The Obligatory Disclaimer

In the course of the day to day working with the accelerator there is a bewildering array of "Accelerator Technospeak" used in the Operations Group and other areas of the Accelerator Division. This glossary is meant to be an attempt at helping the uninitiated understand some of the terms and buzz words that are commonly used in everyday communication within the accelerator group and the lab in general.

Since this glossary was created primarily for Operations Department personnel there are some terms included in this glossary that might be confusing or unfamiliar to those outside of the Operations Department. By the same token there are many commonly understood terms used by other Divisions and groups in the lab that are not well known or non existent within the Operations Department. Many terms will not be found within this document. I have included all terms that I have come across or have been submitted for inclusion. I have also included some definitions of obsolete terms and devices since they still exist in accelerator literature and documentation that is internal to the lab.

Although I have attempted to check all of the entries for accuracy there is no guarantee that all of the definitions are accurate or even current. Entries that come from a Rookie Book or other source are referenced. It is hoped that this glossary will be periodically updated with new material. If anybody has any contributions of terms, definitions or sources of other glossaries to be included please feel free to pass them on, even if they are not related to the accelerator division.

I am grateful for the help of Tony Jackson in helping me research and enter terms until we were both sick of it, John Reyna for supplying an extremely long list of suggestions, Dr. Malensek of the Research Division for allowing me to use his glossary of High Energy Physics Terms, Cons Gatusso for typing skills, and the entire Accelerator Division Operations Department for their suggestions and checking the accuracy of my definitions. I would also like to thank my supervisor Bob Mau for allowing me to spend the enormous amount of time that is necessary for a project of this size.

Sources of terms and definitions from other Laboratory Divisions will be greatly appreciated. Any comments, compliments or complaints are more than welcome.

 			     Original authoring done by:

                                   Jack Standeven
                                Accelerator Division
                                  Operations Group

-Numbers-

080 Module :

The interface module between a microprocessor and its associated CAMAC crate. The microprocessors, such as the Refrigerators, QPM's, and HOG's, use one parallel bus (Multibus) whereas the CAMAC Dataway is a different parallel bus.

130 Module :

An interface module between a console PDP-11/34 and the user-controlled devices at an ACNET console. These modules function as video generators as well as supporting the keyboard, knob, and interrupt button. At this date most of the consoles have been switched over to the new mvax hardware. Eventually all PDP-11 consoles will be phased out and the 130 card will become obsolete.

160 Module :

A card which is capable of generating a ramp waveform which may be a function of time and/or a function of a front panel scale factor, I. This front panel scale factor is generally MDAT but may be any 12 bit digital word. The output of the card is of the form

                   { ( V out ) = I * ( V(I) + G(T) ) }

where V(I) and G(T) are functions of current and time. The card was designed to be used for the Tevatron dipole correction elements. In this usage the output tracks the Tevatron magnet current as represented by the MDAT signal and may contain a "time-bump" which changes the dipole current with respect to the time in the accelerator cycle. These cards are also used for Tevatron RF curves, flying wires, abort kicker waveforms, and some injection magnet waveforms.

165 Module :

A power supply controller for many devices. 165s are used almost exclusivly for time dependant applications. The ramps are loaded from the MCR. The ramp is of the form: { V out = Scale factor * table value * ring energy } The scale factor is set by the D/A value entered by an operator on a parameter page. The table value is a time dependent multiplier set from a 165 control page. The beam energy is represented by MDAT and defaults to full scale if not specified.

175 Module :

Encoder for TCLK. This module generates an eight bit parallel signal, known as a "clock event". This is then shipped to the TCLK transmitter, ( a 176 module ) via a front panel ribbon connector, where it is converted to a serial format and superimposed onto a 10 Mhz signal for transmission. Each 175 module contains 16 prioritized channels. The event is generated whenever a channel receives an external trigger.

177 Module :

A time delay module for many devices around the accelerator. Each module has 8 channels which may be triggered independently, and each may be referenced to as many as 15 TCLK events. Each channel has a programmable delay ranging from 1 microsecond to 65.535 seconds. Upon receipt of a trigger each channel that is enabled outputs a TTL pulse which may be used to trigger any other device.

190 Module :

A module which interface the MADC's around the accelerator to the controls system. It can support up to 128 channels, and is capable of supporting up to 6 plots at a 2.1 Khz rate or a single channel at 70 Khz. It is able to determine which of the devices under its care are in an alarm state, and can decode events on the accelerator clock system.

200 Module :

See abort concentrator module.

279 Module :

A module which provides a programmable delay from a TCLK, MRBS, or TVBS event. The passage of time is measured directly in terms of the number of beam revolutions. A clock "tick" represents 7 RF cycles, so there are 159 ticks per revolution. The clock operates at approximately 7.5 Mhz and is capable of delaying a signal up to 412 turns.

4616 :

Linac RF driver PA tube, with an output of 200 kW. Cathode driver for the 7835 PA tube. Manufactured by RCA.

613 :

Obsolete term. Refered to the Tektronix 613 storage scope that was associated with each ACNET console. It was capable of plotting up to four parameters at a time and retained the image on the screen. 613 also refered to the CAMAC controller card for the storage scope.

7651 :

Linac IPA2 tube, with an output of 2 kW. Drives 4616 driver tube. Manufactured by RCA.

7835 :

Linac PA tube, with an output of 4 MW. Drives linac RF cavity via 9" coaxial transmission line. Manufactured by RCA. 8-Gev MAC : Obsolete device. MAC-16 computer which served as the interface between MR DEC and the 8-Gev devices. It was located in the MAC room. Its functions have been replaced by DEC S.

-A-

A/D , ADC :

Analog to Digital converter (hardware) or the Analog readback of a device (software). The hardware is a device which converts an analog voltage presented at its input to a binary digital representation of that voltage for use by the control system. Most A/D's in the control system have a measurement resolution of less than 5 mv and accept input voltages in the range -10.23 to 10.24 volts. In some applications (Linac and MRPS regulation) special units are used which have a resolution of less than 1.25 mv.

AAL :

Activation Analysis Laboratory of the ES&H Section

Abort :

Terminating the acceleration process prematurely, either by inhibiting the injection mechanism or by removing circulating beam to some sort of dump. This is generally done to prevent injury to some personnel or damage to accelerator components.

Abort Concentrator Module :

A CAMAC 200 module in the Main Ring, Tevatron, and Pbar abort system capable of accepting up to 8 inputs from devices in a given service building. If the permit signal originating from a device disappears, an abort is generated.

Abort Link Generator Module :

A C201 card located at the C0 Service Building which generates the 5 MHz permit signal broadcast around the abort loop.

Abort Logic/Pulse Shifter Interface :

Produces status of Main Ring and Tevatron abort loops. Inputs to Linac Keyswitch Module.

Abort Loop :

The system of electronics which decides to remove the beam from an accelerator in order to protect personnel and/or equipment.

Abort Reset Command (Tev) :

A command sent from the MCR in the form of a TCLK event which clears the latched abort status and restores a beam permit.

Abort System :

The Main Ring and Tevatron abort system at Fermilab is designed to dump the beam promptly on a beam dump. During Fixed Target operation both dumps are located near the long straight section C. During Colliding Beams operation the Tevatron abort system is located in the A0 section of the ring to make room for the Tevatron seperators. The abort magnets are triggered by any one of several abnormal accelerator conditions or radiation alarms. It is routinely fired at the end of an acceleration cycle to purge the accelerator of unextracted beam.

Absolute Pressure :

Units to measure gas pressure. Normally referred to as psia (pounds per square inch absolute) with zero being a perfect vacuum.

Accelerating Column :

Located in the Pre-Acc pit. Set of seven titanium electrodes (eight gaps) arranged in Pierce geometry to accelerate ions to 750 keV. Situated between -750 kV dome and pit wall.

Accelerator :

Any machine used to impart large kinetic energies to charged particles such as electrons, protons, and atomic nuclei. These accelerated particles are then used to probe nuclear or subnuclear phenomena. There are also many accelerators in industrial and medical applications.

Accelerator Studies :

Mode of operation of the accelerator where accelerator performance and/or beam dynamics is studied and tested.

Acceptance :

The measure of the limiting aperture of a transport line, accelerator, or individual device; it defines how "large" a beam will fit without scraping. More technicaly acceptance is the phase-space volume within which the beam must lie in order to be transmitted through an optical system without losses. From an experimenters point of view acceptance is the phase-space volume intercepted by an experimenter's detector system. The complement of emittance.

Accidental Rate :

The rate of false coincidences in an electronic counter experiment produced by products of the reactions of more than one beam particle within the time resolution of the apparatus.

Accumulator:

The storage ring in which successive pulses of antiprotons are collected in order to create an antiproton beam of reasonable intensity for colliding beams physics. The Accumulator is designed to accept a pulse of antiprotons from the Debuncher every few seconds and accumulate up to 5 X 1011 antiprotons in several hours. Some of the design parameters are:

Ring Parameters

• kinetic energy 7.9 GeV
• average radius 75.45 meters
• momentum aperture Dp/p 2.5%
• btron acceptance 10p mm-mrad
• btron tunes, nH 6.611
• nv 8.611
• periodicity 3

  Stack Parameters at Injection

• number of p-'s 8X107
• Dp/p 0.2%
• emittance (both planes) <10p mm-mrad
• fraction of beam accepted >85% of injected pulse

  Final Stack Parameters

• number of p-'s 5X1011
• Dp/p 0.05%
• emittance (both planes) 2p mm-mrad
• peak density 1X105 eV-1
• core width 1.7 MeV (rms)
• total stacking time 5 hours

Achromatic :

The quality of a transport line or optical system where particle momentum has no effect on its trajectory through the system. An achromatic device or system is that in which the output beam displacement or divergence (or both) is independent of the input beam's momentum. If a system of lenses is achromatic, all particles of the same momentum will have equal path lengths through the system.

ACLKWATCHER :

A process on the VAX which decodes TCLK events and generates timing information for internal consumption (for such things as the frequency of data acquisition.)

ACNET :

Accelerator Control NETwork. A system of computers that monitors and controls the accelerator complex. Interfaced to users through consoles in the MCR and elsewhere.

ACNET CONSOLE USER'S GUIDE :

See Console User's Guide.

AD :

Accelerator Division

AD/OPS :

Accelerator Division Operations Department

Adiabatic :

No heat transfer with the environment.

Adiabatic Cooling :

The classical description is a process in which the temperature of a system is reduced without any heat being exchanged between the system and its surroundings. At Fermilab this term is used to describe the process in the Antiproton Source Accumulator storage ring where beam emittances are reduced without affecting beam energy. This process is used in accumulating antiprotons.

