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




Diffraction 2010   Fabrizio Ferro – INFN Genova
              Alignment and vertex reconstruction

Before



                       RMS=1.4cm                     RMS=1.7cm    RMS=3.1m




After



                       RMS=0.8cm                     RMS=1.0cm    RMS=2.3m




    Diffraction 2010               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
                   TOTEM Roman Pots




Diffraction 2010      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
                     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
                                  Roman Pot alignment (at 20s)
                                            Horizontal alignment
  sectors 5-6 (IP5 minus side)                                sectors 4-5 (IP5 plus side)




                                                              Tracks in horizontal pot
     Tracks in vertical pot




                                                                                         preliminary
                              preliminary

                                              Halo protons




Diffraction 2010                            Fabrizio Ferro – INFN Genova
                   “Diffractive” protons at 7 TeV




                                                                    preliminary



                        TOP                     Raw distributions, no
                                                selection:
                                                Diffractive protons +
     preliminary                                background
                        BOTTOM

                                                Estimated Dp/p : 0.06 - 0.12



Diffraction 2010              Fabrizio Ferro – INFN Genova
             A first elastic scattering candidate
                                RPs at 25s




Run 1964.004
Event 13682




Diffraction 2010       Fabrizio Ferro – INFN Genova
  Analysis and data taking still in progress
  Data taking with RP at 25s : collected ~ 3 M events with RP only
                                         ~5M         “    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
                                 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

				
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