J. Billard, DM@LHC 2016

The future of direct detection of Dark Matter

Julien Billard Institut de Physique Nucléaire de Lyon / CNRS / Université Lyon 1

UCLA Dark Matter February 17-19, 2016

1 Introduction to direct detection

The hunt for Dark Matter:

? ? ? ? ? ? ? ? ? ?

2 Julien Billard (IPNL) - DM@LHC Introduction to direct detection

From some basic assumptions: • MB distribution with mean velocity: 300 km/s • Local dark matter density: 0.3 GeV/cm3 • Mass of Dark Matter particle: 100 GeV • Dark Matter ﬂux ~ 100,000 particles/cm2/s ~ 20 million particles/hand/s

Expected WIMP-nucleus scattering rate in a Ge detector: • « Weak scale » cross-section of 10-38 cm2 • Spin-independent coupling • Rate: ~ 20 recoils/kg/day • Mean recoil energy: ~ 10 keV • Direct detection is a very promising dark matter search strategy ! 3 Julien Billard (IPNL) - DM@LHC Suggested by Goodman and Witten (PRD 1985) Introduction to direct detection: state of the art

-37 -1 10 C 10 D D A M -38 M S -2 I l 10 C i 10 t e (2012)

( -39 2 -3 0 CoGeNT D 10 1 10

(2012) D 2 3

)

S CDMS Si

-40 -4 pb u @ cm 10 (2013) 10 p @ e r -41 C SIMPLE (2012) -5 10 D DAMA 10 M COUPP (2012) S CRESST -42 L -6 10 T ZEPLIN-III (2012) 10 section section (2 01 10-43 4) CDMS II Ge (2009) 10-7 EDELWEISS (2011) Xenon100 (2012) cross cross 10-44 LUX (2013) 10-8 zeptobarn 10-45 10-9 nucleon

nucleon -46 -10 -

- 10 Present status of direct detection: 10 10-47 • Event rate is not as high as originally anticipated 10-11 WIMP

WIMP -48 -12 10 • About 30 experiments are aiming at directly detect dark matter 10 -49 -13 10 • There is a conﬂicting region in the low mass region 10 10-50 10-14 1 10 100 1000 104 4 Julien Billard (IPNL) - DM@LHC WIMP Mass GeV c2

@ ê D Introduction to direct detection

Diﬀerential event rate: • Astrophysics • Nuclear physics • Particle physics

Standard assumptions: 10 Zb WIMP on Ge

- Maxwell Boltzmann « OK » (N. Bozorgnia et al. arXiv:1601.04707 ) mass = 10 GeV - Elastic WIMP-nucleus scattering - Spin independent interaction: prop. to A2 Featureless exponential

- Spin dependent interaction: prop. to and Less standard assumptions: - Eﬀective theory: WIMP-nucleus interaction described by 15 mass = 20 GeV operators (A. Fitzpatrick et al. arXiv:1211.2818) —> allows fair comparison between experiments mass = 50 GeV —> Need several targets to map out WIMP-nucleon interaction R. Catena, JCAP 1409 (2014) 5 Julien Billard (IPNL) - DM@LHC Designing a direct detection experiment

The « wish list » for a standard direct detection experiment: • Large exposure (few events per ton-year) • Low and controlled backgrounds • Low energy threshold • Discrimination between signal and background

6 Julien Billard (IPNL) - DM@LHC Thinking outside of the triangle

Detection technique wise:

• Time proﬁle of the scintillation light: DEAP/CLEAN, Darkside

• Nuclear-recoil-only mechanism (bubble chamber): PICO, COUPP, PICASSO

Candidate nuclear recoil or alpha? …use acoustic information

7 Julien Billard (IPNL) - DM@LHC PICO collaboration, PRD 93 Thinking outside of the triangle

Astrophysics wise:

