Muon digit container: Definitions

D. Adams
11oct01 0900

Here we define some of the terms used in the design of muon digit container. We try to be consistent with the terminology of the muon and DAQ and trigger TDR's.

The ATLAS detector includes of a collection of active detector elements. After a triggered crossing, data is read out from a subset of these elements. Some may be read out in multiple time slices.

Technology

The muon spctrometer incorporates four detector technologies:

MDT - Monitored Drift Tube
CSC - Cathode Strip Chambers
RPC - Resistive Plate Chamber
TGC - Thin gap chamber

The MDT and and CSC are used for precision measurement and the RPC and TGC are used for triggering. Most of the coverage is is with MDT and RPC. The CSC and TGC are used in forward regions where the rates are too high for the other technologies.

Channel

A channel is an an independently read out detector element such as a strip or wire.

Module

A module is a collection of channels organized into a mechanical structure. This might also be called a chamber. Chapter 3 of the muon TDR provides a precise definition for each technology.

ROD - readout driver

A collection of channels are read out through a single device known as a readout driver. The muon electronics are arranged so that all chambers for a given technology in a projective tower (eta-phi range) are read in through a single ROD. It is convenient to unpack the data for a single ROD.

ROC - readout crate

A small number of ROD's are read out through a common crate. In the MDT system there are typcially four ROD's in a ROC. This is another unit convenient for data unpacking.

Digit

A digit (or digitization) is the data associated with one channel. The implementation is self-describing, i.e. includes the identifier as well as the data.

Digit container

A digit container holds a collection of digits typically corresponding to all or a subset of the data from a single triggered crossing. It provides means to access digits by identifier, to traverse all digits (an iterator) and (under restricted circumstances) to insert or modify these entries.

Identifier

An identifier is a label for a single readout channnel or collection of channels such as a module.

dladams@bnl.gov