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Search for New Physics with the Compact Muon Solenoid Experiment and QIS-enabled Technology


Wang, Christina Wenlu (2024) Search for New Physics with the Compact Muon Solenoid Experiment and QIS-enabled Technology. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ta74-mz22.


Understanding the fundamental nature of dark matter (DM) — its cosmological origin, constituents, and interactions — is one of the most important questions in fundamental science today. In this thesis, I present two novel and highly complementary approaches to cover the gaps in sensitivity of current DM searches. The searches are enabled by a first-of-its-kind reconstruction technique to search for hidden-sector particles using the Compact Muon Solenoid (CMS) and by new advances in quantum sensing technology to search for axions and hidden-sector DM.

In the first part of this thesis, I present a search for long-lived hidden sector particles, predicted by many extensions of the SM, using a novel technique to reconstruct decays of long-lived particles (LLPs) in the CMS muon detector. The innovative LLP reconstruction technique is sensitive to a broad range of LLP decays and to LLP masses below GeV. The search yields competitive sensitivity for proper lifetime 0.1 - 1000 m with the full Run 2 dataset recorded at the LHC between 2016 - 2018 at √s = 13 TeV. To extend the physics reach of this novel muon detector shower (MDS) signature, I present the model-independence of MDS and the reinterpretation of the search to a large number of LLP models, demonstrating its complementarity with proposed and existing dedicated LLP experiments. Finally, I present a new dedicated MDS trigger that improves the trigger efficiency by at least an order of magnitude and was deployed in 2022, at the start of Run 3 of the LHC operations.

In the second part of the thesis, I present for the first time, the use of a novel quantum sensor, the low-noise and single-photon sensitive superconducting nanowire single photon detectors (SNSPDs), to directly detect dark matter. The low detection threshold and ultra-low dark count rate of SNSPDs can close the gap in DM discovery reach due to the current limitations in detector sensitivity. I will present my work on the development and characterization of SNSPDs for two entirely new experiments to directly detect axions via absorption and hidden-sector DM via electron scattering. The search for axions employs a novel broadband reflector technique with the Broadband Reflector Experiment for Axion Detection (BREAD). A unique parabolic mirror is then used to focus axion-converted photons to the SNSPDs, extending the reach to axion masses of 0.04 - 1 eV. On the other hand, by coupling the SNSPDs with gallium arsenide, a bright cryogenic scintillator well matched to SNSPD detection, a prototype sensing system can be built as a basis of new direct DM detection experiments capable of extending the discovery to DM masses as low as 1 MeV.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:particle physics, LHC, CMS, long-lived particles, muon detectors, higgs portal, inelastic dark matter, hidden valley, axion-like particles, dark photon, heavy neutral leptons, quantum sensors, SNSPDs, GaAs, BREAD, axion, dark photon, dark matter barium fluoride, LYSO:Ce, proton, radiation damage, color center, scintillators Photonics, Field programmable gate arrays, Quantum networks, Radio frequency, Quantum entanglement
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Spiropulu, Maria
Thesis Committee:
  • Golwala, Sunil (chair)
  • Filippone, Bradley W.
  • Papucci, Michele
  • Cheung, Clifford W.
  • Spiropulu, Maria
Defense Date:6 March 2024
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0011925
Office of Science (DOE). Science Graduate Student Research (SCGSR) AwardDE‐SC0014664
Record Number:CaltechTHESIS:03072024-065323362
Persistent URL:
Related URLs:
URLURL TypeDescription article adapted for Chapter 5 adapted for Chapter 5 article adapted for Chapter 6 article adapted for Chapter 6 article adapted for Appendix B
Wang, Christina Wenlu0000-0002-0117-7196
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16320
Deposited By: Christina Wang
Deposited On:25 Mar 2024 18:36
Last Modified:01 Apr 2024 16:40

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