Sun Kee Kim Seoul National University Underground Experiments in Korea ASK 2011 April 11-12, 2011,...
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Sun Kee KimSeoul National University
Underground Experiments in Korea
ASK 2011April 11-12, 2011, Seoul
Questions on our Universe
What is the Universe made of? How big 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 may be answered by understanding the nature of Dark matter and Neutrinos
Quarks and leptons : Spin 1/2
tbcsdue e
,,,,,,,,,,
Gauge Bosons Spin 1 : gZW ,,,
Spin 2 : G
Higgs Bosons : Spin 0
AhhH ,,, 0
Standard Model of Elementary Particles
expected to be discovered at LHC
properties are not understood very well
Great achievement with partcile accelerators during the last century !
Mostly Dark …
Composition of our Universe
006.0005.1 matter
Dark Energy73%
Dark Matter23%
Matter made of known particles 4%
In 1933, Zwicky observed that the rotational speed of galaxies in a cluster of galaxies (Coma
cluster) too fast to be explained by mass of galaxies in the cluster
Existence of dark matter by astronomical observations
Gravitational lensing by cluster of galaxies
Collision of galaxy clusters
Rotation curves of galaxies
Cosmic Microwave BackgroundDensity of dark matter around the sun ~
0.3 GeV /cm3
~ 5 x 10-
28 kg/cm3
First idea of WIMP in 1977by B.W.Lee and S. Weinberg
WIMP(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
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
Elastic scattering of SUSY WIMP with ordinary nucleus
XLIIInd Rencontres de MORIOND Sun Kee Kim, Seoul National
University
8
rEE
R
RerE
R
dE
dR0/
0
0
)χ~
χ~
( 01
01 NN
Elastic Sacttering of WIMP off a nuclues in the detector
Direct Search for WIMP
R : event rateR0: total event rateE0: most probable incident kinematic energyr : kinematic factor, 4MwMN/(MW+MN)2
• Recoil energy < 100 keV• Expected event rate
<1/kg/day or less
WIMP
Recoiled nucleus
Status of WIMP search
vsun=232km/s sun
earth
vorbit=30km/s
=60o
2-6 keV
A=(0.0129±0.0016) cpd/kg/keV2/dof = 54.3/66 8.2 C.L.Fit :Acos[w(t-t0)]
DAMA Annual Modulation
Neutrino mass and mixing
needs to be measured DayaBay, DCHOOZ, RENO
needs to be measured
measurable by neutrino oscillation
Transition bb allowed
Forbidden transition
Z
Energy
Z Z+1 Z+2
Q
bb
100Mo
100Ru
100Tc
Neutrinoless Double Beta Decay
2022/1 ~0
MmT
0νββ decay occurs when mν≠0 and ν = ν
Status of DBD searches
S13
100 meV
25 meV
2meV
need 1 ton detector
Positive signature?
Challenges for Rare Processes
Dark Matter (Direct detection of WIMP)- Very weak interactions with ordinary matter : Rare- Very low energy signals- Large background - Nuclear recoil vs electron recoils
Neutrinoless Double Beta Decay Search - Life time is expected to be very long : Rare - Large background - 2νββ vs 0νββ Self background
These searches cannot be performed without an Underground Laboratorywithout an excellent detector
performance
Cosmic ray 106eV ~ 1020eV, p, He,…
Nuclear interaction - secondary particles
1 muon /second/10 cm x 10 cm at sea level
Muon interaction creates neutrons
Neutron- mimic WIMP signal- generate radioactive isotopes
Neutrons from rocks can be avoided by a proper shielding
But, if muons interact within the shield, neutrons can enter the detector
Need to reduce the muon flux as much as possibleDeep underground experimental site
Why underground Laboratory ?
