Download or read book The LZ Dark Matter Experiment written by Kelly M Stifter and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to a compelling body of astrophysical and cosmological evidence, dark matter has come to be accepted as a crucial ingredient of modern cosmology, yet its physical nature remains one of the most pressing questions in the field of physics. One historically favored model of dark matter is weakly interacting massive particles, or WIMPs. LUX-ZEPLIN (LZ) is a next-generation dark matter detector designed to achieve field-leading sensitivity to much of the remaining accessible parameter space within the WIMP dark matter paradigm. To help realize the full-scale LZ detector, the System Test R&D platform was constructed at SLAC National Accelerator Laboratory to validate the performance of critical LZ subsystems at scales approaching or comparable to the LZ design. In this dissertation, I present results showing that the passivation of the high voltage electrodes in citric acid leads to a significant reduction in spontaneous emission of single electrons, potentially limiting a major instrumental background by up to several orders of magnitude and enabling a more sensitive dark matter search. The LZ detector has now been assembled at the Sanford Underground Research Facility (SURF) in Lead, South Dakota and is taking early data. I also give a first look at commissioning data that captured the first light from electrons in the LZ detector, and share methods to validate the in situ performance of the high voltage electrodes.

Download or read book Background Modeling and First Searches for Low Energy Signals in The LUX ZEPLIN LZ Dark Matter Experiment written by Daniel Kodroff and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past half-century overwhelming evidence has mounted indicating the existence of a non-baryonic and enigmatic dark matter that constitutes approximately 85% of the total matter in the universe. Among the potential dark matter detection methods, dual- phase time projection chambers (TPCs) have emerged as the leading detector technology. LUX-ZEPLIN (LZ) is a direct detection dark matter experiment located at the 4850-ft depth level of the Sanford Underground Research Facility in South Dakota, USA, employing a 7 tonne active volume of liquid xenon in a dual-phase TPC. It's surrounded by an instrumented xenon "Skin" region and gadolinium-loaded liquid-scintillator outer detector, primarily serving as active vetoes for gamma-ray and neutron backgrounds, respectively, and contained within an ultra-pure water tank. The LZ detector began its first science run in December of 2021 and released its first results in the Summer of 2022. In order to ensure a low-background environment, a comprehensive material assay and selection campaign, for detector components, along with a xenon-purification campaign were pursued prior to and during construction. These mitigations have allowed LZ to achieve a background rate of 63.0 ± 4.5 x 10-6 events/keVee/kg/day in the low- energy region, approximately 60 times lower than that of its predecessor, the LUX experiment. LZ performed comprehensive measurements to constrain backgrounds in situ and construct a well-constrained time-dependent background model to use in searches for novel physics signals within this low-energy (