• Annual modulation: DAMA/LIBRA, XMASS, CoGeNT

• Directional detection: DRIFT, MIMAC, DM-TPC, Newage

Recoil map in galactic coordinates

F. Mayet et al., Phys. Rep. 2016 8 Julien Billard (IPNL) - DM@LHC The low mass situation

EDELWEISS collaboration, arXiv:1603.05120 10−38 DAMIC ] 2 CoGeNT 2012 10−39

DAMA/LIBRA −40 10 CRESST 2015

10−41 CDMSLITE CRESST 2014 CDMSII-Si CRESST 2012 SuperCDMS-LT −42 10 EDELWEISS-II

−43 WIMP-nucleon cross section [cm 10 LUX EDELWEISS-III

10−44 4 5 6 7 8 9 10 20 30 WIMP Mass [GeV/c2] 9 Julien Billard (IPNL) - DM@LHC The low mass situation: DAMA

K. Freese et al., Rev. of Modern Phys. (2012) DM-Ice collaboration, arXiv:1602.05939 100 kg 250 kg

• 1.3 ton-year exposure of NaI crystals with no discrimination • Claim for a 9.3 sigma Dark Matter induced annual modulation over 14 annual cycles • In strong tension with existing limit but… We can’t explain this modulation… • Dedicated NaI experiments to either confirm or definitely rule out this result as Dark Matter: • DM-ICE: Looking for modulation from the Southern Hemisphere (not enough stats yet) • SABRE: High purity NaI crystals and active vetoing of the 3 keV X-ray/Auger from 40K • COSINUS: NaI crystals with active particle identification from heat and scintillation • and others such as ANAIS and KIMS 10 Where to look for Dark Matter?

-37 -1 10 C 10 D D A M -38 M S -2 I l 10 C i 10 t e (2012)

( -39 2 -3 0 CoGeNT D 10 1 10

(2012) D 2 3

)

S CDMS Si

nucleon -46 -10 -

- 10 10 -47 -11 10 Everywhere !! 10 WIMP WIMP 10-48 10-12 10-49 10-13 10-50 10-14 1 10 100 1000 104 11 Julien Billard (IPNL) - DM@LHC WIMP Mass GeV c2

@ ê D The neutrino background

Neutrino interactions with Dark Matter experiment target material

8 J. Billard et al., PRD 89 (2014) ] 10 -45 -1 WIMP signal: m = 6 GeV/c2, = 4.4x10 cm2 χ σχ-n pp Total CNS background 7Be Weak neutrino-electron 105 pep

8B 102 pp

Event rate [(ton.year.keV) − 10 hep

1 keV threshold: atmospheric 10−4 100 evt/ton/year on Ge detector

10−3 10−2 10−1 1 10 102 Recoil energy [keV]

12 Julien Billard (IPNL) - DM@LHC The neutrino background

Neutrino interactions with Dark Matter experiment target material

8 J. Billard et al., PRD 89 (2014) ] 10 -45 -1 WIMP signal: m = 6 GeV/c2, σ = 4.4x10 cm2 χ χ-n Neutrino-electron pp Total CNS background 7Be background Weak neutrino-electron 105 pep negligible for Ge cryogenic detectors BUT 8B problematic for Xe based detectors 102 pp

Event rate [(ton.year.keV) − 10 hep

1 keV threshold: atmospheric 10−4 100 evt/ton/year on Ge detector

10−3 10−2 10−1 1 10 102 Recoil energy [keV]

12 Julien Billard (IPNL) - DM@LHC The neutrino background

Neutrino interactions with Dark Matter experiment target material

Event rate [(ton.year.keV) − 10 hep WIMP or neutrino (8B)?? 1 keV threshold: atmospheric 10−4 100 evt/ton/year on Ge detector

10−3 10−2 10−1 1 10 102 Recoil energy [keV]

12 Julien Billard (IPNL) - DM@LHC The neutrino background

- J. Billard et al., PRD 89 (2014) - C D D A M - M S - IC l i t e (2012)

( - 2 - 0 CoGeNT ] 1 (2012) ] 3

)

- S CDMS Si - u (2013) [ p [ e r - C SIMPLE (2012) - D DAMA (2014) M COUPP (2012) S CRESST CRESST - L - T ZEPLIN-III (2012) (2 01 - 4) CDMS II Ge (2009) - OH EDELWEISS (2011) C ER Xenon100 (2012) EN - 7Be T - N LUX (2013) EU Neutrinos TR TTERIN IN O SCA G - 8B -

