H

H     Horizontal.

H II region     A cloud of glowing gas and plasma in which star formation is taking place. Named for the large amount of ionized atomic hydrogen it contains.

H&C     Hoist and Crane.

H&R     Hoisting and Rigging.

HA     Hazard Assessment.

Hacking     The activity of computer enthusiasts who are challenged by the practice of breaking security measures designed to prevent unauthorized access to one or more computer systems. (Hacking which involves criminal activity is called cracking.)

HAD     Hazardous Atmosphere Detector.

Hadron     Generic name for members of the largest family of elementary particles. Hadrons interact strongly with one another, usually produce additional hadrons in collisions at high energy, and are roughly spherical.

HAGGLeS     HST Archive Galaxy-scale Gravitational Lens Survey.

Half Duplex     Data transmission in either direction, but only one direction at a time.

Half-Life     The time required for the elimination of one half a total dose of radiation from the body.

Half-Life     The time required for a pollutant to lose half its effect on the environment. For example, the half-life of DDT in the environment is 15 years, of radium, 1,580 years.

Half-Life     The time required for half of the atoms of a radioactive element to undergo decay.

Halogen     Any of a group of five chemically-related nonmetallic elements that includes bromine, fluorine, chlorine, iodine, and astatine.

Halogenated Hydrocarbons     A group of organic compounds which include one or more atoms of a halogen, e.g., chlorine or bromine, in their molecular structures.

Halon     Bromine-containing compounds with long atmospheric lifetimes whose breakdown in the stratosphere cause depletion of ozone. Halons are used in fire-fighting.

Handshaking     The procedures and standards (protocol) used by two computers or a computer and a peripheral device to establish communication.

HAP     Hazardous Air Pollutant.

HAPD     Hybrid Avalanche Photo Detector.

HAPPEX     Hall A Proton Parity EXperiment, at the US DOE's Jefferson Lab.

HAPS     Hazardous Air PollutantS.

HAPS     High-Availability Power Supplies.

HAR     Hydrogeological Assessment Report. (TPCA)

Hardware Address     The low level address used by a physical network. Each type of network hardware has its own addressing scheme. For example, Ethernet uses 48-bit hardware addresses assigned by the vendor, while proNET-10 uses small integer hardware addresses assigned when a connection to the network is installed.

Hardware Status     See HSTA.

HASC     House Armed Services Committee. (US)

HASYLAB     The synchrotron radiation laboratory at DESY (Germany)

HAWG     Hazard Analysis Working Group.

Hazard     A threat to workers, public, environment, or property.

Hazard Evaluation System and Information Service     See HESIS.

Hazardous Air Pollutants     Air pollutants which are not covered by ambient air quality standards but which, as defined in the Clean Air Act, may reasonably be expected to cause or contribute to irreversible illness or death. Such pollutants include asbestos, beryllium, mercury, benzene, coke oven emissions, radionuclides, and vinyl chloride.

Hazardous and Solid Waste Amendments     See HSWA.

Hazardous Ranking System     The principal screening tool used by EPA to evaluate risks to public health and the environment associated with abandoned or uncontrolled hazardous waste sites. The HRS calculates as core based on the potential of hazardous substances spreading from the site through the air, surface water, or ground water and on other factors such as nearby population. This score is the primary factor in deciding if the site should be on the National Priorities List, and, if so, what ranking it should have compared to other sites on the list.

Hazardous Substance     Any substance named by EPA to be reported if a designated quantity of the substance is spilled in the waters of the United States or if otherwise emitted into the environment.

Hazardous Substance     Any material that poses a threat to human health and/or the environment. Typical hazardous substances are toxic, corrosive, ignitable, explosive, or chemically reactive.

Hazardous Substance Account     See HSA.

Hazardous Waste     By-product of society that can pose a substantial or potential hazard to human health or the environment when improperly managed. Possesses at least one of four characteristics(ignitability, corrosivity, reactivity, or toxicity), or appears on special EPA lists.

Hazardous Waste Control Account     State fund derived from fees paid by operators of onsite and offsite disposal facilities and used to support the hazardous waste management program of the Department of HealthServices.

Hazards Analysis     The procedures involved in (a) identifying potential sources of release of hazardous materials from fixed facilities or transportation accidents, (b) determining the vulnerability of a geographical area to a release of hazardous materials, and (c) comparing hazards to determine which present greater or lesser risks to a community.

Hazards Identification     Providing information on which facilities have extremely hazardous substances, what those chemicals are, and how much there is at each facility. The process also provides information on how the chemicals are stored and whether they are used at high temperatures.

HAZCOM

HAZard COMmunication. An Occupational Safety and Health Administration (OSHA) standard that requires all employers to instruct their workers on the hazards associated with the chemicals they use.