Download or read book Calibrations for the Improved Search for Dark Matter with the LZ LUX ZEPLIN Experiment written by Madan K. Sharma Timalsina and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hypothetical non-luminous existence of matter is known as dark matter, inferred by the convincing collection of astrophysical and cosmological indirect evidence. In spite of compelling indirect observations, the physical nature of dark matter remains one of the most profound questions in the field of modern physics. A Weakly Interacting Massive Particle (WIMP) is historically the most favored candidate particle for dark matter, which could nicely explain the observed indirect measurements with the direct detection of WIMPs for the first time. The new second-generation direct detection dark matter experiment LZ (LUXZEPLIN), designed for direct detection of WIMP dark matter, has performed the most sensitive search for spin-independent WIMP-nucleon interactions. LZ is located 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ is employing a two-phase xenon detector with an active mass of 7 tonnes. With LZ we have recently managed in the summer of 2022 to provide the most rigorous exclusion limit for spin-independent WIMP-nucleon scattering with an upper limit on the cross-section of 6.5×10−48 cm2 (90 % confidence level) for a WIMP mass of 30 GeV/c2 . The first WIMP search result of LZ utilizes a fiducial mass of 5.5 tonnes of liquid xenon and an exposure time of 60 live days. WIMPs could interact in the cryogenic liquid xenon of the detector’s core by scattering off xenon nuclei, which would then recoil and produce both scintillation light and electric charge. The ratio of the immediately detected scintillation light (S1) and the delayed charge detection (S2) is characteristic for such a nuclear recoil (NR) from hypothesized dark matter, e.g. a WIMP, and differs significantly from an electron recoil (ER) produced by undesired background reactions. However, the precise knowledge of the energy-dependent ratio S1/S2, for which the ER-dominated regime transitions into the NR-dominated regime, is key hereby to separate WIMP dark matter signals from unwanted background signals. We performed calibrations with neutron sources to map out the NR signal region for the WIMP search. Instead, gamma- and beta-ray calibration sources were utilized to map out the ER region, characteristic for background signals to be discriminated against. In this thesis, the calibration data to map out the NR signal region has been extensively studied and compared to the results of a full LZ detector simulation. In addition, another crucial detector calibration, for which all LZ data has to be corrected, is the purity monitoring of the liquid xenon. The chemical purity determines the lifetime of signal electrons against the absorption on impurities during their drift within the liquid xenon time projection chamber of the LZ detector. This electron lifetime analysis has been performed on a daily basis within the framework of this thesis and results have been applied by every data evaluator within the large LZ collaboration and for obtaining the current world’s best exclusion limit on WIMP dark matter.

Download or read book Experimental High Energy Physics Research written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The grant supported research on an experimental search for evidence of dark matter interactions with normal matter. The PI carried out the research as a member of the LUX and LZ collaborations. The LUX research team collected a first data set with the LUX experiment, a large liquid xenon detector installed in the Sanford Underground Research Facility (SURF). The first results were published in Physical Review Letters on March 4, 2014. The journal Nature named the LUX result a scientific highlight of the year for 2013. In addition, the LZ collaboration submitted the full proposal for the Lux Zeplin experiment, which has since been approved by DOE-HEP as a second-generation dark matter experiment. Witherell is the Level 2 manager for the Outer Detector System on the LUX-Zeplin experiment.

Download or read book An Analysis of PMT Signals in the LZ Dark Matter Experiment written by Gavin Cox and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark matter has become one of the longest standing mysteries in physics. The main idea behind dark matter is simple: on the largest of scales, luminous matter cannot account for the observed motion and clustering of galaxies and clusters of galaxies. Some unseen object, particle or force with the ability to interact gravitationally must be present throughout the universe to explain these observations. Since it was first hypothesized in 1933, some progress has been made to improve our understanding of this mystery. The indirect evidence indicating the existence of dark matter is extensive and gives many clues as to possible composition and distribution. LZ is an experiment whose goal is to finally observe the existence of dark matter through direct detection.

Download or read book The LZ Dark Matter Search and Development of a New Gas Phase Technique to Characterize Low Level Electron Emission from Electrode Grids written by Wei Ji and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Matter is needed to explain many cosmological observations and therefore has been proposed for many decades, but it awaits direct detection. One of the most popular classes of dark matter candidates is Weakly Interacting Massive Particles (WIMPs), which have masses in the order of 100 GeV and couple to ordinary matter at weak scale. In WIMP direct detection experiments, we look for WIMPs being scattered by nuclei, a process which produces low energy (smaller than 100 keV) recoiling nuclei that can be observed. We are building LZ, a detector looking for WIMPs using liquid xenon in a dual-phase time projection chamber (TPC), at 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ aims to achieve the world's highest sensitivity to find WIMPs via WIMP-nucleon interactions. After a brief discussion of dark matter and the LZ experiment, this dissertation presents the details of my study to solve the electron emission problem. The LZ TPC will consist of electrode grids and other metallic surfaces that can emit electrons when operated under voltage. Because the charge measurement in the LZ detector is sensitive to single electrons, electrons from the grids can be both a significant nuisance for data collection and a source of background at low-energies, limiting the sensitivity of the experiment for low-mass WIMPs. This has motivated us to develop a test detector to study how to reduce this background. The test detector consists of a pair of grids biased to high voltage and operated in xenon gas. The electric field between the grid causes the electrons to produce electroluminescence scintillation light that is measured by PMTs. This new technique is sensitive to single electrons emitted by the grids, allowing a measurement of emission currents as low as atto-amperes. We used this detector to study the properties of different grids and to determine what treatments can be done to reduce their electron emission. We found that passivation with citric acid reduces electron emission from stainless steel surfaces. This work was supervised by Professor Thomas Shutt and was completed in collaboration with members of the LZ collaboration and the SLAC LZ group.