Neutrinos - C - -

O -

- R - E G N N TERI T AT SC O N RIN - NEUT - E ENT U COHER TR - I N RING - O SCATTE Atmospheric and DSNB Neutrinos - - 13 Julien Billard (IPNL) - DM@LHC [/] The neutrino background

- J. Billard et al., PRD 89 (2014) - C D D A M - M S - IC l i t e (2012)

( - 2 - 0 CoGeNT ] 1 (2012) ] 3

)

Neutrinos - C - -

O - H Going beyond the neutrino ﬂoor: E • Reduce systematic uncertainties on neutrino ﬂuxes - R - E Use target complementarity (F. Ruppin et al, PRD 90G (2014)) N N • TERI T AT SC O N RIN - • Annual modulation (J. Davis,N JCAPEUT (2015)) - E ENT U HER • Directional detectionCO (C. O’hare et al., PRD 92 (2015)) TR - I N RING - O SCATTE Atmospheric and DSNB Neutrinos - - 13 Julien Billard (IPNL) - DM@LHC [/] The neutrino background

- J. Billard et al., PRD 89 (2014) - C D D A M - M S - IC l i t e (2012)

( - 2 - 0 CoGeNT ] 1 (2012) ] 3

)

Neutrinos - C • First detection of CNS! - -

O -

E • Diversifying toward solar neutrino physics - R - E (J. Billard et al., PRD 91 (2015) G N N TERI T AT SC O N RIN - NEUT - E ENT U COHER TR - I N RING - O SCATTE Atmospheric and DSNB Neutrinos - - 13 Julien Billard (IPNL) - DM@LHC [/] The neutrino background

- J. Billard et al., PRD 89 (2014) - C D D A M - M S - IC l i t e (2012)

( - 2 - 0 CoGeNT ] 1 (2012) ] 3

)

- S CDMS Si - u (2013) [ p [ e r - C SIMPLE (2012) - Low D DAMA (2014) M COUPP (2012) S CRESST CRESST - L - WIMP mass T ZEPLIN-III (2012) (2 01 - 4) CDMS II Ge (2009) - OH EDELWEISS (2011) C ER Xenon100 (2012) EN - 7Be T - N LUX (2013) EU Neutrinos TR TTERIN IN O SCA G - 8B -

Neutrinos - C - -

O - High WIMP mass H

- R - E G N N TERI T AT SC O N RIN - NEUT - E ENT U COHER TR - I N RING - O SCATTE Atmospheric and DSNB Neutrinos - - 13 Julien Billard (IPNL) - DM@LHC [/] High WIMP mass region (10 GeV - 1 TeV)

• Motivated by the standard WIMP scenario such SUSY (LSP) • Leading experiment in this search are Noble Gases Dual TPC experiments • Xenon: LUX, XENON, ZEPLIN • Argon: Darkside, ArDM

• XYZ event reconstruction thanks to PMT and drift time —> self-shielding • Particle ID: S1(primary scintillation), S2 (ionization) • Monolithic detectors with controlled backgrounds • Scalable technology • Beneﬁts from the A2 boost factor from SI interaction

14 Julien Billard (IPNL) - DM@LHC High WIMP mass region (10 GeV - 1 TeV)

• Results coming soon from G2 experiments: XENON1T (Xe) and DEAP (Ar) • G3 experiments aim at reaching the neutrino ﬂoor induced by atmospheric neutrinos • Limited sensitivity to light (below 10 GeV) WIMP

XENON collaboration, arXiv:1512.07501

15 Julien Billard (IPNL) - DM@LHC Low WIMP mass region (1 GeV - 10 GeV)

• First motivated by « Low mass hints » and now by no evidence of SUSY at LHC • Leading experiment in this search are mostly cryogenic detectors • Germanium: SuperCDMS, EDELWEISS (Phonon + ionization)

• CaWO4: CRESST (Phonon + scintillation) • More exotic approaches: DAMIC (Si CCD) and NEWS (H/He/Ne Spherical TPC)

Thermometer Interleaved electrodes

Holding clamps

16 Copper housing Low WIMP mass region (1 GeV - 10 GeV)

Why cryogenic solid state detectors are better suited for low mass WIMPs? All the deposited energy ends up in the phonon/heat system: no quantization (~10 meV) Mean energy for electron/hole pair in Ge: ~3 eV (13.8 eV in Xe)

