STATUS OF DIRECT WIMP SEARCH EXPERIMENTS

KIAS, Seoul, Korea

Yeongduk KimCenter for Underground Physics, IBS

Sejong University

2013. 11. 14.

2Outline

1. Dark Matter, Direct detection2. Underground Laboratories in the world.3. Direct search experiments – recent4. Experiments at Center for Underground Physics.5. Summary.

1. Dark Matter, Direct detection2. Underground Laboratories in the world.3. Direct search experiments – recent4. Experiments at Center for Underground Physics.5. Summary.

3Particle candidates

Masses and interaction strengths span many orders of magnitude.

HEPAP/AAAC DMSAG Subpanel (2007)

4WIMP DETECTION

c c

q q

Annihilation

(Indirect detection)P

rodu

ctio

n(A

ccel

erat

or)

WIMP

Correct relic density à Efficient annihilation in early Universe

q q

Annihilation

(Indirect detection)

WIMP scattering(Direct detection)

Pro

duct

ion

(Acc

eler

ator

)

cc ® qq(hadrons), e+e- ,m+m- ,t +t - ,nn ®W +W - ,ZZ ®gg ® Zg

Nucleus Nucleusc c+ ® +

5Detection Principle of Direct Search

0/ 20

0

( )0 00

2 22

2 2 ,

2

( )

2

4 1, 3

RE E r

SI SDDWA

SI SDA AWA WA

p

W

SI SIWp n p p

R

pW

R e F qE rNR

dRd

S

A

JAJ

M

Eu r spm ms s s

ms

m

-=

=

+= =

Spin Independent(SD), Spin-Indepent(SI)

Detector

WIMP

Nucleus

0 , ,W DMu r

WIMP-Nucleus elastic scatteringA,Mass,ER

5

0/ 20

0

( )0 00

2 22

2 2 ,

2

( )

2

4 1, 3

RE E r

SI SDDWA

SI SDA AWA WA

p

W

SI SIWp n p p

R

pW

R e F qE rNR

dRd

S

A

JAJ

M

Eu r spm ms s s

ms

m

-=

=

+= =

ExperimentMeasure this

SUSY models

• ER < 100 keV

)χ~χ~( 01

01 NN ®s 10-6 ~ 10-10 pb

Expected event rate< 1/kg/day

Nuclear Physics

6

Recoil Energy Spectra

Recoil Energy (keV)0 10 20 30 40 50 60 70 80 90 100

Event R

ate

/(k

eV

kg d

ay)

-510

-410

-310

-210

-110

1

10

2 cm-42 = 10WIMP-nucleons

WIMP hits CsI

10GeV20GeV

50GeV

100GeV1000GeV

Recoil energy spectra

Measured Energy (keV)0 2 4 6 8 10 12 14

Event R

ate

/(k

eV

kg d

ay)

-510

-410

-310

-210

-110

1

102 cm-42=10WIMP-nucleons

10GeV

20GeV

50GeV

100GeV

1000GeV

Measured energy spectra

Quenching Effect, energy resolution are critical to compare experiments. Quenching Effect, energy resolution are critical to compare experiments.

a few tens of keV

Recoil Energy (keV)0 10 20 30 40 50 60 70 80 90 100

Event R

ate

/(k

eV

kg d

ay)

-510

-410

-310

-210

-110

1

10

2 cm-42 = 10WIMP-nucleons

WIMP hits CsI

10GeV20GeV

50GeV

100GeV1000GeV

a few keV

Measured Energy (keV)0 2 4 6 8 10 12 14

Event R

ate

/(k

eV

kg d

ay)

-510

-410

-310

-210

-110

1

102 cm-42=10WIMP-nucleons

10GeV

20GeV

50GeV

100GeV

1000GeV

7Direct WIMP detection techniques

W

CRESST DAMAKIMS

XMASSANAIS

CUORE

It is a huge advantage if the detector can measure two different signals and see the correlation between the signals to remove unwanted backgrounds.

WW

N+ _+ _

_+

HPGeCoGeNT

Ionization

XENONZEPLIN

LUXDarkSide

DAMAKIMS

XMASSANAIS

CDMSEDELWEISS

Underground Laboratories

First trial of dark matter experiment in Korea (2000)

9World-wide direct search experiments

SNOLabDEAPCLEAN

PICASSOCOUPPDAMIC

HomestakeLUX

SoudanSuperCDMS

CoGeNT

ModaneEDELWEISS

CanfrancArDM

RosebudANAIS

BoulbyZEPLINDRIFT

Gran SassoXENONCRESST

DAMA/LIBRADarkSide

YangyangKIMS

KamiokaXMASSNewage

JinpingPandaXCDEX

CanfrancArDM

RosebudANAIS

Gran SassoXENONCRESST

DAMA/LIBRADarkSide

KamiokaXMASSNewage

JinpingPandaXCDEX

South PoleDM-ICE

10Muon rates at laboratories

3 orders of magnitude difference in muon rates

Y2L, CUP LAB

Dark Matter ExperimentsDark Matter Experiments

LUX detector installation at Sanford Underground Laboratory.

