Dark Matter Direct Detection Status and Prospects

Jocelyn Monroe, Royal Holloway, University of London

2019 International Workshop on Baryon and Lepton Number Violation Institute for Theoretical Physics, Madrid, ES October 24, 2019 Big Questions for the Dark Sector (a la European Strategy for Particle Physics Update 2019)

1) How do we search for dark matter, depending on its properties?

2) What are the highlights and challenges of the experimental programs, current or near-future, that address different regions of parameter space?

3) How can dark matter detection experiments inform/guide energy and intensity frontier experiments, and vice versa?

Jocelyn Monroe Oct. 24, 2019 / p.2 Big Questions for the Dark Sector (a la European Strategy for Particle Physics Update 2019)

1) How do we search for dark matter, depending on its properties?

2) What are the highlights and challenges of the experimental programs, current or near-future, that address different regions of parameter space?

3) How can dark matter detection experiments inform/guide energy and intensity frontier experiments, and vice versa?

Jocelyn Monroe Oct. 24, 2019 / p.2 χ χ Gravitational Detection Indirect Detection ? e-,ν,γ e+,p,D

Direct Detection Accelerator Production χ χ jet

p p

N N’ χ χ Jocelyn Monroe Oct. 24, 2019 / p.3 Dark Matter Direct Detection

Signal:χN ➙χN χ χ

Backgrounds: γ e- ➙ γ e- n N ➙ n N N ➙ N’ + α, e- ν N ➙ ν N

experimental requirements: particle ID for recoil N, e-, alpha, n (multiple)γ ﬁnal states γ Jocelyn Monroe Oct. 24, 2019 / p.4 1 E = m v2 WIMP Scattering χ D 2 D χ kinematics: v/c ~ 8E-4! q2 = 2m E recoil angle strongly correlated T recoil 4mDmT with incoming WIMP direction r = 2 (mD + mT ) N N (1 cosq) E = E r recoil D 2

Spin Independent: χscatters coherently off of the entire nucleus A: σ~A2 D. Z. Freedman, PRD 9, 1389 (1974)

Spin Dependent: mainly unpaired nucleons contribute to scattering amplitude: σ~ J(J+1)

experimental requirements: measure recoil energy, time, +angle Jocelyn Monroe Oct. 24, 2019 / p.5 100 GeV/c2 WIMP mass Observable: Recoil Energy 1E-45 cm2 WIMP-nucleon SI σ

10 χ

Scintillation

1 χ Heat

0.1 Ionization

experimental requirements: ~1-10s of keV energy threshold, very low backgrounds

Jocelyn Monroe Oct. 24, 2019 / p.6 Backgrounds ? N Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils

Contamination: 238U and 232Th decays, recoiling progeny and 2008 mis-identiﬁed alphas, betas mimic nuclear recoils

Neutrons: 2018 Nuclear recoil ﬁnal state. (alpha,n), U, Th ﬁssion,

cosmogenic spallation pp solar neutrinos μ μ γ N* N D. Malling, UCLA DM’16 n Thanks to L. Baudis

Jocelyn Monroe Oct. 24, 2019 / p.7 Backgrounds ? N Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils

Contamination: 238U and 232Th decays, recoiling progeny and 2008 mis-identiﬁed alphas, betas mimic nuclear recoils

Neutrons: 2018 Nuclear recoil ﬁnal state. (alpha,n), U, Th ﬁssion,

cosmogenic spallation pp solar neutrinos μ μ γ N* N D. Malling, UCLA DM’16 n Thanks to L. Baudis

Jocelyn Monroe Oct. 24, 2019 / p.8 Backgrounds ? N Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils

Contamination: 238U and 232Th decays, recoiling progeny and D.-M. Mei, A. Hime, PRD73:053004 (2006) mis-identiﬁed alphas, betas mimic nuclear recoils

Neutrons: Nuclear recoil ﬁnal state.