Adsorber :

Attracts and holds (by Van der Waal forces) molecular layers of dense gases (i.e. very near condensation temperatures) on porous high surface/volume ratio materials.

Adsorbent :

The material of an adsorber. Silica gel, Alumina, Charcoal. Characterized by high surface/volume ratio.

AEOLUS :

A process on the VAX which collects alarm information from the front-ends, combines that information with appropriate parameters in the database, and sends the package to the console cpus.

Aggregate ON/OFF :

A command used to control the digital status of a block of devices.

AGS :

Alternating Gradient Synchrotron accelerator at Brookhaven National Laboratory on Long Island, New York. It is a 30 GeV combined function proton synchrotron which started operation in 1959.

Air Ionization Chamber :

Devices used by NTF to monitor neutron flux during patient treatment.

ALARA :

As Low As Reasonably Achievable. A safety acronym used to describe the radiation safety philosophy of minimizing occupational radiation exposure.

Alarm :

A message, usually generated by the AEOLUS VAX process, indicating that the digital or analog status of a device is not within the tolerances set for it.

Alarm Display Monitor :

A color television display in the upper right-hand corner of each ACNET console which lists devices currently in a state of alarm.

Alarm screen :

Same as the Alarm Display Monitor (see above)

Alarm system :

The integrated system through which alarms reach the Alarm Display Screen from devices in the field. The front- ends each have their own way of generating alarm codes, which are then forwarded to the AEOLUS process in the VAX. AEOLUS in turn obtains information from the database before sending the combined package to the console cpu. Finally, the Alarm Display Task, a secondary applications program, puts the messages on the alarm screen.

Alpha Function :

( ax, ay ) A measure of the change of the beta function db/dz; a>0 N converging, a Alpha Particle :

A Helium nucleus consisting of two protons and two neutrons, generally seen as a decay product from a heavy radioactive nucleus.

Amplifier :

Any device that amplifies an electronic signal.

Amplitude Control Module :

Linac low-level RF system component that controls the amplitude of the RF gradient by varying the size of the modulator input pulse.

Analog :

Typically a device or circuit that expresses a signal in direct proportion to a physical measurement.

Analog-To-Digital-Converter :

See A/D , ADC

Annihilation :

A process in which a particle and its anti- particle meet and convert spontaneously into photons. It is the inverse of pair production.

Annunciator Board :

Status panel in Linac primary and secondary microprocessors showing status and interrupt levels.

Anode :

Negative electrode or plate of an amplifier tube or discharge tube. In terms of the accelerator it is also taken to mean the power supply cubicles for Booster, Tevatron and Main Ring that contain the transformers for the RF PA anode supplies.

ANSI :

American National Standards Institute

Antiparticle :

A particle having the same mass as a given fundamental particle, but whose other properties, while having the same magnitude, may be of opposite sign, e.g., electrical charge in the case of the electron and positron, magnetic moment in the case of the neutron and antineutron. On collision a particle and its antiparticle may mutually annihilate with the emission of radiation.

Antiparticles :

Each particle has a partner called an antiparticle. Some properties of the antiparticle will be identical in magnitude but opposite in sign to the particle it is paired with. Examples of such properties are electric charge in the case of the electron and positron, and magnetic moment inthe case of the neutron and antineutron. Strangeness and charm are two other properties among many that can vary in sign. When a particle or its antiparticle meet, these properties cancel out in a process called annihilation. The annihilation process between protons and antiprotons are the collisions that take place in the middle of the Tevatron particle detector experiments during colliding beams.

Antiprotons :

Antiparticle to the proton. It is a strongly interacting baryon carrying unit negative charge. It has mass of 938 mev and carries spin 1/2.

Antiquench :

The false appearance of a positive resistive voltage (negative resistance). This is the result of the Quench Protection Monitors's calculation during an actual quench in another cell or due to an instrumentation failure.

AP or APCR :

Antiproton Control Room, located in AP10. Now more commonly referred to simply as AP10.

AP0 :

Accelerator building situated above the pbar target vault enclosure. The power supplies, electronics and maintenance equipment for the pbar target station and lithium lens are located here.

AP1,2,3 :

The beamlines which transport protons and antiprotons between the Main Ring and the Antiproton Source. AP1 serves a dual purpose: First, it transports 120 GeV protons from the Main Ring to the p- production target. Secondly, it transports 8 GeV antiprotons from the AP3 line to the Main Ring (reverse injection). The AP2 line is designed to transport 8 GeV antiprotons from the target vault to the debuncher ring. AP3 exists to transport extracted bunches of p-'s from the Accumulator around the target vault and to ap1, which ultimately brings antiprotons into the Main Ring.

AP4 :

The beamline designed to provide a low intensity beam of 8 GeV protons from the Booster to the Debuncher.

Aperture :

A measure of the physical space available for beam to occupy in a device. Aperture limitations, however, are not always due to the physical size of the vacuum chamber; for instance, a magnetic field anomaly may deflect the beam so that the full available aperture cannot be used.

Aperture scan :

Process of changing the beam position via 3- bumps in a localized area in order to determine the size of the aperture. The beam is moved until is scrapes the side of the beam pipe or encounters an obstruction.

APM :

Applications Program Manager. A function on the console computer which coordinates application task scheduling by making sure the PA or SA executes at the proper periodic rate, recognizes the keyboard interrupt, etc. It also performs console data collection tasks, determines the visible cursor position, shaft encoder position, touch panel x,y position, and the status of the interrupt button.

Apparent Mean Thermal Conductivity :

The effective thermal conductivity of an assemblage of material (Pearlite, super insulation) between specified temperatures.

Application Programs :

Software designed for direct use by a console user. The programs reside on the ACNET consoles.

Archive :

Permanent storage of information regarding a given accelerator system . Magnetic tape is the primary medium. An archive should be distinguished from a "Save", where information is written onto a disk and is likely to be written over at some future date.

ARF1,2,3 :

There are three different radio frequency systems used in the Accumulator and are known as ARF1, 2, and 3. Briefly, ARF1 is a 53 MHz system (h=84) and is used to capture the unbunched beam injected from the Debuncher, decelerate it across the aperture through which the shutter moves, and adiabatically unbunch the beam at the edge of the stack-tail. It is also used to rebunch the unstacked pbars immediately before they are extracted so that the p-'s injected into the Main Ring enjoy a synchronous bucket to bucket transfer. ARF2 is the h=2 system employed to adiabatically capture a portion of the core and accelerate it to the extraction orbit. ARF2 has one suppressed bucket, so only one bunch is unstacked at a time. Since the single bunch is too large longitudinally to fit into the 10-12 MR-size bunches that are wanted, additional RF is energized to shorten up the bunch. ARF3 provides this extra RF. Because it is desirous to perturb the remaining beam in the stack as little as possible, ARF3 is not energized until the beam is on the extraction orbit. Just before the p-'s are extracted, ARF1 is turned on in order to rebunch the beam into 10-11 bunches suitable for synchronous transfer to the Main Ring.

ARGUS :

A process on the VAX which logs off interactive users if the account has been idle for a certain length of time.

ASME :

American Society of Mechanical Engineers

Atmosphere :

A convenient measure of pressure. 1 std atm = 14.696 psia.

Atom :

A particle of matter indivisible by chemical means. It is the fundamental building block of the chemical elements. The elements, such as iron, lead, and sulfur, differ from each other because they contain different kinds of atoms. There are about six sextillion atoms in an ordinary drop of water. According to present day theory, an atom contains a dense inner core (the nucleus) and a much less dense outer domain consisting of electrons in motion around the nucleus. Atoms are electrically neutral.

Atomic % :

A way of describing mixtures, especially of NeH2. Nearly equal to the volume percent.

						  Mole % Ne 
                                    Atomic % Ne = ########### 
                                                  2-Mole % Ne 

For NeH2 only Mole % Ne is higher than Atomic % Ne.

Auto-Gradient :

Feature where the Linac RF gradients are controlled by computer through the Amplitude Control Module. Normally engaged.

Auto Quench Recovery (AQR) :

A computer program residing in the refrigerator micro-p which automatically performs cooldown after a quench.

AUXNETPROCESS :

A process on the VAX which handles routine functions such as the time of day and boot capability for the ACNET network.

-B-

B0 :

A reference point on the Main Ring at which the Collider Detector at Fermilab is located (pronounced "B zero"). Other significant reference points include the D0 collision region, and C0, E0, and F0 regions used for specialized experiments.

B0 Collision Hall :

Also referred to as the Collision Hall. CDF detector at BO resides in this hall during collider operation.

B Clock :

Obsolete. A frequency that was transmitted to a module in the MAC-A PDC crate which was proportional to the change in the Main Ring current. The dI/dT was measured in the magnet cage and transmitted over the Main Ring B-clock link via CC42 cards.

BAO :

Batavia Area Office of the DOE

Back Racks :

Electronics racks behind the primary working region of the Main Control Room; consists of patch panels, link modules, highpotters, and much more.

Background :

Whatever devices are used to make a measurement in an experiment, the measurement is a superposition of events from the target and events from all other sources (background). The background therefore sets a lower limit on the detection of small signals. More generally, background is any unwanted signal.

Bakeout :

To minimize beam loss due to gas scattering, the vacuum within a beam chamber must be as good as possible. The Accumulator is designed to be a high class storage ring capable of circulating the same antiproton beam for hours or days on end. In order to meet the design vacuum of 3x10-10 Torr in the Accumulator provisions have been made to literally bake the Accumulator beam pipe in situ. This causes water vapor, oils, and other contaminants trapped inside the stainless steel to outgas. Turbo and Ion pumps take care of the effluent. A bakeout is done at temperatures of >100º C. Other devices that are baked out are the Tevatron Lambertsons and Seperators.

Barn :

A unit for measuring cross sections. 1 barn = 1024 square centimeters. The units appropriate in high energy physics are usually the millibarn (10-3 barn), the microbarn (10-6), or the nanobarn (10-9 barn).

Baryon :

A collective term for all strongly interacting particles with masses greater than or equal to the mass of the proton. Examples are the proton, neutron, and hyperons.

Basic control :

The ability to change the digital status of a device by interrupting on a parameter page. This function is supported by the database. See basic status.

Basic status :

Digital status of a device as displayed on a parameter page. There are three characters displayed in a standard format (...). The first indicates ON/OFF status; the second indicates the trip/reset status; and the third indicates if the supply is in local or if the breaker has tripped. If all of the digital status for a device is good, three green dots will be present. Some devices have a fourth bit of +/- to show polarity.