12250 kg NaI(Tl) crystals.As a result of a second generation R&D for more radiopure NaI(Tl) by exploiting new chemical/physical radiopurification techniques.(all operations involving crystals and PMTs - including photos - in HP Nitrogen atmosphere)

etching staff at workin clean room

PMT+HV divider

DAMA/LIBRA experiment

Earch velocity (30km/s)

Cu etching with super- and ultra-pure HCl solutions, dried and sealed in HP N2

Earch velocity (30km/s)

13Annual Modulation ?

14Muon, Radon, CoGeNT modulations

15Issues on DAMA’s modulation

Bernabei et al., IJMPA28, 2013

16Can muons be the cause of DAMA modulation ?

Muons can’t make the backgrounds nor the modulation directly.

Only ~ 6 muons hits DAMA detector per day. (DAMA group ~ 2 muons)

Backgrounds : 1000 hits at 2-6 keV per day.modulation size is 10 hits per day.

Muons can’t make the backgrounds nor the modulation directly.

250kg NaI crystals

However, each muon deposits ~ 350 MeV in the crystals. It may generate delayed signals even only 0.1% of the deposit energy.

So far, muon induced neutrons etc can’t explain the DAMA modulation quantitatively. [Ralston arXiv:1006.5255]

17CDMS (Cryogenic Dark Matter Search)

§ 19 Ge and 11 Si detectors in 5 “towers” (2006-2009)§ Ge for high-mass, Si run for low mass § 55.9 kg days in 6 Si detectors (2006-2007)§ 140.2 kg days in 8 Si detectors (2007-2009)

ZIPs: Z-sensitive Ionization and Phonon Detectors

7.6 cm diameter 1.0 cm thick

Six detectorsstacked in each tower

Five towers arranged in cold volume4.75 kg of 4.75 kg of GeGe, 1.1 kg of Si1.1 kg of Si

Phonons read out via TES.à energy measurement

CDMS-II Si: 3 Events in nuclear recoil band observed. : 7.8 events/(kg year)

Surface events w/ 133Ba source

Background events expected.

arXiv:1304.4279

Similar Experiments:EDELWEISS : GE+NTD Sensor

Nuclear recoils w/ 252Cf source

19Noble Liquid TPC

No particle identification Particle identification is possible with S1/S2.

20Double Phase, Time Projection Chamber Detectors

From L. Baudis, TAUP 2013

21Background rejection in XENON100 exp.

Dots : Background dataRed-graded : Neutron recoil events.

8GeV WIMP signal

Dot : data, Blue : Simulation

8GeV WIMP signal

25GeV WIMP signal 226 days X 34 kg Run à only 2 events.Record-low background level.

Aprile PRD 88, 012006

à 0.1 events/(kg year)

22

COGENT

CoGeNT: a dedicated search for low-mass WI MPs• An excellent example of synergy wit h indust r y: Canber ra s

PPCs around since ear ly 80’s.

• Remarkably simple commercial technology leads to applicat ions in double-beta decay (MAJORANA, GERDA) and ast ropart icle physics (CoGeNT).

• Searches for an annual modulat ion require exquisite inst rumental stabilit y. But how much is enough?

• PNNL/UC/Canber ra C-4 expansion (x10 mass, lower bckgs and t hreshold) will make it, or break it.

HDPEbelow

HDPE above

C-4 design

CoGeNTDAMA/LI BRA

+

CRESST M2 cent roid

PRL 107 (2011) 141301

PRD 84 (2011) 055014(one of many inter pretat ions)

CoGeNT: a dedicated search for low-mass WI MPs• An excellent example of synergy wit h indust r y: Canber ra s

PPCs around since ear ly 80’s.

• Remarkably simple commercial technology leads to applicat ions in double-beta decay (MAJORANA, GERDA) and ast ropart icle physics (CoGeNT).

• Searches for an annual modulat ion require exquisite inst rumental stabilit y. But how much is enough?

• PNNL/UC/Canber ra C-4 expansion (x10 mass, lower bckgs and t hreshold) will make it, or break it.

HDPEbelow

HDPE above

C-4 design

CoGeNTDAMA/LI BRA

+

CRESST M2 cent roid

PRL 107 (2011) 141301

PRD 84 (2011) 055014(one of many inter pretat ions)

23

Annual Modulation Signals are (de)claimed.

In addition to DAMA, CoGeNT experiment shows annual modulation too.