(alpha,n), U, Th ﬁssion, Boulby cosmogenic spallation μ μ γ N* N n + discrimination between e- vs. N

Jocelyn Monroe + large, active neutron shielding Oct. 24, 2019 / p.9 Irreducible Backgrounds impossible to shield a detector from coherent neutrino scattering! • “neutrino ﬂoor:” both ν-N and ν-e ν ν contribute backgrounds

Z Φ(solar B8) = 5.86 x 106 cm-2 s-1

N N

Aprile et al., JCAP04 (2016) 027 nuclear recoil ﬁnal state neutrino bound at 10-46-10-48 cm2 in zero-background paradigm JM, P. Fisher, PRD76:033007 (2007) Fisher, JM, P. unless you measure the direction!

Jocelyn Monroe Oct. 24, 2019 / p. 10 Irreducible Backgrounds impossible to shield a detector from coherent neutrino scattering! • “neutrino ﬂoor:” both ν-N and ν-e ν ν contribute backgrounds

Z Φ(solar B8) = 5.86 x 106 cm-2 s-1

N N

Aprile et al.al.,, JCAP04JCAP16 04(2016) (2016) 027 027 nuclear recoil ﬁnal state neutrino bound at 10-46-10-48 cm2 in zero-background paradigm JM, P. Fisher, PRD76:033007 (2007) Fisher, JM, P. unless you measure the direction!

Jocelyn Monroe Oct. 24, 2019 / p. 10 Modulation Signatures Annual event rate modulation: June-December asymmetry ~2-10%. Drukier, Freese, Spergel, Phys. Rev. D33:3495 (1986)

Sidereal direction modulation: asymmetry ~ 20-100% in forward-backward event rate. Spergel, Phys. Rev. D36:1353 (1988) need precise detector stability, + readout capable of direction measurement

Jocelyn Monroe Oct. 24, 2019 / p.11 Big Questions for the Dark Sector (a la European Strategy for Particle Physics Update 2019)

1) How do we search for dark matter, depending on its properties?

2) What are the highlights and challenges of the experimental programs, current or near-future, that address different regions of parameter space?

3) How can dark matter detection experiments inform/guide energy and intensity frontier experiments, and vice versa?

Jocelyn Monroe Oct. 24, 2019 / p.12 Direct Detection Status

Wide range of parameters! Direct detection searches historically optimised for WIMP sensitivity...

Baer et al., arXiv:1407.0017

Jocelyn Monroe Oct. 24, 2019 / p.13 −37 10 CRESST-III 2019 −38 Direct Detection Status10 and CDMSLiteProspects 2017 ] 2 10−39 excluded* at 90% DarkSide-50 2018 conﬁdence level 10−40 Wide range of parameters! [cm

SI −41 σ 10 Direct detection searches historically10−42 optimised for WIMP sensitivity... DEAP-3600 2017 −43 DEAP-3600 2019 10 SuperCDMS proj. DarkSide-50 2018 LUX 2017 10−44 +huge growth of axion-like DM industryPANDAX-II! 2017 DarkSide-LM proj. DEAP-3600 proj. 10−45 XENON1T 2018 Xenon 1TXENON1T (2017) Ionization Signals Xenon-nT2019 LZ proj. 10−46 proj. XENONnTyr proj. −47 t× 10 proj. t× yrproj. −48 DarkSide-20kt× yr 200 10 DARWIN 200 Dark Matter-Nucleon Argo 3000 −49 10 Neutrino floor on xenon 10−50 −3 −2 −1 2 10 10 10 2 1 10 10 Mχ [TeV/c ]

Baer et al., arXiv:1407.0017

Jocelyn Monroe Oct. 24, 2019 / p.13 Low Mass Prospects: Solid State Detectors Detector Technology: Phonons: SuperCDMS and EDELWEISS (Ge), Phonons: CRESST (CaWO4) crystal bolometers with TES for Erecoil & R (timing) TES for Erecoill Transition Edge Sensor readout at O(10 mK) for phonon detection + scintillation/ionization h+ + many new ideas (e.g. skipper CCDs, high e- pressure gas ….)