Batch :

Group of 83 bunches of beam which are the result of one Booster acceleration cycle. The Main Ring and the Tevatron can contain up to twelve of them.

Batch :

A unit of beam corresponding to the output of one Booster cycle. Up to 12 batches of beam can be injected into Main Ring each cycle.

Baud :

A unit of signalling speed; defined as the number of code elements (i.e. bits) per second.

Bayonet :

A low heat conduction, longitudinally extended connector for cryogenic piping. see Transfer Line.

BCS Theory :

This is the successful theory of superconductivity developed in the 1950's and eventually resulting in the Nobel prize for the authors, J. Bardeen, L.N. Cooper, and J.R. Schrieffer, Phys. Rev. 108, 1175 (1957). This is the classic exposition of the BCS theory.

Beacon :

Message on Linac serial data link flashed by a secondary microprocessor when the link repeater upstream of it fails.

Beam :

A slender unidirectional stream of particles or radiation.

Beam-Beam Tune Shift :

When pbars pass through a proton bunch electromagnetic interactions from the proton bunch affect the pbars as if the proton bunch were higher order corrector that includes both horizontal and vertical quadrupole components. To the protons the pbar bunch like wise appears as a similar higher order corrector. The cumulative affect of these pbar-proton bunch high order correction effects is a shift in the tunes. Thus the term beam-beam tune shift.

Beam Cooling :

The process by which a particle beam's phase space volume is reduced, while conserving Liouville's theorem (there are empty spaces between particles). Beam cooling is manifest by a reduction in the transverse beam size (betatron cooling) or by a smaller momentum spread (momentum cooling). Beam cooling is primarily used these days to accumulate beams of antiprotons for p-p colliding beams physics. There exists two ways of cooling a hadron beam: Stochastic (employed at Fermilab and CERN), and Electron (first demonstrated at Novosibirsk).

Beam Damper :

A device for applying a force on the circulating beam in an accelerator to reduce either the excursions from the equilibrium orbit (betatron oscillations) or from equilibrium phase (synchrotron oscillations)

Beam Dump :

A massive object used to absorb an unwanted beam and dissipate the resulting heat. Dumps for high intensity beams are usually composed of large water cooled metal blocks. They must be shielded from the surrounding environment due to the extreme radioactivity induced by the absorbed beam.

Beam Half Width :

( ah, av ) The direct measure of the beam size usually in mm. Given by

                                              "######### 
                                              &e  b  P 
                                        a  =  & v  v  o 
                                         v    &######### 
                                              !   p P 

For 8 GeV line po = p. 3

Beam Inhibit Light Link Module :

Linac Module through which the H- and I- secondary microprocessors can pull the beam inhibit line.

Beam Intensity :

The average number of particles in a beam passing a given point during a certain time interval, given, for example, as the number of protons per pulse or protons per second.

Beam Line :

Beam line is a collective term referring to all the devices used to control, monitor, and produce a beam having particular characteristics. The common elements of a beam line are magnets, intensity monitors, beam position monitors, and collimators.

Beam Loading :

Phenomenon whereby beam being accelerated by an RF cavity changes the gradient and phase of the RF in the cavity.

Beam Loss :

Loss of protons from the beam chamber.

Beam Roll :

A periodic change in horizontal and/or vertical positions during spill. This doesn't include changes caused by humans.

Beam Sample Pulse (BSP) :

Obsolete. A pulse originated in a module of the MAC-A PDC crate which sent a signal around the ring by way of CC42 cards. It was a two-way communication, with each CC42 card echoing back a response to the BSP controller in the PDC crate. The pulse was used in generating the Main Ring sample time, as well as taking voltage-to-ground snapshots if a ramp current fault occured.

Beam Stacking :

A form of multi-turn injection in which a single turn is injected and then moved by acceleration or deceleration to make room for additional turns. This process, also called momentum space stacking, often appears in storage ring applications.

Beam Stop :

Linac primary critical device in the 750 keV line that blocks the beam path to prohibit beam in Linac. Controlled by CARESS and the pulse shifter.

Beam Stop :

A thick metal shield that moves into the beam line in order to prevent beam from entering a specific area. Beam stops are generally critical devices such as the beam stop in the 750-KeV line and the 200 MeV line beam stop.

Beam Switch :

Toggle switch that will inhibit beam to a particular area of the accelerator on HEP pulses according to the logic in the Beam Switch Sum Box. Eight modules of these switches are found in the MCR.

Beam sync clock :

The clocks MRBS and TVBS, for which the basic frequency is directly related to the revolution frequency of the beam. They are derived from their respective LLRF systems. They operate at frequencies of about 7.5 MHz and produce a clock "tick" every 7 bunches. Beam sync clocks are used for all critical timing of beam transfers between accelerators.

Beam Toroid :

A device used for measuring beam intensities by measuring the magnetic field fluctuations produced by the passing beam. The magnetic field fluctuations produce a current in a coil which is wound around a closed circular ring (torus) through which the beam passes.

Beam Turns :

The width of the beam pulse going to Booster divided by the revolution period of the Booster at injection.

Beam Valve :

A pneumatically operated gate valve that closes across the beam pipe to physically isolate one section of beam line from another. Beam valves are commonly used to isolate vacuum allowing the beamline in one sector or house to be brought up to atmosphere for maintenance while keeping adjacent sections under vacuum. In the event of a vacuum burst beam valves are closed automatically to isolate sectors in order to localize the vacuum problem.

Beamline (transport line) :

A series of magnets and vacuum pipe which carry the proton beam from one portion of the accelerator to another.

Beamline microcomputer :

An NTF computer that monitors beamline devices, dose rates, and communicates with the NTF medical microcomputer as well as the local Linac secondary.

Belly Pan :

A design feature of the Linac tanks that allows leaks in the tank welds to be put under vacuum.

Benelex :

A substance similar to G-10 used to hold NTF neutron collimators in position.

Berm :

Earth shielding over the top of a radiation enclosure.

Berm :

Mound of earth found directly above an accelerator enclosure used to absorb excess radiation.

Berm :

A mound of earth over an accelerator or beam line designed to provide shielding against possible ionizing radiation.

Beta function :

A measure of beam width. The beta function details how the beam changes around the accelerator. There are separate Beta functions for the x and y planes. The square root of bx is proportional to the beam's x-axis extent in phase space.

Beta Matching :

Matching of the beam size to the b of the receiving beam pipe.

Beta (b) Particle :

An electron or positron emitted from a radioactive source.

Betatron oscillations :

Stable oscillations about the equilibrium orbit in the horizontal and vertical planes; these oscillations were the first studied in betatron oscillators, hence the name.

Betatron Oscillation :

Betatron oscillation, so named because it was first discussed for betatron accelerators, is the transverse oscillation of particles in a circular accelerator about the equilibrium orbit. The restoring force for the oscillation is provided by focusing components in the magnetic field which act to bend a particle which is off the equilibrium orbit back toward it. In synchrotron accelerators of modern (strong focusing) design there are several cycles of betatron oscillation per revolution of beam particles.

Bias Pulser :

A Linac module that drives the grid of the 7651 tube in the Buncher RF system.

Bias Supply :

Programmable power supply used to power the ferrite tuners of RF cavities in the Booster and Main Ring.

Bimodal Ramp :

The Main Ring magnets are pulsed to create two flattops to allow extraction at two different energies.

Bipolar Supply :

A power supply that has an operating voltage range of positive to minus. A unipolar supply has an operating range from zero to some positive value.

Bit :

This stands for Binary digIT. It may have a value of zero or one and is the smallest unit of measure. See byte and word.

Bleeder resistors :

In the Linac application, the resistors between the High-Voltage Dome and ground that bleed down the charge on the Dome when the power supply is turned off. 4250 MW.

Blind Scaler :

A scaler made without a display for computer readout only.

BLM :

A device used to measure beam loss from the accelerator. The detectors are sealed ionization chambers. BLM stands for Beam Loss Monitor.

Block Transfer (BTR) :

An option for data transfer in the CAMAC links. Although data is transmitted serially, it arrives at the MAC or front-end in a continuous stream rather than in discrete units. The BTR link is on a separate cable from the CAMAC serial link. It is able to transfer information at a 10 Mbit/sec rate in blocks 196 Kbytes in length.

Blow up :

A relatively sudden and usually catastrophic increase in beam size generally caused by some magnetic field error driving the beam to resonance.

Blowing Up Emittances :

To try to keep down beam-beam tune shifts the emittances of the proton bunches are increased. This is known as "blowing up the emittances". Emittances will also blow up unintentionally when the machine is tuned wrong.

Boiling Point :

Any point on a vapor pressure curve. see NBP.

Booster

The rapid cycling proton synchrotron at Fermilab which receives 200 MeV protons from the Linac, accelerates them to 8 GeV, and injects them into the Main Ring for further acceleration.

Booster Clock :

Obsolete. The booster clock was a continuous pulse train of 1 microsecond pulses that was synchronized to the power line. A signal marking a specific time like T1, T4 T8, was indicated by a missing pulse or gap in this continuous pulse train. These times initiated actions which carried the booster through its cycle. It was the primary time standard for all accelerator systems.

Booster Pulse :

That portion of the beam in the Main Ring resulting from the injection of one booster load, viz., about 1/13 of the Main Ring azimuth.

Booster Serial Link :

This is the CAMAC link to which all Booster CAMAC crates are connected and through which control cards communicate with the Booster Serial (DEC BS) front-end.

Boot :

Restarting a computer by means of loading a fresh copy of the managing program(s). In practice a short program is loaded into memory by hand or with special hardware which then reads in more sophisticated (and longer) programs from mass storage to actually reload the system. The system may be thought of as loading itself by its bootstraps. A reboot is an abbreviation for "remote boot". The PDP-11 and MAC-16 have bootstrap loaders which are permanently stored in read only memory (ROM) while the VAX's store their loaders on a floppy disk.

Boson :

An integral spin particle to which Bose-Einstien statistics apply. Such particles do not follow the Pauli exclusion principle. Photons, pions, alpha particles, and nuclei of even mass numbers are examples of bosons.

Bouncer circuit :

Haefely-designed system used to boost Dome voltage to compensate for charge leaving the Dome during the beam pulse. Not installed at FNAL.

BPM :

A diagnostic device used to measure beam positions. BPM stands for Beam Position Monitor.

Breakover :

When a Main Ring or Tevatron power supply SCR shorts and conducts continuously (i.e., while in bypass, etc.).

Bremsstrahlung :

X-ray radiation caused by deflection of high- energy electrons by atomic nuclei.