COGENT3.5 years data

But, CDMS didn’t see annual modulation.

CDMSCoGeNTCollar TAUP2013

Similar Experiments w/ PPC :TEXONO, CDEX, MALBECK

24

2 Jun.

Back

grou

nd L

evel

KIMS-CsI annual modulation data

Time

Back

grou

nd L

evel

• 12 crystals (104.4kg).

• 2.5 year data (Sep. 2009–Feb. 2012)

• Background Level : 2~3 cpd/kg/keV l The mean amplitude from 3 keV to 6 keV is 0.0008±0.0068 cpd/kg/keV

26MALBEK

MAjorana Low-Background BEGe Detector at KIRF

New CoGeNT like experimentdidn’t confirm CoGeNT signal.

Giovanetti TAUP2013

27Low mass WIMPs are observed ?

New data from LUX, DarkSide, KIMS-NaI are expected soon !

Not consistent ! à Do we have multiple components in DM ?

Hope to see the solution soon.

27

DAMA, CRESST, COGeNT, CDMS II ßà XENON100, XENON10, EDELWEISS Discrepancy gets more serious if we take new quenching factor measurements

New data from LUX, DarkSide, KIMS-NaI are expected soon !

Not consistent ! à Do we have multiple components in DM ?

Hope to see the solution soon.

28LUX (Large Underground Xenon) experiment

§ Total 370kg LXe, D=47cm, H=48cm à 250 kg.§ 118kg, 85.3 days run à 10065 kg days

85.3 days data (27.6 kg year)

Not significant events in nuclear recoil region !!CDMS three event ~ 1000 events here.

XENON100

LUX contradicts all low mass claims !! à Does this mean all the low mass signals are rejected ?

32New quenching Factors – Caution !

Recently, the quenching factors are remeasured for NaI(Tl), LXe, CsI(Tl). New measurements are significantly different from the previous measurements.

NaI(Tl)

DAMA region moves !

Phys.Rev. C88 (2013) 035806

LXe

Que

nchi

ng F

acto

rCsI(Tl)

J.H. Lee, to be published.

34

KIMS+ Projects @ CUP

I. KIMS-CsI : Upgrade of CsI(Tl) crystal detector§ Lower threshold ~ 1.5keV, <1dru, counts/(keV kg day).

§ This will help to clear issues about the modulation signals of DAMA.

II. KIMS-NaI : new NaI(Tl) detector• Duplicate DAMA experiment with ultra-low background NaI(Tl) crystals.

• 200kg run in 2015-2016

III. KIMS-LT§ natCanatMoO4 crystals ~ 200 kg year.

§ High sensitivity in low mass WIMP.

§ 2019-2022

10-5 /(keV kg day) with light sensor5 keV threshold.

I. KIMS-CsI : Upgrade of CsI(Tl) crystal detector§ Lower threshold ~ 1.5keV, <1dru, counts/(keV kg day).

§ This will help to clear issues about the modulation signals of DAMA.

II. KIMS-NaI : new NaI(Tl) detector• Duplicate DAMA experiment with ultra-low background NaI(Tl) crystals.

• 200kg run in 2015-2016

III. KIMS-LT§ natCanatMoO4 crystals ~ 200 kg year.

§ High sensitivity in low mass WIMP.

§ 2019-2022

CUP (Center for Underground Physics)at Institute for Basic Science (IBS) formed to support DM and DBD experiments. New underground Lab with ~ 1400m depth is under preparation.

10-5 /(keV kg day) with light sensor5 keV threshold.

35KIMS-NaI ExperimentNaI(Tl) Crystal

CsI Detector

• Direct check for DAMA is necessary even with LUX data.

• NaI(Tl) 200kg exp at CUP.• 2013 : 2 crystals.

DAQ Time : 5.2 daysCsI Detector DAQ Time : 5.2 days

~ 3 dru

DAMA ~ 1druPurification à <1 dru

Activation x-ray + 40K

36

Summary & Sensitivities of KIMS+

CoGent CRESST

KIMS upgrade

KIMS-LT

XENON1T

CDMS

XENONSuperCDMS

Buchmuelleret al.

Trotta et al.

