+publisher:"Brown University" +contributor:("Gaitskell, Richard")

1. Faham, Carlos H. Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment.

Degree: PhD, Physics, 2014, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:386139/

► The existence of non-baryonic cold dark matter is well established through a wealth of complementary observations such as the Cosmic Microwave Background, Supernova Type Ia… (more)

▼ The existence of non-baryonic cold dark matter is well established through a wealth of complementary observations such as the Cosmic Microwave Background, Supernova Type Ia and Big Bang Nucleosynthesis. Despite the overwhelming cosmological evidence, the particle nature of dark matter remains unknown. The leading candidate is a Weakly Interacting Massive Particle (WIMP), a thermal relic from the Big Bang that only interacts through the gravitational and weak forces. A terrestrial detector with high target mass, low background levels and a low energy threshold (keV) should be able to record the rare, faint interactions between ordinary matter and galactic WIMP dark matter. The Large Underground Xenon (LUX) experiment is a 370 kg liquid xenon time projection chamber that aims to detect WIMP recoils with xenon nuclei. The experiment is located a mile underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota. LUX is poised to become the world's most sensitive dark matter detector after only 2 weeks of exposure and will surpass current detection limits by an order of magnitude after 300 days. The LUX experimental program consists of three phases: (1) the LUX0.1 prototype detector during 2007– 2009, (2) the commissioning and operation of the LUX detector at the Sanford surface laboratory during 2009–2012 and (3) the underground deployment and operation of the detector beginning in 2012. This thesis describes the first two phases of the LUX program. LUX utilizes 122 Hamamatsu R8778 photomultiplier tubes (PMTs) to detect photons produced by particle interactions in liquid xenon. The LUX PMT mounting, high voltage distribution, analog signal shaping and gain calibration system are described in detail. The PMTs are shown to have low radioactive background levels, single-photon sensitivity and a 30% photon detection efficiency at the 175 nm liquid xenon scintillation wavelength. Handling protocols and vacuum integrity control based on ion-initiated afterpulses are presented. Xenon purification and energy calibration results are described for LUX0.1. During the LUX surface run, light collection and statistical position resolution measurements were obtained. Additionally, the xenon circulation path was imaged with alpha particles from a Rn222 injection. Advisors/Committee Members: Gaitskell, Richard (Director), Dell'Antonio, Ian (Reader), Landsberg, Greg (Reader).

Subjects/Keywords: LUX

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APA (6^th Edition):

Faham, C. H. (2014). Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:386139/

Chicago Manual of Style (16^th Edition):

Faham, Carlos H. “Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment.” 2014. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:386139/.

MLA Handbook (7^th Edition):

Faham, Carlos H. “Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment.” 2014. Web. 07 Mar 2021.

Vancouver:

Faham CH. Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment. [Internet] [Doctoral dissertation]. Brown University; 2014. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:386139/.

Council of Science Editors:

Faham CH. Prototype, Surface Commissioning and Photomultiplier Tube Characterization for the Large Underground Xenon (LUX) Direct Dark Matter Search Experiment. [Doctoral Dissertation]. Brown University; 2014. Available from: https://repository.library.brown.edu/studio/item/bdr:386139/

2. 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.

Degree: PhD, Physics, 2016, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:674209/

► 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… (more)

▼ 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. Advisors/Committee Members: Gaitskell, Richard (Director), Dell'Antonio, Ian (Reader), Narain, Meenakshi (Reader).

Subjects/Keywords: LUX

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APA (6^th Edition):

Verbus, J. R. (2016). An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:674209/

Chicago Manual of Style (16^th Edition):

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. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:674209/.

MLA Handbook (7^th Edition):

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. Web. 07 Mar 2021.

Vancouver:

Verbus JR. An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector. [Internet] [Doctoral dissertation]. Brown University; 2016. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:674209/.