Bremsstrahlung Radiation :

Electromagnetic radiation, usually in the X-ray region of the spectrum produced by electrons in a collision with the nucleus of an atom. Bremsstrahlung is German for breaking. Bremsstrahlung radiation is produced in regions of high electric potential such as areas surrounding electrostatic septa and RF cavities.

BSP link :

Obsolete. In a hardware context the link was the physical cable between and including the Main Ring CC42 repeaters. In a software context it was the electrical path which carried the beam sample pulse around the ring. See Beam Sample Pulse.

BSS :

Business Services Section

Bubble Chamber :

An instrument for rendering visible the tracks of ionizing particles. Essentially it is a vessel filled with a superheated transparent liquid, commonly hydrogen or deuterium. The passage of an ionizing particle through this liquid is marked by the appearance of a series of bubbles along the particle trajectory. If the liquid is subjected to a magnetic field, as is usually the case, the charged particle trajectories will be curved, the curvature providing information about the particles' charge and momentum. One or more photographs of the tracks are taken with each accelerator cycle for subsequent study. There were two bubble chambers at FERMILAB, both in the Neutrino Area. A 30-inch chamber with a conventional magnet was located in the N3 hadron beam, and a 15-foot chamber with a superconducting magnet was situated at the intersection of the N5 hadron and No neutrino beams. Both of these chambers are no longer used. The 15 ft chamber was discontinued as recently as 1988.

Bucker :

An air core quadrupole magnet used in the Tevatron to eliminate 4-400 Hz structure in the extracted spill.

Bucket :

Stable phase space area where beam may be captured and accelerated.

Bucket (R.F.) :

A bucket is the stable region in longitudinal phase space. The bucket width gives the maximum phase error or timing error at the R.F. cavity which a particle may have and still complete the whole acceleration cycle. The bucket height is the corresponding limit on momentum error.

Bulk Tuner :

A long copper bar, D-shaped in cross section, that runs the length of a Linac RF cavity and roughly determines the correct cavity volume.

Bump :

A localized orbit displacement created by vertical or horizontal correction element dipoles used to steer beam through available aperture or around obstacles.

Bunch :

A group of particles captured in a phase space bucket.

Bunch Rotation :

Prior to extraction from the Main Ring at 120 GeV, the proton bunches destined to be used for p- production are rotated in momentum phase space by 90R so that a large momentum spread and smaller time spread (a given bunch is narrower in time) comes about. The antiprotons produced retain this structure. Upon injection into the Debuncher, the bunches are rotated 90R thereby reducing the momentum spread and broadening the time structure. This permits the Dp/p of the p-'s injected into the Accumulator to be greatly reduced, permitting smaller magnet apertures and more effective stochastic cooling.

Bunch Satellites :

When a bunch is coalesced it is more than likely that the bunch is not ideally coalesced. There are often secondary bunches in buckets to either side of the coalesced bunch. These are known as satellites and are undesireable.

Bus :

An electrical configuration for transmitting signals within a computer system. Outside of a controls context, the term is also used to denote any carrier of electrical power, such as for the Main Ring or Tevatron magnet currents.

Bus :

A rigid electrical conductor generally for carrying high currents and for power distribution to several devices.

Bypass :

A condition which results in the Main Ring and/or Tevatron power supplies being on but are not producing current. In this condition the three rectifying SCR's are disabled and the bypass SCR's are enabled. In the turning on process both the Main Ring and Tevatron are brought up in bypass before engaging the magnet ramps.

Byte :

A byte consists of 8 bits. It may have a signed value of -128 to + 127.

-C-

C-SEAL :

A metal vacuum seal, usually coated with lead or indium, with a c-shaped cross-section. It is used in high radiation environments where O-ring seals would deteriorate.

Cache :

A small, high speed memory which "borrows" information which has been recently used from the main memory in anticipation that the information is the next to be used. For example, an algorithm on the console computer determines which 50 applications programs have been used most. They are the ones privileged to exist on disk DL1 for easy access. A program not cached has to be loaded from the VAX.

Calorimeter :

A device used to determine particle energies by measuring the ionization of a particle shower in a heavy metal, usually iron and lead.

Calorimeter (Special Usage) :

A calorimeter is a device used to measure a particle's energy. A typical calorimeter is made of a series of scintillators sandwiched between pieces of iron. The incoming particle interacts in the iron creating a hadron shower; the shower is picked up by scintillators, and the particle's energy is measured by the amount of light collected from the scintillators.

CAMAC :

Computer Automated Monitor And Control. There is an internationally accepted set of standards for electronic instrumentation which specifies mechanical, electrical, and functional characteristics of the instrument modules. CAMAC hardware is commercially available. Individual modules (cards) fit into a standard 25 slot receptacle (CAMAC crate) which provides common power, control, and data lines. Booster, Main Ring, Tevatron, Switchyard, Debuncher/Accumulator, RF and Console systems utilize the true standard CAMAC hardware.

CAMAC crate :

A commercially available 25-slot crate used to house CAMAC cards and to interface to the accelerator computer system. The crate has a back plane with connections to all cards in the crate. It has +/- 6 volt and +/- 24 volt DC crate voltages for use by the cards. At Fermilab the last four slots are used by the crate controller. All cards are electrically connected to the crate controller by two sets of busses: each card has its own address line, but they all share the same 24 parallel data lines. Also see Crate.

CAMAC Module :

A "control" card plugged into a CAMAC system for a specific input or output function.

Canned Magnet :

Magnets which are completed encased in their own vacuum jackets.

Capacitor Bank :

A group of capacitors located in the "capacitor tree" outside the Master Substation. These capacitors were used to store energy allowing the Main Ring magnets to ramp at 500 GeV without causing a brown out on the local power grid. Since the Main Ring now only ramps to 150 Gev during collider operation the capacitor tree is no longer used and has been converted into a High Rise apartment complex for migratory birds.

Capacitor Tree :

See Capacitor Bank.

Capture :

The process of putting the beam into RF buckets.

Carbon Resistor Thermometer :

A carbon resistor whose temperature sensitivity provides good temperature resolution, especially below <= 10ºK.

Card :

Modular piece of electronics housed in a crate. Cards are typically used to interface a hardware device with a computer system.

Card (Printed Circuits) :

An insulating substrate to which an electronic circuit is bonded and discrete components are attached. Often used as a synonym for a CAMAC module.

CARESS :

Acronym for Central Accelerator Radiation and Electrical Safety System. Hardware dedicated to monitoring and controlling the accelerator safety systems and critical devices. Independent of any other control system. Located in and below the MCR.

Caution :

This is a software term used to warn console users that they are about to change the analog value or digital state of a device. It is generally used in the interrupt sequence during the control of any device which can cause beam loss, machine downtime, or an unsafe condition.

Cavity (R.F.) :

An RF cavity is a volume enclosed by an electronically conducting surface so that it resonates at some radio frequency. The usual application of the term at Fermilab is to the accelerating cavities in the Booster and Main Ring which resonates at a frequency corresponding to the circulation frequency of the beam and thereby apply a synchronized accelerating voltage.

Cavity Short :

A grounded metal rod that goes in and out of the body of an RF cavity. When a station is off it is still a resonant cavity and can remove energy from the beam. By grounding the cavity it is kept from resonating.

CBA :

Colliding Beams Adrastus. Dave Herrup of the MAD group is responsible for this term. It is the name of a colliding beams tune & chromaticity feedback control system that Dave is involved in.

CC27 Card :

Obsolete. Was the Main Ring abort module. It accepted up to 8 inputs; if any of these sensed an abort condition the abort loop was broken and the abort kickers were fired.

CC48 Card :

Obsolete. Monitored crate voltages and temperatures in the utility crate. It can also acted as an F-slot controller, a secondary crate controller which talked to modules for beam loss monitors, a Johnson controller, and a vacuum ion pump readback.

CC130 Card :

Obsolete. MADC controller for the Main Ring. It was capable of storing a limited amount of data from the MADC and transmitting it back to MAC-A and eventually to MR DEC.

CCI CONSOLE :

Obsolete. A computer console that was manufactured by Computer Communications, Inc. consisting of a color TV display, keyboard, and supporting hardware. CCI Consoles were used at Fermilab in the Main Control Room and the switchyard experimental area control centers for monitoring and control of various accelerator and beam line parameters. CCI consoles in the Main Control Room interacted with devices they controlled through the Xerox 530 and MAC-16 computers, which are also ancient history. In the experimental areas, this linkage was usually through a PDP-11 and MAC-16 computer system.

CD :

Computing Division

CDF :

Collider Detector Facility. A huge colliding beam detector located at B0 experimental facility.

CEA Quads :

Six large aperture quadrupole magnets in the N1 line used for focusing the muon beam. These quads were originally used at the Cambridge Electron Accelerator (CEA).

Cell :

A unit of the Main Ring and Tevatron lattices. A cell runs from one F-quad to the next F-quad.

Centroid :

Technically, the center of mass. Used here to describe the center of a beam profile.

Cerenkov Counter :

A detector for charged particles which consists essentially of a transparent medium such as a gas which emits Cerenkov radiation when a charged particle passes through at a velocity greater than the velocity of light in the medium. The mass of a particle in a beam of known momentum can be determined with such a counter by measuring the characteristic angle at which the Cerenkov radiation is emitted.

Cerenkov Radiation :

Light emitted when a charged particle traverses a medium with a velocity greater than the velocity of light in the medium. The Cerenkov light is emitted in a cone centered on the particle trajectory. The opening angle of this cone depends on the velocity of the particle and on the velocity of light in the medium. The phenomenon involved is that of an electromagnetic shock wave and is the optical analogue of sonic boom. Cerenkov radiation provides an important tool for particle detection. 1

Cesium Boiler :

Electrically-heated crucible in the Pre-Acc dome used to vaporize Cesium used to coat the source cathode.

CH :

DOE Field Office, Chicago

Chamber :

A working volume, not necessarily cryogenic. Ex. Bubble Chamber, EMI Chamber.

Channel 13 :

This is a lab-wide closed circuit TV channel used for displaying accelerator data. The data displayed may consist of machine intensities, experimental area intensity requests, measured experimental area intensities, Main Ring and Tevatron ramp waveforms. For colliding beams the batch intensities, store number, Pbar stacking rate, stack size, etc. are displayed.

Charm :

A physical property (quantum number, degree of freedom) carried by a fourth quark. In the original quark model, three quarks ("up", "down" , "strange") are variously combined to produce the known hadrons. The addition of a fourth quark, the "charmed" quark, gives rise to several new hadron states called charmed particles. Proposed to account for an apparent lack of symmetry in the behavior of hadrons relative to that of leptons, to explain why certain reactions of elementary particles do not occur, and to account for the longevity of the Q1 and Q2 particles. 1,5

CHL :

The refrigeration plant which supplies liquid helium and liquid nitrogen to the Tevatron and Switchyard. CHL stands for Central Helium Liquefier.