Soudan MineCDMSCOUPP
Gran SassoDAMA, LIBRA
XENON, CRESST
CUORE, GERDA
Boulby Mine
NAIADZEPLINDRIFT
FrejusEDELWEISS
Super NEMO
SudburyPICASSO
KamiokaXMASS
YangyangKIMS
AMORE
Underground Laboratories
CanfraneANAISIGEX
SuchiwanULGeXenon
Yangyang Underground Laboratory(Y2L)
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
H.C.Bhang, J.H.Choi, S.C.Kim, S.K.KimJ.H.Lee, M.J.Lee, S.J.Lee, S.S.Myung
Seoul National University
U.G.Kang, Y.D.Kim, J.I. LeeSejong University
H.J.Kim, J.H.So, S.C.Yang Kyungpook National University
M.J.Hwang, Y.J.Kwon
Yonsei University
I.S.Hahn Ewha Womans University
Y.H.Kim, K.B.Lee, M. Lee Korea Research Institute of Standard
Sciences
J.LiInstitute of High Energy Physics
Y.Li, Q.Yue
Tsinghua University
KIMS(Korea Invisible Mass Search) collaboration
19
KIMS research program
Dark Matter Search - CsI(Tl) crystal detector
An intermediate result was published (2007) 100 kg array running
Neutrinoless Double Beta Decay Search- Metal loaded liquid scintillator
- HPGe detector + CsI(Tl) crystal + Sn, Zn,.. to excited states, beta+ decays
- CaMoO4 crystal
- scintillation technique - cryogenic technique
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 recoilIsotope 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
KIMS(Korea Invisible Mass Search)
DM search experiment with CsI crystal CsI(Tl) Crystal 8x8x30 cm3 (8.7 kg)
3” PMT (9269QA) : Quartz window, RbCs photo cathode
~5 Photo-electron/keV
22
WIMP search limit with 4 crystals
Nuclear recoil of 127I of DAMA signal region is ruled out unambiguiously
PRL 99, 091301 (2007)
Most stringent limit on SD(pure proton) interactions
Data taking with 12 crystals
12 crystals(104.4kg) running (from 2008) • Stable data taking for more than a
year• Unique experiment to test DAMA annual
modulation
CsI DAQ rate < 6 Hz
Sep. 2009 ~ Aug. 2010
24
Total exposure: 32793 kg days
25
Relative intensity.....
Am calibration
-> ~5 p.e /keV
Am-241 Energy Calibration
E(keV)
13.9keV Np L X-ray17.8keV Np L X-ray20.8keV Np L X-ray26.35keV gammaCs, I X –ray escape59.54 gamma
26
High energy tail events rejection
Additional cut: Muon veto, file up rejection, trigger condition cut, multiple hit rejection
5us
Modeling of Calibration data with asymmetric gaussian function
NR event rate estimation
• Fit the WIMP search DATA with PDF function from
gamma and neutron calibration data
extract NR events rate
n g
Electron recoilNuclear recoil
Best fit
27
28
Surface alpha (SA) events background
222Rn progenies produce this background.
29
CsI(Tl) crystalsA: Rn progeny contaminated -exposed to Rn gas for one week
B: clean
Aluminum foil t=2um x 3 layers
A B
Sides are wrapped by teflon
Study of SA events with Rn progeny contaminated crystal
Tagged as Alpha at part B
BackgroundSurface alpha events
E(keV)
mean time(mt)
30
The logrmt10 distribution for various types of particle
dttpulsedttpulsetrmt )(/)(10 in 10s
PSD parameter
SA
neutron
gammas
31
Modeling WIMP search data with 3 components, SA, NR, gamma
det0
SANR(WIMP)gamma
3keV
10keV
4keV
5keV 6keV
7keV 8keV
9keV
32
Determination of the 90 % C.L. limit of NR event rates
Pdf = f0 x FNR + f1 x FSA + (1-f0-f1) x Fgamma
The posterior pdf of f0 & f1 are obtainedfrom Bayesian analysis method.
