Direct Dark Matter Detection with Noble Gases Cristiano Galbiati Princeton University UCLA DM 2018 Los Angeles, CA February 21, 2018 −38 10 0.6 keV Fluctuations No Quenching nr ] 2 10−39 Threshold FluctuationsBinomial [cm −40 SI 10 σ

10−41

−42 DarkSide-50 Binomial 10 DarkSide-50 No Quenching Fluctuation NEWS-G 2018 LUX 2017 XENON1T 2017 PICO-60 2017 arxiv:1802.06994 −43 PICASSO 2017 CDMSLite 2017 10 CRESST-III 2017 PandaX-II 2016 XENON100 2016 DAMIC 2016 CDEX 2016 CRESST-II 2015 −44 SuperCDMS 2014 CDMSlite 2014 Dark Matter-Nucleon 10 COGENT 2013 CDMS 2013 CRESST 2012 DAMA/LIBRA 2008 Neutrino Floor 10−45 −1 5×10 1 2 3 2 4 5 6 7 8 9 10 Mχ [GeV/c ] PandaX @ CJPL

PandaX-I: 120 kg PandaX-II: 500 kg PandaX-xT: PandaX-III: 200 kg to DM experiment DM experiment multi-ton DM 1 ton HP gas 136Xe 2009-2014 2014-2018 experiment 0vDBD experiment Future Future

CJPL-I CJPL-II

＝Particle and Astrophysical Xenon Experiments

3 PandaX-II 54 ton-day results (SI limit)

• Improved from PandaX- PRL 119, 181302 (2017) II 2016 limit about 2.5 time for mass>30 GeV • Lowest exclusion at 8.6×10-47cm2 at 40GeV/ c2 • Most stringent limit for WIMP-nucleon cross section for mass >100GeV

4 PandaX-xT

▪ Intermediate stage: ▫ PandaX-4T (4-ton target) with SI sensitivity ~10-47 cm2

▫ On-site assembly and commissioning: 2019-2020 5 PandaX @ CJPL-II

• Experimental hall B2 secured • Single ultrapure water pool which hosts PandaX-xT and PandaX-III (modules of high pressure 136Xe TPCs)

PandaX CDEX

6 The LUX-ZEPLIN detector

Instrumentation Conduits Existing Water Tank, and SURF Infrastructure The Cathode High-Voltage Feedthrough Gadolinium-Loaded Liquid Scintillator Veto

LXe Heat Exchanger The Outer Detector PMTs (120)

Dual phase xenon TPC, D-D neutron 7 tonnes fully active tube TPC fabrication is underway

Ultraclean Ti cryostat Low Rn cleanroom Cold PMT testing Titanium PMT array arXiv:1702.02646

TPC prototype

1/3 scale TPC grid prototype Ti TPC field ring

Begin on-site assembly spring 2018, install underground 2019, first data spring 2020. Powerful background rejection: outer detector & xenon skin

– 61-cm thick Gd-loaded liquid scintillator in-situ monitoring of • 97% effective for neutron rejection residual backgrounds – Xenon skin layer for gamma rejection

Energy RoI + Single Scatter RoI + SS Cut + All Vetoes

3.2 ton fiducial 5.6 ton fiducial without outer detector with outer detector December Trip to Reynolds

3

First Side Vessel Sally Shaw

1.6 OD – H. Nelson LZ Status & Operations Planning IPR at LBNL - January 9, 2018 13 LZ Spin-Independent WIMP Sensitivity

-3 10-39 LZ 90%CL Median (Baseline) Zeplin-III (2011) -40 -4 LZ 90%CL Median (Goal) PandaX (2016) 10 LUX WS2013+WS2014-16 CMSSM (1σ) -41 -5 XENON1T (2017) 10 CMSSM (2σ) -6 10-42 -7 10-43 ]

-44 2 ) [pb] -8 10 SI p σ [cm (

-45 SI p

10 -9

10 σ log -10 10-46 -11 10-47 -12 10-48 1 event ν-N coherent σ significance -49 -13 scattering 3 10 1000 tonne-years -14 10-50 10 102 103 WIMP mass [GeV/c2]

• Baseline WIMP sensitivity is 2.3 x 10-48 cm2 @ 40 GeV/c2 (arXiv:1703.0914). • 1000 days, 5.6 tonne fiducial mass. • Begin on-site assembly spring 2018, install underground 2019, first data spring 2020. LZ backgrounds summary 5.6 tonnes, 1000 days

Gamma backgrounds Radon dominates (PMTs, cryostat) are ER backgrounds negligible.