Charge: biased at V, used to measure Scintillation: Erecoil, conﬁgured to reject surface events TES for particle ID detectors reach energy thresholds of < 1 keV, with FWHM < 0.3 keV e.g. PRD 99 (2019) 082013

Jocelyn Monroe Oct. 24, 2019 / p.14 Large Mass Prospects: Liquid Noble Detectors

Detector Technology: dual-phase Time Projection Chambers with multi-tonne liquid Xe, Ar targets

read out primary scintillation: “S1” + proportional gas scintillation from drifted electrons: “S2”

https://lz.slac.stanford.edu/our-research/lz-research

Jocelyn Monroe Oct. 24, 2019 / p.15 Liquid Noble Targets particle identiﬁcation: light vs. time depends on ionization density.

(Argon example)

high light yield, purifyable target, self-shielding, transparent to VUV scintillation, … Amaudruz et al. Astropart.Phys. 85 (2016) 1-23

Jocelyn Monroe Oct. 24, 2019 / p.16 Xenon Detectors Xenon100

XENON 10 (LNGS) ZEPLIN (Boulby)

10 kg 2010

XENON 100 (LNGS) 100 kg LUX (250 kg, SURF), PANDA-X XMASS 2015 (500 kg, CJPL) Aprile et al, arXiv:1805.12565 (0.8t, Kamioka)

1,000 kg XENON 1T (1t, LNGS)

PandaX-4:(4t, CJPL) 2020 XENONnT: (6t, LNGS) LZ: (7t, SURF) 10,000 kg

Future: DARWIN: 50 t Jocelyn Monroe Oct. 24, 2019 / p.17 Argon Detectors Xenon100 DarkSide-50: leading SI limit at 1-5 GeV/c2 for WIMP-nucleus and WIMP-e scattering

Agnes et al., Phys. Rev. Lett.121.081307 (2018) 2010 DarkSide-50 10 kg (50 kg, LNGS) low mass frontier here!

100 kg ArDM (1t, LSC) 1,000 kg 2015

DEAP-3600 (3.6t, SNOLAB) Global Argon Dark Matter 10000 kg Collaboration formed

2020 10,000 kg DEAP-3600: parts-per-billion level “S1” particle ID, 100,000 kg ultrapure acrylic cryostat DarkSide-20k (50t, LNGS) Ajaj et al,Phys. Rev. D (2019)

Future: ARGO: 400 t Jocelyn Monroe Oct. 24, 2019 / p.18 Technology Synergies DarkSide-20k

1. Cryostat technologies: DarkSide-20k cryostat uses technology developed for ProtoDUNEs (1) 2. Photon sensors: low noise, high efﬁciency, cryo Si sensors developed by DarkSide-20k with FBK (LHC Si) 3. Isotopic enhancement: ARIA facility for depletion of Ar-39 in UAr, CERN Vacuum Group collaboration

ProtoDUNE (3) + Data (2) - 1 PE fit - 2 PE fit - 3 PE fit - 4 PE fit 5 cm x 5 cm - 5 PE fit tiled SiPM for comparison:

Charge (Arb. Units) Aalseth, et al. JINST 12 (2017) no.09, P09030

Jocelyn Monroe Charge[Arb. Units] Sept. 24, 2018 / p.16 Technology Synergies DarkSide-20k

ProtoDUNE (3) + Data (2) - 1 PE fit - 2 PE fit - 3 PE fit - 4 PE fit 5 cm x 5 cm - 5 PE fit tiled SiPM for comparison:

Charge (Arb. Units) Aalseth, et al. JINST 12 (2017) no.09, P09030

Jocelyn Monroe Charge[Arb. Units] Sept. 24, 2018 / p.16 Spin-Dependent Interactions

Direct Detection: leading WIMP-p constrating at low mass from PICO-60 kg, 500 kg planned. Best WIMP-n limits at high mass from Xenon-1T, at low mass from collider searches (for speciﬁc operators)

Indirect Detection: leading WIMP-p limit at high mass from neutrino telescopes, via WIMP scattering on p, +capture in the sun, leading to annihilation signatures.

