Non collision background for ATLAS detector

The main task of the group is characterisation and migitation of non-collision background in ATLAS analyses.

Main sources of NBC:


  • Machine induced background
  • Cosmic-ray background
  • Instrumental background
My work is centered about machine induced background. There are many types of this background but the main sources around the ATLAS detector are the beam-gas scattering (elastic and inelastic) and beam halo. Simple diagram showing the creation of these backgrounds is shown in the figure below.

imgedeb8b152e9c531f09031b2a5c261ff9.png

Here is an animation of the creation of beam gas background - beam bunch interacting with a residual molecule in the beam pipe and creating background particles.

beamgasgif.gif

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The lattice geometry in the vicinty of the ATLAS detector is shown below.

img5226e298b827055aa9c558be73e762de.png

Simulation of both background sources are done using the FLUKA software and some existing data sets are located at:

http://bbgen.web.cern.ch/bbgen/

LHC Run 2

The LHC went on upgrade after Run 1 between 2010 and 2013. The operation was restarted in early 2015 for its second research run, reaching 6.5 TeV per beam (13 TeV total center of mass at collision point, the present world record).

An example of a beam background event inside the ATLAS detector is shown below.

imge60e02348045e3f277cdc0704bfbdc5d.png

HL-LHC

The HL-LHC plans to increase luminosity of the LHC around 2025. It will use the newest technology including cutting-edge 11-12 Tesla superconducting magnets, compact superconducting crab cavities, new technology for beam collimation and other improvements. The ATLAS detector will have to be upgraded as well to handle the larger collision rate. Most subdetectors will be upgraded in some way and also a new subdetector, the High Granularity Timing Detector (HGTD) will be installed in the gap between LAr calorimeters.

My work looks at the possibility of using the HGTD for identifying beam background using the detector's superb timing resolution. A schematic image of what we can expect to arrive to the detector including collision events and background is shown below.

img56087429bc09dbe7f3d7ac2d1fad91b3.png

Physics WebpagesRHUL WebpagesCampus Connect • Royal Holloway, University of London, Egham, Surrey TW20 0EX; Tel/Fax +44 (0)1784 434455/437520

Topic revision: r4 - 18 Apr 2018 - HelenaPikhartova

 
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