XENON1T: First Results (arXiv:1705.06655) Elena Aprile Columbia University Patras Axion-Wimp 2017 May 15-19 Thessaloniki, Greece 1 XENON World ~130 scientists from 22 institutions Laboratori Nazionali del Gran Sasso (LNGS), Italy XENON1T Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 2 Phases of the XENON program XENON10 XENON100 XENON1T / XENONnT 2005-2007 2008-2016 2013-2018 / 2019-2023 15 cm drift TPC – 25 kg 30 cm drift TPC – 161 kg 100 cm / 144 cm drift TPC - 3200 kg / ~8000 kg Achieved (2007) Achieved (2016) Projected (2018) / Projected (2023) σ -44 2 σ -45 2 σ -47 2 σ -48 2 SI = 8.8 x 10 cm SI = 1.1 x 10 cm SI = 1.6 x 10 cm / SI = 1.6 x 10 cm Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 3 The XENON1T Experiment Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 4 The XENON1T Experiment Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 4 July 2013 Uwe Oberlack LNGS SC Meeting - 29-Oct-2013 17 Aug. 2014 XENON1T Cryostat 7 XENON1T Cryostat 7 XENON1T Cryostat 7 XENON1T Cryostat 7 XENON1T Cryostat 7 Time Projection Chamber Eur. Phys. J. C 75, no. 11, 546 (2015) Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 8 Cryostat in the Water Tank Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 9 Cherenkov Muon Veto • Active shield against muons • 84 high-QE 8'' Hamamatsu R5912 PMTs • Trigger efficiency > 99.5% for neutrons with muons in water tank • Can suppress cosmogenic background to < 0.01 events/ton/year • No coincidences with TPC found in this science run JINST 9, 11007 (2014) Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 10 XENON1T: All Systems Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 11 Xenon Plants Cryogenics Purification Cryostat ReStoX Distillation (Recovery/Storage) Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 12 Xe Cooling System Goal: liquefy 3300 Kg of Xe and maintain the xenon in the cryostat in liquid form, at a constant temperature and pressure, and so for years without interruption. Redundant Backup LN2 Design goals: PTR PTR ● Stable temperature and pressure control Heat Exchangers ● Reliable, continuous, long term operation ● Resilience to unexpected failures ● High speed circulation with low additional heat load Vacuum insulation Connection to cryostat GXe flow to active cooling tower(s) Main features: LXe circulation ● Redundant PTR cooling systems ● Backup LN2 cooling tower ● LXe flow back Efficient two-phase heat to cryostat exchangers ● One PTR can be serviced TPC PMT while the other is in cables operation Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 13 Detector Stability • LXe temperature stable at -96.07 ℃, RMS 0.04 ℃ • GXe pressure stable at 1.934 bar, RMS 0.001 bar Slow control/Historian monitoring Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 14 Xe Purification Goal: remove electronegative impurities below 1 ppb (O2 equivalent) in the Xe gas fill and from outgassing of detector’s components with continuous circulation of Xe gas at high speed through hot getters Performance: evolution of e-lifetime, monitored regularly with ERs calibration sources, well described by physical model. Current value approaching the max drift time of the LXeTPC. Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 15 Kr Reduction Eur. Phys. J. C77 (2017) no.5, 275 & arXiv:1702.06942 Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 16 Science Run: Exposure SR0: 34.2 live-days SR1: >60 live-days (analyzed) (blinded) • This talk highlights the analysis of the first science run (SR0) • We continue to take data after the earthquake and analyzing SR1 now Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 17 Energy response S1 S2 • Excellent linearity with E =(nph + ne) · W =( + ) · W g1 g2 electronic recoil energy from 40 keV to 2.2 MeV • g1 = 0.1442 ± 0.0068 (sys) PE/ photon corresponds to a photon detection efficiency of 12.5 ± 0.6% (taking into account double PE emission) • Assumptions of past MC sensitivity projected 12.1%. • g2: the amplification of charge signal corresponds to near full extraction of charges from the liquid. Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 18 Light/Charge Yield Stability From Kr83m and activated Xe131m, variation in LY and CY is at ~1% level. Kr83m Kr83m Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 19 Efficiencies • Detection efficiency dominated by 3-fold coincidence requirement • Estimated via novel waveform simulation including systematic 1.0 uncertainties Detection Selection 0.8 • Selection efficiencies Search region estimated from control 0.6 0.4 samples or simulation Efficiency 0.2 WIMP • Search region defined Events / energy (a.u) 0.0 within 3-70 PE in cS1 0 10 20 30 40 50 60 70 Nuclear recoil energy [keV] Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 20 The ER and NR Models Extraction/ Charge - proportional e drift Charge/ scintillation Real Particle Energy scintillation Data propagation deposit emission γ Optical photon propagation LXe g1, g2, and Geant4 e-lifetime from Model microphysics extraction from simulation real data emission real data PMT/ electronics • Simulate LXe response S1 & S2 LCE microphysics & maps from sim and real data detector response to Trigger & Reconstruction fit Rn220 and AmBe S1 & S2 bias calibration data and smearing from waveform simulator Selection • Background and signal predictions Efficiencies from waveform Samples for from tuned models simulator and real statistical data inference JCAP 1604 no. 4, 027 (2016) or models Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 21 The ER and NR Models Extraction/ Charge - proportional e drift Charge/ scintillation Real Particle Energy scintillation Data propagation deposit emission γ Optical photon propagation LXe g1, g2, and Geant4 e-lifetime from Model microphysics extraction from simulation real data emission real data PMT/ electronics response S1 & S2 LCE maps from sim and real data Trigger & Reconstruction S1 & S2 bias and smearing from waveform simulator Selection 1.0 Detection Selection 0.8 0.6 Search region Efficiencies from ciency waveform Samples for i 0.4 E simulator and real statistical 0.2 data inference 0.0 0 10 20 30 40 50 60 70 or models Nuclear recoil energy [keV] Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 22 Fitting Models to Calibration Novel Rn220 internal source Blue: ER, Red: NR; : median, :±2� 8000 8 10 12 4000 keV ee 2000 1000 Phys. Rev. D 95, 72008 (2017) 400 200 220 • Full modeling of LXe and detector 100 (a) Rn calibration 1 2 3 4 5 6 response in cS2b vs cS1 space Corrected S2 bottom8000 [PE] 40 Corrected S150 [PE] 60 4000 keV nr • All parameters fitted with no 2000 significant deviation from priors 1000 400 200 241 100 (b) AmBe calibration 5 10 15 20 25 30 0 3 10 20 30 40 50 60 70 Corrected S1 [PE] Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 23 Background model 10−1 WIMP Reference: • ER and NR spectral shapes NR median - 2σ 10−2 derived from models fitted to Total calibration data ν ER 10−3 acc Events / PE • Other background expectations n anom −4 are data-driven, derived from 10 wall control samples 0 3 10 20 30 40 50 60 70 Corrected S1 [PE] Background & Signal Rates Total Reference Electronic recoils (ER) 62 ± 8 0.26 (+0.11)(-0.07) Radiogenic neutrons (n) 0.05 ± 0.01 0.02 CNNS (�) 0.02 0.01 Accidental coincidences (acc) 0.22 ± 0.01 0.06 Wall leakage (wall) 0.52 ± 0.32 0.01 Anomalous (anom) 0.09 (+0.12)(-0.06) 0.01 ± 0.01 Total background 63 ± 8 0.36 (+0.11)(-0.07) 50 GeV/c2, 10-46 cm2 WIMP (NR) 1.66 ± 0.01 0.82 ± 0.06 Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 24 Event Selection • Data quality and selection cuts tuned to calibration data Reject gas interactions Expected diffusion Single scatter (WIMP-like) Cut Events remaining All Events (cS1 < 200 PE) 128144 1042 kg Data Quality and Selection 48955 Fiducial Volume 180 S1 Range (3 < cS1 < 70 PE) 63 Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 25 Dark Matter Search 8000 40 Corrected S150 [PE] 60 4000 keVnr Blue: ER 2000 Red: NR : median 1000 :-2� 400 200 100 (c) Dark matter search 5 10 15 20 25 30 Corrected S2 bottom [PE] 50 0 3 10 20 30 40 50 60 70 Corrected S1 [PE] • Extended unbinned profile likelihood analysis • Most significant ER & NR shape parameters included from cal. fits • Normalization uncertainties for all components • Safeguard to protect against spurious mis-modeling of background Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 26 XENON1T Results 10−43 ] 2 arXiv:1705.06655 −44 10 XENON100 (2016) [cm σ PandaX-II (2016) −45 10 LUX (2017) 10−46 XENON1T (this work) WIMP-nucleon 10−47 101 102 103 104 WIMP mass [GeV/c2] Elena Aprile (Columbia) XENON1T: First Results @ Patras Axion-WIMP 2017 27 XENON1T Summary First Dark Matter Search Results from the XENON1T Experiment E. Aprile,1 J. Aalbers,2, ∗ F. Agostini,3, 4 M. Alfonsi,5 F. D. Amaro,6 M. Anthony,1 F. Arneodo,7 P. Barrow,8 • First result paper submitted L. Baudis,8 B. Bauermeister,9 M. L. Benabderrahmane,7 T. Berger,10 P. A. Breur,2 A. Brown,2 A. Brown,8 E. Brown,10 S. Bruenner,11 G. Bruno,3 R. Budnik,12 L. B¨utikofer,13, † J.