WIMP Mass (GeV/c2)

37

<2013 KRISS>

0.7keV FWHM for 60keV g

1.2keV FWHM for 5.5MeV a

Am241 full spectrum MMC with gold foil absorberwith C ~ 0.3kg CaMoO4

<2013 KRISS>

Phonon collectorPatterned gold film

MMC

Low temperature detector development @ CUP

Gold film

Gold wires(thermal connection)

s E / E = 0.1% @Qvalue

1.6 keV signal @ 10 mK

38Future Noble liquid detectors

From L. Baudis, TAUP 2013

39SuperCDMS

39

9 kg of Ge arranged in 5 towers (15 iZIPs), Running now! +2V charge

0V phonon

0V phonon-2V charge

Ge

(a) X [mm]Z

[mm

]−2 −1 0 1 2

0

1

2

0V -2V 0V 0V-2V

(b)

phonon

charge

(c)

+2V charge0V phonon

0V phonon-2V charge

Ge

(a) X [mm]Z

[mm

]−2 −1 0 1 2

0

1

2

0V -2V 0V 0V-2V

(b)

phonon

charge

(c)

§ Phonon and charge sensors on both sides§ Surface events : charge on one face§ Thickness of Ge crystals : 1cm è2.5 cm § Mass : 0.25 kg è 0.6 kg § <0.6 expected leaked events in 4 years wi

th 200 kg Ge at SNOLAB!

arXiv:1305.2405

40SNOWMASS projection for Dark Matter: next decade

40

41Many theories …

Hidden sector DM : Hur et al, PLB696, 262 (2011)

42Low mass WIMPs (< 10 GeV)

Asymmetric Dark Matter (ADM) masses are ~ GeV

Cohen, PRD82, 056001

43Conclusions

l Low mass WIMPs issue including DAMA will be cleared with more experiments including KIMS-NaI.

l Deep underground experiments complement the expensive accelerator experiments for DM search.

l Extreme techniques such as lower threshold & background, higher resolution, and more massive detectors, keep emerging for difficult tasks.

l 10-48 cm2 for WIMP-nucleon cross section can be reached in ~ 7 years.

l Low mass WIMPs issue including DAMA will be cleared with more experiments including KIMS-NaI.

l Deep underground experiments complement the expensive accelerator experiments for DM search.

l Extreme techniques such as lower threshold & background, higher resolution, and more massive detectors, keep emerging for difficult tasks.

l 10-48 cm2 for WIMP-nucleon cross section can be reached in ~ 7 years.

Backup SlidesBackup Slides

45SuperCDMS

45

9 kg of Ge arranged in 5 towers (15 iZIPs), Running now! +2V charge

0V phonon

0V phonon-2V charge

Ge

(a) X [mm]Z

[mm

]−2 −1 0 1 2

0

1

2

0V -2V 0V 0V-2V

(b)

phonon

charge

(c)

+2V charge0V phonon

0V phonon-2V charge

Ge

(a) X [mm]Z

[mm

]−2 −1 0 1 2

0

1

2

0V -2V 0V 0V-2V

(b)

phonon

charge

(c)

§ Phonon and charge sensors on both sides§ Surface events : charge on one face§ Thickness of Ge crystals : 1cm è2.5 cm § Mass : 0.25 kg è 0.6 kg § <0.6 expected leaked events in 4 years wi

th 200 kg Ge at SNOLAB!

arXiv:1305.2405

Phonon sensor for AMoRE

rise-time: ~ 0.5ms

<Heat flow optimization>

M.C. Simulation & fitting

MW=30GeV

MW=100GeVMW=150GeV

49Observations for last 100 years confirm Dark Matter.

rWIMP (r) ~ 0.3GeV / cm3

in solar system

1E0657-558 Merging ClusterEqui-Density line from Lensing Effect

“A direct Empirical Proof of the Existence of Dark Matter” by Clowe et al.

X-ray intensity from ChandraObserver (Intergalactic Plasma)

First observation of separated Dark Matter from baryons.

50Phonon measurement with Low temperature detectors

Energy absorption è Temperature increase

Absorber

Thermometer

Thermal link

Choice of thermometers• Thermistors (NTD Ge, doped Si)• TES (Transition Edge Sensor)• MMC (Metallic Magnetic Calorimeter )

Heat sink < 1 K

crystal

MMC

51Surface Event Rejection

• Ionization yield (phonon/ionization) is ~1 for background.

• Nuclear Recoil(WIMP) ~ 0.3

• Combination of yield and “timing” cuts rejects vast majority of background

Loer, WIN 2013

surface event

Nuclearrecoil

rising edge slope

Loer, WIN 2013

52Indirect searches challenge direct exp.

PRL 110, 131302 (2013)PRL 110, 131302 (2013)

AMS-02

PRL 110, 141102 (2013)

53WIMP search at LHC

시간

Mono jet search à 알려진event 이상 Enhancement 발견못함.

54Comparison with Direct Search

55New PMTs enhances DM search in scintillating detectors

XMASS single phase LXe detector14.7 p.e./keV

16.1(0.66) p.e./keV (ANAIS)15.4 p.e./keV (KIMS-NaI)

ANAIS & KIMS-NaI crystals from “Alpha Spectra” coupled with SBA PMTs.

56

57Surface Backgrounds

222Rn

Rn is the main origin for the surface contamination due to the long half-life of 210Pb.