HAZOP     HAZard and OPerability study.

HAZWOPER     HAZardous Waste OPerations and Emergency Response standard. (OSHA)

HB-0     The bend in the DRIP where the beams returning from the rings get injected back into the LINAC.

HBCPT     Heavy Baryon Chiral Perturbation Theory

HBCU     Historically Black Colleges and Universities (US).

HBL     High-energy cut-off BL Lac object.

HBT     Hanbury-Brown-Twiss

HBV     Hepatitis B Virus.

HCAL     Hadron barrel CALorimeter.

HCM     Human Capital Management.

HCP     Hazard Communication Program. (SLAC)

HCPBM     Heavily Charged Particles in Biology and Medicine.

HCS     Hazardous Communications Standard. (OSHA)

HCV     Hepatitis C Virus.

HD     Higher Derivative.

HDF     Hubble deep field.

HDF5     Hierarchical Data Format 5.

HDI     How Do I. SLAC Financial and Human Resources gateway.

HDM     Higgs Doublet Model.

HDMS     Heidelberg Dark Matter Search (Gran Sasso)

HDPE     High Density PolyEthylene.

HDSC     Hardware DeSCripter.

HDSCP     HoDoSCoPe.

HDSPC     High Density Spiral Projection Chamber.

HDX     Hybrid Damped structure.

HEAD     High-Energy Astrophysics Division (American Astronomical Society).

Header     The portion of a packet, preceding the actual data, containing source and destination addresses and error-checking fields.

HEASARC     High Energy AStrophysics Science ARChive (Goddard).

Heat Exchanger     A locked radiation area where radioactive cooling water coming back from the slits, collimators and beam dumps is cooled and demineralized. (The heat exchange is with the cooling tower water.) The radiation levels in the heat exchangers are monitored by OHP.

Heavy Metals     Certain metallic elements having a high density and which are generally toxic, e.g., lead, silver, mercury, and arsenic.

HEB     High-Energy Beam.

HEC     High-End Computing

HED     High-Energy Density science (LCLS).

HEDP     High Energy Density Plasma.

HEDS     High-Energy Density Science. (LCLS)

HEDSD     High Energy Density Science Division

HEE     High-Energy Extraction.

HEFT     High Energy Focusing Telescope.

HEGRA     High Energy Gamma Ray Astronomy telescope. Five-telescope array built in La Palma by a German-Spanish-Armenian collaboration.

HELEN     High Energy physics Latin-American-European Network.

HELEN     High-Energy Laser Embodying Neodymium. British laser brought to LCLS in 2011.

HELIOS     CERN Super Proton Synchroton detector

Helmholtz Coil     A coil in which the first and last winding are separated by 2r where r is the radius of the winding. Used to produce a uniform solenoid field. Designed by Hermann Helmholtz.

Helmholz Alliance     Network of German laboratories and universities involved in the LHC and the ILC.

HENIT     High-Energy North Injection Transport.

HENP     High Energy and Nuclear Physics.

HEP     High Energy Physics.

HeP E-tool     Hazard Evaluation and Planning Electronic tool. (SLAC ES&H) This tool is an activity-based questionnaire intended for use by non-ESH staff, in particular supervisors, activity planners and UTR s. The tool identifies SLAC required permits and plans based on responses to the questions. May be accessed from the WPC website.

HEPA     High Efficiency Particulate Air.

HEPAP     High Energy Physics Advisory Panel.

HEPC     High Energy Photon Conference.

HEPDATA     Physics databases maintained at Durham/Raleigh.

HEPL     W. W. Hansen Experimental Physics Laboratory, Stanford University. (Formerly, High Energy Physics Laboratory.)

Hepnet     High Energy Physics Network. An international network linking computers of High Energy Physics laboratories.

HEPP     High Energy and Particle Physics, a division of the EPS.

HEPT     HElium Proportional Tubes.

Hertz     See Hz. 

HERWIG     Hadron Emission Reactions With Interfering Gluons. A Monte Carlo program.

HESIS     Hazard Evaluation System and Information Service. Sponsored by SDOHS and Cal OSHA. Provides information on chemicals to employers and employees.

HESS     High Energy Stereoscopic System. A next generation system of imaging atmospheric Cherenkov telescopes aimed at the study of cosmic gamma rays. (Namibia) Name honors Viktor Hess, who received the 1936 Nobel prize for his discovery of cosmic rays.

HET     Hobby-Eberly Telescope.(McDonald Observatory)

HETC     High Energy Transport Code

HETDEX     Hobby-Eberly Telescope Dark Energy Experiment.

HEU     Highly Enriched Uranium

Heuristics     In computing and artificial intelligence, common sense rules drawn from experience and used to solve problems.

