Dark Matter Detectors

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Future Noble Liquid

Dark Matter Detectors

Patrick Decowski

GRAPPA - University of Amsterdam / Nikhef decowski@nikhef.nl

May 2013 - Latest Results in Dark Matter Searches

(2)

Patrick Decowski - Nikhef

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Monolithic detectors

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Good self-shielding and homogenous, with high electron mobility

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Inert and excellent scintillators

Noble Gases

Unit Argon Xenon

Z 18 54

A 40 ~132

Liquid Density g/cm³ 1.4 3.06

Energy Loss (dE/dX) MeV/cm 2.1 3.8

Radiation Length cm 14 2.8

Boiling Point @ 1 bar ^oK 87.3 165

Scintillation Wavelength nm 125 175

Scintillation ph/keV 40 42

Ionization e^-/keV 42 64

Lifetime of triplet molecule ns 1600 22

Background Isotope ³⁹Ar (1 Bq/kg) ¹³⁶Xe

Price $ (but UAr) $$$

WIMP-nucleon spin-independent cross section grows as A²

→ Using xenon attractive

(3)

Particle-dependent Response

χ, n β,ɣ

Image E.Pantic

(4)

Patrick Decowski - Nikhef/UvA

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Use ratio of fast-to-slow signal components

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Need many photons

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Works well in

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^{LAr, LNe}

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But also in

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LXe, NaI, CsI

Pulse Shape Discrimination

Electron Recoil Nuclear Recoil

t t

Signal size

DEAP/CLEAN, KIMS, DarkSide, XMASS etc.

Possible to achieve very high ER/NR discrimination

Using scintillation light:

Typical ER/NR discrimination:

LXe [no PSD]: 99.75%

LAr [with PSD]: 99.9999%

(5)

General Considerations

Liquid

S1

Gas Liquid

S1 S2

E ^e_e^-^- ^e^-

Single Phase Dual Phase

(6)

General Considerations

• Simple design

• 4pi PMT coverage

• Position reconstruction ~cm

• Large detector scalability

• Electron drift allows ER / NR discrimination

• Position reconstruction ~mm

• Scalability up to a certain degree, then modularity

(7)

General Considerations

• Simple design

• 4pi PMT coverage

• Position reconstruction ~cm

• Large detector scalability

• Electron drift allows ER / NR discrimination

• Position reconstruction ~mm

• Scalability up to a certain degree, then modularity

Argon Xenon

• Cheap material

• Pulse shape discrimination capability

• Does not have 2ν2β decay isotope

• No isotope with spin

• ³⁹Ar decays at 1Bq/kg → underground argon

• Higher energy thresholds

• Attractive WIMP-nucleon SI cross section scaling

• Excellent self-shielding

• Spin-dependent couplings

• Other than ¹³⁶Xe no natural radioactive isotopes

• Expensive per unit mass

(8)

Kamioka Gran Sasso (LNGS)

Frejus (LSM) SNOLab

SURF

Underground Labs with DM Experiments

Soudan Boulby

Yangyang JinPing

South Pole Canfranc

(9)

Kamioka Gran Sasso (LNGS)

Frejus (LSM) SNOLab

SURF

Underground Labs with DM Experiments

Soudan Boulby

Yangyang JinPing

South Pole Canfranc

(10)

DEAP-3600

@SNOLAB

Ar:

1000kg FV / 3600kg total

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Initially using atmospheric Ar

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Plan to also use UAr

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255 high-QE PMTs

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50cm light guides for n- moderation

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Pulse Shape Discrimination

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DEAP-1: 3x10^-8 suppression

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Detector in 8m Water Tank

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Installation underway

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Start science in Oct 2014, 1st results in early 2015

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DEAP-3600

@SNOLAB

Ar:

1000kg FV / 3600kg total

•

Initially using atmospheric Ar

•

Plan to also use UAr

•

255 high-QE PMTs

•

50cm light guides for n- moderation

•

Pulse Shape Discrimination

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DEAP-1: 3x10^-8 suppression

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Detector in 8m Water Tank

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Installation underway

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Start science in Oct 2014, 1st results in early 2015

Depleted Ar 3000 kg-yr

(12)

DEAP-3600

DEAP

(13)

XMASS

• 100kg / 835kg

• Dark Matter

• Commissioning Run

• BG among the lowest achieved so far:

• 8.2±0.5 mBq ²²²Rn

• <0.28 mBg ²²⁰Rn

• < 2.7 ppt ^natKr

• 14.7 PE/keV

• 1ton / 5ton

• Dark Matter “XENON1T sensitivity”

• Construction 2014-2015

• Science 2016

• 10ton / 25ton

• Multi-purpose:

• ^DM

• ^{solar pp-ν}

• ^0ν2β

XMASS-1 XMASS-1.5 XMASS-II

(14)

XMASS Background

All 680 PMTs

Original

Cu ring around PMTs

Cu plate over gaps in rings

→ New PMTs for XMASS 1.5

Al Seal with ²³⁸U & ²¹⁰Pb

ev/day/keV/kg

MC assuming Al contamination Data

Expected MC

XMASS-I Refurbishment

Refurbishment reduced BG to 1/100

(15)

DarkSide-G2

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Scale up of DS-50, using same Boron loaded Liq. Scint. neutron veto system

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~3.6t fiducial / 3.8t active LUAr (e.g.

depleted ³⁹Ar)

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Will use both S2/S1 identification and Pulse Shape Discrimination

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Allows excellent BG rejection

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If funded, commissioning in 2017

558 3” PMTs

@LNGS

(16)

@Jinping

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Everything built for 1 ton target, staged approach:

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^Phase-1a:

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25kg fiducial / 120kg total [ongoing]

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^Phase-1b:

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300kg fiducial / 500kg total

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^Phase-2:

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1 ton fiducial / 1.5 total

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Phase-1a science run started ~Feb 2014

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Phase-1b late 2014

PandaX

142x R8250 PMTs

37x R11410 PMTs

(17)

Projected PandaX Sensitivity

(100 days x 25 kg)

(1yr x 300 kg)

Phase-1a: 25 kg [ongoing]

Phase-1b: 300 kg

(18)

LZ

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8 tons Xe - 5.6t fiducial

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Reuse LUX watertank

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New Gd-LS for (α,n) and spallation-n veto

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Pending funding,

installation start 2016 HV

25 tons Gd-LS

2x241 PMTs

1.5m

@SURF

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LZ Fiducial Claim

With nothing:

→2.8ton FV

Xe veto optically separated from main

TPC

→4.1ton FV

CLAIM:

Xe veto+Gd-LAB

→5.6ton FV

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XENON1T

1.1m

XENON1T

1.4m

XENONnT

Double amount of LXe (~7 tons), ~double # PMTs Design XENON1T with as much reuse as possible

(21)

Calibration Aspects

LZ DarkSide-G2

How to bring calibration sources close to the detector?

“Articulated Arm”

• In-situ calibration of ER

• ^Tritium

• ^83m^Kr

• Neutron sources

• ^DD

• ^YBe

• ^AmLi

(22)

DARWIN: the ultimate DM detector

~400 3” PMTs

~500 3” PMTs

21t LXe total → 14t Fiducial

Ar Xe

ASPERA Design Study

Start construction in 2020

(23)

Energy [keV]

0 500 1000 1500 2000 2500

]-1 keV× -1 y× -1 t×Rate [evts _-1

10 1 10 102

Total

Materials

222Rn

85Kr

β β 2ν

7Be pp+

Fiducial Mass [t]

2 4 6 8 10 12 14 16

]-1 y× -1 t×Rate in ROI [evts

1 10 102

Materials

85Kr β

β 2ν

Total β

β Total w/o 2ν

7Be pp+

222Rn

L. Baudis et al, arXiv:1309.7024

2-30keV

0.1ppt of ^natKr

DARWIN

0.1 μBq/kg 222Rn

Background dominated by solar & 2ν2β neutrinos

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Neutrino fluxes

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Neutrino background will start to dominate

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Solar neutrinos

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Atmospheric neutrinos

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Electronic recoil discrimination

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Finite discrimination→ if sufficient ER events, they will leak into NR

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Coherent Neutrino Scattering

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Nuclear recoil!

Neutrino Energy [MeV]

10-1 1 10 10² 10³

]-1 .MeV-1 .s-2 Neutrino Flux [cm

10-3

1 103

106

109

1012

1013

pp pep hep

7Be_384.3keV 7Be_861.3keV 8B

13N 15O 17F dsnbflux_8 dsnbflux_5 dsnbflux_3 AtmNu_e AtmNu_ebar AtmNu_mu AtmNu_mubar

J. Billard et al, arXiv:1307.5458

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Neutrino Backgrounds

Energy [keV]

1 2 3 4 5 6 7 8 10 20 30 40 10²

]-1 keV× -1 y× -1 t×Rate [evts _-3

10 10-2

10-1

7Be pp+

WIMP 100 GeV/c2

WIMP 40 GeV/c2

β β 2ν

cm2

10-47

2× cm2

10-48

2×

Energy [keV]