Chop Time Selector :

Module in the preacc control room that selects times generated by predets and sends them on to the 750 keV choppers.

Chopper :

Electrostatic device that selectively deflects a portion of the beam pulse to control intensity in the linac or beam turns in booster. Two are found in the 750 keV lines, and one in the 200 MeV area.

Chopper :

A fast electrostatic beam deflector used to select a particular part of the beam during the time that beam is available. The 200 MeV Chopper is a fast electrostatic kicker at the end of Linac that deflects beam to either of two sides of a magnetic septum. One side of the septum bends the beam into the Booster for acceleration while the other side (straight ahead) sends the beam to a dump. Normally most of the beam goes to the dump and only a small amount is "chopped" out for the booster. There is one "chop" for every booster pulse or booster batch.

Chromatic aberration :

Beam spreading out due to different momentum particles being bent by the quadrupole fields at different angles.

Chromaticity :

The ratio of tune spread to momentum spread of the beam.

               Dnx = Cx(Dp/p)

where n is the tune, Cx is the horizontal chromaticity, and p is the momentum. Chromaticity affects the focussing and bending properties of magnets by making them sensitive to particle momentum. This results in focusing and bending dispersion of the beam in a manner analogous to an optical system.

Chute :

Passageway leading from the 200 MeV area to the booster radiation enclosure. The 200 MeV transport line to the booster travels through this.

CLIB :

Acronym for Console object LIBrary. It is a collection of commonly used or convenient routines kept on the Development VAX which can be called upon by applications programmers.

Clock :

A series of digital pulses generated at regular intervals used to mark time. Clocks at Fermilab generally operate at either 15 Hz or in the MHz range, and can be encoded with timing information to be sent around the accelerator.

Clock, (Tevatron) :

Also known as TCLK. Although the name implies it is only used for the Tevatron, it is essentially the master clock for the accelerator. It operates at a 10 MHz rate and is able to transmit encoded events at about a 1 MHz rate. There are 256 possible events (displayed in 2-digit hexadecimal numbers) which the clock can send out.

Clock, (Beam Sync.) :

See Beam sync. clock.

Clock, (Main Ring) :

Most Main Ring events are controlled from TCLK. There is a 1 MHz phase reversal clock dedicated to Main Ring which translates TCLK events into phase reversal events for use by MAC-A, DEC B, and DEC C.

Clock decoder :

Any card, such as a 177 or 279, which recognizes a clock event and acts on it. Most of the decoder modules in the accelerator are based on a custom made Fermilab chip built specifically for decoding TCLK. The 177 modules decode TCLK only; the 279 modules can decode MRBS and TVBS as well.

Clock encoder :

A card, such as a 175 module, which stamps a bit pattern (clock event) onto a clock signal for recognition by a device.

Clock event :

A bit pattern superimposed on the clock frequency at a certain time in the accelerator cycle which is broadcast through the accelerator for decoding and action by a set of devices. Since they are eight bits long there can be a total of 256 unique events.

Clock Generator :

Modules in the preacc control room (one for H- , one for I-) that take the 1 MHz clock and convert it to light pulses to send to the domes via fiber optic cables.

Clock Module :

Module in the preacc control room that converts all the phase reversals on the booster clock to 1-gaps, as well as providing backup 15 Hz and 1MHz clocks for the linac in case the booster clock fails.

Clockodile :

A console applications program which monitors the clock events actually being sent out on the link. It currently resides on D33.

Closed orbit :

The ideal orbit of particles in the accelerator. Betatron oscillations are superimposed on this orbit.

CNSCOM :

CoNSole COMmon. An area in console memory via which information flows between APM, PLD, DPM, and the applications programs (See APM, PLD, and DPM.)

Coalescing :

Coalescing is the production of one high intensity bunch from several lower intensity bunches. This is done by turning on several coalescing RF cavities at F0 that run at 2.5 MHz and 5.0 MHz which are lower than the 53 MHz of the Main Ring RF. The superposition of these two frequencies produces an RF wave that is linear through the region of the bunches to be coalesced. The bunches are pushed into the central bucket and then injected into the Tevatron. During a pbar shot, this can be seen on TV channel MS 30.

Coasting Beam Safety System :

Part of the radiation safety system that protects personnel from circulating beam in Main Ring, Tevatron, and the Accelerator/Debuncher. This system controls beam valves that are inserted into the beam tube to dissipate circulating beam when an unsafe situation is detected.

Coasting Beam Valve :

Special beam line valves that close in order to stop circulating beam in the Main Ring, Tevatron, and Accumulator/Debuncher. These devices are part of the Coasting Beam Radiation Safety Systems.

Cockcroft-Walton Accelerator :

A high-voltage DC accelerator, especially for the acceleration of protons. The DC voltage is produced from a circuit of rectifiers and capacitors to which a low AC voltage is applied. The PreAcc accelerator at Fermilab is a Cockcroft-Walton design.

Cockcroft-Walton Accelerator :

Often referred to as Pre-acc at Fermilab. It is a large electrostatic accelerator which provides the first accelerating step to the protons from the ion source. The Pre-acc increases the energy of the protons to 750 KeV and injects them into the Linac. The apparatus is based on a development of the Greinacher voltage doubling circuit, a constant potential circuit in which capacitors in series are charged in alternate half-cycles.

Cogging :

The process of spacing bunches of protons or antiprotons in the Main Ring or Tevatron so that they will collide at the proper points in the ring. It is used only in colliding beams mode.

Coincidence :

(1) A coincidence or logic unit generates an exactly timed output signal whenever the time overlap of input signals satisfies a preselected coincidence requirement. (2) Occurring or existing at the same time.

Cold Box :

Usually low pressure vessel providing vacuum insulation for cryogenic heat exchangers. Often, loosely, synonymous with refrigerator box.

Cold Cathode Gauge :

An ionization vacuum gauge with no hot filament which uses electrons spiralling in a magnetic field to ionize any gas present. The ions produced are drawn to electrostatic plates. The current produced in this way is interpreted as a pressure. This type of gauge operates down to about 1 E-5 torr.

Cold Valve :

A valve with I zero heat leak. Usually pneumatically activated by a noncondensable gas through long connecting tubes.

Collider Detector at Fermilab (CDF) :

The apparatus used for experiments designed to measure the results of colliding beams of protons and antiprotons. CDF experiments study the highest energy collisions ever produced in a laboratory. This allows physicists to probe much deeper into the structure of matter than heretofore possible.

Colliding Beams :

Oppositely directed particle beams brought together at small or zero angle to produce high energy reactions. Because even the most intense beams are dilute compared to ordinary solid matter used as targets, the beams must be recirculated many times through the interaction point to obtain a useful number of interactions. The apparatus for recirculating beams for long periods of time are called storage rings. The motivation for this arrangement is to make available the entire kinetic energy of the beams in the center of mass of the interacting particles. At Fermilab the two counter circulating beams used are protons and antiprotons. The reason that antiprotons are used is that they only differ in charge from a proton but have the same mass. They can be injected into the same accelerator with the same bend field in the opposite direction and circulate along the same orbit. A proton on proton collider, such as the SSC, requires two separate beamlines to circulate protons in opposite directions.

Collimator :

A collimator is generally a large block of steel or iron, sometimes having an adjustable aperture, that enables one to choose the beam cross section or angular divergence. It is also used to absorb the beam halo and if closed further it can be used to control the intensity.

Collimator :

A movable, solid block of material which can be used to limit beam size or to stop it altogether. They are sometimes used as safety system critical devices.

Collision :

A close approach of two or more particles, photons, atoms or nuclei during which quantities such as energy, momentum, and charge may be exchanged.

COM :

COMputable. A process scheduling state on the VAX meaning that a given process is ready to use the cpu.

Common request list :

When an applications program displays data from accelerator devices it has to generate a list of what information is wanted. This list is assembled on the console computer and consists of DI/PI [device index/property index] pairs. The list is put together in the console computer by the console DPM task from information in the database. It is then organized and sent to the front end for further processing before requests for data are made to devices in the field.

Compiler :

A program which converts programs from problem oriented language (Fortran, BASIC, COBOL, etc.) into machine language.

Compressor Building :

A building located at each zero location of the Main Ring that contains several Mycom Helium compressors. The compressors draw low pressure Helium from the suction header in the Main Ring tunnel and send high pressure Helium along the discharge line atop the Main Ring berm to each of the satellite refrigerator buildings.

Computer Room :

This room is located in the Cross Gallery across the hall from the Main Control Room (South). It houses many of the computers for the Accelerator Division. Included are the Operational and Development VAXs, Console computers, the front end computers, and the associated peripheral equipment.

Computing Counter :

A device that measures pulse frequencies with great accuracy. Used for the display of the linac master oscillator frequency.

Condenser :

An extended surface heat exchanger for the purpose of extracting the heat of vaporization of fluid.

Conditioning :

Vacuum term. The process of running voltage in a septa or separator at a high level over a period of time to clean up the vacuum. After a high voltage beamline device such as a Septa or Separator is baked out it is then run at a high voltage to burn off any oils, dust, or sharp edges that the bakeout didn't get. The voltage is turned on at a low level and slowly raised over time to avoid sparking in the device which can spoil vacuum. By burning off these things the ability of the device to pump down to operating vacuum is greatly improved.

Conduction, Thermal :

Solid heat flow. Similar to electrical conduction.

Convection, Natural :

A transfer of heat by a stream driven by density differences that result from distinct heating and cooling regions.

Convection, Forced :

A transfer of heat by a stream driven by external means between a region and itself, or between regions, of different temperature.

Console :

A standard set of screens and other devices from which an operator or systems specialist controls and monitors devices in the accelerator complex. Each console includes a color TV monitor, a color Lexidata screen, a 613 storage scope, a touch panel and an alarm screen. Each console station is supported by a PDP-11 computer. There are currently 7 consoles in the MCR, and numerous others at locations such as AP-10, Booster West Gallery, CHL, and CDF.

Console crate :

A CAMAC crate which acts as the interface between the console PDP-11/34 processor and the console hardware. It holds the video generator modules (CC130's), the Lexidata interface (134), the 613 interface, and the TSCC crate controller cards which accept serial data coming from the TSCC link driver in the computer room.