PICASSO, SIMPLE, PICO-2, PICO-60 (CF3I), ICECUBE, SUPER-K, PANDAX-II

Aprile et al., arXiv:1902.03234 Amole et al., arXiv:1902.04031

Jocelyn Monroe Oct. 24, 2019 / p.6 Direct Detection: Candidate Signal predicted modulation A~0.02-0.1, t0=152.5 days DAMA/LIBRA: measure (0.0095±0.0008) cpd/kg/keV, t0 = (145±5) d in 2.17 tonne-yr.

update new DAMA result + new COSINE CSLNGS, March 2018 CSLNGS, March

many other searches, on Ge, CsI, Xe, etc. observe no evidence of modulation.

In the same underground laboratory: XENON100: Xe, 4.8σ exclusion of DAMA, test of leptophilic dark matter arXiv:1507.07748

Using the same target (NaI): ANAIS (LSC), SABRE (AU), COSINE-100 (Y2L) COSINE-100, arXiv:1903.01198 ~consistent at 1σ, project 3σ test in 5 years. ANAIS, arXiv:1903.03973 Jocelyn Monroe Oct. 24, 2019 / p.6 Direct Detection: Candidate Signal predicted modulation A~0.02-0.1, t0=152.5 days DAMA/LIBRA: measure (0.0095±0.0008) cpd/kg/keV, t0 = (145±5) d in 2.17 tonne-yr.

update new DAMA result + new COSINE CSLNGS, March 2018 CSLNGS, March

many other searches, on Ge, CsI, Xe, etc. observe no evidence of modulation.

In the same underground laboratory: XENON100: Xe, 4.8σ exclusion of DAMA, test of leptophilic dark matter arXiv:1507.07748

Using the same target (NaI): ANAIS (LSC), SABRE (AU), COSINE-100 (Y2L) COSINE-100, arXiv:1903.01198 ~consistent at 1σ, project 3σ test in 5 years.

Jocelyn Monroe Oct. 24, 2019 / p.6 Direct Detection Status

Wide range of parameters! Direct detection searches historically optimised for WIMP sensitivity...

+big recent expansion of interest in laboratory axion searches!

axion model space dark matter = axions = part axions Baer et al., arXiv:1407.0017

Jocelyn Monroe May 13, 2019 / p. 7 Carena, ESPPU 2019 Axion Searches

the self-annihilation cross section, and spin-dependent DM-nucleon interactions

Ellis et al., ESPPU Physics Brieﬁng Book, CERN-ESU-004 (2019)

+many interesting new ideas in quantum measurement techniques, atom interferometers,Aprile et al., arXiv:1902.03234 …

Amole et al., arXiv:1902.04031 Jocelyn Monroe Oct. 24, 2019 / p.24 XENON100, arXiv:1404.1455 Bump Hunts in Direct Detection search for axio-electric effect:

Signal: peak in electron recoil spectrum at axion-like particle (ALP) mass. Backgrounds: electron recoils, ~1E-4/(keV kg day).

Contraints on new pseudoscalars at ~10 keV/c2 via ALP-electron coupling. Projected reach of DARWIN is >x20.

Constraints on vector particles at 0.1-100 MeV/c2 via limits on kinetic mixing to hidden sector. (arXiv:1901.10478)

Constraints on new scalar (and vector) bosonic SuperWIMPs in 10-100 keV/c2 (arXiv:1709.02222) PANDAX-II, arXiv:1707.07921 PANDAX-II, Jocelyn Monroe Oct. 24, 2019 / p.25 Big Questions for the Dark Sector (a la European Strategy for Particle Physics Update 2019)

1) How do we search for dark matter, depending on its properties?

2) What are the highlights and challenges of the experimental programs, current or near-future, that address different regions of parameter space?

3) How can dark matter detection experiments inform/guide energy and intensity frontier experiments, and vice versa?

