An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector

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Title
An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector
Contributors
Verbus, James R (creator)
Gaitskell, Richard (Director)
Dell'Antonio, Ian (Reader)
Narain, Meenakshi (Reader)
Brown University. Physics (sponsor)
Copyright Date
2016
Abstract
We propose a new technique for the calibration of nuclear recoils in large noble element dual-phase time projection chambers (TPCs) used to search for WIMP dark matter in the local galactic halo. This technique provides a measurement of the low-energy nuclear recoil response of the target media using the measured scattering angle between multiple neutron interactions within the detector volume. Several strategies for improving this calibration technique are discussed, including the creation of a new type of quasi-monoenergetic 272 keV neutron source. We report results from a time-of-flight-based measurement of the neutron energy spectrum produced by an Adelphi Technology, Inc. DD108 neutron generator, confirming its suitability for the proposed calibration. The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon TPC operating at the Sanford Underground Research Facility in Lead, South Dakota. Our proposed calibration technique for nuclear recoils in liquid xenon was performed in situ in the LUX detector using a collimated beam of mono-energetic 2.45 MeV neutrons produced by the DD108 fusion source. The nuclear recoil energy from the first neutron scatter in the TPC was reconstructed using the measured scattering angle defined by two-site neutron events within the active xenon volume. We measured the absolute charge (Qy) and light (Ly) yields at an average electric field of 180 V/cm for nuclear recoil energies spanning 0.7 to 74 keV and 1.1 to 74 keV, respectively. This calibration of the nuclear recoil signal yields will permit the further refinement of liquid xenon nuclear recoil signal models and clearly demonstrates measurable ionization and scintillation signals in this medium at recoil energies down to O(1 keV). The low-energy reach and reduced systematics of this calibration have particular significance for the low-mass WIMP sensitivity of several leading dark matter experiments.
Keywords
LUX
liquid xenon
nuclear recoil
light yield
charge yield
neutron generator
dark matter
WIMP
Dark matter (Astronomy)
Notes
Thesis (Ph.D. -- Brown University (2016)
Extent
xxiii, 263 p.

Citation

Verbus, James R., "An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector" (2016). Physics Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:674209/

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