HF     High Frequency. Allocated band of radio frequencies from 3MHz to 30 MHz.

HFAG     Heavy Flavor Averaging Group.

HFB     Hartree-Fock-Bogoliubov

HFBR     High-Flux Beam Reactor (Brookhaven)

HFF     Heavy Fermion Formalism

HFS     HyperFine Structure constant

HGHG     High-Gain Harmonic Generation.

HGO     Haleakala Gamma Ray Observatory.

HGRF     High-Gradient Radio-Frequency.

HGVPU     Horizontal Gap Vertical Polarization Undulator

HHCPT     Heavy Hadron Chiral Perturbation Theory

HHG     High Harmonic Generation

HHLM     High-Heat Load Monochromator (LCLS-II-HE)

HHMI     Howard Hughes Medical Institute.

HHW     Household Hazardous Waste.

HHWR     Heating Hot Water Return.

HHWS     Heating Hot Water Supply.

HIC     Heavy Ions Collision

Hierarchical Routing     Routing that is based on a hierarchical addressing scheme. Most Internet routing is based on a two-level hierarchy in which an Internet address is divided into a network portion and a host portion. Gateways use only the network portion until the datagram reaches a gateway that can deliver it directly. Subnetting introduces additional levels of hierarchical routing.

HIF     Heavy Ion induced Fusion. Also, Heavy Ion Fusion.

Higgs Boson     The last particle of the Standard Model, predicted by Peter Higgs, a Scottish theorist. Discovered at the LHC on July 4, 2012.

Higgsino     SUSY partner of the elusive Higgs boson.

High Energy Equipment Pool     See HEEP.

High Energy Physics     See HEP.

High Energy Physics Network     See Hepnet.

High Frequency     See HF. 

High Voltage Ready     See HVR.

High-Level Radioactive Waste     See HLW.

HILAC     Heavy Ion Linear Accelerator.

HIMAC     Heavy-Ion Medical Accelerator in Chiba, Japan. Began operating in 1994.

HIP     A program for symbolic calculation of Feynman diagrams.

HIP     Holding Ion Pump.

Hi-Potting     A troubleshooting technique. The process of increasing a voltage potential to a specified high level, with respect to ground, in order to check for failure or ground fault in a magnet. Used to measure very high resistances, or the voltage at which an insulator will break down.

HIPPI     High Intensity Pulsed Proton Injector (CERN).

HippoDraw     A data visualization program for displaying histograms developed by Paul Kunz (SLAC) and Jeff Gould (Gould Software).

HiRes     High Resolution Fly's Eye, an experiment.

HIT     Heidelberg Ion Therapy centre.

Hitomi     X-ray satellite (Japan). Means 'pupil of the eye.'

HIV     Human Immunodeficiency Virus.

HIVE     HANNA Immersive Visualization Environment (Stanford)

HJ     Hamilton-Jacobi

HKT     HyperKahler with Torsion

HLA     High-Level (physics) Applications. (LCLS)

HLAM     Horizontal LAMbertson. A septum magnet used to extract the scavenger beam from the LINAC to the positron target. Designed by Glen Lambertson. See Septum.

HL-LHC     High Luminosity Large Hadron Collider

HLS     Hydrostatic Leveling System.

HLS     Haag-Lopuszanski-Sohnius

HLT     High-Level Trigger.

HLW     High-Level Radioactive Waste. Waste generated in the fuel of a nuclear reactor and found at nuclear reactors or nuclear fuel reprocessing plants. It is a serious threat to anyone who comes near the wastes without shielding.

HM     Hazardous Materials. (DOE)

HMBP     Hazardous Material Business Plan.

HMC     Hybrid Monte Carlo

HMP     Hazardous Materials Program. (DOE)

HMPID     High Momentum Particle Identification Detector (ALICE).

HMSF     Hazardous Materials Storage Facility.

HMTA     Hazardous Materials Transportation Act. (49 U.S.C. Sec. 1801 et seq)

HOA     Hand-Off-Automatic.

HOC     Halogenated Organic Compound.

Hodoscope     A detector, usually used for triggering and based on scintillation counters with very short output pulses, which records the paths of ionizing particles by means of ion counters enclose array. (From the Greek pathviewer)

hohlraum     In inertial confinement fusion reaction experiments, a gold-lined, pencil-eraser-sized chamber that contains the nuclear energy. From the German for 'small hollow.'

HOM     Higher Order Modes.

Hood Capture Efficiency     The emissions from a process which are captured by hood and directed into the control device, expressed as a percent of all emissions.

Horizontal Lambertson     See HLAM.

Host     The current computer being used in a network. Also called a server.

