ZEUS was a

particle detector In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nu ...

that operated on the HERA (''Hadron Elektron Ring Anlage'') particle accelerator at the German national laboratory DESY in

Hamburg (male), (female) en, Hamburger(s), Hamburgian(s) , timezone1 = Central (CET) , utc_offset1 = +1 , timezone1_DST = Central (CEST) , utc_offset1_DST = +2 , postal ...

. It began taking data in 1992 and was operated until HERA was decommissioned in June 2007. The scientific collaboration behind ZEUS consisted of about 400

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

s and technicians from 56

institute An institute is an organisational body created for a certain purpose. They are often research organisations ( research institutes) created to do research on specific topics, or can also be a professional body. In some countries, institutes ca ...

s in 17 countries. The ZEUS detector comprised many different detector components, including a depleted uranium plastic- scintillator

calorimeter A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimete ...

, a central tracking detector (which was a

wire chamber A wire chamber or multi-wire proportional chamber is a type of proportional counter that detects charged particles and photons and can give positional information on their trajectory, by tracking the trails of gaseous ionization. was located via ...

), a

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...

microvertex detector and muon chambers. In addition, a solenoid provided a magnetic field. Like its partner experiment H1, the ZEUS experiment studied the internal structure of the proton through measurements of

deep inelastic scattering Deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons, muons and neutrinos. It provided the first convincing evidence of the reali ...

by colliding

leptons In particle physics, a lepton is an elementary particle of half-integer spin (spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), and neutr ...

(

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

s or positrons) with protons in the

interaction point In particle physics, an interaction point (IP) is the place where particles collide in an accelerator experiment. The ''nominal'' interaction point is the design position, which may differ from the ''real'' or ''physics'' interaction point, where ...

of ZEUS. These measurements were also used to test and study the Standard Model of

particle physics Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...

, as well as to search for particles beyond the Standard Model.

Background

The German national laboratory DESY was founded in 1959 and started operating its first particle accelerator in 1964. Since then, it has been a highly regarded center for

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they a ...

science, astroparticle physics, and the development, construction and operation of particle accelerators. The design effort for ZEUS can be traced back to 1982. A Letter of Intent was submitted in 1985. The ZEUS detector was operational with the first collisions of the HERA collider in 1992. The last electron–proton collisions at ZEUS were recorded on 30 June 2007. The other multi-purpose experiment at the HERA collider was the competing H1 experiment. Since May 2012, the former ZEUS detector hall has been used as a lab space for the international European XFEL project.

Detector

The main components of the ZEUS detector were the tracking components, the calorimeter and the muon detectors. The purpose of the ZEUS detector was to collect data to allow the reconstruction of physics events in a consistent way so they can be analyzed.

Calorimeter

The ZEUS

Calorimeter A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimete ...

was a

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

scintillator based sampling calorimeter and divided into three main sections: the BCAL (Barrel CALorimeter), FCAL (Forward CALorimeter), and RCAL (Rear CALorimeter). Each section was subdivided transversely into towers, and longitudinally into EMC (Electro-Magnetic Calorimeter) or HAC (HAdronic Calorimeter). The smallest subdivision in the calorimeter was called a cell. Each cell was read out by two photomultiplier tubes (PMTs), which helped ensure that there were no holes in the coverage if one of the two PMTs failed. Uranium was chosen as an absorber so that the

would be compensating.

Electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

and

s deposit energy differently from

hadron In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the e ...

s, but in a compensating calorimeter the response (e) for an electromagnetic cascade is equal to the response (h) for a hadronic cascade of the same energy (i.e. ). In the ZEUS calorimeter neutral pions interacted with uranium atoms to produce slow-moving

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

s which were captured by the scintillator and increased the hadronic signal. Another advantage of using uranium as the absorber was that the natural radioactivity allowed the calorimeter's sensitivity to be conveniently monitored.

Notes

External links

http://www-zeus.desy.de/ - Official homepage

ZEUS experiment record
on INSPIRE-HEP {{coord, 53.574603, 9.89555, format=dms, type:landmark_region:DE-HH, display=title Buildings and structures in Altona, Hamburg Particle experiments