Jocelyn Monroe Oct. 24, 2019 / p.26 (thanks to H. Murayama) new sociology • WIMP should be explored at least down to the neutrino ﬂoor • heavier? e.g., wino @ 3TeV • dark matter deﬁnitely exists • naturalness problem may be optional? • need to explain dark matter on its own • perhaps we should decouple these two • do we really need big ideas like SUSY? • perhaps not necessarily heavier but rather lighter and weaker coupling?

Jocelyn Monroe Oct. 24, 2019 / p.27 ESPPU Summary: Dark Matter

(M. Carena, ESPPU Dark Sectors Summary Talk) Jocelyn Monroe Oct. 24, 2019 / p.28 ESPPU Summary: Dark Matter

(M. Carena, ESPPU Dark Sectors Summary Talk) Jocelyn Monroe Oct. 24, 2019 / p.29 Complementarity: Higgs Portal Example D. Cerdeno, IPPP April 2018 Cerdeno, IPPP D.

Jocelyn Monroe May 13, 2019 / p. 26 ESPPU Summary: Dark Matter

(M. Carena, ESPPU Dark Sectors Summary Talk) Jocelyn Monroe Oct. 24, 2019 / p.31 Direct Detection: Is the Neutrino Bound the End? No.

• sensitivity scales with sqrt(time) instead of linearly in time (with zero background)

(energy, angle, time) of neutrino background vs. DM signal differ. • no ν bound for directional detectors Grothaus, Fairbairn, JM, Phys.Rev.D90 (2014)

10−44 LZ (5σ Discovery, 15 t×yr) DarkSide-20k (5σ Discovery, 200 t×yr) ARGO (5σ Discovery, 3000 t×yr) 10−45 A ν background paradigm…

] −46 for non-directional detectors 2 10 [cm -n χ −47 the discovery reach σ 10 depends on ν ﬂux errors

and on ν-e discrimination. 10−48 simulation with 10−49 10−2 10−1 1 10 102 Jocelyn Monroe 2 May 13, 2019 / p. 24 Mχ [TeV/c ] What can future dark matter direct detection experiments tell us about the neutrino?

Jocelyn Monroe May 13, 2019 / p. 13 What can future dark matter direct detection experiments tell us about the neutrino?

(Xe) (Ar)

Jocelyn Monroe May 13, 2019 / p. 13 ν-less Double Beta Decay

The liquid Xenon dark matter searches aim for competitive sensitivity to neutrinoless double beta decay.

example: P. Bras, IDPASC 2018 projected sensitivity in LZ: Analysis: bump hunt. big opportunity: Q-value= signiﬁcant Xe-136 2458 keV target mass (~600 kg) exclusion detection big challenges: backgrounds, energy resolution, and nuclear matrix element uncertainty

Jocelyn Monroe Oct. 24, 2019 / p.34 ν-less Double Beta Decay

The liquid Xenon dark matter searches aim for competitive sensitivity to neutrinoless double beta decay.

example: Thanks to L. Baudis Xenon1T energy resolution big opportunity: Q-value= signiﬁcant Xe-136 2458 keV target mass (~600 kg) detection big challenges: backgrounds, energy resolution, and nuclear matrix element uncertainty

recent demonstration of sensitivity to rare processes: Xe-124 two-neutrino double e- capture, arXiv:1904.11002

Jocelyn Monroe Oct. 24, 2019 / p.34 What ν physics can future dark matter detectors do?

https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos Jocelyn Monroe Oct. 24, 2019 / p.35 What ν physics can future dark matter detectors do?

(Ar)

(Xe example)

https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos (Ar) Jocelyn Monroe March 21, 2019 / p. 13 2 Upper limit on |Ue4| at 10 keV mass ~ 0.02 Sterile ν Signatures at 90% CL from beta decay.

The beta decay energy spectrum is modiﬁed Dragoun, Venos, Phys. 3 (2016) 77-113 by neutrino mass and mixing.