Council of Science Editors:

Verbus JR. An Absolute Calibration of Sub-1 keV Nuclear Recoils in Liquid Xenon Using D-D Neutron Scattering Kinematics in the LUX Detector. [Doctoral Dissertation]. Brown University; 2016. Available from: https://repository.library.brown.edu/studio/item/bdr:674209/

3. Chapman, Jeremy J. First WIMP Search Results from the LUX Dark Matter Experiment.

Degree: PhD, Physics, 2014, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:386289/

► A wealth of astrophysical evidence confirms that 26% of the energy density of the universe is comprised of a mysterious, non-baryonic, dark matter. A leading… (more)

▼ A wealth of astrophysical evidence confirms that 26% of the energy density of the universe is comprised of a mysterious, non-baryonic, dark matter. A leading candidate for dark matter is the Weakly Interacting Massive Particle (WIMP) that is suggested both by the relic abundance of dark matter, and extensions to the standard model of particle physics. WIMPs interact with baryonic matter only through gravity and the weak nuclear force. The Large Underground Xenon (LUX) dark matter experiment aims to detect WIMPs through this weak interaction. LUX is a 370 kg two-phase (liquid/gas) xenon time projection chamber designed to detect nuclear recoils from interactions with WIMPs. Particle interactions in LUX are observed by 122 photomultiplier tubes (PMTs). Signals from these PMTs are processed by custom-built analog electronics. The data acquisition system (DAQ) is composed of commercial digitizers with firmware customized for the LUX experiment. The LUX DAQ is optimized to provide a high rate and a large dynamic range during precision calibrations involving radioactive sources, while also delivering a low threshold for maximum sensitivity. The LUX detector is housed in a 300 tonne water tank on the 4850 ft level of the Sanford Underground Research Facility, in Lead, SD. The first WIMP search results are based on 85.3 live-days of data-taking. This non-blind analysis yields 160 events in the WIMP search energy range in a 118kg fiducial volume. A profile likelihood analysis of this data supports the background-only hypothesis, producing the highest constraint on the WIMP-nucleon interaction cross-section to date. The minimum 90% C.L. upper limit is 7.6x10^-46 cm2 for a WIMP mass of 33 GeV/c2. In particular this run has strongly ruled out hints of signal in the low-mass regime between 6 and 20 GeV/c2 recently suggested by several direct detection experiments. LUX will continue to undergo engineering and calibrations runs to improve detector sensitivity. The subsequent 300 live-day blinded WIMP search will extend the WIMP limit of LUX by a factor of x5 above a mass of 20 GeV/c2. Advisors/Committee Members: Gaitskell, Richard (Director), Narain, Meenakshi (Reader), Tucker, Greg (Reader).

Subjects/Keywords: dark matter

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APA (6^th Edition):

Chapman, J. J. (2014). First WIMP Search Results from the LUX Dark Matter Experiment. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:386289/

Chicago Manual of Style (16^th Edition):

Chapman, Jeremy J. “First WIMP Search Results from the LUX Dark Matter Experiment.” 2014. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:386289/.

MLA Handbook (7^th Edition):

Chapman, Jeremy J. “First WIMP Search Results from the LUX Dark Matter Experiment.” 2014. Web. 07 Mar 2021.

Vancouver:

Chapman JJ. First WIMP Search Results from the LUX Dark Matter Experiment. [Internet] [Doctoral dissertation]. Brown University; 2014. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:386289/.

Council of Science Editors:

Chapman JJ. First WIMP Search Results from the LUX Dark Matter Experiment. [Doctoral Dissertation]. Brown University; 2014. Available from: https://repository.library.brown.edu/studio/item/bdr:386289/

4. Geringer-Sameth, Alex. Comprehensive Approaches and Results in the Indirect Dark Matter Search.

Degree: PhD, Physics, 2013, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:320646/

► Dark matter is an essential ingredient in our modern understanding of the Universe. However, its fundamental role in cosmology is matched only by its conspicuous… (more)

Subjects/Keywords: dark matter

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APA (6^th Edition):

Geringer-Sameth, A. (2013). Comprehensive Approaches and Results in the Indirect Dark Matter Search. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320646/

Chicago Manual of Style (16^th Edition):

Geringer-Sameth, Alex. “Comprehensive Approaches and Results in the Indirect Dark Matter Search.” 2013. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:320646/.

MLA Handbook (7^th Edition):

Geringer-Sameth, Alex. “Comprehensive Approaches and Results in the Indirect Dark Matter Search.” 2013. Web. 07 Mar 2021.

Vancouver:

Geringer-Sameth A. Comprehensive Approaches and Results in the Indirect Dark Matter Search. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:320646/.

