Author: Matthew Anthony Publisher: ISBN: Category : Languages : en Pages :
Book Description
An abundance of cosmological evidence suggests that cold dark matter exists and makes up 83% of the matter in the universe. At the same time, this dark matter has eluded direct detection and its identity remains a mystery. Many large international collaborations are actively searching for dark matter through its potential annihilation in high-density regions of the universe, its creation in particle accelerators, and its interaction with Standard Model particles in low-background detectors. One of the most promising dark matter candidates is the weakly interacting massive particle (WIMP) which falls naturally out of extensions of the Standard Model. A variety of detectors have been employed in the search for WIMPs, which are expected to scatter with atomic nuclei, yet none have been more successful than dual-phase liquid xenon time projection chambers (TPCs). The first ton-scale liquid xenon TPC, XENON1T, began operating in 2016 and with only 34.2 days of data has set the most strict limits on the WIMP-nucleon interaction cross sections for WIMP masses above 10 GeV/c^2, with a minimum of 7.7 × 10−47 cm^2 for 35 GeV/c^2 WIMPs.
Author: Yixiong Meng Publisher: ISBN: Category : Languages : en Pages : 217
Book Description
Cosmological and Astrophysical observations provide compelling evidences for the existence of dark matter in the universe. One class of dark matter candidates, the Weakly Interacting Massive Particles (WIMPs), has been predicted in many particle physics theories. Direct detection experiments using dual- phase liquid noble element detectors report the best sensitivities to the detection of the dark matter particles. The next generation direct detection experiments using the same technology, are actively been built and expected to give a factor of 100 improvement on the current best sensitivity. This thesis discusses the measurement of nuclear recoils in a dual-phase liquid argon detector using a bunched neutron beam generated by linear accelerator facility at accelerator laboratory in Notre Dame University. Nuclear recoils of en- ergy ranging from 10.8 keVnr to 49.9 keVnr are measured under different drift field configurations. An electric field quenching on nuclear recoils in liquid argon is dis- covered and quantified for the first time. This quenching effect is also found to be drift field and recoil energy dependent. By varying the drift field amplitude from 100 V/cm to 1000 V/cm for each nuclear recoil energy, the quenching effect are measured as a function of nuclear recoil energy and drift field amplitude. Results from this measurement is used in the direct dark matter detection experiment to calculate the final sensitivity of direct dark matter search. A separate work on the optimization of detector design for the XENON1T detector is also discussed in detail. Finite element simulation tool is used to design and optimize the electric field in XENON1T time projection chamber. As part of the design of XENON1T detector, electron transparency across metal grids of different geometrical configurations are also studied.
Author: Evan Shockley Publisher: Springer Nature ISBN: 3030877523 Category : Science Languages : en Pages : 127
Book Description
This thesis summarizes the original analysis work performed by the author on data from XENON1T, a search for dark matter with a ton-size noble liquid detector operated at Gran Sasso Underground Laboratory in Italy. The nature of dark matter is one of the most open and pressing questions of modern physics, and the unique data acquired with this detector allows the exploration and investigation of several potential scenarios. The analysis of Dr. Shockley searches for a class of elusive elementary particles that interact with the electrons of ordinary atoms, instead of the nucleus. Results of the analysis present, with high confidence, an excess with respect to the expected background. Beyond more mundane explanations, this additional rate of electron-mediated interactions might be a first hint of physics beyond the standard model. This accessible thesis provides details on the detector, the data, and the theory, delivering to the reader an in-depth and coherent picture of the search for physics beyond the standard model.
Author: Brian Gregory Lenardo Publisher: ISBN: 9780438289567 Category : Languages : en Pages :
Book Description
This dissertation focuses on the characterization of xenon as a detection medium for low energy particle physics. In particular, there are two signals that we are interested in exploring: the interactions of WIMP dark matter inside an earth-bound detector, and the coherent elastic scattering of neutrinos off of nuclei. Both are predicted to produce low energy (10−1--102 keV) nuclear recoils, which can be measured in a low-threshold detector. One well-established technique for measuring these signals is the dual-phase xenon emission detector, which measures primary scintillation light and electroluminescence from ionized electrons to reconstruct information about each interaction inside the target volume. To understand the data produced in an experiment, one must understand how the scintillation and ionization signals relate to the incident particle type and energy deposited. Calibrating the response of the detector medium is of crucial importance for both interpreting existing data and calculating the physics reach of current or future experiments. The ultimate goal of this dissertation is to provide a set of robust models of xenon ionization and scintillation emission which can can be used to calculate signals and simulate the response of liquid xenon detectors in experiments searching for low energy nuclear recoil signatures. In the work below, I begin with a detailed description of the physics of interest. Chapter 2 introduces the dual-phase xenon TPC and discuss its benefits for these types of experiments. In Chapter 3, we draw upon previous literature to develop a model of xenon scintillation and ionization yields. This model is fitted simultaneously to a compilation of available data to allow it to incorporate differences in operating conditions, such as applied electric field, across different experiments. Chapter 4 extends this modeling effort to work within the LUX collaboration, which operated a 300 kg liquid xenon TPC with world-leading sensitivity to dark matter WIMP interactions. LUX performed the lowest-energy nuclear recoil calibration measurements to date, allowing us to extend our model to lower energies and establishing the sensitivity of LUX to a broader range of WIMP models. Chapter 5 delves in greater detail into the time structure of scintillation in liquid xenon. We provide new data on scintillation pulse shapes for low energy nuclear recoils, and use the differences between electron- and nuclear-recoil pulse shapes to establish a new background discriminant for use in LUX data analysis. Finally, in Chapter 6 we describe an ongoing project at LLNL to provide new data of ionization yields at lower energies than the LUX measurements. These experiments will have direct implications on the sensitivity of liquid xenon detectors in general to both low-mass WIMPs and nuclear reactor neutrino scattering. Here we describe the development of the xenon detector system and the preliminary characterization and calibration work that was performed in preparation for the main experiments.