2 10 KeV sterile mass, mixing |Ue4| = 0.02 big opportunity: beta decays of big challenges: backgrounds nuclear physics have sensitivity to uncertainties, 10-100 keV sterile νs “shape - 1” = understanding energy [ ﬁt (w/o, w/ sterile) / resolution at % level ﬁt to null hypothesis] - 1

Jocelyn Monroe Oct. 24, 2019 / p.36 Conclusions & Outlook

Direct detection of dark matter is key to identifying whether potential new particle discoveries make up the astrophysical missing mass.

Direct detection experiments aim to reach the neutrino ﬂoor within the coming decade. Direct detection probes above the center of mass energy of the LHC, perhaps can tell us the next energy scale in particle physics!

Should we re-evaluate search strategies beyond WIMPs? Yes. Many new ideas for non-standard searches in direct detection … and today’s background may be tomorrow’s signal. (T. Kajita, 2015)

More Slides Is High Mass Interesting? (1)

Yes. >few hundred GeV is above LHC reach, but accessible in direct detection experiments.

In EFT approach, the spectrum from possible interactions (e.g. momentum dependent) does not have the typical WIMP exponential. Information isn’t only at threshold!

Beyond SUSY, variety of models can have DM candidates up to few TeV, e.g. • little Higgs, • warped extra dimensions, • walking technicolor • MIMPs • composite states …

1803.08044

Jocelyn Monroe Oct. 24, 2019 / p. 42 Is High Mass Interesting? (2) Sensitivity to composite dark matter, e.g. Hardy, Lazenby, March-Russell, West JHEP 07 (2015) dark nuclei, formed of k bound states of self-interacting light dark nucleons.

Scattering process now has a form factor from the nuclear dark matter and the target.

example: dark nucleon mass = 1 GeV, r = 1 fm, and per-SM nucleon xsec = 1E-46 cm2.

Kirk, Butcher, JM, West, JCAP 1710 (2017) 10, 035

exclusion detection

DEAP + Xenon1T could detect at 3sigma Solar ν-Electron Scattering

Via neutrino-electron elastic scattering, LAr dark matter experiments can observe the unmeasured CNO solar neutrino ﬂux! (via spectral deformation) +with O(500 t-y), study the “solar metallicity problem”. Franco et al., JCAP 1608 (2016) 08 Cerdeno, Davis, Fairbairn, Vincent, JCAP 1804 (2018) 37

big opportunity: distinguish exclusion betweendetection high vs. low metallicity.

big challenges: Rn background suppression and uncertainty on cosmogenics *Xe-136 background makes LXe CNO challenging Baudis et al., JCAP 1401 (2014) 044,

Jocelyn Monroe Oct. 24, 2019 / p. 44 Geo ν-Electron Scattering

PLR analysis of energy, time, and direction shows sensitivity at 95% CL to measure K-40 geo-neutrino ﬂux with O(100) t-yr exposure.

study with 500 neutrino background events

example: geo-, solar-, reactor-ν -induced electron recoil directions, at LNGS. challenge: measure the direction of ~1 MeV e- recoils…. Leyton, Dye, JM, Nature Commun. 8 (2017) 15989 Jocelyn Monroe Oct. 24, 2019 / p. 45 Decay: Sterile Neutrino Dark Matter Status, Prospects

Excess x-ray ﬂux at 3.5 keV observed by XMM-MOS/PN, Chandra, Suzaku, NuStar in some targets but not others.

Prospect to test atomic line background hypotheses in near-future experiments (XRISM ++)

Amole et al., arXiv:1902.04031 Jocelyn Monroe Oct. 14, 2019 / p.22 Fixed- Target Searches

Renaissance of the ﬁxed-target! New sociology of DM searches.

Many new experiments planned or proposed for hidden sector searches.

Major synergistic topic of Dark Sectors group at ESPPU. Ellis et al., ESPPU Physics Brieﬁng Book, CERN-ESU-004 (2019)

Jocelyn Monroe Oct. 14, 2019 / p.45