Council of Science Editors:

Geringer-Sameth A. Comprehensive Approaches and Results in the Indirect Dark Matter Search. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320646/

5. Huwe, Paul M. Dark Matter Substructure in High Redshift Clusters of Galaxies.

Degree: PhD, Physics, 2013, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:320536/

► For my graduate research, I have focused on the creation of high resolution weak lensing mass maps in order to study dark matter substructure in… (more)

Subjects/Keywords: dark matter

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APA (6^th Edition):

Huwe, P. M. (2013). Dark Matter Substructure in High Redshift Clusters of Galaxies. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320536/

Chicago Manual of Style (16^th Edition):

Huwe, Paul M. “Dark Matter Substructure in High Redshift Clusters of Galaxies.” 2013. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:320536/.

MLA Handbook (7^th Edition):

Huwe, Paul M. “Dark Matter Substructure in High Redshift Clusters of Galaxies.” 2013. Web. 07 Mar 2021.

Vancouver:

Huwe PM. Dark Matter Substructure in High Redshift Clusters of Galaxies. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:320536/.

Council of Science Editors:

Huwe PM. Dark Matter Substructure in High Redshift Clusters of Galaxies. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320536/

6. McCleary, Jacqueline Elizabeth. Dark Matter Substructure in Very Low Redshift Galaxy Clusters.

Degree: Department of Physics, 2017, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:792597/

► This work sets forth the methods and first results of our study of ∼ 1E14 M⊙ mass substructures in very low redshift (z < 0.12)… (more)

Subjects/Keywords: Physics; Astrophysics; Galaxy Clusters; Cosmology

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APA (6^th Edition):

McCleary, J. E. (2017). Dark Matter Substructure in Very Low Redshift Galaxy Clusters. (Thesis). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:792597/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

McCleary, Jacqueline Elizabeth. “Dark Matter Substructure in Very Low Redshift Galaxy Clusters.” 2017. Thesis, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:792597/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

McCleary, Jacqueline Elizabeth. “Dark Matter Substructure in Very Low Redshift Galaxy Clusters.” 2017. Web. 07 Mar 2021.

Vancouver:

McCleary JE. Dark Matter Substructure in Very Low Redshift Galaxy Clusters. [Internet] [Thesis]. Brown University; 2017. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:792597/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

McCleary JE. Dark Matter Substructure in Very Low Redshift Galaxy Clusters. [Thesis]. Brown University; 2017. Available from: https://repository.library.brown.edu/studio/item/bdr:792597/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

7. de Viveiros Souza Filho, Luiz Angelo. Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments.

Degree: PhD, Physics, 2009, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:241/

► A wealth of evidence indicates that ~23% of the universe is composed of dark matter. For the past two decades, several experiments have attempted to… (more)

▼ A wealth of evidence indicates that ~23% of the universe is composed of dark matter. For the past two decades, several experiments have attempted to detect dark matter directly or indirectly. Nevertheless, its nature remains one of the most elusive problems in fundamental physics today. XENON10 is a direct detection experiment, using a liquid Xe Time Projection Chamber (TPC) to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Particle interactions in the 15 kg liquid Xe target generate scintillation (S1) and ionization (S2) signals. WIMP (and neutron) interactions produce nuclear recoils. The dominant backgrounds (gamma rays and beta particles) produce electron recoils. The S2/S1 ratio is larger for electron recoils than for nuclear recoils, allowing for the rejection of electron recoil backgrounds with ~99.6% efficiency. XENON10 operated underground at the Laboratori Nazionali Gran Sasso in Italy during 2006-2007. Analysis of its WIMP Search run of 58.6 live-days and 5.4 kg fiducial mass resulted at the time in the most sensitive limits on the Spin-Independent WIMP-nucleon cross-section, setting an upper limit of 8.8x10^-44 cm² for a WIMP mass of 100 GeV/c² (90% C.L.). The large scale experiment LUX (300 kg) is designed to improve the sensitivity to WIMP interactions by two orders of magnitude, and will be deployed in the Sanford Laboratory at the Homestake Mine in 2009-2010. Next-generation Xe TPC detectors with masses in the order of 1-10 tonnes are already in the design stage, with planned deployment in the next ten years. In dark matter search experiments, backgrounds are the biggest factor limiting sensitivity. This work presents a discussion of the use of liquid Xe detectors in dark matter experiments; details the construction of background models through the use of Monte Carlo simulations; identifies and characterizes the major sources of background; explores how shielding and detector design affect the background event rate; and explains the techniques used to reduce the effect of backgrounds on the detector sensitivity. Advisors/Committee Members: Gaitskell, Richard (director), Dell'Antonio, Ian (reader), Landsberg, Greg (reader).

