A Study of the Detection of Long-Lived Charged Particles With an Auxiliary Detector Above the ATLAS Muon Spectrometer (ADAM)

• Author / Creator

  Kelly, Joseph M

• The Auxiliary Detector above the ATLAS Muon spectrometer (ADAM) is a proposed particle detector. Its function is to detect the decay products of beyond the standard model (BSM) particles produced in the 14 TeV proton-proton collisions at the Large Hadron Collider (LHC) which evade detection by the ATLAS (A Toroidal LHC ApparatuS) experiment.
  Long-lived particles (LLPs) are a feature of many BSM theories. One such model is supersymmetry (SUSY), a theoretical framework that predicts for each boson and fermion in the Standard Model (SM), there may exist a “superpartner” fermion or boson, respectively. In particular, when this model is extended to also include the theoretical graviton particle, which defines “minimal supergravity” (mSUGRA), there is the possibility of a supersymmetric tau lepton, or “stau” with lifetimes of up to a year.
  ADAM is a low-cost addition to the existing ATLAS detector to extend its physics reach. This thesis provides a comprehensive simulation of the production, transport and detection of exceptionally long-lived stau particles, that come to rest in the ATLAS detector before decaying, the subsequent decays of these particles can be monitored in a background-free way during planned and unplanned Technical Stops. The ADAM detector is deployed above the ATLAS detector, effectively turning the upper region of the cavern into a 13,000 cubic meter fiducial volume for detecting the decays of LLPs. While a particular model and parameter set is used in this work, the resultant heavy charged particle featured in the model is not unique amongst BSM theories, therefore the results may extrapolate to other models. Under the specific scenario of mSUGRA physics at the LHC during run 4, and based on the cross-section of the proton-proton → stau-(anti)stau process in the mSUGRA model, the expected integrated luminosity of 715 inverse femtobarns over the course of run 4, and the operational schedule of the LHC, our
  experiment showed up to 132.3 ± 0.9 events recorded by the ADAM detector, and at least three events for stau masses under 148 GeV for all lifetimes, or up to 222 GeV for one year lifetimes.

• Subjects / Keywords

  • ATLAS
  • Supersymmetry
  • Supergravity
  • MSSM
  • MSUGRA
  • LHC
  • Long lived charged particles
  • Beyond Standard Model
  • Large Hadron Collider

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-wf4e-2g32

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.