CEBAF Nomenclature Document (CND)


The purpose of the CEBAF Nomenclature Document (CND) is to provide a standard system of unique names to represent pieces of accelerator and experimental equipment. Naming is mostly limited to objects found along the beam line. Nomenclature identification is used on drawings, schematics, computer software, and other sources of information. IOCs and equipment racks have their own independent naming scheme. Items in the LERF and Halls may be included.

Name Construction

All names have a maximum of nine characters, a minimum of five characters, and all letters are upper case. Names are constructed from a set of up to five codes, which reveal the object's system, type, sector, locator, and element number. Only the first three codes are required. The letters S V V X X Y Y Z Z are used to symbolize the five codes in a nine-character name. The meaning of these letters is as follows:

S Technical System A single letter is used to symbolize a major system such as a C for cryogenics or M for magnets.
VV Component Type Two letters are used to symbolize component types such as CV for check valve (Cryogenics system). All component types are dependent on a technical system. In other words the component type may have a different meaning depending on the system. For example CV means Yao Cavity if paired with the Instrumentation system or it means 12GeV Dipole when paired with the Magnet system.
XX Sector or Subsystem Two characters, which can be a number or letter in either position, are used to symbolize a location, a subsystem, or a large piece of equipment. For example, 1L is used for the North Linac, 29 is used for the vacuum system in the Cryogenic Test Facility, and 3E is used for the third extractor. Sectors and subsystems are not tied to a particular technical system. Not all technical systems use the XX positions. In which case, the positions are left blank
YY Locator Two numbers are used to symbolize a location within a sector (XX), such as the sequential numbering of quadrupoles within a sector. All non-girdered components are numbered per the upstream quad. Exceptions: Dipoles are numbered sequentially within a sector. Cryomodules match the 'zone' number (first module is #2 and the last is #26). This number controls the upstream components.
ZZ Element Number Optionally one or two trailing letters or numbers are used to provide more specificity when naming a component. An example of the usage of element numbers is using numbers 1 through 8 to indicate the cavities in a cryomodule. Using H to indicate a horizontal configuration for a beam position monitor is another example.

Example: IDA2C04

This is an Insertable Beam Stop in Line B of the BSY between quad girders 04 & 05. This is broken down as follows:

I Instrumentation System
DA Beam Stop, retractable
2C Line 'B' - Beam Switchyard
04 Located down beam of the 4th Quad


A Nomenclature Document was first published as part of CEBAF Technical note 91-083 in October 1991. Updated revisions were published and distributed in December 1992 and 1993. The document was converted to a menu-driven computer data base in 1994, which provided a search capability. The software was upgraded in March/April 1995 to include the capabilities to print or browse through the entire document. 1n 1996, the nomenclature was added to the JLAB web home page.

Somewhere along the line it seems the database was abandoned and an Excel file was used instead. In 2015 the nomenclature was moved to its current home on the accelerator Intranet web server and database where a form-based interface allows easy up-keep for maintainers.