Zeus (particle detector)

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For other uses, see Zeus (disambiguation).

The DESY South Hall where the ZEUS experiment is located.

ZEUS is a particle detector that was operation at HERA (Hadron Elektron Ring Anlage) in DESY, Hamburg. It began operating together with HERA in 1992 and was functional until HERA was decommissioned in June 2007. Leptons (electrons or positrons) were collided with protons by HERA in the interaction point of ZEUS. ZEUS was operated by an international collaboration of about 400 physicists from 42 institutes in 15 countries. The ZEUS detector comprises many components, including a depleted uranium-plastic scintillator calorimeter, a Central Tracking Detector, which is a wire chamber, a silicon microvertex detector and muon chambers. In addition a solenoid provides a 1.43 T magnetic field. The ZEUS experiment studies the internal structure of the proton through measurements of deep inelastic scattering. These measurements are also used to test and study the Standard Model of particle physics, as well as searching for particles beyond the Standard Model.

1 Background
2 Detector
- 2.1 Calorimeter
3 Notes
4 External links

[edit] Background

DESY was founded in 1959 and started colliding electron beams in 1964 in the DESY experiment. Since then, it has been a highly regarded centre for Particle Physics. The HERA collider began operation in 1992. The design effort for ZEUS can be traced back to 1982^{[citation needed]}. The last electron-proton collisions at ZEUS were recorded at approximately 11:20 p.m CET on June 30th 2007. The ZEUS detector is now in the process of being decommissioned and dismantled.

[edit] Detector

The ZEUS detector is comprised of many components ^[1]. The purpose of the ZEUS detector is to reconstruct physics events in a consistent way so they can be analyzed. The main components of the ZEUS detector are the Tracking Components, The Calorimeter and the Muon Detectors.

[edit] Calorimeter

The ZEUS calorimeter is a Uranium-Scintillator sampling calorimeter and is divided into 3 main sections the BCAL (Barrel CALorimeter), FCAL (Forward CALorimeter) and RCAL (Rear CALorimeter). Each section is subdivided transversely into towers and longitudinally into EMC (Electro-Magnetic Calorimeter) or HAC (HAdronic Calorimeter). The smallest sub devision in the calorimeter is called a Cell. Each cell is read-out by two Photomultiplier tubes, this redundancy helps to ensure that there are no holes in the detector if a PMT fails.

Uranium was chosen as an absorber because of its ability to compensate. Leptons (and photons) and Hadrons deposit energy differently than each other. In general the proportion of energy deposited from an Electromagnetic Cascade (e) is different from that in Hadronic Cascade (h). In most Physics experiments e/h > 1 which compromises the energy measurement. In the ZEUS calorimeter π⁰s interact with Uranium atoms to produce slow moving neutrons which are captured by the scintillator and increase the hadronic signal. Another advantage of using Uranium as the absorber is that the natural radioactivity allows one to monitor the calibration of the experiment over time.