Console Disk :

There are two RL02 disks for each console. The top, or "0" disk, contains the operating system and other management programs which are a permanent part of the console. The bottom, or "1" disk, holds the applications programs which usually claim only a temporary residence on the console.

Console hardware :

See Console.

Console Users Guide :

This is an Accelerator Division publication, Software Documentation Memo No. 62.3, which describes the ACNET consoles and contains useful information for writing applications programs for the consoles. Also known as the "Green Book".

Controlled access :

Method used to enter an accelerator enclosure when three conditions have not been met: 1) A radiation survey has been performed in the enclosure. 2) The proper power supplies to the devices in the enclosure have been padlocked off. 3) The safety system has been broken requiring a search and secure.

Controls Hardware Release (HDWREL) :

A type of document published by the Accelerator Division Controls group and distributed within the Division (including the Operations group) which details the operation of new control cards and other hardware built by the Controls group.

Controls Software Release (SFTREL) :

A document also published by the Controls Group which includes detailed information on new applications programs and other software paraphernalia.

Controls Software Update (SFTUPD) :

New versions of Software Releases which update information on applications programs, etc. This type of document is currently being phased out in favor of multiple versions (xx.1, xx.2, etc.) of the Software Release.

Converter :

A thin piece of material used to generate electron- positron pairs from incident photons via the process of pair production.

Cooper Luminosity :

A measure of integrated luminosity when CDF is up and data collecting. Accelerator division integrated luminosity continues to integrate when beam is in the machine even though CDF is down. Cooper luminosity is named after John Cooper of CDF who suggested the measure.

Core :

The most dense region of the p- beam in the Accumulator. Thee beam cooling systems act to 'push' the p-'s into the core and keep them there. The design parameters include:

               intensity          5x1011
               Dp/p 0.05% (H4 MeV)
               emittance          2p mm-mrad (both planes)
               peak density       1x105 eV-1

Core :

The active memory section of a computer system in which stored data may be most readily accessed by the CPU. Generally when program execution is complete, data stored in core is lost.

Corona Rings :

Curved metal surfaces shielding the outside of high-voltage devices to forestall the ionization of air by electric discharges. Used in the HV sources for the preaccelerators. hardware built by th

Correction element :

Additional magnet inserted in an accelerator's lattice to correct for manufacturing defects, variations in power supplies and magnets, obstacles in the beam path, etc.

Coupling :

A generally undesirable situation in which motions in the transverse plane (or transverse-longitudinal) planes are not independent, but are related in some way.

Coupling Capacitor :

A capacitor used to couple AC voltages to parts of an electrical circuit while blocking DC voltages.

CPLD :

Central Program LoaDer. A program on the VAX which loads applications programs onto the console disk. When a program is called by a console computer it works in conjunction with PLD to assure that the console has the newest version of the program.

Cpu :

Central Processing Unit. That part of a computer or microprocessor which performs calculations and makes decisions, as opposed to memory functions, clocks, etc.

CPU (Central Processor Unit) :

The main "thinking" component of a computer system. All arithmetic and logical functions are performed by the CPU of a system. In addition, the CPU is in control of all data acquisition and storage.

Crash Cord :

A yellow and black rope in the Transfer Hall and in some of the experimental target halls. Its purpose is to protect individuals from radiation caused from the beam. If an individual is inside one of these areas and realizes beam is about to be turned on, he pulls the crash cord which immediately turns off the accelerator.

Crate :

A repository for control cards. Each type of crate has a different protocol for accessing and distributing information which must be recognized by the respective front-end. There are CAMAC, NIM, Multibus, Unibus, and several less important types of crates. The cards for each of these crates are not interchangeable.

Crate (CAMAC Crate) :

A standardized receptacle for electronic circuit modules providing a common set of data, control, and power lines.

Crate controller :

The card(s) in a given crate which decodes address information arriving on the link and distributes messages to the appropriate cards in that crate. These cards also arbitrate the data and messages to and from each card in the crate, as they all share the same data lines.

Crate save/restore :

Using the D1 save/restore program to save/restore parameter values of all devices controlled by a particular crate.

Crates and slots page :

An applications program which allows the user to examine the types of microprocessors residing in a given building and its status. There is an individual applications program for each of the serial front-ends (B59, T96, P66, and S54).

Critical Device :

A device that can prevent beam from entering a specific accelerator area. Generally critical devices are designed for fail safe operation. The Radiation Safety System provides permits for critical devices.

Critical Device Failure :

A safety system condition where the Radiation Safety System (RSS) for an area drops before the critical device for that area has been turned off to remove beam from the area. Results in a pulse shifter inhibit and must be reset at the CARESS racks.

Critical Magnetic Field :

This is the maximum magnetic field that a superconductor can tolerate before abruptly returning to the normal resistive state.

Critical Point :

The point on the vapor pressure curve at which the heat of vaporization is zero and the temperature and pressure exhibit a maximum.

Cross Section :

A measure of the probability of the occurrence of a specified interaction between a particular incident particle and a specified target particle or system of particles. Unless otherwise specified, the cross section is given by the reaction rate per target particle for a specified process (e.g. capture), divided by the flux of the incident.

Critical Temperature, Pressure :

The temperature and pressure at the critical point.

Crowbar :

When a device turns itself off, typically due to overcurrent.

Crowbar :

Electronic safety circuits which turn off power when current and/or voltage goes to a dangerous level.

Crowbar Compare Circuit :

Modulator and PA protection circuit that shuts down the RF system if the current from the modulator to the PA anode exceeds certain limits.

Cryogen :

By convention one of the gases condensing below 150ºK.

Cryogen :

A refrigerant to be used in a refrigerator for producing low temperatures. To reach superconducting temperatures, liquid gases such as Nitrogen are used in succession with liquid helium to reach the lowest temperatures. 1

Cryogenic :

A system or equipment that operates at a temperature set by convention at 150ºK.

Cryogenic Valve :

see Extended Stem

Cryogenics :

The production and maintenance of very low temperatures, and the study of phenomena at these temperatures.

Cryogenics :

Cryogenics is the technology of the production and effects of very low temperatures. The adjective "cryogenic" is frequently used when describing liquid hydrogen targets and the phenomena of superconductivity. The niobium-titanium alloy used for superconducting magnets becomes superconducting at a temperature of 11 degrees K.

Cryostat :

A vacuum insulated vessel for cryogenic fluids. see Dewar.

Cryostat :

A vessel for maintaining a constant low temperature.

CTF :

Cancer Therapy Facility. Now called Neutron Treatment Facility (NTF). A small area in the Linac Gallery devoted to cancer treatment using neutrons produced on a beryllium target by 66 MeV protons diverted from between the fifth and sixth tanks of the linac during periods when it is not needed to fill the Booster. The facility consists basically of the neutron beam line, a treatment enclosure with patient positioning apparatus, a few offices, patient preparation rooms, etc.

CUB :

Central Utility Building. This facility provides LCW for accelerator cooling as well as chilled water for air conditioning systems. It is located directly behind the Booster pond.

CUR :

CURrent. A process scheduling state on the VAX indicating that a given process is currently operating.

Cursor :

A visible marker on the screen which indicates where on the screen a user may be interacting with the program.

CURVES MAC :

Obsolete. This was a MAC-16 computer located in the Mac Room (see Mac Room) and used for calculation of the ramps for the Main Ring RF high and low level systems.

CVT :

Stands for Constant Voltage Transformer. It provides proper voltage for Main Ring and Tevatron power supply SCR firing circuits.

Cyber :

These were computers present in the High Rise which were used primarily for analyzing experimental results. Accelerator Division personnel did not normally use the Cybers but could access them through the proper port selector connections at the terminals. There were three Cyber 175's which each had 256k-60 bit words of memory, and one Cyber 875 which had a million 60 bit words of memory. The Cybers shared the workload of experimental analysis with the VAX cluster in the High Rise. The Cybers are no longer with Fermilab. Sometime ago they were obsolete and sold for scrap.

Cycle Period :

The length of time between successive repetitions of a periodic phenomenon. The Fixed Target cycle consists of injecting the beam into the Main Ring, raising the magnetic field and accelerating the beam to 150 Gev, injecting the beam into the Tevatron, raising the Tev magnetic field and accelerating the beam, extracting the beam to Switchyard experimental areas, reducing the magnetic field in the accelerators and preparing for the next injection. The Fixed Target cycle time is about 60 seconds. The Colliding Beams cycle is 120 seconds long. Each of the Colliding Beams preparation steps are in 120 second cycles as well as the ramp up to 900 GeV and the low beta squeeze cycles.

Cyclotron :

A particle accelerator in which the particles move in a constant magnetic field in a spiral orbit, the energy of the particles begin increased by the application of an alternating electric field at constant frequency. Authors side note. In college we actually made one of these in a coffee can being blissfully unaware of the X-ray or Radiation hazard we had created. It was demonstrated for a professor and promptly confiscated to disappear into the low level radiation storage locker never to be seen again.

Cyclotron Magnet, Chicago :

The large magnet from the synchrocyclotron used by Fermi and his colleagues at the University of Chicago now used not as an accelerator, but as a particle-momentum analyzing device (spectrometer) in the N1 muon beam of the Neutrino Area. It is located in the Muon Lab Enclosure. The magnet is so massive that it was moved in several pieces, assembled and the building then built around it.

-D-

D/A :

Digital to Analog converter (hardware) or a setting value for a device (software). The hardware is a unit which accepts a number from the control system (binary encoded) and converts it to a corresponding output voltage. Such a device is the complement of an A/D converter. In many instances the output is used to program the output of a power supply. In such a situation the transfer function of the power supply is assumed to be a constant. A user should be aware of this potential problem. Most D/As in the accelerator control system output voltages in the range of -10 to 10 volts and have a resolution of 12 bits (including the sign bit).

D0 Collision Hall

Collider Detector at D0 interaction region.

D to A Line :

The transport line joining the Debuncher and Accumulator. Extraction/injection is realized by means of sets of pulsed magnetic septa and kicker magnets all oriented to displace the beam horizontally. The Accumulator injection kicker is unique in that a physical shutter moves into the aperture when the kicker is fired to shield the already circulating stack from the magnetic field if the kicker (only the injected beam is perturbed).

DABBLE :

An interactive program on the Operational VAX which implements changes in the system database.

DAC :

Digital-to-Analog converter. It is an electronic circuit which takes a digital message, usually transmitted on a link, and converts it to an analog voltage for use by a device. This usually means that the circuit has many input lines (generally 8, 12, or 14) corresponding to the number of bits in the digital word and a single output line whose voltage represents the sign and magnitude of the digital word.

Damper :

Device used to damp out coherent transverse beam oscillations.