Author: Adam Michael Brown Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Abstract: The XENON collaboration has published stringent limits on specific dark matter - nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 t-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method we present. The approximate likelihood is constructed in bins of reconstructed energy, profiled along the signal expectation in each bin. This approach can be used to compute an approximate likelihood and therefore most statistical results for any nuclear recoil spectrum. Computing approximate results with this method is approximately three orders of magnitude faster than the likelihood used in the original publications of XENON1T, where limits were set for specific families of recoil spectra. Using this same method, we include toy Monte Carlo simulation-derived binwise likelihoods for the upcoming XENONnT experiment that can similarly be used to assess the sensitivity to arbitrary nuclear recoil signatures in its eventual 20 t-year exposure
Author: Valerio D'Andrea Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Abstract: We report on a blinded analysis of low-energy electronic recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3) events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter
Author: Zachary Greene Publisher: ISBN: Category : Languages : en Pages :
Book Description
XENON1T is the first tonne-scale TPC, and with 278.8 days of dark matter data has set the strictest limits on WIMP-nucleon interaction cross sections above WIMP masses of 6 GeV/c^2, with a minimum of 4.1 x10^{-47} cm^2 at 30 GeV/c^2. XENON1T and the analysis that led to this result are discussed, with an emphasis on electronic and nuclear recoil calibration fits, which help discriminate between background and WIMP-like events. Interactions in liquid xenon produce light and charge that are measured in TPCs. These signals are attenuated by electronegative impurities including O_2 and H_2O, which are homogeneously distributed throughout the liquid xenon. The decrease in observables enlarges the uncertainty in our analysis, and can decrease our sensitivity. Methods on measuring the charge loss are presented, and a physics model that describes the behavior of the electronegative impurity concentration over the lifetime of XENON1T is derived. The model is shown to successfully explain the more than two years of data.
Author: Guillaume Plante Publisher: ISBN: Category : Languages : en Pages :
Book Description
This thesis describes the research conducted in the context of the XENON100 dark matter search experiment. I describe the initial simulation results and ideas that influenced the design of the XENON100 detector, the construction and assembly steps that lead into its concrete realization, the detector and its subsystems, a subset of the calibration results of the detector, and finally dark matter exclusion limits. I also describe in detail the new improved measurement of the important quantity for the interpretation of results from LXe dark matter searches, the scintillation efficiency of low-energy nuclear recoils in LXe.
Author: Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
Xenon has recently been the medium of choice in several large scale detectors searching for WIMP dark matter and neutrinoless double beta decay. Though present-day large scale experiments use liquid xenon, the gas phase offers advantages favorable to both types of searches such as improved intrinsic energy resolution and fewer fluctuations in the partition of deposited energy between scintillation and ionization channels. We recently constructed a high pressure xenon gas TPC as a prototype for the NEXT (Neutrino Experiment with a Xenon TPC) neutrinoless double beta decay experiment and have demonstrated the feasibility of 0.5% FWHM energy resolution at the 136Xe double beta Q-value with 3-D tracking capabilities. We now present results from this prototype on the simultaneous observation of cintillation and ionization produced by nuclear recoils at approximately 14 bar pressure. The recoils were produced by neutrons of approximately 2-6 MeV emitted from a radioisotope plutonium-beryllium source, and primary scintillation (S1) and electroluminescent photons produced by ionization (S2) were observed. We discuss the potential of gaseous xenon to distinguish between electron and nuclear recoils through the ratio of these two signals S2/S1. From these results combined with the possibility of using columnar recombination to sense nuclear recoil directionality at high pressures we envision a dual-purpose, ton-scale gaseous xenon detector capable of a combined search for WIMP dark matter and neutrinoless double beta decay. This work has been performed within the context of the NEXT collaboration.
Author: Matthew Anthony
Author: Yixiong Meng
Author: Evan Shockley
Author: Brian Gregory Lenardo
Author: Adam Michael Brown
Author: Valerio D'Andrea
Author: Zachary Greene
Author: Guillaume Plante
Author: 
Author: Elena Aprile