MDTOfflineMonitoringPlotsRun2JR



Introduction

  • MDT Tube:
    MDTtube.jpg

A charged particle traversing the gas-filled drift tube ionizes the gas. The electrons drift toward the central wire (held at a positive potential) and an avalanche develops where the electric field is high, very close to the wire. The signal induced on the wire is mainly due to the positive ions moving away from the wire. The leading edge of the signal is related to the distance of the particle track from the wire.

The drift time is recorded by a Time-to-Digital Converter (TDC) and the size of the electrical pulse induced on the wire. is recorded by an Analog-to-Digital Converter (ADC). Particles crossing the tube close to the wire (short drift time) contribute a large ADC value. The ADC values are not linear with charge; the values saturate.


  • Time Disribution:
    timedist2.jpg

A typical drift time distribution (TDC values) for a parallel beam of incident charged particles.

The maximum drift time in the 1.5 cm radius tube is about 730 ns.


  • Drift:
    diehldrift.jpg

The relationship between the drift distance in the MDT tube and the measured drift time.


  • Multilayers:
    mdtlayers.jpg

MDT chambers are constructed with two multilayers of MDT tubes. Each multilayer consists of either three or four layers of drift tubes.

A few chambers in special locations have fewer multilayers and layers and in some cases hold smaller diameter tubes


Cross-sectional view in the r-z projection. Barrel MDT chambers are green; Endcap MDT chambers are blue.

Eta region numbers are indicated on the chambers. There are 16 phi sectors in both barrel and endcap.


Barrel Muon chambers. View is perpendicular to the beam axis.

MDT chambers are blue (small sectors; even sector numbers) and orange (large sectors, odd sector numbers).

Examples of the MDT chamber naming convention:

    EML2A07.   Endcap Middle station, Large chamber. Side A, Eta region 2, phi sector 7

    BOS5C16   Barrel Outer station, Small chamber, Side C, Eta region 5, phi sector 16


MDT BIL barrel chambers with two four-layer multilayers. (Most MDT chambers have three-layer multilayers)

The drift time circles in each tube are shown as well as the reconstructed track..

A track segment is a part of a track with at least three hits.

Run 2 Muon data quality monitoring Twiki.

.

Relevant Links

MDT Shifter Histograms

Global

ADC Spectra

        ON Segment

Description of variable: ADC values for MDT hits that are required or not required to be on a segment

Recall that ADC values are not linear with collected charge.

Expected features: The main noise peak should be below 50. A second peak may be below 80. MuonSegment applies noise cut of 80.


TDC Spectra

        ON Segment

Description of variable: TDC value for MDT hits that are required or not required to be on a segment. An ADC cut is applied.

Expected features: The shape of the on-segment spectrum should be similar to what is shown, with a fast rise at t0 and a fast drop at tmax.

Expect a t0 around 80 ns and a tmax around 810 ns. The drift time is approximately 730 ns.


Total Hits

|

        NO ADC Cut

Description of variable: Number of MDT hits per event without and with ADC cut.

Expected features: The mean will depend on beam conditions.


Regional (BA, BC, EA, EC)

ADC and TDC distribution histograms are included per region.

Number of Hits

Description of variable: Total number of MDT hits for each multilayer. Hits have an ADC cut of 80.

Expected features: Look for chambers that are significantly higher or lower than their neighbors.


Drift Time

Drift Time by sector. The expected drift time is approximately 730 ns.


Occupancy Vs LB

Description of variable: Chamber occupancy shown as a function of Lumi Block (LB) as the run progresses.

Each horizontal bin is 3 Lumi Blocks. A Lumi Block duration is 1 minute.

The occupancy is organized by region and separated by layer. Outer and Extra are put in the same histogram.

Expected features: There will be a gradual decrease in occupancy during a run as the luminosity decreases.

Look for abrupt changes in occupancy during a run.


Efficiency

Description of variable: Efficiency is defined as the number of hits obtained on a segment divided by the number of tubes expected to be traversed by the segment.

Expected features: Efficiencies should generally be in the ~0.6-1.0 range across the region.

Low efficiency rates in one of the multilayers; note this in whiteboard entry.

Single white areas may be indicative of dropped chambers, but widespread blocks can simply mean low statistics (no need to note this in most cases):

Ex pert Contact List

* For questions about the MDT offline monitoring code, contact Heather Russell: heather.russell@cernNOSPAMPLEASE.ch


Major updates:
-- JuliaLynneGonski - 2015-07-27


Responsible: JuliaLynneGonski
Last reviewed by: Never reviewed


Topic attachments
I Attachment History Action Size Date Who Comment
JPEGjpg MDTtube.jpg r1 manage 46.0 K 2015-09-22 - 07:31 JosephRothberg MDT Tube
JPEGjpg diehldrift.jpg r1 manage 49.3 K 2015-09-22 - 13:18 JosephRothberg Drift
JPEGjpg mdtlayers.jpg r1 manage 105.8 K 2015-09-22 - 08:36 JosephRothberg Multilayers
JPEGjpg timedist.jpg r1 manage 33.4 K 2015-09-21 - 18:04 JosephRothberg Time Distribution
JPEGjpg timedist2.jpg r1 manage 60.9 K 2015-09-21 - 18:15 JosephRothberg Time Disribution
Edit | Attach | Watch | Print version | History: r24 < r23 < r22 < r21 < r20 | Backlinks | Raw View | Raw edit | More topic actions...
Topic revision: r22 - 2015-09-22 - JosephRothberg
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    Atlas All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2021 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
or Ideas, requests, problems regarding TWiki? use Discourse or Send feedback