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In track helix parameterization the distance of closest approach to the origin of coordinates. This quantity is signed in such a way that |1/k + d0| is the distance between the origin of coodinates and the helix center in the x-y plane. (k is the pro perly signed helix curvature).
Digital to Analog Converter
A Dalitz plot is a way to represent the entire phase space, viz, all essential kinematical variables, of any three-body final state in a two-dimensional histogram.
Reference Link (http://rd11.web.cern.ch/RD11/rkb/PH14pp/node39.html)
Objectivity requires the use of C++ classes that are defined in Data Definition Language, (DDL), files. DDL files have a name with a .ddl suffix.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/objectivity1/objectivity1.html#terms)
The name given to moving data between sites.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/Computing/Offline/DataDist/)
Component of Drift Chamber front-end electronics. Multiplexes data and commands between fiber-optic link to Readout Module (ROM) and 12 front-end assemblies (FEAs) in one quadrant.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/Detector/CentralTracker/electronics/doc/dc_elec_diom.ps.gz)
Sets environment variable OO_FD_BOOT to specify what data will be used, also see mc12boot, cond14boot, etc.
Sets environment variable OO_FD_BOOT to specify what data will be used, also see mc12boot, cond14boot, etc.
A database is where an application's persistent data is stored. A database is physically represented by a database file, which is made up of all containers and basic objects stored in the database.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/objectivity1/objectivity1.html#terms)
Each database is identified both by its file system location and by a unique Database ID, (DBID), number.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/objectivity1/objectivity1.html#terms)
Reference Link (http://www.slac.stanford.edu/BFROOT/www/Computing/Online/DataFlow/OnlineDataFlow.html)
The debugger, dbx, is available on all BaBar platforms.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/debug/debug.html)
A debugger is a tool that allows one to trace problems in a program at the source code level. A debugger enables you to control a program's execution, symbolically monitor program control, flow, variables, and memory locations.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/debug/debug.html)
A developer database is a federation that becomes part of the user's private test release environment. It is copied from the reference database associated with the base software release. A developer database contains a default copy of the condition data, and is otherwise initially empty (the Event Store contains no data).
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/objectivity1/objectivity1.html#types)
The smallest data element provided by the DAQ. It corresponds to one hit.
Representation in the reconstruction of a single readout channel. E.g. a DchDigi corresponds to one hit wire.
the combination of detector signals from a real background event and a simulated physics event to form a realistic simulated event; performed in SimApp by overlaying background and physics digitizations.
Dip angle is the angle between the track momentum and the x-y plane.
In track helix parameterization, the polar angle between the z-axis and the track momentum.
Direct CP violation: The decay rate B -> f is different form the decay rate for Bbar -> fbar. Direct CP violation has been observed in the Kaon system and recently also in the B meson system. In order for direct CP violation (=CP violation in decay) to occur 3 conditions must be met: (1) more than 1 amplitude for single decay (2) weak phase difference between amplitudes not equal to 0 (3) strong phase difference between amplitudes not equal to 0
Distance of closest approach a) of a track to a reference point or line, e.g., the z-axis passing through the coordinate origin, or through the beam spot center, or to a vertex. b) of a track to a sense wire in the Dch.
The Distributed Histogramming Package (DHP) provides a means of collecting histograms simultaneously across multiple nodes of the online farm, viewing them while the run is still in progress, and collecting and storing them at the end of the run.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/Computing/Online/EventProc/jas/1999-05-19-Forum-JAS/online-dhp.html)
System for accumulating histograms in processes distributed across a farm of computers, while providing a single view of the full statistics to clients. Used in BaBar to accumulate data quality monitoring histograms in the OEP / Level 3 processes in the online system. Implemented as an application of the BaBar Distributed Object Tree (DOT) software.
client-server system that provides a general framework for publishing a set of strongly-typed information from a distributed collection of processes, with a means for obtaining a unified view of all the information from a client. A type-specific "merge" operation can be defined that will be used by the framework to combine information from multiple sources. Typically this operation might be to sum or average contributions from the sources.
A type of tape storage medium. DLT-IV has a storage capacity of 35 Gb uncompressed.
Please see DOCA
DRC is the three letter acronym, (TLA), for the Detector of Internally Reflected Cherenkov radiation, which is more commonly abbreviated as DIRC.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/detector/detector.html)
The second component of the BaBar tracking system is the drift chamber, (DCH). It is used primarily to achieve excellent momentum resolution and pattern recognition for charged particles with p_t > 100 MeV/c.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/doc/workbook/detector/detector.html#systems)
This is the charged particle trigger of the detector's Level 1 trigger system.
Reference Link (http://www.slac.stanford.edu/BFROOT/www/Detector/Trigger/trigger_whatsit.html)
Ds meson (quark content c-sbar) with spin J.
To add an entry to the Glossary use the BaBar Glossary Submission Form.
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Last significant update: 10-Sept-2002