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Overview of Dark Matter Searches with Liquid Nobles

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Overview of Dark Matter Searches with Liquid Nobles Overview of Dark Matter searches with liquid nobles Marcin Kuźniak [email protected] 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 1 Outline ● Dark matter detection ● Noble liquid technology ● Physics landscape – High mass WIMPs ● Spin-independent ● Spin-dependent – Low mass WIMPs ● Status of experimental Ar and Xe programs ● Target complementarity ● Main challenges moving forward ● (Biased) selection of new ideas ● Summary 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 2 DM direct detection signature Direct detection ● Only through rare interactions with ordinary matter ● After the interaction, recoiling nucleus deposits energy (heat, 100 GeV WIMP light, electric charge, ...) in the detector Nuclear recoil spectrum ● featureless, ~exponential ● lower threshold =>more sensitivity ● natural radioactivity is a background astrophysics detector response particle/nuclear physics 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 3 Backgrounds 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 4 Liquid noble detectors Excitation Heat Nuclear recoils (NR) Ar and Xe are used for WIMP detection. ● Ar inexpensive and advantageous for purification and background rejection Why noble elements? ● High light yield, transparent to their own scintillation ● Easy to purify and scalable to very high masses ● (At least) two available detection channels: scintillation and ionization 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 5 Single or dual phase DEAP gas DarkSide approach approach Detect primary scintillation light (S1) from the original event. Ionization charge drifted to high field gas phase region and converted to secondary scintillation (S2). ● Time projection chamber (TPC): time diff. S2-S1 and top PMTs used to localize event ● Electronic recoil discrimination: ● S2/S1 in Xe ● In Ar PSD on S1 only is superior (S2 still used for position reconstruction) ● Dual phase: better position resolution (up to a few meters detector size) ● Single phase: higher coverage with photosensors, more scalable, operation simplicity, easier to make radiopure 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 6 Pulse shape discrimination (PSD) Ar singlet and triplet excited states have well separated lifetimes (6ns vs. ~1.5us) Single phase LAr: scintillation channel is sufficient for b/g rejection no need for the ionization channel PMT signal: Prompt : 0-150ns Late: 150ns-10μs Neutron (AmBe) γ(22Na) 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 7 Liquid noble gas experiments single phase XMASS DEAP-3600 Ar Xe LUX Xenon1T ArDM DarkSide-50 LZ dual phase 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 8 Status and prospects Allowed 95% CL region for CMSSM, approx. * * sketched by hand, ● No new WIMP detection claims for illustration ● LAr and LXe dominate searches in the spin-independent sector >~2 GeV/c2 ● Continued search towards the neutrino floor still very well motivated ● see e.g. Roszkowski et al., Rept.Prog.Phys. 81 (2018), 066201 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 9 Status and prospects: high mass Large exposure ● New limits published ~twice a year ● Roadmap in place for reaching the ● Beautiful results from LUX, XENON and PandaX neutrino floor ● Multiple new results from LAr detectors, reducing ● Scale-up requires global consolidation the sensitivity gap of efforts and R&D 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 10 Status and prospects: low mass Low threshold ● Leading exclusions from DarkSide-50 and XENON1T (both S2-only) ● The neutrino floor soon within reach ● Multiple noble liquid-based and other technologies ● Still much work on low-energy calibration still in play in different parts of the mass spectrum and backgrounds (SuperCDMS, CRESST, NEWS-G, DAMIC) ● Room for exciting R&D and new ideas! 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 11 Spin-dependent limits XENON1T, Phys. Rev. Lett. 122, 141301 (2019) PICO-60, Phys. Rev. D 100, 022001 (2019) ● Fluorine based target (PICO-60) remain on the lead for WIMP-proton cross- section ● LXe detectors dominate the WIMP-neutron sector 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 12 New low-mass and SD results from LXe LUX ● Uses prompt scintillation signal consisting of single detected photons ● exploits the double photoelectron emission effect at VUV wavelengths arXiv:1907.06272v1 XENON1T arXiv:1907.11485v1 ● S2-only analysis ● 258 days livetime ● 30% used to inform cuts ● Limit extracted from the rest ● In absence of S1, Z-cut is based on S2 width 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 13 New industry standard: effective field theory ● Allows to more fully explore complementarity between different targets in multiple possible WIMP