Sun Kee KimSeoul National University

Highlight of the KIMS Highlight of the KIMS research program and plan research program and plan

2nd China-Korea Workshop on Dark Matter SearchNov. 23-25, Seoul

Brief History

2000.12.16 Mini-workshop on WIMP search with crystals, Seoul (Henry Wong, Jin Li)

2001.3.21 Beijing Mini-workshop, Beijing 2001.9.13 Cold Dark Matter Mini-workshop, Taipei 2003.9.23 TEXONO-KIMS joint meeting, Beijing 2004.1.29 TEXONO-KIMS Joint workshop, Yongpyung 2006.2.6 Workshop on the underground experiments at

Yangyang 2006.10.11 1st China-Korea joint seminar 2007.11.22 2nd China-Korea joint seminar

Questions on Universe

What is the Universe made of?How large is the Universe?How did the Universe begin?What is the destiny of the Universe?What is the meaning of life in the Universe?…

“The most incomprehensible thing about the world is that it is comprehensible”- A. Einstein -

Some of these questions can be answered by understanding the nature of Dark matter and Neutrinos

Mostly Dark matter, Dark energy

Composition of Universe

02.002.1 matter

Known ~ 4%

property of neutrinosnot known very well

Galactic Dark Matter

Density of dark matter around the sun ~ 0.3 GeV /cm3

~ 5 x 10-28 kg/cm3

rotation velocity curve

WIMP

Cs

IRecoiled nucleus

Direct detection of galactic dark matter

Recoil energy ~ 10’s keVEvent rate < 1/kg/day

WIMPWIMP(Weakly Interacting Massive Particles)(Weakly Interacting Massive Particles)

Excellent CDM candidate

Relic abundancev

hA

13272 scm103

Annihilation cross section of a particle with a weak scale interaction

132522 scm10~)GeV100(~ vA

velocityrealtive : section, crossn annhilatio: ,7.0~//100

AMpcskm

Hh

LSP in SUSY

First idea of WIMP in 1977by B.W.Lee and S. Weinberg

Spin Dependent Interaction qqdL qaxial55

2 2 232( 1)spin FG J J

1

( )p p n na S a SJ

Spin Independent Interaction

qqaL qscalar 224

( )scalar p nZf A Z f

2A

Isotope J Abun <Sp> <Sn>133Cs 7/2 100% -0.370 0.003

127I 5/2 100% 0.309 0.07573Ge 9/2 7.8% 0.03 0.38129Xe 1/2 26% 0.028 0.359131Xe 3/2 21% -0.009 -0.227

Elastic scattering of SUSY WIMP with ordinary nucleusElastic scattering of SUSY WIMP with ordinary nucleus

Gaitskell’s summary talk IDM2004

current best limit(CDMS)

only positive result(DAMA)

Status of Direct Dark Matter Search

Neutrino oscillation

Neutrino mass and mixing

needs to be measured DayaBay, DCHOOZ, RENO

needs to be measured

measurable by neutrino oscillation

Neutrinoless Double Beta Decay

S13

2022/1 ~0

MmT

100 meV

25 meV

2meV

from Ejiri’s talk (IDM2006)

need 1 ton detector

energy resolution is very importantsum electron energy / Q

R = 5%

Status of DBD searches

Issues

Dark Matter What is it ? WIMP?, Axion,… What is its nature? Mass, SUSY,…

Neutrinos What is absolute mass? Majorana or Dirac? Magentic moment? Mixing angle?

Underground experiments on-Direct dark matter search-Neutrinoless double beta decay search-Neutrino magnetic moment with strong source

may shed light on these issues

Research Program of KIMS

Dark Matter Search - CsI(Tl) crystal detector

Running result was published talks today- Ultra-low energy HPGe detector R&D setup is running talks today

Neutrinoless Double Beta Decay Search- Metal loaded liquid scintillator Pilot experiment is running – a preliminary result

- CaMoO4 crystal

R&D effort is on going talks tomorrow

Rare event experimentBackground reduction is a critical research programUnderground laboratory is essential

Development of Cryogenic Detector R&D effort is on going talk tomorrow

Yangyang Underground Laboratory

Korea Middleland Power Co.Yangyang Pumped Storage Power Plant

Yangyang Underground Laboratory

Minimum depth : 700 m / Access to the lab by car (~2km)

(Upper Dam)

(Lower Dam)

(Power Plant)

Construction of Lab. buildings done in 2003

Easy to get large mass with an affordable cost Good for AM study High light yield ~60,000/MeV Pulse shape discrimination Moderate background rejection Easy fabrication and handling Cs-133, I-127 (SI cross section ~ A2) Both Cs-133, I-127 are sensitive to SD interaction

WIMP search with CsI(Tl) Crystals

nuclear recoil

electron recoil

Name Weight (kg)

Data(kg days)

S0406 6.7 237

S0501A 8.7 1147

S0501B 8.7 1030

B0510A 8.7 616

B0510B 8.7 616

B0511 8.7

B0601 8.7

B0605A 8.7

B0605B 8.7

B0606A 8.7

B0606B 8.7

B0607 8.7

B0608 8.7

published PLB(2006)

made of new powderexpecting ~ 2cpd

Total crystals 8.7 kg x 12 = 104.4 kg

started data taking

Pilot run

Engineering run

published PRL(2007)

Crystals and data taking

Spin independent limitSpin independent limit

Nuclear recoil of 127Iof DAMA signal region

is ruled out unambiguiously

Nuclear recoil of 127Iof DAMA signal region

is ruled out unambiguiously

ρD=0.3 GeV/c2/cm3

v0=220km/s

vesc=650km/s

PRL 99, 091301 (2007)

Systematic uncertaintyFitting, Quenching factor

energy resolution...combined in quadrature

~ 15% higher than w/o syst.

