Visits to DELPHI/LHCb

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Visits to DELPHI/LHCb

• Ph.Charpentier

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The travel and the arrival
Parking
Elevator
Posters
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Surface visit

• Split into parties of up to 10 visitors
• If needed, could be 1 (e.g. 45 visitors for 4
  guides)
• Warn the gérants de site when arriving for
  opening the sas
• Maximum 2 groups in the cavern
• Go to the lift with 2 groups immediately
• The guides should use their access card, not the
  sas
• Fill in the logbook next to the lift (name,
  number of visitors, time)
• Make an introduction to the other groups showing
  them the surface posters (big-bang, LHC machine
  etc)
• For safety reasons, dont let people into the
  construction hall
• About 20 mn in the cavern, not more
• One group could go down once the first group is
  back

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A bit of history

• Collaboration started in 1981
• Founded by Ugo Amaldi (spokesperson until 1992)
• Approved in 1983
• 1982-1985 prototyping
• 1986-1988 installation
• 1989-2000 data taking
• 2001 dismantling
• Ongoing analysis and publications
• LEP started on 14.07.1989, stopped on 2.11.2000
• DELPHI is the only part of LEP detector remaining
  intact
• In fact only the barrel is left, the endcaps have
  been dismounted
• LHCb is the experiment on LHC at pit8
• Under construction, hence not a visit area

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DELPHI in numbers

• Manpower 500 physicists 500 engineers /
  technicians
• 3 years of construction installation
• Weight 3200 tons (2000 barrel 2600 endcaps)
• Total length of cables 1100 km
• Many cables carry up to 16 electronics signals
• 3 level of electronics rooms on one side, 2 on
  the other
• Electronics power 500 kW
• Data acquisition and control
• 75 microprocessors for signal treatment
• 15 powerful workstations on the surface for
  control
• 2 large mainframes for data collection
• Data transfer on optical link or Intranet
• http//delphi-expo.web.cern.ch/DELPHI-Expo/Visitin
  gDELPHI.html - numbers

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The DELPHI detector
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The detectors

• Set of cylindrical detectors around the beam pipe
• Beam pipe beryllium and carbon fibre (11 cm in
  diameter)
• ee- collisions at the center
• 3 functions
• Locate the particles
• Measure their momentum / energy
• Identify their nature (electron, pion, proton,
  kaon, muon)
• From the center to the outer
• Very precise at center
• Less and less precise going to the outside
• Tracking devices (4 layers VD, ID, TPC, OT)
• Identification device (RICH)
• Solenoid
• Electromagnetic calorimeter (lead absorber)
• Hadronic calorimeter (iron absorber)
• Muon detector

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Vertex Detector

• Silicon ladders (precision 7µm) not yet
  presented

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Inner Detector (ID)

• Centre jet chamber
• Drift chamber made of 24 sectors of 24 wires each
• Measure the time electrons take to go from the
  track to the wire
• Outside straw tubes
• 5 layers

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Time Projection Chamber

• Ionisation in a gas
• Argon methane
• Electric field // axis
• Electrons drift towards the outside
• Located using a wire chamber with pads
• Measure the drift time
• V 6.7 cm/µs
• Get the distance
• 3 dimension device

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Ring Imaging Cherenkov

• Particles can go faster than light
• In a given medium
• Not in vacuum!
• Effect similar to the sound barrier
• Light shock-wave instead of sound shock-wave
• Emission angle linked to the speed and the
  refraction index
• Measuring the angle measures the speed
• Light is focused by mirrors to form rings
• Radius of ring depends on the angle

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Calorimeters

• Stop particles in heavy material
• Instrument it to count the number of particles
  created in the shower
• Energy proportional to number of particles
• Lead absorber electrons and photons
• HPC detection based on the TPC technique
• Iron absorber hadrons (i.e. all others except
  muons and neutrinos)
• HCAL detection based on streamer tubes

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Solenoid

• Superconducting solenoid
• Cooled with liquid helium at 4.7 K
• No power consumption
• 5000 Amperes
• Magnetic field 1.2 T
• Largest superconducting solenoid in the world

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Useful infos

• http//delphiwww.cern.ch/
• main DELPHI page
• http//delphi-expo.web.cern.ch/DELPHI-Expo/Visitin
  gDELPHI.html
• Detailed description for guides
• All links therein pointing to specific detector
  descriptions
• Phone numbers
• Gerant de site 77801 or 160378
• TSO Bernard Corajod 163350
• Ph.Charpentier 74244 or 160167
• R.Jacobsson 73619 or 163730