Download or read book Dark Matter Searches with the LUX and LZ Experiments written by Sally Shaw and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Extending the Physics Reach of the LUX and LZ Dark Matter Experiments by Lowering the Scintillation Threshold written by Nellie Marangou and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book PMT Studies and Loop Antenna Development for the LZ Dark Matter Experiment written by Theresa Maria Antonie Fruth and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dark Matter Searches with the LUX and LZ Experiments written by S. Shaw and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Estimating LUX ZEPLIN s Sensitivity to Sub GeV Dark Matter Scattering Off Electrons in Xenon written by Gus Eberlein and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprising 85% of the mass of the universe, dark matter is one of the most pressing outstanding questions of physics. When it comes to directly detecting dark matter, the LUX-ZEPLIN (LZ) experiment has unparalleled sensitivity. We examine the detector's capability to detect sub-GeV dark matter scattering off the electrons in xenon, LZ's scintillation medium. We develop a signal model by calculating the expected DM-electron event rates as a function of electron recoil energy and as a function of the number of freed electrons. Alongside an established backgrounds model, this signal model is used to simulate events in the LZ detector. With this simulated data and a cut-and-count analysis, we are able to estimate cross sections of dark matter-electron scattering down to which LZ can detect the signal over the background. We find that LUX-ZEPLIN will be able to detect certain light dark matter models at a much greater sensitivity than previous direct detection experiments.

Download or read book High Voltage Electrode Development and the LZ Experiment s WIMP Search written by Ryan Edward Linehan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Approximately 15% of the matter density in the universe is composed of Standard Model particles, while the other 85% is composed of an enigmatic "dark" matter whose fundamental properties are unknown. In recent decades, there has been substantial interest in performing a direct detection of scattering between dark matter and Standard Model particles, but currently no such signature has been verifiably observed. The LUX-ZEPLIN experiment was built to perform such a direct detection of dark matter using a dual-phase xenon time projection chamber (TPC), which can observe both light and charge signals from an interaction in the xenon. The dual-phase xenon TPC technology is critically dependent on maintaining strong drift and extraction fields in order to observe the charge signal. These fields are established by a set of four stainless steel wire mesh high voltage electrode grids that span the full width of the TPC. During operation, these grids achieve wire surface fields well above 15 kV/cm. These high fields can produce spurious charge signals and signals from real radioactive decays with atypical light-to-charge ratios, both of which can lead to low-energy backgrounds in LZ science data. As a result, substantial effort in the design, construction, validation, and operation of these grids was required to ensure that the LZ detector could be used to pursue world-leading dark matter searches. This work presents a detailed characterization of these efforts, from grid design all the way through first science run data with LZ. This work also presents two analyses performed within the first six months of datataking: the first science run searching for WIMP dark matter, and an analysis of radiogenic backgrounds from the high voltage grids. While the former analysis represents an immediate world-leading sensitivity to WIMP dark matter between about 10 GeV/c^2 and 10 TeV/c^2, the latter analysis lays a new foundation for the background model needed to search for dark matter at much lower masses, down to approximately 1 GeV/c^2.