pp solar neutrinos, elastic scattering on atomic electrons

Coherent neutrino scattering on xenon nuclei 80

70 100% Background Model Errors

10% Background Model Errors 60 1% Background Model Errors 50

40

30

20

10 Number of WIMP-like events needed 0 0 2 4 6 8 10 Expected number of background events “Zero Background” condition (<0.1 background events) necessary to conduct discovery program DEAP-3600 Status

Mark Boulay DEAP Collaboration: 75 researchers in Canada, UK, Germany and Mexico + new groups joining from DarkSide DEAP-3600 Detector (single-phase) 3600 kg argon in sealed ultraclean Acrylic Vessel (1.7 m ID) very strict control of Vessel is “resurfaced” materials in-situ to remove deposited Rn daughters after construction

255 Hamamatsu R5912 HQE PMTs 8-inch (Light Sensors)

50 cm light guides +

3.5 meters PE shielding provide neutron moderation

Steel Shell immersed in 8 m water shield at SNOLAB

Mark Boulay overview of backgrounds: see Bjoern Lehnert R1-5 Full WIMP ROI alphas on surface full energy alphas neutrons (lose energy) (in argon) degraded α’s

“nuclear recoil band”

γ’s Slide from MG Boulay – TAUP 2017, Sudbury 39Ar “beta/gamma band” PRELIMINARY Slide from MG Boulay – TAUP 2017, Sudbury data collected so far

Planning to collect data until 2020

Currently analyzing 1 year dataset (Nov. 2016 to Nov. 2017) first analysis First Dark Matter Search with DEAP-3600 – 9,870 kg-days July 2017 arXiv:1707.08042

4.4 live days

Selected ROI for < 0.2 leakage from β’s

9,870 kg-day exposure

No events observed in ROI

Mark Boulay WIMP exclusion with DEAP-3600 First Result

DEAP-3600 4.4 days Slide from MG Boulay – TAUP 2017, Sudbury The Global Argon Dark Matter Collaboration ArDM A Single Global Program for Direct Dark Matter Searches DarkSide Currently taking data: ArDM, DarkSide-50, DEAP-3600 DEAP }Next step: DarkSide-20k at LNGS (2021-) MiniCLEAN Last Step: 300 tonnes detector, location t.b.d (2027-) −41 ] 10 2 WARP (2007) −42 DarkSide-20k approved by INFN 10 [cm SI

σ 43 DarkSide-50 (2015) and LNGS in April 2017 and by 10− DEAP-3600 (2017) −44 NSF in Oct 2017 10 LUX (2017)

XENON1T (2017) −45 Officially supported by LNGS, LSC, 10 XENON1T (proj.) PANDAX-II (2017) and SNOLab 10−46 DEAP-3600 (proj.) WIMP-nucleon XENONnT (proj.) 30 tonnes (20 tonnes fiducial) of −47 10 LZ (proj.) DarkSide-20k (100 t yr proj.) DarkSide-20k (200 t yr proj.) low-radioactivity underground −48 10 Future 300-tonne GADMC Detector (1000 t yr proj.) Future 300-tonne GADMC detector (3000 t yr proj.) argon 10−49 Neutrino floor on xenon 14 m2 of SiPM coverage 10−50 10−2 10−1 1 10 WIMP mass [TeV/c2] Questionnaire for Requesting the Status of Recognized Experiment at CERN

The DarkSide Collaboration & The Global Argon Dark Matter Collaboration October 24, 2017

Letter of Intent ​ ​ ​ ​ September 8, 2017 ​ ​ ​ ​ Rev B ​ ​

Scientists at LNGS, LSC, and SNOLAB are joining in an international effort to mount a ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ phased argon dark matter program with the goal of being sensitive to the neutrino floor. This ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ effort will include a broad collaboration of scientists and will represent the global community for ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ dark matter searches with argon. This letter is an update of a previous communication dating ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 2017, which detailed the first conception of the program; this letter was expanded to ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ capture the intent of all institutions and scientists participating in the program. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

In this document, the undersigned representatives of groups working on argon dark ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ matter searches, including Brazilian, Canadian, Chinese, French, German, Greek, Italian, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican, Polish, Romanian, Russian, Spanish, Swiss, US, and UK groups among others, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ memorialize their intent to form a Global Argon Dark Matter Collaboration to carry out a program ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ for direct dark matter searches, consisting of two main elements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

