- Research topics
Introduction to the DELPHI experiment
The DELPHI Detector Setup
Four different detectors have been
constructed to collect data on electron-positron collisions: ALEPH,
DELPHI, L3 and OPAL. Sweden participates in one of these detector
collaboration, the DELPHI.
DELPHI (DEtector with Lepton, Photon and Hadron Identification) is a
general purpose detector for e+e- physics at LEP on and above the
Z0, offering three-dimensional information on curvature and energy
deposition with fine spatial granularity as well as identification of
leptons and hadrons over most of the solid angle. It has been
operating since 1989.
The detector is installed in a cavern 100 m below ground. It
consists of a cylindrical section (the barrel), covered with two end-caps.
A superconducting solenoid provides a 1.23 T solenoidal field of
high uniformity parallel to the beam axis in the volume containing
barrel tracking detectors. Tracking relies on the Vertex Detector,
the Inner Detector, the Time Projection Chamber, the
Outer Detector and forward drift chambers.
Electromagnetic showers are measured in the barrel with high
granularity by the High Density Projection Chamber, and in the end-caps by the Forward Electromagnetic Calorimeter. The smaller polar angles, essential for detecting electrons
and positrons from two-photon processes and for luminosity
measurements, were covered until 1994 by the Small Angle Tagger
and the Very Small Angle Tagger. Later SAT was replaced with
the Small angle TIle Calorimeter. In addition, scintillator
systems are implemented in the barrel and forward regions for
triggering purposes and in order to achieve complete hermeticity for
high energy photon detection.
The iron return yoke of the magnet is instrumented with limited
streamer mode detectors to create the Hadron Calorimeter which
serves also as filter for muons, which are identified in two drift
chamber layers. In 1994 a layer of Surrounding Muon Chambers
was installed outside the end-caps to fill the gap between the barrel
and forward regions.
Charged particle identification is provided mainly by liquid and gas
Ring Imaging Cherenkov Counters both in barrel and forward