BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Purification of large volume of liquid argon for the LEGEND-200 ex periment DTSTART;VALUE=DATE-TIME:20210917T171500Z DTEND;VALUE=DATE-TIME:20210917T173000Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-74@indico.physics.ucsd.edu DESCRIPTION:Speakers: Grzegorz Zuzel (Jagiellonian University)\nThe LEGEND -200 experiment is under construction at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. Its main goal is a background-free search for neut rinoless double beta decay of Ge-76. Up to 200 kg of bare high purity germ anium (HPGe) detectors with enrichment in Ge-76 beyond 86% will be deploye d in liquid argon (LAr). The LAr will serve as cooling medium for the dete ctors as well as a passive and an active shield. For the latter the LAr in strumentation will be composed of light guiding fibers connected to silico n photomultipliers detecting scintillation light of argon. It has been alr eady shown in the GERDA experiment that the LAr veto was a very powerful t ool for background rejection and minimization. Details of the LAr veto sys tem will be presented in a dedicated talk. \n The scintillation properti es of LAr (attenuation length\, triplet life time) are worsened by presenc e (at a sub-ppm level) of electronegative impurities such as oxygen\, wate r and nitrogen due to quenching and absorption processes. As a consequence \, the efficiency of the LAr veto may be significantly influenced. In orde r to achieve best possible performance of the veto\, LAr will be purified during initial filling of the LEGEND-200 cryostat. \n The design\, const ruction and performance of a system capable to purify 65 m3 (91 tons) of l iquid argon to sub-ppm level will be presented. The quality of the process ed liquid is monitored in real time by measuring the triplet life time and simultaneous direct measurement of concentrations of impurities like wate r\, oxygen and nitrogen down to 0.1 ppm. Scintillation properties of LAr f illed into the cryostat are also be determined in real time by a dedicated apparatus (LLAMA). For the LAr filled into the cryostat the measured trip let life time is in the range of 1.3 mico_s. If needed\, the LAr purificat ion system may be also used later to purify LAr filled in the cryostat in the loop mode. A dedicated cryogenic pump has been installed on its bottom . The pump is capable to circulate the LAr between the purification system and the cryostat.\n\nhttps://indico.physics.ucsd.edu/event/1/contribution s/74/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/74/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurement of the underground argon radiopurity for Dark Matter d irect searches DTSTART;VALUE=DATE-TIME:20210917T174500Z DTEND;VALUE=DATE-TIME:20210917T180000Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-8@indico.physics.ucsd.edu DESCRIPTION:Speakers: Pablo Garcia Abia (CIEMAT)\nA major worldwide effort is underway to procure the radiopure argon needed for DarkSide-20k (DS-20 k)\, the first large scale detector of the new Global Argon Dark Matter Co llaboration. The Urania project will extract and purify underground argon (UAr) from CO2 wells in the USA at a production rate of 300 kg/day. Additi onal chemical purification of the UAr will be required prior to its use in the DS-20k LAr-TPC. The Aria project will purify UAr using a cryogenic di stillation column (Seruci-I)\, located in Sardinia (Italy). Assessing the UAr purity in terms of Ar-39 is crucial for the physics program of the Dar kSide-20k experiment. DArT is a small (1 litre) radiopure chamber that wil l measure the Ar-39 depletion factor in the UAr. The detector will be imme rsed in the active liquid Ar volume of ArDM (LSC\, Spain)\, which will act as a veto for gammas from the detector materials and the surrounding rock . In this talk\, I will review the status and prospects of the UAr project s for DarkSide-20k.\n\nhttps://indico.physics.ucsd.edu/event/1/contributio ns/8/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Development of a Pulsed VUV Light Source With Adjustable Intensity DTSTART;VALUE=DATE-TIME:20210917T183000Z DTEND;VALUE=DATE-TIME:20210917T184500Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-30@indico.physics.ucsd.edu DESCRIPTION:Speakers: Austin McDonald (University of Texas at Arlington)\n Precise characterization of photodetectors sensitive to vacuum ultraviolet (VUV) require a calibration source able to:i) produce and transmit photon s in the VUV (128nm - 200nm)\, ii) control the light intensity and reliabl y obtain single photon transmission\, iii) produce a pulsed photon emissi on so as to correlate the source with the VUV readout.In this talk\, we w ill present the development of gas based pulsed spark. This source emits V UV light in the range produced by noble element detectors and is coupled w ith a gas based attenuator capable of delivering single photon intensities to the device under test. We will present the first data taken with this device as well as highlight some of its recent applications in the develop ment of novel VUV photon detectors.