Transcript Visit to DELPHI/LHCb

Visits to DELPHI/LHCb
Ph.Charpentier
18/11/04
DELPHI visits, PhC
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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, don’t 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
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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 + 2*600 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
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http://delphi-expo.web.cern.ch/DELPHI-Expo/VisitingDELPHI.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)
 e+e- 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
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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)
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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
QuickTime™
et un
QuickTime™ et un
décompresseur
TIFF
compressé)
décompresseur
TIFF(non
(non compressé)
sont
requis
pour
visionner
cette
image.
sont requis pour visionner cette
image.
 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
QuickTime™ et un
décompresseur TIFF (non compressé)
sont requis pour visionner cette image.
 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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QuickTime™ et un
décompresseur TIFF (non compressé)
sont requis pour visionner cette image.
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Useful infos
 http://delphiwww.cern.ch/
 main DELPHI page
 http://delphi-expo.web.cern.ch/DELPHI-Expo/VisitingDELPHI.html
 Detailed description for guides
 All links therein pointing to specific detector descriptions
 Phone numbers
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Gerant de site: 77801 or 160378
TSO: Bernard Corajod 163350
Ph.Charpentier: 74244 or 160167
R.Jacobsson: 73619 or 163730
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