Subjects/Keywords: Dark Matter

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APA (6^th Edition):

de Viveiros Souza Filho, L. A. (2009). Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:241/

Chicago Manual of Style (16^th Edition):

de Viveiros Souza Filho, Luiz Angelo. “Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments.” 2009. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:241/.

MLA Handbook (7^th Edition):

de Viveiros Souza Filho, Luiz Angelo. “Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments.” 2009. Web. 07 Mar 2021.

Vancouver:

de Viveiros Souza Filho LA. Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments. [Internet] [Doctoral dissertation]. Brown University; 2009. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:241/.

Council of Science Editors:

de Viveiros Souza Filho LA. Optimization of Signal versus Background in Liquid Xe Detectors Used for Dark Matter Direct Detection Experiments. [Doctoral Dissertation]. Brown University; 2009. Available from: https://repository.library.brown.edu/studio/item/bdr:241/

8. Malling, David Charles. Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment.

Degree: PhD, Physics, 2014, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:386168/

► The dominant component of matter in the universe, referred to as dark matter, cannot be explained by the standard model of particle physics. A leading… (more)

▼ The dominant component of matter in the universe, referred to as dark matter, cannot be explained by the standard model of particle physics. A leading candidate for dark matter is the weakly interacting massive particle (WIMP). The WIMP theory is well motivated by several extensions of the standard model, and has been tested directly in the laboratory over the last 30 years. The Large Underground Xenon (LUX) experiment seeks to identify the signatures of WIMP interactions with baryonic matter. LUX measures particle interactions at the keV level by the detection of single-photon signals in a 250 kg Xe target mass. The LUX detector inner fiducial region is the lowest measured background particle detector in the world at keV energies, with background rates at the level of 1E-3 counts/keV/kg/day. Low background rates are essential for identifying WIMP interactions in the detector, which occur with frequencies <1/kg/(5 years). LUX completed its first low-background science run at the Sanford Underground Research Facility in August 2013. WIMP search results are reported from an 85 live day analysis. The experiment places the tightest constraint on WIMP spin-independent interaction cross-sections to date. Results from LUX also exclude several potential dark matter signal claims from other direct detection experiments, for WIMP masses in the range 6-15 GeV. The LUX result is the product of low detector background rates and high photon signal collection efficiency. Analysis of the first WIMP search data has provided direct characterization of low-energy backgrounds in LUX. Measured background rates were found to be in agreement with expectations based on models of detector material radioactivity. The data also provides the first measurements of intrinsic radioactive contaminants in the detector, including short-lived cosmogenic Xe radioisotopes. I will describe the LUX background model, detailing work which was used in the design and early performance projections of the LUX detector, as well as background measurements which constrain and support the model. Advisors/Committee Members: Gaitskell, Richard (Director), Savvas, Koushiappas (Reader), Cutts, David (Reader).

Subjects/Keywords: Dark matter

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APA (6^th Edition):

Malling, D. C. (2014). Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:386168/

Chicago Manual of Style (16^th Edition):

Malling, David Charles. “Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment.” 2014. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:386168/.

MLA Handbook (7^th Edition):

Malling, David Charles. “Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment.” 2014. Web. 07 Mar 2021.

Vancouver:

Malling DC. Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment. [Internet] [Doctoral dissertation]. Brown University; 2014. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:386168/.

Council of Science Editors:

Malling DC. Measurement and Analysis of WIMP Detection Backgrounds, and Characteri- zation and Performance of the Large Underground Xenon Dark Matter Search Experiment. [Doctoral Dissertation]. Brown University; 2014. Available from: https://repository.library.brown.edu/studio/item/bdr:386168/

9. Michney, Ryan J. Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields.

Degree: PhD, Physics, 2014, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:419354/

► In recent years, weak gravitational lensing has become an indispensable method for understanding the concentration of matter on the largest scales. Galaxy clusters, the largest… (more)

