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Appendix A

Glossary of Terms

The physics part of this chapter derives mainly from "The ATLAS-Experiment Glossary" [60].absorption lossThat part of the transmission loss due to the dissipation or conversation into other forms of energy.
 acceleratorA machine used to accelerate particles to high speeds and thus high energy compared to their rest mass-energy.
 ALEPHA particle detector of the LEP accelerator.
 ALICEA future particle detector for the LHC accelerator.
 ASDBLRThe analogue chip of the front-end electronics of the ATLAS TRT.
 ASICA custom microchip designed for a specific application.
 ASTRALName of the combined ASDBLR and DTMROC chip.
 ATLASA future particle detector for the LHC accelerator.
 back-end electronicsThe electronics outside the detector.
 baryonA hadron made from three quarks. The proton (uud) and the neutron (udd) are both baryons. They may also contain additional quark-antiquark pairs.beamThe particle stream produced by an accelerator usually clustered in bunches.bosonA particle that has integer intrinsic angular momentum (spin) measured in units of (spin = 0, 1, 2,...). All particles are either fermions or bosons. The particles associated with all the fundamental interactions (forces) are bosons. Composite particles with even numbers of fermion constituents (quarks) are also bosons.bottom quarkThe fifth flavor of quark (in order of increasing mass), with electric charge -1/3.bremsstrahlungRadiation emitted by a charged particle under acceleration.
 calorimeterA device that can measure the energy deposited in it.
 characteristic impedanceThe impedance of a circuit that, when connected to the output terminals of a uniform transmission line of arbitrary length, causes the line to appear infinitely long.charm quarkThe fourth flavor of quark (in order of increasing mass), with electric charge +2/3.
 CMSA future particle detector for the LHC accelerator.
 colliderAn accelerator in which two beams travelling in opposite directions are steered together to provide high-energy collisions between the particles in one beam and those in the other.CP-violationCP-violation is one of three conditions outlined in 1964 by Russian physicist Andrei Sakharov to account for the observed imbalance of matter and antimatter in the universe.cross talkAn undesired signal disturbance introduced in a transmission circuit by mutual coupling with other transmission circuits.
 daughter board (also stamp board)The PCB with bonded die(s). This PCB does the actual signal read out.
 DELPHIA particle detector of the LEP accelerator.
 detectorAny device used to sense the passage of a particle. Also a collection of such devices designed so that each serves a particular purpose in allowing physicists to reconstruct particle events.
 DMILLMixed analog-digital BiCMOS technology.
 doseThe term dose (absorbed dose) refers to the mean energy imparted by ionizing radiation to the matter in a volume divided by the mass contained in the respective volume.down quarkThe second flavor of quark (in order of increasing mass), with electric charge -1/3.DTMROCThe digital chip of the TRT-front-end electronics.
 electromagnetic compatibilityThe condition or situation whereby a device or system is capable of functioning satisfactorily in the electromagnetic environment without introducing intolerable disturbance to that environment
 electromagnetic interactionThe interaction due to electric charge; this includes magnetic effects which have to do with moving electric charges.electronThe least massive electrically charged particle, hence absolutely stable. It is the most common lepton, with electric charge -1.electronvoltThe energy of radiation is usually measured in units of electronvolt (eV). This unit is defined as the energy gained by an electron when it is accelerated through a potential difference of one volt. The relation between the SI unit and the electron volt is:

