The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC in the Davis cavern at the Sanford Underground Research Facility, Lead, South Dakota, 4850 feet below the surface. The underground environment reduces the cosmic ray flux by a factor of $10^6$, but there remains a potential background from γ-rays emitted from the decays of $^{40}$K,...
LIGO's detection of the black hole quasinormal modes has proved the existence of the light rings outside the event horizon. Other sub-dominant long-lived modes depend on the existence and properties of the horizon, as well as the black hole hairs outside. These modes may reveal themselves in future gravitational-wave detectors as echoes. In this work, we study the ringdown of a de...
Many dark matter search experiments active today, and to be activated in the future, utilize xenon as a target mass in dual phase time projection chambers (TPC). Although xenon has seen widespread use in liquid noble gas detectors, and is currently employed by the XENON1T, LUX, and PandaX-II detectors; the process of energy deposition for nuclear recoils in liquid xenon is not precisely...
Very high energy gamma rays up to 200 GeV have been observed from the quiescent Sun. While this emission is thought to originate from hadronic cosmic rays interacting in the Sun’s atmosphere, the mechanism is not well understood. Another potential source of gamma rays from the Sun is gravitationally captured dark matter. Weakly interacting massive particles (WIMPs) accumulating in the solar...
The LUX-ZEPLIN (LZ) experiment aims to directly detect WIMP particles interacting with xenon nuclei. These interactions produce scintillation and ionization signals within the active region of the detector which identify their presence. It is the goal to trigger correctly on ionization pulses that come from WIMPs and to avoid triggering on dark current from PMTs. This presentation...
John Armstrong
University of Maryland
DMSS Abstract
Modern dark matter direct detection experiments such as LUX-Zeplin require low backgrounds to reach sensitivities necessary to claim detection. When deep underground and isolated from cosmic rays, the dominant backgrounds come from radioactive impurities. While a getter can effectively remove electronegative impurities, noble gas...
An important topic in dark matter research is the search for sub-GeV dark matter. Direct detection searches for sub-GeV dark matter can be conducted through scattering on Silicon nuclei utilizing a detector with energy threshold on the order of 10 eV. This low threshold can be achieved by thermalizing a Transition-Edge Sensor (TES) based detector with gram scale silicon absorbers. This talk...
The latest release of the Noble Element Scintillation Technique (NEST) is presented here. Noble element target media have become common in rare event searches, and an accurate comparison model is critical for understanding and predicting signals and unwanted backgrounds. Like its predecessors, NESTv2.0 is a simulation tool written in C++ and is based heavily on experimental data, taking into...
Dual-phase time projection chambers (TPCs) filled with liquid xenon (LXe) are a
widely-used technique for the direct search for dark matter in the form of weakly
interacting massive particles (WIMPs). One of the upcoming experiments exploiting
this technique is XENONnT, which aims at Dark Matter detection through the
scattering of WIMPs off the xenon nuclei. XENONnT will be filled with 8 t of...
Self-shielding in ton-scale liquid xenon (LXe) time projection chambers (TPCs) presents a unique challenge for calibrating detector response to interactions in the TPCs innermost LXe volume. Calibration isotopes must be injected directly into the LXe to reach the central volume of the TPC, where they must either decay away with a short half life, or be purified out. I present a summary of the...
XENON1T is a liquid xenon time projection chamber (TPC) designed to look for elastic recoils of dark matter particles with xenon nuclei. To increase the sensitivity of the experiment, we need to decrease the background in the detector. One background that is specific to low-energy recoils comes from so called single electrons trains that follow interactions in the TPC over time scales of...
Many leading WIMP direct detection experiments use liquid xenon as a target to observe scattering dark matter. Currently, these detectors search for WIMPS in the GeV-TeV mass energy range, and require larger and larger detectors to gain sensitivity. An alternate analysis channel investigates the energy spectrum of individual extracted electrons. Through this channel, xenon TPCs, regardless of...
An important step in the XENON1T analysis pipeline is distinguishing electronic recoil events (ERs) from nuclear recoil events (NRs) inside the detector. ERs come from background, while NRs are evidence of a possible signal. This is currently done by hand using a profile likelihood method. The goal is to maximize the acceptance of correctly classified NRs while rejecting as many ERs as...
A brief overview of experimental activities at the University of Montreal is given concerning the search for the Dark Matter (DM) in the PICO experiment (SNOLAB, Ontario, Canada) as well as at the accelerator laboratory in Montreal. Newly proposed methods of DM detection using the superheated liquid gas will be briefly discussed.
