How to Identify Muons

Preamble

This page was originally created by Giuseppe Barbagli and extended by Achim Geiser

1. General MUON finding in ZEUS using ORANGE

GMUON

The General MUON finding (GMUON) package in ORANGE is based on a combination of the GLOMU, BREMAT, MAMMA, MPMATCH, MUFO, MIP, MV, and MUBAC muon finders described below (available from release 2003b onwards). A rudimentary BAC match and FMUON standalone information based on the MFCTS tables are provided in addition. Further extensions are forseen.

The algorithm finds prompt muons based on an "OR" of all these packages, and combines the information into a single entry per muon candidate as much as possible. The basic format of this entry is independent of the respective finder. Cross references to more detailed information for each finder and cross-correlations between the different finders are provided. In the case of ambiguities, alternative reconstructions of the same muon are sometimes listed. A muon quality flag is provided which should help the non-expert user to select good quality muon candidates from this list as a starting point for an analysis. Since muon quality is process specific, for critical applications it is recommended that the user redefine his/her own quality criteria based on the information provided.

Feedback on 'features', bugs, missing information and/or possible improvements is greatly appreciated.

Further technical information can be found here. A ZEUS note is in preparation.

MUON

In ORANGE releases 2003a and earlier, only a restricted subset of the information above based on the GLOMU, MIP, MAMMA and MUBAC finders is available as documented in ...

MV

Finds prompt muons anywhere in the CAL (+CTD) with a neural network algorithm. This is the most advanced CAL-based algorithm available, fully optimized for muons with p > 2 GeV, with good efficiency for muons down to p > 1 GeV. It also provides a link to BREMAT (see below).

For documentation, see ...

MUONFIND (MIP)

Finds prompt muons in the CAL+CTD based on the association of a MIP (Minimum Ionising Particle) calorimeter island to a high momentum track. Good algorithm for very high momentum muons. Large background at low momenta.

For documentation, see ...

ISITAMU

Group of routines to flag muons looking at calorimeter information, developed in the early years of ZEUS. It is available in Phantom.

See the section on ISITAMU in the Phantom Manual.

MUTRIG

Finds muon background events in the TLT. It is available in Phantom.

Information about MUTRIG can be found in the Phantom Manual

FCALMU

Finds muons in FCAL with a neural network algorithm. Superseded by MV package (see above).

See here for FCALMU code and information

See also the ZEUS note 96-134

MUFFIN

Finds muons using as many detectors as possible, especially suitable for cosmic and beam-halo muons overlapping with events. Currently only available on UNIX platforms.

Information can be found on the MUFFIN Homepage and in ZEUS note 98-025.

3. Muons in the Barrel and Rear region

BREMAT

Looks for muons combining CTD and B/RMUON information. For low momentum muons seen in the inner muon chambers only, a sophisticated match based on position, angle, and the full error matrix information is performed (4 d.o.f.). For higher momentum muons also reaching the outer muon chambers, a momentum consistency check based on an independent muon momentum measurement from the muon spectrometer is added (5 d.o.f.).

Further documentation on the algorithm can be found in ZEUS note 99-063.

GLOMU

Looks for low momentum muons combining CTD, calorimeter and B/RMUON information. Also used by the TLT. For muon track segments it is possible either to do a fast reconstruction of track segments from raw data or the use of reconstructed quantities. CTD tracks, transported to a reference surface with a Runge-Kutta integration, are matched with track segments. Calorimeter clusters compatible with m.i.p. passage are identified. A final match combining muon track segments, CTD tracks and calorimeter clusters is performed.

See here for GLOMU information, technical details and instructions. Some further documentation on the algorithm can be found in the original ZEUS note 93-120. ZEUS note 93-120.

4. Muons in the Forward region

A general description of the recostruction software for Forward Muons can be found in the:
FMUON OFFLINE web page.

MPMATCH

The MPMATCH2 finder looks for muons combining CTD and FMUON information. FMUON information is extracted from the MFRTZ forward muon tables, which also provide independent momentum information based on a Kalman filter fit. Muon chamber tracks are matched to CTD tracks using a sophisticated matching procedure based on the full error matrix, including an overall momentum fit. An option to match directly to the primary vertex is also forseen, but not yet fully implemented. Significant parts of the algorithm are based on the MVMATCH package

Further documentation on the algorithm and parameters can be found in the link above. For even more information contact Massimo Corradi.

MUFO

Looks for muons combining CTD and FMUON information. The algorithm is very similar to the MPMATCH algorithm. CTD tracks are reextrapolated to the CAL entry face using a private algorithm instead of using the VCPARCAL information. An option to match directly to the primary vertex using the momentum from the muon spectrometer only is provided.

Further documentation on the algorithm can be found in ... (ZEUS note in preparation). For more information contact Graziano Bruni.