electroweak interactionIn the Standard Model, electromagnetic and weak interactions are related (unified), physicists use the term electroweak to encompass both of them.event:What occurs when two particles collide or a single particle decays. Particle theories predict the probabilities of various possible events occurring when many similar collisions or decays are studied. They cannot predict the outcome for any single event.far-field regionThe region of the field of an antenna where the angular field distribution is essentially independent of the distance from the antenna
 fermionAny particle that has odd-half-integer (1/2, 3/2, ...) intrinsic angular momentum (spin). As a consequence of this peculiar angular momentum, fermions obey a rule called the Pauli-Exclusion Principle, which states that no two fermions can exist in the same state at the same place and time. Many of the properties of ordinary matter arise because of this rule. Electrons, protons and neutrons are all fermions, as are all the fundamental matter particles, both quarks and leptons.flavorThe name used for the different quark types (up, down, strange, charm, bottom, top) and for the different lepton types (electron, muon, tau). For each charged lepton flavor there is a corresponding neutrino flavor. In other words, flavor is the quantum number that distinguishes the different quark/lepton types. Each flavor of quark and charged lepton has a different mass. For neutrinos we do not yet know if they have a mass or what the masses are.
 front-end electronicsThe electronics detached on the detector.
 ghostA secondary image or signal resulting from echo, envelope delay distortion, or multipath reception.
 gluonThe carrier particle of strong interactions.ground loopA condition where the local grounds at each end of a length of cable or of two distant points in system are at a different potential. This sometimes causes
 hadronA particle made of strongly-interacting constituents. These include the mesons and baryons. Such particles participate in residual strong interactions.Higgs bosonThe carrier particle or quantum excitation of the additional force needed to introduce particle masses in the Standard Model. Not yet observed.interactionA process in which a particle decays or it responds to a force due to the presence of another particle (as in a collision). Also used to mean the underlying property of the theory that causes such effects.kaonA meson containing a strange quark and an anti-up (or an anti-down) quark, or an anti-strange quark and an up (or down) quark.L3A particle detector of the LEP accelerator.
 LEPThe LEP is the largest particle collider in the world. In a ring 27 km in circumference, buried about 100 m underground, bunches of electrons and positrons race round in opposite directions as they are accelerated to almost the speed of light.leptonA fundamental fermion that does not participate in strong interactions. The electrically-charged leptons are the electron, the muon, the tau, and their antiparticles. Electrically-neutral leptons are called neutrinos.LHCThe Large Hadron Collider at the CERN laboratory in Geneva, Switzerland. LHC will collide protons into protons at a center-of-mass energy of about 14 TeV. When completed in the year 2005, it will be the most powerful particle accelerator in the world. It is hoped that it will unlock many of the remaining secrets of particle physics.LHCbA future particle detector for the LHC accelerator.
 LVDSLow-Voltage Differential Signaling is a data interface standard which is defined in the TIA/EIA-644 and the IEEE 1596.3 standards.
 masssee rest mass.mesonA hadron made from an even number of quark constituents. The basic structure of most mesons is one quark and one antiquark.
 microstripA transmission line consisting of a metallized strip and a solid ground plane metallization separated by a thin, solid dielectric.muonThe second flavor of charged lepton (in order of increasing mass), with electric charge -1.neutrinoA lepton with no electric charge. Neutrinos participate only in weak and gravitational interactions and therefore are very difficult to detect. There are three known types of neutrino all of which are very light and could possibly even have zero mass.neutronA baryon with electric charge zero; it is a fermion with a basic structure of two down quarks and one up quark (held together by gluons). The neutral component of an atomic nucleus is made from neutrons. Different isotopes of the same element are distinguished by having different numbers of neutrons in their nucleus.neutron fluenceParticle fluence is defined as the number of particles traversing a unit area in a certain point in space in a unit period of time.
 OPALA particle detector of the LEP accelerator.
 particleA subatomic object with a definite mass and charge.
 photonThe carrier particle of electromagnetic interactions.pionThe least massive type of meson, pions can have electric charges 1 or 0.pixel detectorA semiconductor detector made of wafers with very small rectangular two- dimensional detector elements.
 positronThe antiparticle of the electron.
 protonThe most common hadron, a baryon with electric charge (+1) equal and opposite to that of the electron (-1). Protons have a basic structure of two up quarks and one down quark (bound together by gluons). The nucleus of a hydrogen atom is a proton. A nucleus with electric charge Z contains Z protons; therefore the number of protons is what distinguishes the different chemical elements.quark (Austrian: Topfen - Farmer's Cheese)A fundamental fermion that has strong interactions. Quarks have electric charge of either 2/3 (up, charm, top) or -1/3 (down, strange, bottom) in units where the proton charge is 1.
 reflectionThe abrupt change in direction of a wave front at an interface between two dissimilar media so that the wave front returns into the medium from which it originated.
 rest massThe rest mass of a particle is the mass defined by the energy of the isolated (free) particle at rest, divided by the square of the velocity of the speed of light.
 roof boardThe PCB designed to cover one half of the tension plate with mounted daughter boards.
 slew rateTime dervative of output voltage in response to a sudden change in input voltage.
 SPSThe Super-Proton Synchrotron is a circular accelerator, 6 km in circumference, buried underground. It was built originally to accelerate protons but it has since operated as a proton-antiproton collider, a heavy-ion accelerator, and an electron/positron injector for LEP. As a proton-antiproton collider in the 1980s, it provided the first observations of the W and Z particles, the carriers of the weak force.
 Standard ModelPhysicists' name for the theory of fundamental particles and their interactions. It is widely tested and is accepted as correct by particle physicists.
 strange quarkThe third flavor of quark (in order of increasing mass), with electric charge -1/3.strawThe detecting element of the TRT.
 striplineA transmission line consisting of a conductor above or between extended conducting surfaces.
 tau leptonThe third flavor of charged lepton (in order of increasing mass), with electric charge -1.tension plateThe PCB of the barrel placed on the end of the straws. This PCB supplies the mechanical fastening for the read-out wires and connects the input-signal to the read-out daughter boards.
 termination:The load connected to a transmission line, circuit, or device. For a uniform transmission line, if the termination impedance is equal to the characteristic impedance of the line, wave reflections from the end of the line will be avoided.
 top quarkThe sixth flavor of quark (in order of increasing mass), with electric charge 2/3. Its mass is much greater than any other quark or lepton.trackThe record of the path of a particle traversing a detector.
 transition radiationTransistion radiation is produced when a relativistic particle traverses an inhomogeneous medium.
 transmission lineThe conductive connections between circuit elements that carry signal power.TRTTransition Radiation Tracker, the central vertex detector for the ATLAS detector.
 up quarkThe least massive flavor of quark, with electric charge 2/3.
 vertex detectorA detector in collider experiments positioned as close as possible to the collision point. The goal of a vertex detector is to measure particle tracks very close to the interaction point.
 waveguide below cutoffA waveguide operated in a frequency range such that there is no real propagation of energy and incident fields are attenuated exponentially with length.
February 9, 2000 - Martin Mandl
Copyright © CERN 2000