3rd Berkeley Workshop on the Direct Detection of Dark Matter
DARKSIDE:CHALLENGES, PERSPECTIVES AND PLANS
Emilija Pantic UC DAVIS for the DarkSide collaboration
- DarkSide-50 brief intro and status - DarkSide-20k CPP
Look for references here 1 [email protected] http://darkside.lngs.infn.it/collaboration 26 DarkSide-50 LAr dual phase TPC 3D positioning O (few mm) Light + Charge S2/S1 discrimination of ERs Pulse shape discrimination of ERs f90 = fraction of S1 in the first 90ns 1
Eextr 90 f 35000 S2 0.9 0.8 Nuclear Recoils 30000 50% 65% - - 0.7 80% e e 90% 25000 - - Edrift e e 0.6 e- e- 200V/cm 20000 f90 0.5
S1 0.4 15000
0.3 Electronic Recoils 10000 0.2 5000 0.1
0 0 1 100 150 200 250 300 350 400 450 46kg of LAr S1S1 [PE] [PE] 38 3” PMTs 7 TPB as wavelength shifter ER Rejection power >10 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop cathode/anode = ITO on fused silica 83mKr S1 Light Yield: Teflon as reflector 7.0 ± 0.3 PE/keV @ 200 V/cm extraction grid 2 First Results from the DarkSide-50 Dark Matter Experiment at LNGS, Phys.Lett. B 743 26 DarkSide-50 Veto Detectors: 30t Liquid Scintillator Veto (LSV) = TMB + PPO + PC 1000t Water Cherenkov Veto (WCV) Neutrons that scatter in the TPC can be detected via capture
signal on 10B or thermalization signal in LSV. radiopure Tag radiogenic n Tag radiogenic � Tag cosmogenic n � � n prompt prompt
LSV delayed LSV LSV
Water WCV WCV WCV Pantic (UC Davis) on DarkSide @ Berkeley Workshop 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop >99.1% efficiency to veto radiogenic neutrons via delayed capture on 10B and 1H (AmBe + MC) 3 The veto system of the DarkSide-50 experiment, JINST 11, no.03, P03016 (2016) 26 Intrinsic background of Underground Argon With respect to Atmospheric Ar: > factor of 300 reduction of intrinsic radioactivity in UAr ~ factor of 1400 reduction of 39Ar activity −1 10 AAr Data at 200 V/cm
s] (LSV Anti-coinc.) × −2 UAr Data at 200 V/cm Multidim. 10 39Ar in (LSV Anti-coinc.) kg 85
× Kr (Global Fit) spectral fit of 10−3 atmospheric Ar MC (g4ds) on 1000 mBq/kg 39Ar (Global Fit) AAr/UAr 10−4 plus delayed −5 coincidence 10 tagging 39Ar in 10−6 Events / [50 PE underground Ar −7 10 0.73± 0.11 mBq/kg Pantic (UC Davis) on DarkSide @ Berkeley Workshop 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop 10−8 0 1000 2000 3000 4000 5000 6000 S1 [PE]
Background in ROI = ~50% β-events + ~50% of �-events 4 Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016) 26 Dark Matter search data for 70d UAr Reject: Select abnormal clustering of S1 signal Single scatters AAr prompt/delayed signal in LSV Use Hinkley f90 model preceding �-like event in vetoes Fit to AAr data Scale to UAr data UAr top and bottom of TPC in drift Derive 0.01 ER leakage ev. / S1 bin Energy [keVnr] 20 40 60 80 100 120 140 160 180 200 1 90 f 0.9 WIMP Search Region 250 0.8 50% 0.7 90% 99% 200 0.6 No events in the NR acceptance contours from AmBe in WIMP search 0.5 150 DS50 + SCENE region. 0.4 100 0.3
0.2 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop 50 0.1 0 0 50 100 150 200 250 300 350 400 450 S1 [PE] 5 Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016) 26 Latest DarkSide-50 Dark Matter search result 0.007 t yr 3 42 10 10 0.01 t yr ] 2
DarkSide-50 2 LUX3yr projection WS2013 43 10 DarkSide–50 2015 10
LUX WS2014–16
1 XENON100 2016 44 10 10
8B PandaX–IILUX 2016 WS2013+WS2014–16 LUX WS2013 0 45 10 10
1 46 10 10 WIMP–nucleon cross section [zb] Pantic (UC Davis) on DarkSide @ Berkeley Workshop 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop WIMP–nucleon cross section [cm 2 10 101 102 103 104 105 WIMP Mass [GeV/c2] 6 Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016)! PLOT adapted from Results from a search for dark matter in the complete LUX exposure arXiv:1608.07648 (2016) 26 DarkSide-50 Short Term Plan New data almost one full year: -test and utilize blind analysis in steps -re-optimize full analysis chain -implement improved background model for 30 0 V/cm ERs 20 10
38000 40000 42000 44000 46000 -finalize background model for “Cherenkov S1 [PE] 6 50 V/cm plus ER” events 4 2
38000 40000 42000 44000 46000 Other studies/publications: ! S1 [PE] 15 100 V/cm -G4DS simulation framework! 10 -G4DS recombination model ! 5 -ER background spectrum! Counts 38000 40000 42000 44000 46000 S1 [PE] -f90 model! 10 150 V/cm
-alpha background! 5 -alpha yield**!
38000 40000 42000 44000 46000 800 S1 [PE] -combined energy scale! 200 V/cm -detector performance! 600 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop 400 -CALIS*! 200
-S2/S1! 38000 40000 42000 44000 46000 -Effective field theory S1 [PE] 7 *CALIS - a CALibration Insertion System for the DarkSide-50 dark matter search experiment - Paper submitted! **Effect of Low Electric Fields on Alpha Scintillation Light Yield in Liquid Argon - Paper submitted 26 DarkSide-20k challenges and status
2.9m 0.35m
16m 8m 4m
10m Pantic (UC Davis) on DarkSide @ Berkeley Workshop 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop @LNGS @LNGS 11m 15m 8 26 How to collect 50 000 kg of underground argon and then purify and distill to arrive to 30 000 kg by 2020 ? Pantic (UC Davis) on DarkSide @ Berkeley Workshop 2016 Pantic (UC Davis) on DarkSide @ Berkeley Workshop
9 Each purification or distillation step introduces a loss. 26 URANIA and ARIA Urania UAr extraction/ purification@100kg/d Ar extraction expected to Extraction&purification