Thesis
Simulation based study of neutron backgrounds at Fermilab MINOS tunnel and SNOLAB for SBC dark matter search
Master of Science (M.S.), Drexel University
Jun 2024
DOI:
https://doi.org/10.17918/00010700
Abstract
A simulation-based study of neutron backgrounds at the Fermilab MINOS Tunnel and SNOLAB locations is presented in support of the Scintillating Bubble Chamber (SBC) dark matter search effort. Two principal sources of background neutrons were investigated- neutrons from decay chains of radioactive elements in surrounding rock as well as cosmogenic muon-induced neutrons. The resulting bubble rates for rock neutrons were found to be 1.11 ± 0.07 total events per hour (including single and multiple bubble events) and 0.74 ± 0.06 single bubbles per hour based on measured SNOLAB neutron rates. For muon-induced neutrons, the MINOS tunnel is found to have 0.96 - 1.62 total events per hour and 0.59 - 0.89 single bubbles per hour. The bubble rates from muon-induced neutrons at SNOLAB are significantly lower given its greater depth. For SNOLAB, the muon induced neutrons create only 0.48 - 0.69 total events in a year and 0.27 - 0.41 single bubbles per year. In addition to bubble rates, a background scintillation veto study was conducted in the form of energy deposits as well as scintillation detection efficiency in both liquid argon (LAr) and liquid carbon tetrafluoride (LCF₄). The average energy of rock neutron single bubble events in both volumes is just under 1 MeV, with a majority of events depositing over 10 keV. Muon-induced neutron events are significantly more energetic, higher by factors of approximately 45 and 160 times in LAr and LCF₄, respectively. Preliminary results for photon collection yields provide initial values for LCF₄ and validate SBC expectations for LAr. With a detection threshold of approximately 10 keV, LAr scintillation will be useful for a neutron background veto.
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Details
- Title
- Simulation based study of neutron backgrounds at Fermilab MINOS tunnel and SNOLAB for SBC dark matter search
- Creators
- Daniel Pyda
- Contributors
- Russell G. Neilson (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- vi, 24 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 991021890313504721