Download or read book Background and Sensitivity Studies for the LUX ZEPLIN Dark Matter Experiment written by Umit Utku and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The LUX Dark Matter Experiment written by Patrick Phelps and published by . This book was released on 2014 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark matter, the mysterious substance that seems to make up most of the mass of the universe, has never been detected in the laboratory. In this document I outline the current world's leading experiment, LUX, to look for a class of dark matter, the Weakly Interacting Massive Particle. I outline the general principles of searching for dark matter through low background detectors and event rejection, I move on to a description of the LUX experiment and its performance, reviewing its internal structure and subsystems including a novel heat exchange system that expedited system readiness and resulted in a stable platform for WIMP searching. The LUX energy reconstruction is then examined, followed by a breakdown of signal fluctuations as a function of energy as part of our understanding of back- ground discrimination in this class of detectors. Finally, I review the first LUX WIMP search result, culminating in the world's most sensitive limit on the spin- independent WIMP-nucleon cross section, before moving to a discussion of next steps in the search for dark matter for LUX and next generational experiments.

Download or read book Dark Matter Explained written by Kristi Lew and published by Enslow Publishing, LLC. This book was released on 2018-12-15 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists believe that the universe is mostly made up of dark matter, a mysterious substance that is different from the ordinary matter people can touch, smell, see, and interact with. Dark matter cannot be directly observed, but it can be studied by examining its effect on ordinary matter. Simplified explanations of complex scientific concepts and fascinating images will help students understand how physicists employ Kepler's laws of planetary motion, gravitational lensing, particle colliders, and other theories and tools to learn about dark matter. Informative sidebars explore related timely topics in depth, while a Further Reading section provides several resources for additional study.

Download or read book DETECTION OF GAMMA X EVENTS IN LUX AND LZ DARK MATTER DETECTORS written by Corey Herr and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple astrophysics observations, including analysis of the cosmic microwave background and gravitational lensing by galaxy clusters, show that there is a missing mass component that we cannot see through telescopes. We call this missing mass dark matter. It is estimated that dark matter makes up about 26.8% of the Universes energy while baryonic matter, the everyday matter that we observe, only makes up about 5%. Dark matter is believed to be composed of Weakly Interacting Massive Particles (WIMPs). WIMPs do not interact via the electromagnetic force and thus cannot be observed optically. LUX-ZEPLIN (LZ) is a next generation experiment that will attempt to detect dark matter directly using a 10-tonne liquid xenon detector. I have examined the effect that a class of backgrounds called gamma-X events have on the LUX-ZEPLIN (LZ) detector. Gamma-X events are ordinary particles (such as photons and electrons) that havedetector signatures similar to dark matter due to anomalous signal collection.

Download or read book Dark Data written by David J. Hand and published by Princeton University Press. This book was released on 2022-02-15 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Data describe and represent the world. However, no matter how big they may be, data sets don't - indeed cannot - capture everything. Data are measurements - and, as such, they represent only what has been measured. They don't necessarily capture all the information that is relevant to the questions we may want to ask. If we do not take into account what may be missing/unknown in the data we have, we may find ourselves unwittingly asking questions that our data cannot actually address, come to mistaken conclusions, and make disastrous decisions. In this book, David Hand looks at the ubiquitous phenomenon of "missing data." He calls this "dark data" (making a comparison to "dark matter" - i.e., matter in the universe that we know is there, but which is invisible to direct measurement). He reveals how we can detect when data is missing, the types of settings in which missing data are likely to be found, and what to do about it. It can arise for many reasons, which themselves may not be obvious - for example, asymmetric information in wars; time delays in financial trading; dropouts in clinical trials; deliberate selection to enhance apparent performance in hospitals, policing, and schools; etc. What becomes clear is that measuring and collecting more and more data (big data) will not necessarily lead us to better understanding or to better decisions. We need to be vigilant to what is missing or unknown in our data, so that we can try to control for it. How do we do that? We can be alert to the causes of dark data, design better data-collection strategies that sidestep some of these causes - and, we can ask better questions of our data, which will lead us to deeper insights and better decisions"--