Anatomy of a particle detector

5 April 2000

BaBar detector sm

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Like many modern detectors in particle physics experiments, the BaBar detector at SLAC consists of a series of concentric layers that surround the pipe in which particles beams collide head-on - in this case in the PEPII facility. Here an image of the "forward end" of the detector (so-called because the particles produced in the collisions tend to go in this direction) has been labelled to show the various layers. (It corresponds to the back of the schematic view).

Working from the centre, BaBar contains the major elements listed below.

  • Unseen here but at the heart of BaBar, the Silcon Vertex Tracker, to allow measurement of the paths of very short-lived particles
  • The Drift Chamber, used to track longer-lived charged particles. (BaBar Drift Chamber Project)
  • The DIRC (Detection of Internally Reflected Cherenkov light), to identify different charged particles through their Cherenkov radiation
  • The Calorimeter, to detect and measure the energy of photons and electrons. (How does a Calorimeter work?)
  • The Magnet coil (a solenoid), to bend the paths of charged particles for momentum measurement
  • The IFR (Instrumented Flux return), in which the iron for the magnetic flux return detects and measures the energy of hadrons using RPCs (Resistive Plate Counters)


Credit: BaBar