33
NR events rate for det0 to det12
Determined from Bayesian method
- 90% limit- 68% interval
3-11 keV
Counts/day/kg/keV
preliminary
KIMS WIMP search
Spin Independent Spin Dependent
preliminary
Sep. 2009 ~ Feb. 2011
Plan on Annual Modulation Stuudy
Taking data for more than 18 months 2 year data by this summer
~ 3 counts/day/kg/keV
DBD Searches at KIMS
Passive targets : HPGe + CsI(Tl) [Nuclear Physics A 793 (2007)]
64Zn EC+b+ decay 124Sn bb to excited states of 124Te 122Sn EC+b+ decay
Active targets
124Sn 0νbb : Sn loaded Liquid scintillator
[Astropart. Phys. 31,412 (2009)]
84Sr EC+b+ decay : SrCl2 crystal 92Mo EC+b+ decay : CanatMoO4 crystal 100Mo 0νbb decay : Ca100MoO4 crystal
R&D effort is on going birth of AMORE
β+EC decay of 92Mo
511keV γ
511keV γ
Gamma detector
Active crystalwith 92Mo
Conceptual setup
• 92Mo nucleus is double EC and beta plus EC isotope
• EC/β+ Q-value=627keV, ECEC = 1,650keV• Abundance = 92Mo: 14.84%, 100Mo: 9.63%• e+ stops in active(CaMoO4) Crystal.
/EC
37
• PMTs & CsI crystals are crossly connected.• Lead shielding(10 cm)• CaMoO4 is surrounded by 14 CsI crystals
T1/2 > 2.3 x 1020y (90% CL)Paper in preparation
• U - CsI(Tl) crystals• Th - CsI(Tl) crystals• K – 1inch PMT• K – CsI(Tl) crystals• K – CaMoO4 crystal
38
β+EC decay of 92Mo
New HPGe detector at Y2L
Will be used for - Measurement of internal background- DBD search with beta+
~527 cc~2.8kg
39
Co60/Cs137/Ba133
Energy Resolution
CaMoO4 for ββ
resolutionCompton edge
CaMoO4 + LAAPD at -159oC
CaMoO4 DBD for Mo-100 (3034 keV), Ca-48(4272 keV)
high energy less background Mo-100 enrichment >90% not so difficult for Mo-100 search, Ca-48 need to be depleted Scintillator at room temp; 10-20% of CsI(Tl) at 20o increases at lower temp. Decay time ; 16 μ sec Wavelength; 450-650ns-> RbCs PMT or APD Can be used as cryogenic detector (absorber)
Z
Energy
Z Z+1 Z+2
Qbb
100Mo
100Ru
100Tc
Mo-100 2nβ
Tl-208Bi-214
Signal (m=0.4eV)
Ca-48 2nββ
Ca-48 Depletion neededFirst 40Ca100MoO4 crystal
after big bang
S35
SB28CMO-3
D44 mmxL51mm~300g
40Ca100MoO4
Advantages of using cryogenic calorimeters High energy resolution (ΔE/E < 1/1000)
Ultra low energy threshold ( < 1 eV)
Simultaneous readout of Charge or Light
discrimination of particle type (e, alpha, nuclear recoils)
Cryogenic Detector
e-h pair production : 3.6 eV in Si, 2.9 eV in Ge ( *kT (T=0.1K)~10 μeV) (BG 1.11 eV in Si, 0.67eV in Ge) 2/3 energy goes to phonons…
For nuclear recoil ~10% goes to ionization
1 keV energy deposit : ~ 60 photons (CsI(Tl)) , ~280 e-h pairs (Si)
Cryogenic Detector
Absorber
Thermometer
Thermal link
Heat sink < 100 mK
, , , etc.Energy absorption Heat (Temperature)
Choice of thermometers• Thermistors (doped Ge, Si)• TES (Transition Edge Sensor)• MMC (Metallic Magnetic Calorimeter )• STJ, KID etc.