Luke-Neganov eﬀect

1 Et = Er + 3 eV EQΔV

Ba calibration 356 keV line

• SuperCDMS « CDMSLite » and EDELWEISS have similar HV performances: 60 eVee threshold

• Limited by phonon resolution: progress ongoing

• Expect a HV limit from EDELWEISS soon ! 17 Julien Billard (IPNL) - DM@LHC Low WIMP mass region (1 GeV - 10 GeV)

Q. Arnaud et al., To be submitted 10−38 CRESST 2015 DAMIC

−39 CoGeNT 2012

] 10 2 CDMSLITE DAMA 10−40

10−41 CRESST 2012 SCDMS CDMSII-Si 10−42

EDELWEISS-III 10−43

10−44 LUX WIMP-nucleon cross section [cm −45 10 Neutrino background J. Billard et al., Phys. Rev. D (2014) 10−46 7×10−1 1 2 3 4 5 6 7 8 9 10 20 WIMP Mass [GeV/c2] 18 Julien Billard (IPNL) - DM@LHC Low WIMP mass region (1 GeV - 10 GeV)

Q. Arnaud et al., To be submitted 10−38 CRESST 2015 DAMIC

−39 CoGeNT 2012

] 10 2 CDMSLITE DAMA 10−40

10−41 CRESST 2012 EDELWEISS-III 2017 SCDMS CDMSII-Si 10−42 Ton-scale cryogenic experiments 43 EDELWEISS-III 10− SuperCDMS-EURECA

Light Dark Matter (below Lee-Weinberg limit) is also becoming motivated (e.g. hidden sectors) • For a 100 MeV DM : - recoil energy of a target nucleus ~ 1 eV - recoil energy of a target electron ~ 50 eV

• First experimental result from XENON 10 (2012) as sensitive to single electron • No new S2 only analyses from LXe experiments because of large single-e- background • Most sensitive experiment in the future will be solid state detectors thanks to lower W-value R. Essig et al., PRL 109 (2012) R. Essig et al., arXiv:1509.01598 mA’ >> me mA’ << me

19 Julien Billard (IPNL) - DM@LHC Directional detection

Directional detection aims at measuring both the recoil energy and direction using gas TPC

Leading experiments are: DRIFT, DM-TPC, MIMAC and Newage DM-TPC collaboration (2016) Great experimental challenges: Intrinsic angular resolution: ~20 degrees RMS Thresholds: 1 keV (energy), 10 keV (directional) Exposure: ~100 g (DRIFT) Target: Fluorine (excellent spin-dependent coupling) 50 keVr, 2mm Unique possibility to probe the nature of Dark Matter from: Astrophysics Particle physics J. Billard et al., PRD 83 (2011) B. Kavanagh, PRD 92 (2015) Event rate

20 Number of WIMP events Directional detection

• Thanks to the rotation of Solar System around Galactic Center, WIMPs are coming from Cygnus • Solar neutrinos are coming from … the Sun

C. O’hare et al., PRD 92 (2015) 1.6 keV - 3.3 keV WIMPs February 60°

Neutrinos

In detector frame WIMPs

September Neutrinos 120°

• Depending on angular resolution, the irreducible neutrino background can be largely subtracted • But of course, we first need massive directional experiments… but this could be a great motivation!!

21 Julien Billard (IPNL) - DM@LHC Conclusions

Take away points: • Direct detection is entering in a new phase of G2 experiments with much improved sensitivities

• Noble gas TPC is the leading search strategy above 10 GeV while solid state (cryogenic) experiments are particularly well suited for low WIMP mass

• Both strategies will soon encounter the ultimate neutrino background (first detection of CNS!)

• Many experiments are dedicated to better understand the DAMA situation claiming a Dark Matter detection for the last ten years or so

• Directional detection is getting ready to probe the nature of Dark Matter in a « post-discovery » era

• Meanwhile we should keep an open mind and not be afraid of more exotic scenarios 22 Julien Billard (IPNL) - DM@LHC