Dark Current :

Current that flows from a photomultiplier tube in the absence of light. The main sources of dark current are ohmic leakage due to imperfect insulation and thermionic emission.

Data Selector :

Part of the monitor/control module for the Haefely power supply which selects either the voltage readback or the command voltage for display on the front of the module.

Database :

A list of properties for each device on the ACNET system, kept on the Operational VAX. These properties include mnemonics, alarm limits, descriptor texts, and scaling information.

Datalogger :

A program residing on the VAX which allows for the automatic and regular acquisition of data from a given set of devices, each with its own frequency. The limit is about 900 devices.

DBM :

This acronym stands for Data Base Manager. This is a process on the VAX which maintains the database. All accesses to the information in the database must be through routines which interface with this database manager.

DBPEEKER :

A program on the operational VAX which allows the user to look at the database of a particular device or set of devices.

Debuncher :

A radio frequency cavity phased so that particles at the leading edge of a bunch of beam particles (higher momentum particles ) are decelerated while the trailing particles are accelerated, thereby reducing the range of momenta in the beam. Such a device may be placed between two stages of acceleration to increase the efficiency of capturing the beam in the second stage as, for example, with the 200 MHz debuncher cavity installed between the Linac and Booster at Fermilab.

Debuncher; Booster :

Something of a misnomer. The debuncher is used to reduce the momentum spread of the Linac beam by decelerating particles with higher than nominal energy and accelerating those with lower energy.

Debuncher ;

The first of the two rings (as seen by the pbars) comprising the Antiproton source. The Debuncher designed to accept a pulse of newly produced antiprotons, bunch rotate and adiabatically debunch the beam, then betatron cool the beam in preparation for injection into the Accumulator. Design parameters include:

               kinetic energy     8.0 GeV
               average radius     80.42 meters
               number of pbar-bunches injected       80
               momentum aperture Dp/p     4%
               btron acceptance   20p mm-mrad
               btron tunes (H & V)        9.75
               periodicity        3
               phase advance/cell 60R

DEC :

Digital Equipment Corporation, manufacturers of the PDP and VAX series computers and perpetrators of the UNIBUS.

DEC-B :

This is a PDP-11/55 computer located in the Mac Room. It is used for Main Ring power supply calculations.

DEC-BS :

This is the Booster Serial front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Booster Serial Camac Link.

DEC-C :

This is a PDP-11/55 computer located in the Mac Room. It is used for Main Ring Power Supply ramp control.

DEC-P :

This is the Antiproton front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Antiproton Serial Camac Link.

DEC-S :

This is the Switchyard front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Switchyard Serial Camac Link. These devices include all Switchyard devices, most 8-Gev devices, and TCLK.

DEC-T :

This is the Tevatron front-end, a PDP-11/44, located in the Computer Room. It is used to interface and control devices on the Tevatron Serial Camac Link.

Decay :

A transformation in which an atom, nucleus, or subatomic particle changes into two or more objects whose total rest energy is less than the rest energy of the original object.

Decay Length :

The average distance a species of a particle at a given energy travels before decaying.

Decay Muon :

A muon produced via pion or kaon decay.

Decay Pipe :

The 400 meter long beam pipe downstream of the Neutrino Area target train. The p and K particles produced at the target decay in flight through the decay pipe into the muons and neutrinos used by the experiments. The length of the decay pipe is determined by the decay half-life of the p and K particles and their velocity.

Deceleration :

The process of decelerating the antiproton stack to a set momentum for the E760 experiment located at AP50 in the Antiproton Source

DECnet :

A system developed by the Digital Equipment Corporation which links the DEC computers together. Just about any DEC computer system (worldwide) may be connected to DECnet so that a communication link may be established between computer systems. Decnet is the largest single computer network in the United States.

Decwriter :

A hardcopy terminal located in the computer room. There are dedicated Decwriters which interface with each of the VAX computers and other Decwriters that can be connected to the PDP-11's.

Defocussing Quadrupole Magnet :

A quadrupole magnet that focuses beam in the vertical plane and defocuses in the horizontal plane.

Density :

The mass per unit volume of anything. (g/cm3)

Detector Building :

The airplane hanger shaped building in the Meson Area providing weather protection, crane coverage, and utility connections for the "upstream" end of the experiments in that area. Beam line monitoring and tuning is also conducted from the operations area on the mezzanine floor of the Detector Building. Also called Meson Hall.

Deuteron :

The nucleus of the deuterium atom (an isotope of the hydrogen) consisting of a proton and a neutron.

Development VAX :

This is a VAX-11/785 used for software development. It is located in the Computer Room.

Device Index (DI) :

This is a number assigned by DBM to all devices entered into the database. This number is then used by software routines to access information about a device from the database.

Dewar :

A vacuum insulated, cryogenic radiation insulated, low conduction heat loss vessel for cryogenic fluids.

Dewar :

A dewar is a vacuum insulated container for keeping material, chiefly liquids, cold or hot. The common thermos bottle is an example of a dewar. In the accelerator business dewars are often used to store large quantities of cryogenic liquids. In Pbar the nitrogen dewars are used to submerge the stochastic cooling electronics in order to reduce the amount of thermally induced electronic noise.

DFG :

Acronym for Dipole Function Generator. It is the card which controls and provides the output waveform for the Tevatron correction dipole regulators. These are also known as 160 modules.

Diffracted Beam :

Particles exhibit wave like characteristics in their passage through matter. In striking a target the incident beam scatters off nucleons. The scattered waves then combine according to the superposition principle and the peak of this scattered wave is called the diffracted beam. Diffraction takes place when the wavelength of the incident beam is short compared to the interaction distance.

Diffusion pump :

After a mechanical (roughing) pump is used to remove about 99.99% of the air in the beam tube, the remaining air can then be removed by a diffusion pump, down to about 1E-5 torr.

Digital Status :

Indicates whether a given device is on or off, and whether or not it has been reset. Usually there are also digital bits which signify interlock status, etc.

Digital Voltmeter (DVM) :

A modern solid state device capable of measuring voltage and displaying the value in digitized form. The term is also used loosely for the digital multimeter which can measure current and resistance as well.

DIO :

Direct Input/Output. It is generally used in the context of processor I/O.

Dipole :

A magnet with two pole faces, used to bend the beam either horizontally or vertically.

Direct Muon :

A muon produced by the direct interaction of a proton with a target rather than produced as a decay product.

DISC Cerenkov Counter :

A DISC (Differential Isochronous Self- Collimating) Cerenkov counter is used to identify particles over a wide range of masses and can also be used to give an independent calibration of the average momentum of a beam line. The DISC Cerenkov counter at Fermilab is located in the M6 beam in the Meson Lab.

Discriminator :

A discriminator is a circuit that accepts signals of various shapes and amplitudes, and for each input signal that is above threshold, it outputs a standardized logic pulse. The outputs are of standard amplitude and duration, completely independent of all characteristics of the input except time of occurrence.

Disk :

A device carrying magnetically encoded information which can be read by a computer system. The information load is usually in the few to hundreds of megabytes range.

Diskette :

Also known as a "floppy disk". A small device which carries magnetically encoded information readable by a computer or microprocessor.

Dispersion :

Quality of a beam transport system at a given point that defines the variation of the transverse position of the beam with variations in beam momentum. Usually expressed in meters.

Dispersion :

Spread in beam positions due to a spread in particle momenta. ( Dx = Dx(z)(Dp/p) --> where Dx is the horizontal dispersion as a function of z, the longitudinal coordinate )

Dispersion (high and zero) :

Dispersion of the momentum variety can be looked at as the size of a beam as a function of the momentum spread. Dipoles can create dispersion or take it away (particles of different momenta will be bent at different angles by a dipole with uniform field), as can quadrupoles. In the case of the Antiproton source, high dispersion regions are good places for beam pickups to sense improper momenta- a good place to install momentum cooling pickups. Low (or zero) dispersion regions are suitable for sensing beam displacements primarily due to btron oscillations- similarly a good region in which to install pickups and kickers for btron cooling systems. As an aside, momentum cooling kicker electrodes are also placed in low dispersion areas, because placing them in high dispersion areas could induce unwanted heating of the beam.

Divergence :

The angle that the trajectory of each particle makes with the beam axis. Accelerator systems always try to reduce beam divergence.

DL0 Disk Drive :

The upper disk drive on a console PDP-11/34. It contains the console operating system management programs and system common block areas.

DL1 disk drive :

The lower disk drive on a console PDP-11/34. It contains images of the most used applications programs on that console.

DOE :

U.S. Department Of Energy

Dogleg :

A two (or more) dipole system which first bends the beam away from a given path and then straightens it so that it parallels the original path.

Dogleg :

A shifting of the beam axis by a pair of dipole magnets, such that the initial and final beam axes are parallel.

Dome (Pre-Accelerator) :

The -750 kilovolt direct current terminal of the Cockcroft Walton preaccelerator containing, among other things, the proton source for the accelerator.

Dosimeter :

An instrument used for measuring or evaluating the absorbed dose of radiation. It may depend on the measurement of ionization for its operation or may simply involve the darkening of a piece of photographic film ("film badge").

Dome :

A large rounded box, maintained at a high potential, that houses the ion source and supporting equipment in the preaccelerator.

DOSYL :

DOcument SYstem Locator. A documentation system residing on the Development VAX which is used to reference Operations Bulletins, Technical Memos, Software Releases, etc. It contains information which can be accessed by keyword, date, author, or subject concerning major documents released by the Accelerator Division or the Publications Office.

Doublet :

A system of two quadrupoles in close proximity, and with opposite polarity, used to simultaneously constrain the beam size in two dimensions at some point downstream.

Doublet (Quadrupole) :

A beam optical system consisting of two quadrupoles of opposite sign which provides net particle focusing in all planes.

Doughnut club :

The group of Physicist, Specialist, and Techs that gathers each morning to read the bulletin board in the west entrance MCR while eating doughnuts and spilling coffee.

Download :

To write an operating program from one machine to another. Often the programs are stored in one machine and written onto the second if problems develop during operation.

Downstream :

A relative term which corresponds to the direction that the protons travel in that portion of the accelerator.

DPM :

Data Pool Manager. A task on the console computer which accesses the database in the VAX in order to organize request lists for setting and reading data.