Host Name Resolution     A mechanism with static and dynamic elements for resolving host names into numeric addresses. The Internet Name Server Protocol accesses an Internet Name Server which provides dynamic name-to-number translation (this process is specified in IEN 116). The Domain Name Protocol accesses a Domain name Server which provides dynamic name-to-number translation (this process is specified in RFCs 1033 and 1034). A static local host table can also be accessed for name-to-number translation.

Host Table     An ASCII text file where each line is an entry consisting of one numeric address and one or more names associated with that address. Host tables are used to resolve host names into numeric addresses.

Hostname     The name given to a machine. See also FQDN.

HP     Health Physics.

HP     Health Physicist.

hPa     Hectopascal. 100 Pascals.

HPC     High Performance Computing.

HPD     Hybrid PhotoDiode

HPF     High Performance FORTRAN. An evolving industry standard based on FORTRAN 90 + a FORALL statement + data partition directives that will be available on IBM's POWERparallel Systems like the 9076 SP1.

HPI     Human Performance Improvement.

HPL     High Power Laser

HPLC     High Performance Liquid Chromatography

HPRF     High-Power RF.

HPS     Hutch Protection System.

HPS     Heavy Photon Search. (experiment)

HPSB     High-Performing Sustainable Building.

HPSS     High-Performance Storage Systems.

HPT     Health Physics Technician.

HPTM     High Power Target Module.

HPW     Harvard-Pennsylvania-Wisconsin detector.

HPWR     High PoWeR.

HQ     DOE HeadQuarters (Washington, DC).

HQ     High-field Quadrupole.

HQEFT     Heavy Quark Effective Theory.

HQET     Heavy Quark Effective Theory

HQH     Hybrid Quark Hadron.

HR     Human Resources Department (SLAC).

HRA     High Radiation Area.

HRBP     Human Resource Business Partners. (SLAC)

HRD&S     Human Resources Development and Services. (SLAC)

HRIS     Human Resources Information Systems.

HRMS     Human Resources Management System.

HRS     Hazard Ranking System. (CERCLA)

HRSC     Hoisting and Rigging Safety Committee.

HSA     Hazardous Substance Account. A California state fund derived from fees paid by persons who deposit more than 500 pounds per year of hazardous or extremely hazardous waste to onsite or offsite hazardous waste disposal facilities. This is the primary funding source for the State Superfund program. (CH&SC Sec. 25300 et seq)

HSD    Health and Safety Directive.

HSS     Health, Safety and Security office. (DOE)

HST     Hubble Space Telescope.

HSWA     Hazardous and Solid Waste Amendments. The 1984 law which amended RCRA and created a federal program for underground tanks.

HTL     Hard Thermal Loop

HTM    Hierarchical Triangular Mesh.

HTML     HyperText Markup Language. The standard language used for creating hypermedia documents within the World Wide Web. It specifies the layout and linking commands present in the hypertext documents themselves.

HTS     High Temperature Superconductivity

HTSC     Hartle-Thorne-Sedrakian-Chubarian

HTTP     Hypertext Transfer Protocol. The standard application-level protocol for distributed, collaborative, hypermedia information systems. It describes the way that hypertext documents are fetched over the Internet and is most commonly associated with the World Wide Web.

HUE     Historically Under-represented Ethnicities

HUP     Hutch User's Panel. (LCLS)

HV     High Voltage.

HV     Heating and Ventilating unit.

HV     t Hooft-Veltman

HVAC     Heating, Ventilation and Air Conditioning.

HVR     High Voltage Ready. A klystron SDS message indicating that a given klystron is ready for use.

HVTC     High Voltage Terminal Cabinet.

HWA     Health and Welfare Agency (California).

HWCL     Hazardous Waste Control Law. (CH&SC Sec. 25100 et seq)

HWMC     Hazardous Waste and Material Coordinator.

HWSA     Hazardous Waste Storage Area.

HWSY     Hazardous Waste Storage Yard.

HX2     Heat Exchanger 2 (LCLS-II)

HXC     Hard X Corrector.

HXRSS     Hard X-ray Self-Seeding

Hydrocarbons     A large group of organic compounds composed largely of carbon and hydrogen.

Hydrogeology     The geology of ground water, with particular emphasis on the chemistry and movement of water.

Hydrology     The science dealing with the properties, distribution, and circulation of water.

HYP     HYPercubic.

Hyperlink     An element in an electronic document that links to another place in the same document, or to an entirely different document. Typically, you click on the hyperlink to follow the link. Hyperlinks are the most essential ingredient of all hypertext systems, including the World Wide Web.

hyperon     A heavy version of a neutron. Hyperons can be made artificially in accelerators, where they are unstable and decay quickly.

Hz     Hertz. The basic unit of frequency measurement that replaced the former unit of cycles per second (cps). One hertz is equal to one cycle per second.