H1 (particle detector)
Encyclopedia
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 high-energy particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a...
in operation at HERA (Hadron Elektron Ring Anlage
Hadron Elektron Ring Anlage
HERA was a particle accelerator at DESY in Hamburg. It began operating in 1992. At HERA, electrons or positrons were collided with protons at a center of mass energy of 318 GeV. It was the only lepton-proton collider in the world while operating...
) in DESY
DESY
The DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....
, Hamburg
Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...
. It began operating together with HERA in 1992. Leptons (electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s or positron
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
s) are collided with proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s by HERA in the interaction point
Interaction point
In particle physics, an interaction point is the place where particles collide. One differentiates between the nominal IP, which is the design position of the IP, and the real or physics IP, which is the position where the particles actually collide...
of H1. H1 is operated by an international
collaboration of about 400 physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
s from 42 institute
Institute
An institute is a permanent organizational body created for a certain purpose. Often it is a research organization created to do research on specific topics...
s in 15 countries
Country
A country is a region legally identified as a distinct entity in political geography. A country may be an independent sovereign state or one that is occupied by another state, as a non-sovereign or formerly sovereign political division, or a geographic region associated with a previously...
. The detector
is about 12 x 15 x 10 meters big and weighs 2800 tons. It is accompanied by an electronics trailer 3 stories high.
While H1 is a general purpose detector its main design feature is an asymmetric construction
to cope with the boost
Boost
-Science, technology and mathematics:* Automotive:** Boost, positive manifold pressure in cars, see Turbocharger#Pressure increase.*** a loose term for turbo or supercharger** A slang term meaning to start a vehicle, see jump start...
ed center of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...
in the laboratory frame due to the large energy imbalance of the colliding beams.
In the forward (incident proton) direction the instrumentation has higher granularity to give a better
resolution for refined measurement of the proton remnant left after the collision with the incident lepton.
The reaction products, often including the proton remnant and the scattered lepton, are detected by several subdetectors. Combination of their information allows the identification of particles from the reaction,
or a least the reconstruction of the overall reaction kinematics. This in turn allows the classification of
the reaction. From the center outwards, H1's most important systems are:
- Silicon trackersSemiconductor detectorThis article is about particle detectors. For information about semiconductor detectors in radio, see Diode#Semiconductor_diodes, rectifier, detector and cat's-whisker detector....
for the determination of primary and secondary vertices. - Jet chambers for the measurement of charged particle tracks.
- Liquid ArgonArgonArgon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
(LAr) calorimeter for the measurement of electromagneticElectromagnetic radiationElectromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
and hadronic showers. - Lead/scintillating fibre calorimeter (SpaCal) in the backward direction for the measurement of the scattered lepton.
- Muon detectors in the iron magnet yoke surrounding H1 and in the forward direction.
In addition to these systems, H1 has several helper systems, such as a luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
system, ToF (time of flight) detectors and radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
monitors. Also in the course of time additional detector systems have been added as the focus on special physics processes has become bigger. For example, forward instrumentation for diffractive physics has been added far down the HERA tunnel.
The most interesting physics topics treated at H1 include
- Cross sectionCross section (physics)A cross section is the effective area which governs the probability of some scattering or absorption event. Together with particle density and path length, it can be used to predict the total scattering probability via the Beer-Lambert law....
measurements of reactions with charged and neutral electroweak currents - Studies of proton structure and determination of quarkQuarkA quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...
and gluonGluonGluons are elementary particles which act as the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles....
parton distribution functionsParton (particle physics)In particle physics, the parton model was proposed by Richard Feynman in 1969 as a way to analyze high-energy hadron collisions. It was later recognized that partons describe the same objects now more commonly referred to as quarks and gluons... - Tests of QCDQuantum chromodynamicsIn theoretical physics, quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons . It is the study of the SU Yang–Mills theory of color-charged fermions...
in jetJet (particle physics)A jet is a narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a particle physics or heavy ion experiment. Because of QCD confinement, particles carrying a color charge, such as quarks, cannot exist in free form. Therefore they fragment into hadrons...
and particle production - Production of heavy quarkQuarkA quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...
s (charmCharm quarkThe charm quark or c quark is the third most massive of all quarks, a type of elementary particle. Charm quarks are found in hadrons, which are subatomic particles made of quarks...
and bottomBottom quarkThe bottom quark, also known as the beauty quark, is a third-generation quark with a charge of − e. Although all quarks are described in a similar way by the quantum chromodynamics, the bottom quark's large bare mass , combined with low values of the CKM matrix elements Vub and Vcb, gives it a...
) - Diffraction (physics with the exchange of a pomeronPomeronIn physics, the pomeron is a Regge trajectory, a family of particles with increasing spin, postulated in 1961 to explain the slowly rising cross section of hadronic collisions at high energies.-Overview:...
) - Search for physics beyond the Standard ModelStandard ModelThe Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
(For example the substructure of quarks / contact interactionAction at a distance (physics)In physics, action at a distance is the interaction of two objects which are separated in space with no known mediator of the interaction. This term was used most often in the context of early theories of gravity and electromagnetism to describe how an object responds to the influence of distant...
s, LeptoquarkLeptoquarkLeptoquarks are hypothetical particles that carry information between quarks and leptons given a generation and allowing quarks and leptons to interact. They are color-triplet bosons that carry both lepton and baryon numbers. They are encountered in various extensions of the Standard Model, such as...
s, magnetic monopoleMagnetic monopoleA magnetic monopole is a hypothetical particle in particle physics that is a magnet with only one magnetic pole . In more technical terms, a magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring...
)
The H1 detector took data until the shutdown of HERA in June 2007.