Spin dependent limitsSpin dependent limits

Pure proton casePure proton case Pure neutron Pure neutron casecase

PRL 99, 091301 (2007)

SCIENCE, July 2007SCIENCE, July 2007

ULE HPGe Detector for low mass WIMP

5g detector in operation at Y2L

20 g detector in preparation by TEXONO

Talks by See Yue Qian Shin Kai LinHau-Bin Li

Loading Snbase scintillator: PC+PPO(4g/l)+POPOP(30mg/l)

Liquid Scintilator for 0

very stable over a year

NIMA 570, 454(2007)

1.1 liter 30% Tin-loaded Liquid scintilator124Sn 124Te + 2-decay

Liquid Scintilator for 0

T1/2 > 4x1019 yr at 90% C.L

9 Months data

2287keV

previous limit :T1/2 < 2.4x1017 yr at 90% C.L

TMSN loading

paper in preparation

DBD search with HPGe

124Sn (5.79%) 124Te* 124Te+γ

(1) > 2.31018 y (2) > 6.71018 y

(3) > 7.91018 y

Nucl. Phys. A 793, 171 (2007)

(TB-Sn)

0 Search with HPGe

140 hours

> 1.31020 yearsZn plate : 8cm x 8cm x 1cm

F.A.Danevich et al., Nucl. Instrum. Meth. A 544, 553 (2005)

I.Bikit, et al., Appl. Radiat. Isot. 46, 455 (1995)

Nucl. Phys. A 793, 171 (2007)

HPGe + CsI(Tl) 0

332 hours

CaMoO4 for ββ

CaMoO4 (PbMoO4 , SrMoO4...) DBD for Mo-100 (3034 keV), Ca-48(4272 keV) Similar to CdWO4 but no hazard with Cd. and

low Z Light output; 10-20% of CsI(Tl) at 20o, increase

with lower temp. Decay time ; 16 μ sec Wavelength; 450-650ns-> RbCs PMT or APD Pulse shape discrimination

resolutionCompton edge

CaMoO4 + LAAPD at -159oCPSD for alpha/gamma

Sensitivity of CaMoO4

Mo-100 2nuMo-100 2nu

Ca-48 2nuCa-48 2nu

Tl-208Tl-208

Bi-214Bi-214 Signal (m=0.3eV)Signal (m=0.3eV)

10kg (100Mo) 0.01 /kg/keV/year 6% FWHM resolution 5year 8x1024 y(~200 meV)

Ca,Mo purification : 0.01 evt/keV/kg/y at 3MeVCa,Mo purification : 0.01 evt/keV/kg/y at 3MeVActive veto(5cm PbWo4(PbMoO4)) + 15cm low bg Active veto(5cm PbWo4(PbMoO4)) + 15cm low bg Pb + 30cm LSCPb + 30cm LSCTime correlation , Pulse shape discriminationTime correlation , Pulse shape discrimination

Current best limit on 100Mo : 4.6x1023 y by NEMO3 with 6.9kg 100Mo

Proc. New View in Particle Physics (VIETNAM ’2004) Aug. 2004, p.449

IEEE Nucl. Sci. 52, 1131 (2005)

NIMA, in print (2007)

Crystal Growth (ISTC program)

New crystal 25 mm x 25 mm x 123 mm

installed @ Y2L, taking data now J.I.Lee’s talk tomorrow

Newer crystals

Newest crystal

Underground Lab. Space

Current Lab. ~ 100m2

New Lab. space40 m x 20 m = 800 m2

909090909090

실험실 공간

320 sq m8m

40m

실험실공간

800 sq m

20m

40m

Planned underground Lab.

지하공간

800 sq m

실험실 1

100 sq m

실험실 1

100 sq m

실험실 1

100 sq m

실험실 1

50 sq m

실험실 1

50 sq m

지원시설

50 sq m

40.00

20.0

0

사무실

49 sq m실험실 1

100 sq m

Current Lab. space

Underground Lab.

•Lab. 10x10=100m2 x 3•Lab. 10x5 = 50m2 x 2•Mini Machine shop•Liquid N2/He facility•Parking space•Service/utility space

Summary

DM/DBD : Hottest research topicsKIMS started to produce good physics

resultsA lot of efforts for new detector

developmentCompetitive DBD search can be realized

rather soonPossibility of larger underground

laboratory space at Y2L is being exploredCooperative and harmonious

international collaboration will be essential