CDF Glossary
The Collider Detector at Fermilab
The CDF Group at the University of Chicago
 

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Axial- something that is aligned with the beam pipe or beam axis.

Barn- A unit of area equalling 10 to the -24 square centimeters, which is used to measure cross section.

Beam constraint- to require the track to come from the interaction vertex in order to obtain better momentum resolution.

Calorimeter- a device that can measure the energy deposited in it by particles traveling through it.  There are two types of calorimeters in the CDF detector, an electromagnetic calorimeter (detects electrons and photons) and hadronic calorimeter (detects hadron jets).

CDF- Collider Detector at Fermilab- an experimental collaboration committed to studying high energy particle collisions at the Tevatron in order to discover the properties of and interactions among the particles that make up the universe.

CMU- Central MUon System- part of the CDF detector that detects muons.  It sits outside the calorimeters and uses drift chambers to reconstruct hits.

CMP- Central Muon UPgrade- part of the CDF detector that detects muons, which extended the coverage for Run II.

CMX- Central Muon EXtension- part of the CDF detector that detects muons at larger angles than what the CMU/CMP covers.

COT- Central Outer Tracker- the main Run II tracking chamber.  It provides stereo position measurement of charged particle tracks.   The curvature of each track, due to the magnetic field from the surrounding superconducting solenoid magnet, allows us to measure the momentum of each charged particle.

CP- A symmetry operation incorporating the combined operations of C (charge conjugation) and P (parity), transforming a particle to its antiparticle (or vice versa) as well as from being right-handed to left-handed.

Cross section- A measure of the probability that a collision between two given particles will result in a specific event, with area units.  At the Tevatron, the cross section for top quark production at 1.8 TeV is approximately 6.2 picobarns, where one picobarn is 10 to the -12 barns.

CTC- Central Tracking Chamber- the main Run I tracking chamber.  It is a large drift chamber that provides stereo position measurement of charged particle tracks.

D0- the other experimental collaboration of scientists conducting research on the fundamental nature of matter at the Tevatron.  The research is focused on precise studies of interactions of protons and antiprotons.  It involves an intense search for subatomic clues that reveal the character of the building blocks of the universe.

Drift chamber- A tracking chamber containing many high-voltage anode wires and filled with a gas.  When a charged particle (produced in a collision) passes through the gas, some of the gas molecules become ionized.  the electrons released in this process travel to the anode, ionizing more molecules along the way.  By knowing the rate at which these electrons 'drift' towards the anode, and the number of electrons that reach the anode, physicists can calculate the precise track of a charged particle as it passes through the drift chamber.

Electroweak theory- the theory of the unified electromagnetic and weak interactions.

Event- a product of the interaction of a proton and an anti-proton.

Fermilab- Fermi National Accelerator Laboratory- the largest laboratory in the US for studying particle physics.  Fermilab advances the understanding of the fundamental nature of matter and energy by providing leadership and resources for qualified researchers to conduct basic research at the frontiers of high energy physics and related disciplines.

Forward-Backward Asymmetry- an asymmetry in the angle particles (such as electrons and muons) that are scattered in a collision.

FPGA- Field Programmable Gate Array- a programmable integrated circuit.

Good Run List- the list of the run numbers of data that is considered to be good.

Granularity- In particle physics (especially concerning the calorimetry systems), granularity is the level of subdivision in the eta and phi directions.  Finer granularities mean that a particle's energy deposition pattern can be known more precisely, while coarse granularities denote less precision.

HEP- High Energy Physics- the branch of physics that studies matter, energy, space, and time, and searches for the fundamental particles and forces of the universe.  It is also known as particle physics.

Higgs boson- a theoretical spin-0 boson that is the proposed mechanism by which particles acquire mass.

Impact parameter (d0)- the shortest distance of a particle trajectory from the primary vertex in the transverse plane to the point where the particle decays.

Invariant mass- the mass of a particle or system of particles when measured from any frame of reference.

Isolation- the amount of energy that is deposited in a cone around a track.  It is used for distinguishing between an isolated particle (such as an electron from a Z decay) and a particle in a jet.

Jet- a cluster of particles emerging from a collision in roughly the same direction, mostly hadrons.

Main Injector- the last acceleration ring through which protons and antiprotons pass before they are injected into the Tevatron.  Here, they reach energies of 150 GeV.

Monte carlo- a method of creating data based on the Standard Model to be used in a simulation of a proton - antiproton collisions.

Ntuple- a data-type used to store CDF data, a compact way to store event information.

Particle tagging- The identification of a type of particle (e.g. b quark).

Partons- quarks and gluons.

Physmon- Physics Monitor- A computing process that reconstructs and processes events, so that physics processes can be used to monitor the operation of the detector.

QCD- Quantum Chromodynamics- A theory that describes the interactions of quarks and gluons.  It explains the strong force.

QED- Quantum Electrodynamics- A theory of light and matter that describes how photons interact with electrons, and it incorporates special relativity.

Rest mass- the mass of a particle at rest.

Run- A well defined set of data, a collection of events.

Run I- The run of the Tevatron that lasted from 1992 to 1996.

Run II- The run of the Tevatron which started in the beginning of 2002 and is still going.

Scintillator- Material that emits light in response to charged particles. When charged particles interact with the scintillator, electrons in the atoms in the scintillator become excited.  When the atoms return to ground state, their electrons emit photons (light).  Physicists can then use this light to 'see' the particles' tracks.

Sea quarks- quarks created from quark-quark or quark-gluon collisions.

SLT- Soft Lepton Tag- Low energy leptons that are used to help identify jets containing quarks from higher generations, particularly bottom quarks present in their decay.

SM- Standard Model- the current model physicists have for the structure of the universe.  It is a model explaining the fundamental particles and forces.

Spin - The intrinsic angular momentum of a particle; for bosons, this value must be an integer, while for fermions, it must be half an odd integer.

Stereo- measured by wires in the COT and used with axial measurements to give three-dimensional coordinates of a track. The stereo wires in the COT are angled three degrees from the beam line.

SUSY- Supersymmetry- a theory relating the properties of bosons (integer spin) to fermions (half integer spin), giving every boson a supersymmetric fermion partner, and vice versa.  For example, a quark, which is a fermion, would have a supersymmetric partner of a squark, which would be a boson.  Supersymmetric partners would have all the same properties as each other except for mass and spin.

SVT- Silicon Vertex Trigger- a trigger processor that allows the accumulation of very large samples of hadrons containing bottom quarks.

Tevatron- the world's highest-energy particle accelerator, located about 30 feet below the ground at Fermilab.  A series of accelerators add energy to protons and anti-protons, accelerating them to speeds around 99.9999% of the speed of light in a vacuum, and colliding them inside the collider detectors.

Track- the record of the path of the trajectory of a particle in the detector.

Transverse- Anything perpendicular to the beam axis.

Trigger- 1. a processor that selects which events to store for analysis.  2. the criteria used for the selection of which events to store.

Trigger efficiency- how often a given trigger path will successfully identify a certain kind of event.

Vertex- the point from which particles emerge, such as the location of the collision in the detector.  The z position of the event.

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by Mark Stankevitz (glossary originally by Lynette Wehmer)