Example
Metallic Magnetic Calorimeter (MMC)
Magnetic material (Au:Er) in dc SQUID
junctions
Field coil
Au:Er(10~1000ppm)paramagnetic systemmetallic host: fast thermalization ( ~ 1ms) Can control heat capacity by magnetic field
g = 6.85 mT Δε = 1.5 eV1 keV 109 spin flips
U. of Heidelberg
45
Experimental setup at KRISS with MMC
45
~ 500 m thick brass
base temperature : 13 ~ 100 mK
crystal size ~ 1 cm 0.7 cm 0.6 cm
46
Performance of CMO+MMC
FWHM = 11.2 keV
42 keV
FWHM = 1.7 keV
Emission line of Mo : 18keV
Astroparticle Physics, 2011
5.5 MeV alpha
60keV gamma
high energy resolution suitable to search for Mo-100
0νββ
low energy thresholdsuitable to search for WIMP
Cryogenic detector0.5% FWHM 15 keV
FWHM
Scintillation technique 5% FWHM resolution
CaMoO4 DBD Sensitivity
5 years, 100 kg 40Ca100MoO4 7.0x1026 years -> 20 – 70 meV
Dark matter sensitivity of CaMoO4 cryogenic experiment
Bottino et al
Trotta et al
Ellis et al
CaMoO4
CDMS 2008 SuperCDMS 25kg
XENON10 2007
XENON100 6000 kgd
CMSSM, Ellis et al
CMSSM, Markov chain Trotta et al
Effective MSSM, Bottino et al
Eth=10 keV(5 and 100 kg year)
Eth=1 keV(5 and 100 kg year)
AMoRE Collaboration Korea (39)
Seoul National University : H.Bhang, S.Choi, M.J.Kim, S.K.Kim, M.J.Lee, S.S.Myung, S.Olsen, Y. Sato, K.Tanida, S.C.Kim, J.Choi, S.J.Lee, J.H.Lee, J.K.Lee, H.Kang, H.K.Kang, Y.Oh, S.J.Kim, E.H.Kim, K.Tshoo, D.K.Kim, X.Li, J.Li, H.S.Lee (24)Sejong University : Y.D.Kim, E.-J.Jeon, K. Ma, J.I.Lee, W.Kang, J.Hwa (5)Kyungpook national University : H.J.Kim, J.So, Gul Rooh, Y.S.Hwang(4)KRISS : Y.H.Kim, M.K.Lee, H.S.Park, J.H.Kim, J.M.Lee, K.B.Lee (6)
Russia (16)ITEP(Institute for Theoretical and Experimental Physics) : V.Kornoukhov, P. Ploz, N.Khanbekov (3)
Baksan National Observatory : A.Ganggapshev, A.Gezhaev, V.Gurentsov, V.Kuzminov, V.Kazalov, O.Mineev, S.Panasenko, S.Ratkevich, A.Verensnikova, S.Yakimenko, N.Yershov, K.Efendiev, Y.Gabriljuk (13)
Ukraine(11)INR(Institute for Nuclear Research) : F.Danevich, V.Tretyak, V.Kobychev, A.Nikolaiko, D.Poda, R.Boiko, R.Podviianiuk, S.Nagorny, O.Polischuk, V.Kudovbenko, D.Chernyak(11)
China(3)Tsinghua University : J.Li, Y.Li, Q.Yue(3)
4 countries8 institutions
69 collaborators
49
국가대형연구시설구축지도 (National Facility Road Map (NFRM))21 개 S 군에 선정됨 (NFRM 에는 282 제안 중 69 선정 , 69 개는 다시 S,A,B 군으로 분류 )
SUMMARY
51
KIMS :Results using 3409 kg days data (PRL 99, 091301 (2007))
100 kg crystals installed in the shield and data taking is on going
PSD result shown today Annual modulation study in progress
DBD searches in various isotopes : Zn-64, Sn-124, Sn-122, Mo-92, Sr-84
Some best limits
Competitive DBD search using CaMoO4 crystals can be realized rather soon A new collaboration AMORE was formed
Thank you
Channeling
Orange: w/o channeling
Green: w/ channeling
When channeling is accounted, I recoil is preferred better chance for KIMSBut, because of Blocking, the effect of channeling might be smaller than DAMA Claimed
Na recoil
I recoil
Savage, Gelmini, Gondolo and Freese, arXiv 0808.3607
Well known technology to bend particle beam with crystal. Studied a lot in 1960s
Quenching is expected to be less PSD may not work? Less studied for low energy ions.
Practically lower the trehsold
Channeling
Understanding Quenching factorbetter is important.Plan to measure quenching factor and channeling effect using a neutron setupAlso simulation study is on going together
CsI(Tl) Q.F NaI(Tl) Q.F