The first element of the program is the DarkSide-20k experiment at LNGS, whose ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ science goal is to perform a dark matter search with an exposure of 100 tonne·yr of ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ low-radioactivity underground argon (the low intrinsic background, free from any background ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ other than that induced by atmospheric neutrinos, may also permit a 200 tonne·yr exposure for ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ extended operation). This detector will be competitive with next generation liquid xenon dark ​ ​ ​ ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ matter searches at high WIMPs masses and will be built in time to start data taking by 2021. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

The second element of the program is a low-radioactivity underground argon detector ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ with a fiducial mass of a few hundred tonnes. The science goal is to perform a dark matter ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ search with an exposure of 1,000 tonne·yr with sensitivity reaching to the neutrino floor, to ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ identify coherent nuclear scattering of atmospheric neutrinos, and to perform a high-precision ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8​ ​ ​ measurement of intermediate energy solar neutrinos (pep, CNO, low energy B​ ). All groups ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​​ ​ ​ ​ have agreed to the continuing collaboration towards the development of a depleted argon ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ detector at the scale of a few hundred tonnes, working together to select a design and site ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ based on technical and scientific requirements. Decisions on technical design will be informed ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ by data collected with the precursor DEAP and DarkSide detectors. The groups will also ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​ ​ ​ ​ ​ ​ develop low radioactivity argon to allow for the multi-hundred tonne detector. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

The proposal to build DarkSide-20k, submitted to the Italian INFN and to LNGS, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ reviewed well, and INFN and LNGS approved the DarkSide-20k experiment in April 2017. The ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ scope of the INFN contributions is €40M. The proposal submitted to the US NSF reviewed well, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and the collaboration is now awaiting the approval decision by the US NSF. The capital funding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​​ ​ ​ ​ ​ ​ for DarkSide-20k under discussion with the US NSF is $13M. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Deep underground laboratory support for global collaboration towards discovery of dark matter utilising liquid argon detectors.

To whom it may concern;

As hosts of the existing operational liquid argon direct dark matter detectors, and as proponents and supporters of the Underground-GRI initiative, the LNGS, SNOLAB and LSC deep underground research facilities are pleased to recognize the collaborative developments within the global liquid argon dark matter community. The DarkSide project at LNGS, the DEAP project at SNOLAB and the ArDM project at LSC are all developing new technologies and capabilities to search for WIMP dark matter, and are beginning to coalesce into one collaboration to develop future, larger generations of liquid argon direct dark matter detectors. We encourage and support the development of this global community, with a focus on the development of DarkSide-20k at LNGS in the first instance, and a larger detector at a location to be determined from scientific requirements, in the future. Using available assay and research infrastructure, the three deep underground research facilities will support the activities and development of the various generations of liquid argon detectors.

Aldo Ianni Stefano Ragazzi Nigel J.T. Smith Director, LSC Director, LNGS Director, SNOLAB

Urania to Aria to LNGS

• Volatilità relative => 1.007

• Valori tipici >1.5

• Numero di stadi teorici => ordine delle migliaia

• HETP = 10 cm

• H=200-400 m

• Usuali = 20-30 m

• Fuori terra 325 m

• A sezioni separate

DarkSide-50 • P. Agnes et al. (The DarkSide Collaboration), “DarkSide-50 532-day Dark Matter Search with Low- Radioactivity Argon”, arxiv:1802.07198.

• P. Agnes et al. (The DarkSide Collaboration), “Constraints on Sub-GeV Dark Matter-Electron Scattering from the DarkSide-50 Experiment”, arxiv: 1802.06998.

• P. Agnes et al. (The DarkSide Collaboration), “Low- mass Dark Matter Search with the DarkSide-50 Experiment”, arxiv:1802.06994. Ionization-Only (S2-Only) Signals

1. The PMTs have zero dark rate at 88 K so a signal is always real

2. The gain in the gas region (~70 PE/e-, reduced to 23 PE/e- when accounting for the 30% QE of the PMTs) means that we are sensitive to a single extracted electron

3. The radioactivity rate in the detector is remarkably low, so …

4. We don’t need PSD

5. The electron yield for nuclear recoils rises at low energy 0.4 e- 0.5 10 eVee 0.45 10% Detector 0.4 Threshold 4 e- 100 eVee 0.35 Analysis 0.3 Threshold