interaction channels ● Multiple papers and formulations available (NREFT, ChiralEFT, ...) ● Formalism initially developed for SD searches, and first employed by LUX in 2016 – P. Klos et al., PRD 88, 083516 (2013) – LUX, PRL 116, 161302 (2016) ● Then generalized to the SI case and employed by XENON1T for WIMP-pion exclusion in 2019 – M. Hoferichter et al., PRD 94, 063505 (2016) – XENON1T, PRL 122, 071301 (2019) ● Nuclear form factors available for many targets including LXe, and since recently also for LAr, PRD 99, 055031 (2019) ● Codes available online for analysts: WIMPy, ChiralEFT 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 14 XENON1T: WIMP-pion exclusion Phys. Rev. Lett. 122, 071301 (2019) ● ChiralEFT driven interpretation ● Generally, many operators and coupling types and dark matter scenarios can be addressed on similar grounds ● Complementary work to follow soon for LAr experiments 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 15 Other channels ● DM-electron ● Axion-like particles, dark photons: XENON1T arXiv:1907.11485v1 DarkSide-50 Phys. Rev. Lett. 121, 111303 (2018) ● Boosted DM arXiv:1712.07126 So far projections, no published limits 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 16 LAr detectors 20 10 ● More than 300 scientists 10 kg DarkSide-50 (50 kg, LNGS) from 15 countries and 60 institutions ● Officially supported by 100 kg underground labs: LNGS, LSC, and SNOLAB ArDM (1t, LSC) 2 1000 kg 0 15 DEAP-3600 (3.3t, Global Argon Dark Matter SNOLAB) Collaboration formed DarkSide-20k 20 20 (50t, LNGS) 100000 kg Argo: 400 t Slide courtesy J. Monroe 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 17 On Sept. 8, 2017 an information session was held at the Canadian Embassy in Rome to announce the formation of the Global Argon Dark Matter Collaboration, including members from the Darkside-50, DEAP-3600, ARDM and MiniClean collaborations. The membership totals 350 scientists from 68 institutions in 12 countries and has an immediate objective of a 20,000 kilogram detector called DarkSide-20k to be sited at the Gran Sasso Laboratory in Italy, using argon from an underground source in Colorado, USA, with further removal of the isotope 39Ar at a cryogenic distillation column in Sardinia. The overall objective is a reduction of 39Ar content by a factor of more than 15,000 with a high throughput, which will enable a low-background search for the mysterious dark matter, known to account for most of the matter in the universe, but not yet directly observed. A longer term objective of the collaboration is the creation of a detector with 300,000 kg or more low-radioactivity argon at a future site and technology to be determined. This detector will have the capability of reaching to the so-called "Neutrino floor" created by coherent atmospheric neutrino scattering and will have excellent ability to reject low-energy pp solar neutrino events, through the strong electron discrimination capability of liquid argon, providing unambiguous selection of nuclear recoils from weakly interacting massive dark matter candidates. At the same time, it will also have the ability to perform very precise measurements of higher- energy solar neutrinos such as 7Be, pep, and CNO neutrinos. 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 18 DarkSide-50 low-mass limit PRL121, 081307 (2018) S2-only analysis. Ionization-only signal allows sensitive searches for low mass WIMPs: • Two cases: no quenching fluctuations and binomially distributed fluctuations • Background measured at higher energy is extrapolated to low energy Future improvements require reduction of quenching fluctuation systematic and further background reduction 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 19 arXiv:1905.05811 DEAP-3600 status ● Detailed backgrounds model based on the first calendar year of data (~2017, open analysis) ● Unprecedentedly low Rn level ● The best pulse-shape discrimination achieved in LAr ● Collecting blinded data since Jan 2018 ● 20% left non-blind ● Plan to keep collecting data at least until end of 2020 PRD 100, 022004 (2019) 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 20 DEAP-3600 result and plans PRD 100, 022004 (2019) ● Leading WIMP exclusion in Ar ● Acceptance reduced due to cuts against events induced by alpha activity in the neck – Ongoing development of multivariate analysis expected to recover much of acceptance lost due to neck event cuts – In parallel, planning for a hardware upgrade ● Other physics papers in preparation 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 21 DarkSide-20k and beyond ● Urania plant for underground argon Seruci-0 extraction ● ARIA facility for chemical purification and isotopic separation ● Key projects also for Argo 29-08-2019 Marcin Kuźniak – LIDINE2019, Manchester 22 DarkSide-20k LAr veto concept CERN Neutrino Platform: ● 2 almost identical cryostats built
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