DRF1,2,3 :

Like the Accumulator, the Debuncher employs 3 unique radiofrequency systems. DRF1 is an h=90 (53 MHz) system used to capture the p- bunches as they are injected, rotate the bunches 90R in phase space to reduce their momentum spread, then to adiabatically debunch the beam. It may not be obvious, but the p-'s coming off of the production target will retain the same RF structure as the incident protons had, hence DRF1 can be flocked to MRRF. There are 2 unique types of cavities comprising DRF1. Cavities 1 and 8 are referred to as adiabatic cavities and are able to operate at a lower voltage than the other 6 cavities in order to adiabatically debunch the beam. Cavities 2-7 are called 'Rotators' and primarily serve the function of capturing and bunch rotating the injected pbars. DRF2 is a barrier bucket system operating at h=4. The Debuncher is physically longer than the Accumulator, by H200 nsec, so a gap is put into the circulating Debuncher beam to make the beam fit into the Accumulator. This also permits time for kicker magnets to reach full field without perturbing the beam. DRF2 creates one bucket (the other 3 are suppressed) which prevents particles from entering, hence a gap in the beam is created. The bucket height of DRF2 is greater than the beam energy spread, so a barrier is created. DRF3 is also a h=4 system and is used only during studies as an aid in exploring the aperture, chromaticities, and other properties where moving the beam around the aperture radially is useful. Varying its frequency permits one to move the beam to the inside or outside of the central orbit.

Drift Chamber :

A series of drift chambers are used to detect particle trajectories. They are similar to multi-wire proportional chambers, except the wire spacing is increased. The correlation between the position of an ionized track produced by a charged particle and the time of appearance of an electric pulse at the wire is used to measure the distance of the trajectory from the wires.

Drift Tube :

In Linac a long copper torus, containing a quadrupole magnet, through which beam passes during acceleration in a linac RF cavity. The beam is shielded from the electric field in the cavity while in the drift tube, and is accelerated by the field while passing between drift tubes.

Drift Tube :

Tube inside a Linac RF cavity in which beam is protected from the sinusoidally varying accelerating field when the field gradient is against the forward momentum direction of the beam. When the beam travels out of the drift tube and into the accelerating gap the beam sees a positive gradient and is accelerated.

Drive Loop :

Termination of the Linac coaxial transmission line leading from the PA to the RF cavity which couples the energy in the transmission line to the magnetic fields in the cavity.

Driver :

The 4616 power amplifier tube (200 kw output) used in linac to drive the 5 MW PA.

Dry engine :

Cryogenic device which cools the helium by allowing it to do work against a piston. It is used to cool the shell side of the heat exchangers. other properties

Dugan :

Pbar term. Unofficially used to describe the rate of stacking pbars. 1 Dugan = 1 mA/Hr. Named in honer of Dr. G.Dugan who used to be head of pbar.

Dumb module :

A relative term designating any card or module which does no on-board data processing or error checking. For dumb modules these functions are usually performed by the front- end.

Dump :

An area of steel and dense concrete into which unwanted beam can be steered so that its energy can be dissipated in a safe and controlled manner. This term also refers to a Tevatron ramp trip during which the stored energy of the ring is dissipated through high power resistors.

Dump resistor :

Resistor which is switched into the Tevatron magnet circuit in order to dissipate the stored energy in the magnets in the event of a ramp trip.

Duoplasmatron :

A type of ion-producing source that develops protons by extracting positive ions from an arc struck in hydrogen gas. The I- source in the PreAcc used to be a duoplasmatron. Both sources are now magnetrons.

Duplex :

Simultaneous two-way independent transmission in both directions. This may also be referred to as full duplex.

Dynamics :

The study of the motion of particles under the influence of forces. Dynamics deals with the causes of motion, as opposed to kinematics which deals with its geometric description.

-E-

E17 Kicker :

The kicker magnet responsible for moving Main Ring beam from the circulating orbit to the extraction orbit for injection into the Tevatron. The misfiring of this magnet can result in severe quenches in E and F sectors.

E-Z Writer :

Applications programs which store commonly used plot information for convenient display on the Lexidata or storage scope. Currently residing on D77, B67, M77, M78, T102, T107, S67, and P77.

EAD :

Experimental Areas Division. The downstream beam area of Switchyard. Switchyard Operations Department and switchyard experiment areas are part of EAD.

Early Bird Report :

At the end of owl shift the Main Control Room crew chief writes a one page summary of the past 24 hrs and the proposed schedule of accelerator operations for the next 24 hrs. This summary is then posted on the bulletin board outside the west MCR entrance with the last 24 hrs of the log book.

East (West) Anode Supply :

The high voltage d.c. power supply for the anodes of the power amplifiers located under the east (west) gallery of the booster.

Echoing :

The returning of information from a computer or some part of the control system to insure that the information was received correctly.

Eddy Current :

Localized current flowing in a conductor in response to a changing magnetic field.

Electron :

A stable, elementary, negatively charged particle. Electrons have the smallest amount of mass of all the subatomic particles. Electrons may be in bound states around nuclei where they determine chemical properties of elements, may radiate through space as electron beams or g-rays or through conductors to form an electrical current. Electrons are spin 1/2 fermions and interact via the electro-magnetic and weak forces.

Electron Shower :

These are usually called electron-photon showers and are made by high energy electrons or photons passing through a medium. A parent electron radiates photons in traversing a medium, and the photons convert to electron-positron pairs, which again radiate. The number of electrons and photons therefore increase exponentially until ionization loss becomes important and no further radiation is possible.

Electron Volt (eV) :

The amount of kinetic energy gained by an electron when it is accelerated through an electric potential difference of 1 volt. It is equivalent to 1.603x10-12 erg. It is a unit of energy or work, not voltage. Particle energies at FERMILAB are typically measured in billions of electron volts (GeV).

Electrostatic Septum :

The septum is the principal component of a beam splitting system. Static electric charges produce a different field on opposite sides of the septum. Segments of beam on opposite sides of the septum will be deflected opposite directions, thus cutting the beam into two parts, or "splitting the beam".

EMC :

Event Message Code. A list of alarms assembled by the appropriate front-end. This list is eventually given to AEOLUS, which organizes the data for display on the alarm screens.

Emergency loop :

System of microswitches which when opened (by pulling on a crash cord on the tunnel wall) will disable the radiation and electrical safety systems for that particular enclosure.

EMI :

The EMI (External Muon Identifier) is a set of muon detectors (proportional wire chambers) attached to the outer shell of the 15-foot bubble chamber. In conjunction with the chamber it aids in the interpretation of neutrino and antineutrino interactions by positively identifying muon tracks in the chamber. Note that the 15-foot bubble chamber is no longer used.

Emittance :

The area in phase space occupied by a particle beam. The units are mm-milliradians for transverse emittance and eV-sec for longitudinal emittance.

Emittance :

( pe ) Defined as the effective area of the beam in phase space and given by ?x' dx where x' is the divergence.

Emittance Probe :

Linac device used to measure the size of the phase space ellipse occupied by the beam, done by measuring the divergence of the beam at a number of points across the beam axis.

Emulsion (Nuclear) :

A photographic substance designed for the detection of ionizing particles. When high speed charged particles traverse the emulsion, they cause ionization tracks which show up when the emulsion is developed. The charge, energy, and momenta of the particles may be deduced from their range in the emulsion, from the grain density of their tracks, and from their curvature in a magnetic field.

Enable :

A request for beam sent to the prom module in the preacc control room. Three types of enables exist: HEP, NTF, and P-bar.

Enclosure :

A portion of the accelerator tunnel.

End pulse :

Pulsing of the QXR magnets at the end of flat top to extract the final fast spill. An attempt is made to extract all the beam remaining in the Tevatron during that pulse.

Energy Doubler/Saver :

The name originally given to the Tevatron. It is an "energy doubler" because it permits acceleration of protons to about 1000 GeV which is twice the energy attainable in the Main Ring. It is an "energy saver" because the superconducting magnets permit the acceleration of beam using less electrical energy than the Main Ring uses to reach the same energy. 1

Enthalpy :

The sum H of the internal energy U and the work energy PV of a fluid at a given temperature and pressure.. H = U + PV. (J/g)

Entropy :

The measure of system disorder. The function of state of a thermodynamic system. (dQ/dmdT) EPA :

Environmental Protection Agency

EPB :

Extracted Proton Beam. This term refers to 5 and 10 foot dipoles and quadrupoles originally designed for use in the Switchyard.

EPO :

Environmental Protection Officer

ERM :

Event Request Modules. These are the CAMAC 175 Modules which encode events onto the Tevatron clock. They are located in the MAC room.

Error Codes :

Messages which appear in red on the TV or Lexidata screens which carry information about the controls system pertinent to the fact that you have no data. These messages can be deciphered from D11 or using the error help facility under the utility window on the consoles.

ES1, ES2 :

Electrostatic Septa 1 and 2 responsible for guiding Tevatron beam to the extraction orbit for delivery to switchyard. ES1 and ES2 are located at D0.

ES&H :

Environment, Safety and Health.

ESEP :

Vertical splitting septa in the proton line. It is called ESEP because it is located in enclosure E in Switchyard.

ESHPAC :

ES&H Policy Advisory Committee

ETHERNET :

The link and communication protocol which is generally used between computer systems. It is a half-duplex link which transmits data serially (both directions) at a 10 Mbyte rate. The primary use in the Accelerator Division is for the link between the Linac front-end (a PDP-11) and the Linac Primary Station (a 68000 microprocessor). This type of link is also used on site for the DECnet link between the AD VAXCluster and the FNAL VAX Cluster.

Ethernet Controller Board :

Board found in the linac primary microcomputer that handles communication with the Ethernet link.

Eurobus Crate :

One of two small crates in the preacc control room containing cards used to interface the local microcomputer to the Haefely power supply controls.

Expansion :

To make the volume in which a given mass, or mass flow, resides suddenly larger as in Joule-Thomson and engine expansion.

Expansion Efficiency :

The ratio of the actual change in enthalpy to the ideal (isentropic) change.

                                                DH Real 
                                        eff. = ########## 
                                                DH Ideal 

Expansion Engine, Turbine :

Devices that are driven by gases, extract work, and lower the temperature of the gas.

Extended Stem :

Modifier for valves with long stems for cryogenic service.

External Interrupt Panel :

This 16 input panel (with on/off switches for each input) is used to interface external interrupt signals, which may be clock events, to the computer processor interface cards. These panels are located behind the PDP-11 Status Display Units and are also behind the Mac computers.

Extraction :

The process of taking the protons out of the accelerator in a controlled fashion once acceleration has been accomplished. Extraction from the Tevatron takes place during the flattop of the ramp.

Extraction :

The controlled removal of beam from one portion of the accelerator in order to send it to the next one.

Extractor :

An electrostatic device used to extract ions from the magnetron ion source in PreeAcc. It consist of a pair of plates mounted beneath the source connected to a pulsed power