0.25

Fiducialization

Acceptance 0.2 arxiv:1802.06994 0.15 × Trigger efficiency

S2 Identification (f <0.15) 0.1 × 90

0.05

0 10 20 30 40 50 60 70 80 90 S2 [PE] DS-50 DATA Center PMT Getter Off 102 Getter On

day] Fit

× - 1 Ext. e - kg

10 2 Ext. e 's ×

- e N

1 [0.05

/ arxiv:1802.06994 PE

10−1 Events S2=30

10−2 0 0.5 1 1.5 2 2.5 3 Ne- 103 0.6

First 100 days day] L/K BR Ratio = 0.11 ± 0.01

2 × 10 Last 500 days kg

day] 0.4 × ×

Single S2(500d) - e 10

S1 + S2(500d) [N

kg

/ 0.2

×

- e 1 0

Events 0 50 100 Ne- 10−1 arxiv:1802.06994

10−2 Events / [0.5 N

10−3 0 20 40 60 80 100 Ne- 900

241 800 AmBe Data G4DS Fit 700 Single S2 S1 + S2

- 600 e

500

400

Events / N 300 arxiv:1802.06994

200

100

0 10 20 30 40 50 60 70 80 90 100 Ne- 100

90 241Am13C Data G4DS Fit 80 Single S2 70 S1 + S2 241 13

- Am C γ e 60

50

40 Events / N arxiv:1802.06994 30

20

10

0 10 20 30 40 50 60 70 80 90 100 Ne- EAr [keVnr] 10−2 10−1 1 10 102 10 1 10 102 103 9 EXe [keVnr]

8

7 ]

nr 6

/keV 5 - Xe Data

[e 4 LUX 2016 y

Q ZEPLIN-III 2011 arxiv:1802.06994 3 XENON10 2011 Ar Data Manzur et al. 2010 ARIS 2 XENON10 2009 SCENE Aprile et al. 2006 AmBe - AmC - ARIS - SCENE 1 Xe Model Joshi et al. 2014 Bezrukov et al. 2011 Joshi et al. 2014 Cross Calibrated 0 10−3 10−2 10−1 1 ε 232Th Cryo 105 40K 60Co 238 238 Ulow Uup 235 85 104 U Kr 39Ar DATA

103

102 arxiv:1802.07198 Events / [2 keV]

10

3 1 ×10 0 0.5 1 1.5 2 2.5 3 Energy [keV] E [keVnr] 1 2 3 4 5 6 7 8 9 10 11 12 131415 102 1 2 3 ee E [keV ] 3 10 2 DM spectra σ =10-40 cm2 Data 10 10 χ 2 G4DS MC All Mχ=2.5 GeV/c day] day] day] Cryostat γ-rays × 2 × × M =5.0 GeV/c2 10 χ PMTs γ-rays 10 2 39 85 kg 1 Mχ=10.0 GeV/c Ar + Kr kg kg × × ×

ee nr - e 10 1 10−1 arxiv:1802.06994 1 10−1 −2 Events / [keV Events / [keV

Events / [N 10

10−1 10−2 10−3 0 5 10 15 20 25 30 35 40 45 50 Ne- −38 10 0.6 keV Fluctuations No Quenching nr ] 2 10−39 Threshold FluctuationsBinomial [cm −40 SI 10 σ

10−41

−42 DarkSide-50 Binomial 10 DarkSide-50 No Quenching Fluctuation NEWS-G 2018 LUX 2017 XENON1T 2017 PICO-60 2017 arxiv:1802.06994 −43 PICASSO 2017 CDMSLite 2017 10 CRESST-III 2017 PandaX-II 2016 XENON100 2016 DAMIC 2016 CDEX 2016 CRESST-II 2015 −44 SuperCDMS 2014 CDMSlite 2014 Dark Matter-Nucleon 10 COGENT 2013 CDMS 2013 CRESST 2012 DAMA/LIBRA 2008 Neutrino Floor 10−45 −1 5×10 1 2 3 2 4 5 6 7 8 9 10 Mχ [GeV/c ] E [keVee] 0.2 0.4 0.6 0.8 1 1.2 102

DM spectra σ =10-36 cm2 Data 10 χ 2 G4DS MC All Mχ=10 MeV/c

day] Cryostat γ-rays × M =100 MeV/c2 χ PMTs γ-rays 2 39 85 1 Mχ=1000 MeV/c Ar + Kr kg ×

- e

10−1 arxiv:1802.01427 arxiv:1802.06998

−2

Events / [N 10

10−3 0 5 10 15 20 25 30 Ne- 10−36 ] 2 [cm e σ 10−37

10−38 arxiv:1802.06998

FDM=1 DarkSide-50 XENON100 Dark Matter-Electron XENON10

10−39 10 102 103 Mχ [MeV] The End