\n\nhttps://indico.physics.ucsd.edu/eve nt/1/contributions/30/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/30/ END:VEVENT BEGIN:VEVENT SUMMARY:The LZ Krypton Removal Chromatography System DTSTART;VALUE=DATE-TIME:20210917T180000Z DTEND;VALUE=DATE-TIME:20210917T181500Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-82@indico.physics.ucsd.edu DESCRIPTION:Speakers: Andrew Ames (SLAC\, Stanford University)\nTrace radi oactive noble gases are a source of electron recoil backgrounds in liquid xenon dark matter experiments\, and cannot be mitigated by self-shielding. Naturally occurring krypton\, which contains trace amounts of the beta em itter krypton-85\, is found in commercially available research-grade xenon at a level of 1-100 parts-per-billion. In the LZ dark matter experiment\, we require the xenon in the detector to contain no more than 300 parts pe r quadrillion krypton. This limit reduces the rate of electron recoil even ts from krypton-85 to be comparable to the solar neutrino contribution. To achieve this\, krypton is removed from the xenon using gas charcoal chrom atography prior to its deployment in the detector. In this talk\, I will p resent an overview of the krypton removal chromatography system\, which wa s designed\, built and operated by LZ at SLAC.\n\nhttps://indico.physics.u csd.edu/event/1/contributions/82/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/82/ END:VEVENT BEGIN:VEVENT SUMMARY:Development and characterization of a slow wavelength shifting coa ting for background rejection in liquid argon detectors DTSTART;VALUE=DATE-TIME:20210917T190000Z DTEND;VALUE=DATE-TIME:20210917T191500Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-40@indico.physics.ucsd.edu DESCRIPTION:Speakers: David Gallacher (Carleton University)\nAlpha decays occurring on surfaces of a liquid argon (LAr) detector\, particularly in l ocations where light collection is incomplete\, can result in prompt appar ent low-energy events that reconstruct similar to dark-matter induced nucl ear recoil events. Alphas and nuclear recoils preferentially excite argon into the singlet state\, which decays with a characteristic time of ~6 ns. To convert the argon scintillation light to visible\, a wavelength shifte r\, TPB\, is typically used due to its short (O(ns)) re-emission time\, th at will preserve the LAr scintillation timing. By coating the problematic detector surface with a wavelength shifting coating with a decay time cons tant much longer than the LAr singlet time\, the pulse-shape of alpha deca ys from these regions will be modified by the coating\, with O(10^5) rejec tion efficiency expected. We describe the development of a pyrene-doped p olymeric wavelength shifting film for the DEAP-3600 experiment\, which wil l be deployed in the next major physics run after the completion of a suit e of hardware upgrades to the detector. We will present an overview of the alpha background rejection technique using the long-time constant wavelen gth shifter coating\, the development and testing of the films to ensure c ryogenic stability for operation in a LAr environment\, and the suite of c haracterization measurements of the film’s critical operational paramete rs\, including relative photo-luminescent quantum yield\, emission spectru m\, and characteristic decay time\n\nhttps://indico.physics.ucsd.edu/event /1/contributions/40/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/40/ END:VEVENT BEGIN:VEVENT SUMMARY:Fluorescence light yield and time constants of acrylic (PMMA) exci ted with UV light DTSTART;VALUE=DATE-TIME:20210917T184500Z DTEND;VALUE=DATE-TIME:20210917T190000Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-45@indico.physics.ucsd.edu DESCRIPTION:Speakers: Emma Ellingwood (Queen's University)\nRare-event sea rches\, like those for dark matter or neutrinoless double-beta decay\, go to extreme lengths to mitigate various forms of background. Acrylic (poly (methyl methacrylate) or PMMA) is frequently used as a container for scint illating liquids in rare-event searches. Weak fluorescence has been obser ved in certain types of PMMA at room temperature\, introducing a potential source of background. Building on previous work presented at LIDINE 2019 \, by using the optical cryostat with large numerical aperture located at Queen’s University\, we quantify the light yield of the acrylic used in the DEAP dark matter search from room-temperature down to 4 K\, and expres s it relative to the common wavelength shifter TPB. We also study the tim e constants involved.