10-1

4× 1 2 3 4 5 6 7 8 910 20

]-1 keV× -1 y× -1 t×Rate [evts ^-3₁₀

10-2

10-1

1 10 102

WIMP 100 GeV/c2

WIMP 40 GeV/c2

WIMP 6 GeV/c2

: Sum ν

8B ν:

: atm ν

: DSNB ν

: hep

ν 2×10^-47 cm²

cm2

10-48

2×

cm2

10-45

4×

ν + N → ν + N ν + e^- → ν + e^-

L. Baudis et al, arXiv:1309.7024

ER/NR 99.5%, 50% NR accept

Expected recoil spectra in Xe

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Ultimate limits

Adapted from SNOWMASS Report arXiv:1310.8327

1 10 100 1000 10⁴

10 ⁵⁰ 10 ⁴⁹ 10 ⁴⁸ 10 ⁴⁷ 10 ⁴⁶ 10 ⁴⁵ 10 ⁴⁴ 10 ⁴³ 10 ⁴² 10 ⁴¹ 10 ⁴⁰ 10 ³⁹

10 ¹⁴ 10 ¹³ 10 ¹² 10 ¹¹ 10 ¹⁰ 10 ⁹ 10 ⁸ 10 ⁷ 10 ⁶ 10 ⁵ 10 ⁴ 10 ³

WIMP Mass GeV c²

WIMPnucleoncrosssectioncm2 WIMPnucleoncrosssectionpb

8B Neutrinos

Atmospheric and DSNB Neutrinos

CDMS II Ge (2009) Xenon100 (2012)

CRESST CoGeNT (2012)

CDMS Si (2013)

EDELWEISS (2011)

DAMA SIMPLE (2012)

ZEPLIN-III (2012) COUPP (2012)

7Be

Neutrinos

NEUTR

INO C OHER ENT SCATTERIN G

NEUTRINO COHERENT SCATTERING

(27)

Ultimate limits

1 10 100 1000 10⁴

10 ⁵⁰ 10 ⁴⁹ 10 ⁴⁸ 10 ⁴⁷ 10 ⁴⁶ 10 ⁴⁵ 10 ⁴⁴ 10 ⁴³ 10 ⁴² 10 ⁴¹ 10 ⁴⁰ 10 ³⁹

10 ¹⁴ 10 ¹³ 10 ¹² 10 ¹¹ 10 ¹⁰ 10 ⁹ 10 ⁸ 10 ⁷ 10 ⁶ 10 ⁵ 10 ⁴ 10 ³

WIMP Mass GeV c²

WIMPnucleoncrosssectioncm2 WIMPnucleoncrosssectionpb

8B Neutrinos

CDMS II Ge (2009) Xenon100 (2012)

CDMS Si (2013)

EDELWEISS (2011)

DAMA SIMPLE (2012)

SuperCDMS Soudan Low Threshold SuperCDMS Soudan CDMS-lite

XENON 10 S2 (2013)

CDMS-II Ge Low Threshold (2011)

SuperCDMS Soudan

Xenon1T LZ LUX

DarkSide G2

DarkSide 50

DEAP3600

PICO250-CF3I PICO250-C3F8

SNOLAB SuperCDMS

7Be

Neutrinos

NEUTR

XENONnT

DARWIN

Adapted from SNOWMASS Report arXiv:1310.8327

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Reach of Future Detectors

L. Baudis, Physics of the Dark Universe 1, 94 - 108 (2012).

@ Mχ 50-100 GeV

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Conclusions

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Due to scalability, many nobel liquid proposals to explore WIMP

parameter space

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Next months will bring clarity into

which projects will be selected in the G2-downselect in the US

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The ultimate backgrounds will be coming from neutrinos

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I hope we will not only discover coherent neutrino scattering…

1 10 100 1000 10⁴

10 ⁵⁰ 10 ⁴⁹ 10 ⁴⁸ 10 ⁴⁷ 10 ⁴⁶ 10 ⁴⁵ 10 ⁴⁴ 10 ⁴³ 10 ⁴² 10 ⁴¹ 10 ⁴⁰ 10 ³⁹

WIMP Mass GeV c²

WIMPnucleoncrosssectioncm2

8B Neutrinos

CDMS II Ge (2009) Xenon100 (2012)

CDMS Si (2013)

EDELWEISS (2011)

DAMA SIMPLE (2012)

SuperCDMS Soudan Low Threshold SuperCDMS Soudan CDMS-lite

XENON 10 S2 (2013)

CDMS-II Ge Low Threshold (2011)

SuperCDMS Soudan

Xenon1T LZ LUX

DarkSide G2

DarkSide 50

DEAP3600

PICO250-CF3I PICO250-C3F8

SNOLAB SuperCDMS

7Be Neutrinos NEUTR

XENONnT

DARWIN