The muon index is general purpose container for the parameters
to describe an address of any part of the muon system.
A translator class
At the broadest level the muon system is divided into a central region (WAMUS) and two forward regions (FAMUS north and south). In each region there are wire devices and scintillator devices. The proportional drift tube (PDT) is the central wire device, and the mini drift tube (MDT) is the forward wire device. The muon scintillator (MSC) has common properties in all regions of the muon system, differing only in physical size and number of photomultiplier tubes attached to a single scintillator.
At the next level the muon system is organized into three layers: an A-layer between the calorimeter and iron toroid magnet, a B-layer immediately outside the toroid, and a C-layer at the outer limit of the detector. The muon structures divide into 8 octants each covering a 45 degree section of the detector. In the central region, the structure are also split into 3, 4, or 5 barrels along the z-axis of the detector.
At the finest level of the muon system the wire devices are split into 3 or 4 planes and segmented in a fashion that roughly corresponds to the pseudorapidity, eta. The scintillator effective resides in a single plane and is divided in both the eta and phi directions. MDT units are in eight-wire groups and scintillator can have either one or two tubes associated with one physical piece.
The section describes a rigid group of elements in the muon system: one WAMUS PDT chamber, one FAMUS MDT octant, or the set of scintillators mounted on one PDT chamber or one MDT octant. The cell describes an individual readout channel within one section.
Monte Carlo events are based on a simple vector of integers and conversions to and from MuoIndex are supported.
The geometry package is based on ``modules'' which correspond to sections, and ``channels'' which correspond to cells. The geometry package expects a single integer for each of these functions which MuoIndexTrans can extract from a MuoIndex. In addition, the PDT geometry is based on the Run I geometry which is given by a local coordinate system, supported by MuoIndexTrans.
Raw data is in the L3 format and is also defined by integer ``modules'' and ``channels'', but are not the same as those used by geometry. L3 format modules correspond to individual readout devices (1/2 a Muon Readout Card) and contain multiple sections for MDT and MSC data. L2 format appears for the purposes of simulation and diagnostics in the offline software and differs from the L3 format due to the severe time constraints at L2, but are also supported by the MuoIndexTrans class.
// Central A-layer octants: 0 = (0+7), 3=(3+4)
// Central B/C-layer: 0,1,2,3,4
// Central B/C, octants 5,6: 0,1,3,4
// Wire A-Layer : 0,1,2,3
// Central A, Octant 5,6: 0,1,2
// Wire B/C-Layer : 0,1,2
MuoIndexTrans :
.cpp
.hpp
3.0 Monte Carlo Addressing
The GEANT Monte Carlo has an index format that pre-dates the MuoIndex definition. It consists of a simple STL vector of six integers. The contents, and map to MuoIndex parameters, are defined as follows:
The PDT geometry was defined in Run I and is in a coordinate system local to each PDT chamber. The local coordinate system is based on an orientation of the PDT chamber such that the readout electronics is up and at the near end. Within the local coordinate system planes count with 0 at the top and 2 or 3 at the bottom, and wires in a plane count from 0 at left.
The MDT geometry ignores the eight-wire groupings and counts each wire in the plane individually from 0 at the end nearest the beam line to a maximum of 383 in some C-layer octants.
The MSC geometry ignores the parameter for the number of tubes, and treats all tubes on the same piece in the same way.
Time constraints in L3, make it highly desirable to have certain channels readout directly after one another. This includes readout of the PDT channels that share the same connected wire and readout of MSC channels that come from to the same piece of scintillator. Readout of eight-tube units of the MDT may also be in this category.
In order to diagnose DSP data readout problems, the channels are read in increasing order of their channel id. This order is set by the physical location of the input cables. For the PDTs the cables arrive in an order prescibed by the local geometry, but that order does maintain the rule that keeps both channels from the same connected wire in direct succession.
The L2 trigger has the constraint that each 4-byte hit sent to the system should have sufficient address information to distinguish it from other hits that might come from other front ends into the same trigger card. This often requires duplicating some of the module id information in the L2 hit address.
Within the L2 trigger card the address is routed based on the address and the bits may be remapped internally into a scheme that provides the fastest lookups within the L2 DSPs. To facilitae routing and remapping the hit addresses are split into bit fields as much as possible.
The following hit addresses are the current proposal.