CSC local efficiency measurements from run II data

NEW 03.11.2015 UPDATED 11.11.2015 - add link to DP note itself

This twiki page contains the PDF versions of the plots in CMS DP-2015/052. Clicking on a small image will open a full-size PNG. Click the pdf version link at the top of each image to access the PDF version (better quality of course.)

Abstract

The endcap muon detector of CMS is composed primarily of Cathode Strip Chambers (CSCs). In run II of LHC, the CMS experiment has collected data from pp collisions at 13 TeV centre-of-mass energy. The CSC system underwent several improvements between runs I and II and this document includes a diagram of the updated detector, and presents measurements of the efficiencies for the CSC system to provide i) trigger primitives for the muon trigger of CMS, and ii) reconstructed muon track segments in each CSC traversed by a muon track.

Contacts

CMS DPG conveners of the CSC group <cms-dpg-conveners-csc@cern.ch>

References

This is the link to CMS DP-2015/052:

The following published CMS papers are useful for understanding the terminology of the CSC system, and the concepts of muon reconstruction, and the Tag & Probe technique:

Figures

Figure Caption
pdf version
cms-dp-2015-052 cms run ii.png

One quadrant of the CMS detector, showing the Muon Detector system in Run 2

A schematic showing the approximate positions of the major detector elements in CMS, after the upgrades of LHC Long Shutdown 1. The major addition to the Muon system was the installation of a fourth ring of CSCs (ME4/2) and two rings of RPCs (RE4/2, RE4/3) in station 4 of both endcaps. There are two independent regions of strips in the ME1/1 CSCs. The inner region is called ME1/1A and the outer ME1/1B. The 48 strips of ME1/1A are read out separately in Run 2. In Run 1, these strips were ganged into 16 channels.

pdf version
cms-dp-2015-052 lct eff.png

Measured efficiency (%) of each CSC in the CMS Endcap Muon detector, to provide a Level-1 Trigger Primitive

The efficiency (in %, with statistical uncertainties only) of each CSC in the CMS Endcap Muon Detector to provide a Trigger Primitive for input to the CMS Level-1 Trigger. A Trigger Primitive in a CSC is a pattern of hits consistent with arising from a muon track crossing the chamber. These efficiencies were obtained using a Tag & Probe technique in which Z → μ μ candidates are selected based on the invariant mass of the combination of a reconstructed global muon (tag) with a reconstructed track (probe). The probe track is projected into the CSC system and a nearby trigger primitive is searched for in each CSC the track traverses. To reduce backgrounds and ensure the probe actually enters the CSC under consideration, compatible hits in a CSC downstream are also required. In rings ME2/1, 3/1, and 4/1 each chamber covers 20° in φ; all other chambers cover 10° in φ.

pdf version
cms-dp-2015-052 seg eff.png

Measured efficiency (%) of each CSC in the CMS Endcap Muon detector, to provide a reconstructed muon track segment

The efficiency (in %, with statistical uncertainties only) of each CSC in the CMS Endcap Muon Detector to provide a reconsgtructed muon track segment. A Segment in a CSC is a straight-line track segment reconstructed from the hits on the 6 layers of a CSC. Segments are used as seeds for the full CMS Muon track reconstruction algorithm, and are the basis of both the High-Level Trigger and Offline muon reconstruction. These efficiencies were obtained using a Tag & Probe technique in which Z → μ μ candidates are selected based on the invariant mass of the combination of a reconstructed global muon (tag) with a reconstructed track (probe). The probe track is projected into the CSC system and a reconstructed segment is searched for in each CSC the track traverses. To reduce backgrounds and ensure the probe actually enters the CSC under consideration, compatible hits in a CSC downstream are also required. In rings ME2/1, 3/1, and 4/1 each chamber covers 20° in φ; all other chambers cover 10° in φ.


Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf cms-dp-2015-052_cms_run_ii.pdf r1 manage 50.6 K 2015-11-03 - 18:41 TimCox  
PNGpng cms-dp-2015-052_cms_run_ii.png r1 manage 403.4 K 2015-11-03 - 18:41 TimCox  
PDFpdf cms-dp-2015-052_lct_eff.pdf r1 manage 142.3 K 2015-11-03 - 18:41 TimCox  
PNGpng cms-dp-2015-052_lct_eff.png r1 manage 806.5 K 2015-11-03 - 18:41 TimCox  
PDFpdf cms-dp-2015-052_seg_eff.pdf r1 manage 202.7 K 2015-11-03 - 18:41 TimCox  
PNGpng cms-dp-2015-052_seg_eff.png r1 manage 733.3 K 2015-11-03 - 18:41 TimCox  
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