▼ In recent years, weak gravitational lensing has become an indispensable method for understanding the concentration of matter on the largest scales. Galaxy clusters, the largest virialized structures in the universe, provide a crucial environment in which to examine cosmological evolution. Because most matter is non-luminous, weak lensing provides an opportunity for direct measurement of large scale mass clustering, independent of considerations involving cluster dynamics. This study takes advantage of the large amount of deep and high quality optical imaging freely available from the Subaru Telescope data archive to perform a semi-blind cluster search across an extraordinarily large field of view, 10.34 deg2 of the sky, at high source density (utilizing 1.27 × 106 galaxies). Our precise 2D mass reconstruction, spanning five low-extinction Milky Way windows, detects 90 unique cluster candidates above S/N≥3. Of these, 67 possess S/N≥4, and 18 possess S/N≥5. From the fields analyzed, 43 independently confirm prior detections, 6 of these match (but with offsets in the location of the cluster barycenter), and the remaining 47 represent potential new cluster discoveries. Previous cluster candidates in these regions were uncovered through non-WL techniques, therefore, our analysis represents a significant contrast against other wide-field cluster search methods, and is one of the largest lensing surveys completed to date. Convergence reconstructions also detect SZ & X-ray cluster candidate PLCKG100.2-30.4 in multiple independent waveband data, but fails to measure the more observationally difficult PLCKG18.7+23.6. We estimate the mass of the former, as well as that of clusters Abell 383, Abell 1672, and RXCJ1651.1+0459. The scale of this project necessitated the invention of numerous automated data reduction algorithms and a comprehensive pipeline optimizing the shape information and object detections of deep-field galaxies in available imaging. Most notably, a novel flux-independent identification system for stars was created in order to find ideal stellar objects necessary for accurate PSF circularization. Our techniques allow us to stack and circularize Subaru images to better than <0.5% mean ellipticity without introducing spurious effects. Advisors/Committee Members: Dell'Antonio, Ian (Director), Dell'Antonio, Ian (Reader), Gaitskell, Richard (Reader), Tucker, Gregory (Reader).

Subjects/Keywords: Observational Astronomy

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APA (6^th Edition):

Michney, R. J. (2014). Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:419354/

Chicago Manual of Style (16^th Edition):

Michney, Ryan J. “Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields.” 2014. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:419354/.

MLA Handbook (7^th Edition):

Michney, Ryan J. “Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields.” 2014. Web. 07 Mar 2021.

Vancouver:

Michney RJ. Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields. [Internet] [Doctoral dissertation]. Brown University; 2014. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:419354/.

Council of Science Editors:

Michney RJ. Quality-Selected Lensing Analysis of Galaxy Clusters in Subaru Telescope Fields. [Doctoral Dissertation]. Brown University; 2014. Available from: https://repository.library.brown.edu/studio/item/bdr:419354/

10. Cook, Richard Ian. Measuring Weak Lensing Sensitivity and Systematics.

Degree: PhD, Physics, 2012, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:297715/

► The Universe is expanding at an ever increasing rate. The mysterious source of this acceleration has been dubbed "dark energy" and constitutes 70% of the… (more)

▼ The Universe is expanding at an ever increasing rate. The mysterious source of this acceleration has been dubbed "dark energy" and constitutes 70% of the energy-density of the Universe. To understand the nature of this force we must measure the expansion of the universe and the growth of structure with significant precision. Clusters of galaxies are the most massive gravitationally-collapsed structures in the universe and offer an ideal probe of the growth and evolution of structure. Numerous methods for detecting and measuring cluster masses exist including X-ray flux, spectroscopic redshift, and weak gravitational lensing measurements. Weak lensing is the coherent distortion of galaxy images by intervening mass and is used as an unbiased indicator of the mass of galaxy clusters. The accuracy of each of these methods for measuring clusters masses will depend in part on the accuracy of weak lensing measurements, which will be used both as a mass calibration technique and a detection technique. It is therefore critical that we understand the factors affecting weak lensing sensitivity and the correspondence to other mass measurement techniques. Orthogonal Transfer (OT) Imagers offer significant advantages for weak lensing measurements. By correcting atmospheric distortions using real-time guide-star position information and shifting charge across the CCD they can increase the number of detected galaxies and increase the signal-to-noise of weak lensing detections. One outstanding question has been whether the charge-shifting correction induces unwanted systematic effects in weak lensing measurements. I study the systematic effects from OT guiding using stellar observations and show that the magnitude of the improvement to image quality far exceed the magnitude of any possible systematic effects. I demonstrate the utility of OT imagers for weak lensing by detecting the cluster Abell 781A using the Orthogonal Parallel Transfer Imaging Camera. I use this data to measure the sensitivity of weak lensing detections and the significant discrepancy between mass estimates of Abell 781D. Finally, I show that OT imagers can also be used to probe atmospheric conditions during observations, informing our choice of observing strategy and further illustrating the facility of OT guiding. Advisors/Committee Members: Dell'Antonio, Ian (Director), Gaitskell, Richard (Reader), Koushiappas, Savvas (Reader), Dell'Antonio, Ian (Reader).