Weakly interacting massive particles (WIMPS), the leading candidate for dark matter, interacts differently than what we would expect with ordinary baryonic matter. These interactions require very sensitive detectors. Being much cheaper than xenon, when superheated, ultra-purified water can act as a sensor to detect these rare events. Alongside replicating other WIMP detectors the bubble...
As higher mass particles are eliminated as possibilities in the search for dark matter, it is important to explore new types of detectors that are more specialized at looking for lower mass particles. For this purpose, super-cooled water has been explored as a target material for future detectors. This talk will go over the motivations for a detector of this type, the operational data that has...
If dark matter interacts weakly then one possible experimental signal would be an annual modulation in the interaction rate caused by the combined motion of the sun and earth moving through the dark matter halo. The DAMA-LIBRA experiment has observed such a modulation in their detector in a way not described by known modulating backgrounds such as atmospheric muon rate (thickness/density of...
The HAYSTAC experiment looks for axions, a type of cold dark matter (CDM) particle predicted in the context of the standard model of electroweak interactions. If they exist, axions fall very low on the mass scale, and their presence could be detected when they convert to radiofrequency photons in the presence of a strong magnetic field. HAYSTAC consists of a microwave cavity resonator that is...
Among the proposed explanations for the hierarchy problem, or the relative weakness of gravity compared to the other fundamental forces, is the existence of extra dimensions. To test this, we probe the diphoton spectrum for high-mass events using proton-proton collisions at $\sqrt{s}$ = 13 TeV. We present here the analysis results using 2016 data, corresponding to a 35.9 fb$^{-1}$ integrated...
Standard searches for dark matter attempt to identify interactions with dark matter particles; a complementary search would involve looking for “dark forces”. As an example, if a dark force mediated by a “dark photon” exists, dark matter particles could pick up a tiny electric charge due to kinetic mixing with normal photons. Stable millicharged dark matter particles could become bound in...
In the last century, several astrophysical observations have provided strong evidences of the existence of dark matter in the Universe. This dark matter, non-luminous, and weakly interactive with ordinary matter, could be composed of massive particles called WIMPs.
XENON1T, the third direct detection experiment designed by the XENON collaboration, consists of a dual-phase (liquid-gas) time...
LUX-ZEPLIN is dark matter direct detection experiment which will take data a mile underground in Lead, South Dakota starting in 2020. Krypton backgrounds must be minimized to decrease backgrounds to an acceptable level. Special cylinders fitted with purge volumes around the neck of the cylinders will be constructed to store the xenon. The cylinders have an upper limit of 15...
COSINE-100 is a NaI(Tl) dark matter direct detection experiment, with the goal of testing DAMA's claim of dark matter detection by looking for an annual modulation signal. It consists of eight NaI(Tl) crystals, adding to a total of 106 kg, and 2000 liters of a liquid scintillator veto. Located at the Yangyang Underground Laboratory, South Korea, COSINE-100 has been running since September...
Significant evidence, both astrophysical and cosmological, points to the existence of dark matter. The fundamental nature of dark matter, however, remains unknown. One appealing candidate for dark matter is the weakly interacting massive particle (WIMP). Direct detection experiments aim to observe the low energy scattering of WIMP particles off normal matter, and detectors based on noble...
Liquid Xenon detectors are playing a pivotal role in the search for both dark matter and neutrinoless double beta decay. The principle of these detectors is based upon the measurement of scintillation light from the liquid xenon. The light response of these detectors to nuclear and electronic recoils must therefore be particularly well understood. While many such calibrations have been...
nEXO (next-generation Enriched Xenon Observatory) is a proposed experiment to search for neutrinoless double beta (0νββ) decay of 136Xe with a projected half-life sensitivity of ~10^28 years using 5×10^3 kg of isotopically enriched liquid-xenon in a time projection chamber (TPC). Targeting this sensitivity requires addressing and reducing the backgrounds in the detector. Of particular...
The search for neutrinoless double beta decay has spawned dozens of detectors looking for this rare decay and to determine whether neutrinos are Majorana or Dirac particles. Majorana neutrinos are required for most See-Saw Mechanisms for mass generation, as well as many models of sterile neutrinos, but is severely limited in what mechanisms it can rule out. Should a discovery be made, the next...
DAMIC for Dark Matter in CCDs, will search for dark matter particle interaction with silicon CCDs. The experiment takes place at SNOLAB where 8 CCDs are used. We measure the energy spectrum of ionization events in the bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. Thus it’s necessary to measure and understand our background noise. I will give an...