\n\nhttps://indico.physics.ucsd.edu/event/1/contribut ions/45/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/45/ END:VEVENT BEGIN:VEVENT SUMMARY:CrystaLiZe: A Solid Future for LZ DTSTART;VALUE=DATE-TIME:20210917T181500Z DTEND;VALUE=DATE-TIME:20210917T183000Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-51@indico.physics.ucsd.edu DESCRIPTION:Speakers: Scott Kravitz (Lawrence Berkeley National Lab)\nRado n and its daughter decays continue to limit the sensitivity of WIMP direct dark matter searches\, despite extensive screening programs\, careful mat erial selection and specialized Rn-reduction systems. This problem is only expected to worsen as experiments grow in size. For liquid xenon TPCs\, w e propose to address this through crystallizing the xenon. Once solid\, th e xenon will no longer admit external Rn into the bulk\, allowing existing Rn to decay away. These decays can also be efficiently vetoed using the t ime structure of the decay sequence and the fixed position of daughter iso topes. In this case\, the limiting background for WIMP searches would be n eutrinos from the sun and from cosmic ray muons. In this talk\, I will arg ue that an instrumental radon tag in a crystalline xenon TPC\, perhaps as an upgrade to LZ\, may be the quickest path to reaching the neutrino floor and present preliminary results from a solid xenon test stand which indic ate its viability as a detector medium.\n\nhttps://indico.physics.ucsd.edu /event/1/contributions/51/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/51/ END:VEVENT BEGIN:VEVENT SUMMARY:Results from the Xeclipse Liquid Purification Test System for XENO NnT DTSTART;VALUE=DATE-TIME:20210917T170000Z DTEND;VALUE=DATE-TIME:20210917T171500Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-83@indico.physics.ucsd.edu DESCRIPTION:Speakers: Joseph Howlett ()\nAs liquid xenon detectors grow in scale\, novel techniques are required to maintain sufficient purity for c harges to survive across longer drifts. The Xeclipse test facility at Colu mbia University was built to test the removal of electronegative impuritie s through cryogenic filtration powered by a liquid xenon pump\, making pos sible a far higher mass flow rate than gas-phase purification through hot getters. This talk will outline the results of this R&D\, which were used to guide the design and commissioning of the XENONnT liquid purification s ystem. Thanks to this innovation\, XENONnT has achieved an electron lifeti me greater than 10 milliseconds in an 8.5 ton target mass\, perhaps the hi ghest purity ever measured in a liquid xenon detector.\n\nhttps://indico.p hysics.ucsd.edu/event/1/contributions/83/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/83/ END:VEVENT BEGIN:VEVENT SUMMARY:Modeling the Effect of Impurities on the Electron Lifetime in Liqu id Xenon for nEXO DTSTART;VALUE=DATE-TIME:20210917T173000Z DTEND;VALUE=DATE-TIME:20210917T174500Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-79@indico.physics.ucsd.edu DESCRIPTION:Speakers: Ako Jamil (Yale University)\nnEXO is a 5 tonne liqui d xenon (LXe) time projection chamber (TPC) planned to search for the neut rinoless double beta decay of $^{136}$Xe with a target half-life sensitivi ty of about $10^{28}$ years. Electrons from an event within the TPC will b e drifted up to $1.3\\\,\\mathrm{m}$ and to ensure minimal charge loss nEX O aims to reach an electron lifetime of $10\\\,\\mathrm{ms}$. This lifetim e is inversely proportional to the concentration of electro-negative impur ities\, for which multiple species with different attachment cross-section s may be important. Various sources for impurities such as diffusion out o f commonly used plastics\, desorption from metal surfaces and leaks to atm osphere were investigated. This talk will go over measurements of outgassi ng from plastics and relevant parameters to extrapolate to the effect impu rities have on the electron lifetime in large liquid xenon detectors.\n\nh ttps://indico.physics.ucsd.edu/event/1/contributions/79/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/79/ END:VEVENT BEGIN:VEVENT SUMMARY:Barium Tagging for the NEXT Neutrinoless Double Beta Decay Program DTSTART;VALUE=DATE-TIME:20210917T191500Z DTEND;VALUE=DATE-TIME:20210917T193000Z DTSTAMP;VALUE=DATE-TIME:20260909T030401Z UID:indico-contribution-12-87@indico.physics.ucsd.edu DESCRIPTION:Speakers: Karen Navarro (University of Texas at Arlington)\nTh e NEXT collaboration is pursuing a phased program to search for neutrinole ss double beta decay (0nubb) using high pressure xenon gas time projection chambers. The power of electroluminescent xenon gas TPCs for 0nubb deriv es from their excellent energy resolution (\n\nhttps://indico.physics.ucsd .edu/event/1/contributions/87/ LOCATION: URL:https://indico.physics.ucsd.edu/event/1/contributions/87/ END:VEVENT END:VCALENDAR