Subjects/Keywords: Weak Lensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cook, R. I. (2012). Measuring Weak Lensing Sensitivity and Systematics. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:297715/

Chicago Manual of Style (16^th Edition):

Cook, Richard Ian. “Measuring Weak Lensing Sensitivity and Systematics.” 2012. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:297715/.

MLA Handbook (7^th Edition):

Cook, Richard Ian. “Measuring Weak Lensing Sensitivity and Systematics.” 2012. Web. 07 Mar 2021.

Vancouver:

Cook RI. Measuring Weak Lensing Sensitivity and Systematics. [Internet] [Doctoral dissertation]. Brown University; 2012. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:297715/.

Council of Science Editors:

Cook RI. Measuring Weak Lensing Sensitivity and Systematics. [Doctoral Dissertation]. Brown University; 2012. Available from: https://repository.library.brown.edu/studio/item/bdr:297715/

11. Sorensen, Peter F. A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment.

Degree: PhD, Physics, 2008, Brown University

URL: https://repository.library.brown.edu/studio/item/bdr:11023/

► Recent astrophsyical observations indicate that about 23% of the matter in the universe exists as non-luminous, non-baryonic dark matter. General thermodynamic arguments suggest that if… (more)

▼ Recent astrophsyical observations indicate that about 23% of the matter in the universe exists as non-luminous, non-baryonic dark matter. General thermodynamic arguments suggest that if an as-yet undiscovered weakly interacting particle were in thermal equilibrium in the early universe, it could have a cosmologically interesting relic abundance today. Dark matter particles are predicted to have collapsed into isothermal halos on a galactic scale. Minimal super-symmetric extensions of the standard model predict the existence of a stable particle with a mass in the range 10-1000 GeV c -2, and a an interaction cross section with ordinary matter σχ < 10 -36cm 2. For the past two decades, numerous experiments have been deployed with the aim of direct or indirect detection of dark matter. XENON10 is a direct-detection liquid Xe experiment, with event-by-event 3D position reconstruction. Since dark matter does not interact electromagnetically, it's signature in a Xe detector is expected to be a low-energy nuclear recoil. Particle interactions in Xe create scintillation light ( S1) and ionization. The ionization is drifted across the active Xe target and converted into a proportional scintillation signal ( S2) by an external electric field. The ratio y = log10( S2/ S1) is larger for β and ɣ background events than for nuclear recoils, as determined by neutron calibration data. This allows event-by-event discrimination of background from the expected signal. In 2007 XENON10 eclipsed CDMS II as the most sensitive direct-detection experiment, excluding the existence of particle dark matter with a cross-section (normalized to a single nucleon) σχ > 10 -43cm 2at a particle mass of 100 GeV c -2(90% C.L.). Liquid Xe technology is extremely promising since it is easily scaled to larger target mass, which will allow greater sensitivity to particle dark matter interactions. I discuss the XENON10 detector, deployment, operation, analysis and dark matter exclusion results. I also present a new method to determine the light yield of Xe for nuclear recoils, which is essential for calibrating the nuclear recoil energy scale and understanding the detector threshold. Advisors/Committee Members: Gaitskell, Richard (Director), Robert, Lanou (Reader), Dell'Antonio, Ian (Reader).

Subjects/Keywords: WIMP

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Sorensen, P. F. (2008). A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:11023/

Chicago Manual of Style (16^th Edition):

Sorensen, Peter F. “A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment.” 2008. Doctoral Dissertation, Brown University. Accessed March 07, 2021. https://repository.library.brown.edu/studio/item/bdr:11023/.

MLA Handbook (7^th Edition):

Sorensen, Peter F. “A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment.” 2008. Web. 07 Mar 2021.

Vancouver:

Sorensen PF. A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment. [Internet] [Doctoral dissertation]. Brown University; 2008. [cited 2021 Mar 07]. Available from: https://repository.library.brown.edu/studio/item/bdr:11023/.

Council of Science Editors:

Sorensen PF. A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct Detection of Dark Matter: The XENON10 Experiment. [Doctoral Dissertation]. Brown University; 2008. Available from: https://repository.library.brown.edu/studio/item/bdr:11023/

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