Liquid Noble DM Detectors Hugh Lippincott Cosmic Science Working - PowerPoint PPT Presentation

Liquid Noble DM Detectors Hugh Lippincott Cosmic Science Working Group 20 April 2017

Current status DS-50 – 2.6 tonne-day exposure LAr, background free (50 kg fiducial, 50 days) Xenon100 – 17.6 tonne- day exposure LXe, ~5 events (30-40 kg fiducial, ~500 days) PandaX-II – 33 tonne-day exposure, ~3 events (334 kg fiducial, ~100 days) LUX – 40 tonne-day exposure, ~3 events (100 kg fiducial, ~400 days) 2 4/20/17 Presenter | Presentation Title or Meeting Title

Very near future DS-50 – Still running, expect ~40-50 tonne-day exposure (half that in hand), after another 2 years (x20 improvement) DEAP-3600 – full since November, 500 tonne-days raw exposure so far (my guess would be ~100 tonne-days with fiducial cuts, maybe matches LUX) 3 4/20/17 Presenter | Presentation Title or Meeting Title

Very near future PandaX-II – still running, up to factor x3 improvement at this point? XENON1T – Running interrupted by earthquake in January, >=40 days in hand, supposedly 1 ton fiducial (would match LUX exposure) 4 4/20/17 Presenter | Presentation Title or Meeting Title

Near future -43 10 LZ projected σ 5 Median Significance σ -44 -8 3 Median Significance 10 90% CL Median (Baseline) XENON1T 90% CL -45 10 ) [pb] ] 2 [cm SI -46 p -10 10 σ ( SI 10 p σ log -47 10 -48 -12 10 significance n t e ν v e σ -N coherent 1 3 1000 tonne-years scattering -49 10 3 2 10 10 10 } 2 WIMP mass [GeV/c ] LZ – 5.6 ton fiducial – begins 2020 (trying to advance) Nothing revolutionary XENONnT – 86% LZ by mass – upgrade to begin in in design 2018 in parallel with XENON1T operation 5 4/20/17 Presenter | Presentation Title or Meeting Title

Mid to long term future - Argon • DarkSide-20K – “start operation 2021…” – Merger of DS50, DEAP, MiniCLEAN, ArDM – 20 tonne argon, two phase TPC – Approved at INFN as of this month – SiPMs for light readout • SNR decreases with increasing surface area • 5x5 cm tile demonstrated in March – Low radioactivity (Ar39 depleted) argon • Aria – isotopic purification using distillation column the size of Eiffel tower – under construction • Urania – underground argon at large scale • Argo/DEAP-nT - mid 2020s – Kton –year exposures – R&D starting now (e.g. digital SiPM array) 6 4/20/17 Presenter | Presentation Title or Meeting Title

Mid to long term future - Xenon • • LZ – not currently working on G3 DARWIN – successor to XENON – – Can break 1e-48 barrier if hit targets 40ton active (~$100M in xenon, worlds annual production) – Expecting 0.5 neutrino events in – 1000 days (2020-2023) Not that much bigger than LZ/XENONnT – Proposed project start in 2019-2020 -41 10 -42 10 -43 DarkSide-50 10 ] 2 XENON100 PandaX Cross Section [cm -44 X U 10 L -45 10 DEAP-3600 XENON1T -46 10 XENONnT / LZ -47 10 DarkSide-20k -48 y) 10 × DARWIN (200 t -line (Billard) ν -49 10 5 6 8 10 20 30 40 60 100 200 400 600 1000 2 WIMP mass [GeV/c ] 7 4/20/17 Presenter | Presentation Title or Meeting Title

Xenon-Argon ~100 GeV WIMP considerations • Xenon is a better target for the most part – At high mass, 3.2x better sensitivity per unit mass – At low mass, >>3.2x better sensitivity (lower threshold) – More flexible physics • Spin dependent couplings, double beta decay, axion searches, electron interaction searches, etc – Denser (better self-shielding, smaller detectors/unit mass) – Not as cryogenic – 165K vs 85K (may have been a factor in PMT operation) • Two major exceptions – Cost – raw material is much more expensive • Although the effort needed to find low radioactivity argon is significant. Unclear how this scales, probably argon still comes out way ahead for ~100 tonne scales, assuming it works – Electron recoil rejection • Rn/pp solar neutrinos are the biggest backgrounds in LZ/XENONnT. Because ER rejection is only ~1e-3-1e-4, you need to do really well at radon mitigation. Argon does not have this problem (~1e-8 or better) • How important is the last decade to the neutrino floor? – LZ expects 0.5 neutrinos, so diminishing returns starts then – ~x50 increase in exposure gives ~x10 sensitivity 8 4/20/17 Presenter | Presentation Title or Meeting Title

Other ideas • Xenon – Doping with He/Ne for low mass sensitivity – use existing detector, extend reach down to 1 GeV or below in optimistic scenario (my EC proposal from 2015) • Not competitive with dedicated detector like SuperCDMS, but not too bad either Reach thermal DM production parameter space in <1 year! – Single electron counting – P. Sorensen at CV workshop • Optimize on S2, forget about S1 The only existing limits on dark sector DM are from liquid xenon targets • R&D on eliminating electron backgrounds observed in LUX/XENON100 • Proposal for 10 kg scale, could then scale up and observe freeze-in/freeze-out regions ���� ������ - ������� ����� ������� [ �� � ] ���� ������ - ������� ����� ������� [ �� ] �� - �� �� - � �� - �� �� - � �� - �� �� - � LZ Helium S2-only Xe ������ �� �� - �� �� - � 3 events �� - �� �� - � �������� �� 1 kg-year �� - �� �� - � � � � � LZ Helium Xe �� - �� �� - � � � � � 3 events �� - �� �� - � � �� ν 1 kg-year LZ Neon �� - �� � � ν �� - � LZ Xe � � � �� - �� ��� � � �� �� ��� ���� ������ ���� [ ��� / � � ] 8 plots from Essig et al, cf. arXiv:1703:00910 9 4/20/17 Presenter | Presentation Title or Meeting Title

Superfluid helium detector (Hertel, McKinsey, etc) : partitioning • Aiming for 1 MeV to 1 GeV dark matter Nuclear Recoil – Detection of either He recoils (100 MeV 1 dm masses) or electron recoils (<100 0.8 Energy Fraction MeV) 0.6 • Excitations in superfluid He 0.4 ound up. – Excimers (He2* molecules, created with 0.2 eV-scale excitations) 0 – Photons, rotons, at meV scale 10 1 10 2 10 3 10 4 10 5 Recoil Energy [eV] • Demonstration of excimer detection George Seidel, unpub. Electron Recoil 1 using TES sensors in He (1605.00694) Singlet Excimers Triplet Excimers 0.8 • Rotons are “high-momentum phonons” IR photons Energy Fraction Phonons/R-/R+ 0.6 – Difficult to detect, but many ideas (HERON, quantum evaporation) 0.4 0.2 0 10 1 10 2 10 3 10 4 10 5 Recoil Energy [eV] 23 10 4/20/17 Presenter | Presentation Title or Meeting Title

Superfluid helium detector (Hertel, McKinsey, etc) • Backgrounds – Standard radioactivity, neutrinos, gammas (LHe is radiopure) – Alan’s gamma-NR background – Arguments for low dark rate • Can do ER discrimination using excimers at 20 eV and above 1 kg-y, superCDMS bg levels, 5eV calorimeter, some assumptions on roton detection 11 4/20/17 Presenter | Presentation Title or Meeting Title