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Sun Kee Kim Seoul National University

Underground Experiments in Korea. Sun Kee Kim Seoul National University. ASK 2011 April 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?

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Sun Kee Kim Seoul National University

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  1. Underground Experiments in Korea Sun Kee Kim Seoul National University ASK 2011 April 11-12, 2011, Seoul

  2. 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? • … Some of these questions may be answered by understanding the nature of Dark matter and Neutrinos “The most incomprehensible thing about the world is that it is comprehensible” - A. Einstein-

  3. Standard Model of Elementary Particles Quarks and leptons : Spin 1/2 properties are not understood very well Gauge Bosons Spin 1 : Spin 2 : Higgs Bosons : Spin 0 expected to be discovered at LHC Great achievement with partcileaccelerators during the last century !

  4. Composition of our Universe Mostly Dark …

  5. Existence of dark matter by astronomical observations 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 Gravitational lensing by cluster of galaxies Collision of galaxy clusters Rotation curves of galaxies Cosmic Microwave Background Density of dark matter around the sun ~ 0.3 GeV /cm3 ~ 5 x 10-28 kg/cm3

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

  7. WIMP (Weakly Interacting Massive Particles) Relic abundance Annihilation cross section of a particle with a weak scale interaction  Excellent CDM candidate LSP in SUSY

  8. Elastic scattering of SUSY WIMP with ordinary nucleus Spin Dependent Interaction Spin Independent Interaction XLIIInd Rencontres de MORIOND Sun Kee Kim, Seoul National University

  9. Direct Search for WIMP WIMP Recoiled nucleus Elastic Sacttering of WIMP off a nuclues in the detector • Recoil energy < 100 keV • Expected event rate • <1/kg/day or less R : event rate R0: total event rate E0: most probable incident kinematic energy r : kinematic factor, 4MwMN/(MW+MN)2

  10. Status of WIMP search 2-6 keV DAMA Annual Modulation =60o vorbit=30km/s sun vsun=232km/s A=(0.0129±0.0016) cpd/kg/keV 2/dof = 54.3/66 8.2  C.L. Fit :Acos[w(t-t0)] earth

  11. Neutrino mass and mixing measurable by neutrino oscillation needs to be measured DayaBay,DCHOOZ, RENO needs to be measured

  12. Neutrinoless Double Beta Decay Energy 100Tc Forbidden  transition 100Mo Transition bb allowed Qbb 100Ru Z Z Z+1 Z+2 0νββ decay occurs when mν≠0 and ν = ν

  13. Status of DBD searches Positive signature? 100 meV 25 meV 2meV need 1 ton detector S13

  14. 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 • 2νββvs 0νββSelf background • These searches cannot be performed • without an Underground Laboratory • without an excellent detector performance

  15. Why underground Laboratory ? 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 possible • Deep underground experimental site

  16. Underground Laboratories Sudbury PICASSO Boulby Mine NAIAD ZEPLIN DRIFT Soudan Mine CDMS COUPP Canfrane ANAIS IGEX Frejus EDELWEISS Super NEMO Gran Sasso DAMA, LIBRA XENON, CRESST CUORE, GERDA Kamioka XMASS Suchiwan ULGe Xenon Yangyang KIMS AMORE

  17. Yangyang Underground Laboratory(Y2L)

  18. Yangyang Underground Laboratory Korea Middleland Power Co. Yangyang Pumped Storage Power Plant (Upper Dam) (Power Plant) (Lower Dam) Construction of Lab. buildings done in 2003 Minimum depth : 700 m / Access to the lab by car (~2km)

  19. KIMS(Korea Invisible Mass Search) collaboration H.C.Bhang, J.H.Choi, S.C.Kim, S.K.Kim J.H.Lee, M.J.Lee, S.J.Lee, S.S.Myung Seoul National University U.G.Kang, Y.D.Kim, J.I. Lee Sejong University H.J.Kim, J.H.So, S.C.Yang Kyungpook National University M.J.Hwang, Y.J.Kwon Yonsei University I.S.Hahn EwhaWomans University Y.H.Kim, K.B.Lee, M. Lee Korea Research Institute of Standard Sciences J.Li Institute of High Energy Physics Y.Li, Q.Yue Tsinghua University

  20. 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 • CaMoO4crystal • - scintillation technique • - cryogenic technique

  21. WIMP search with CsI(Tl) Crystals 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 electron recoil nuclear recoil

  22. 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

  23. WIMP search limit with 4 crystals PRL 99, 091301 (2007) Nuclear recoil of 127I of DAMA signal region is ruled out unambiguiously Most stringent limit on SD(pure proton) interactions

  24. 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 Total exposure: 32793 kg days Sep. 2009 ~ Aug. 2010

  25. Am-241 Energy Calibration Am calibration -> ~5 p.e /keV 13.9keV Np L X-ray 17.8keV Np L X-ray 20.8keV Np L X-ray 26.35keV gamma Cs, I X –ray escape 59.54 gamma Relative intensity..... E(keV)

  26. High energy tail events rejection 5us Additional cut: Muon veto, file up rejection, trigger condition cut, multiple hit rejection

  27. NR event rate estimation n g Electron recoil Nuclear recoil Best fit • Fit the WIMP search DATA with PDF function from gamma and neutron calibration data •  extract NR events rate • Modeling of Calibration data with asymmetric gaussian function

  28. Surface alpha (SA) events background 222Rn progenies produce this background.

  29. Study of SA events with Rn progeny contaminated crystal Sides are wrapped by teflon CsI(Tl) crystals A: Rn progenycontaminated -exposed to Rn gas for one week B: clean A B Background Surface alpha events Aluminum foil t=2um x 3 layers Tagged as Alpha at part B mean time(mt) E(keV)

  30. The logrmt10 distribution for various types of particle PSD parameter neutron SA gammas in 10s

  31. Modeling WIMP search data with 3 components, SA, NR, gamma 3keV 4keV det0 6keV 5keV SA NR(WIMP) gamma 8keV 7keV 10keV 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 obtained • from Bayesian analysis method.

  33. NR events rate for det0 to det12 Counts/day/kg/keV preliminary • Determined from • Bayesian method • 90% limit • 68% interval 3-11 keV

  34. KIMS WIMP search Spin Independent Spin Dependent preliminary

  35. Plan on Annual Modulation Stuudy Taking data for more than 18 months  2 year data by this summer Sep. 2009 ~ Feb. 2011 ~ 3 counts/day/kg/keV

  36. 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

  37. 511keV γ Gammadetector Active crystal with 92Mo 511keV γ Conceptual setup β+EC decay of 92Mo • 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.

  38. β+EC decay of 92Mo • PMTs & CsI crystals are crossly connected. • Lead shielding(10 cm) • CaMoO4 is surrounded by 14 CsI crystals • U - CsI(Tl) crystals • Th - CsI(Tl) crystals • K – 1inch PMT • K – CsI(Tl) crystals • K – CaMoO4 crystal T1/2 > 2.3 x 1020y (90% CL) Paper in preparation

  39. New HPGe detector at Y2L Will be used for - Measurement of internal background - DBD search with beta+ ~527 cc ~2.8kg Co60/Cs137/Ba133 Energy Resolution

  40. Compton edge resolution Energy 100Tc 100Mo Qbb 100Ru Z Z Z+1 Z+2 CaMoO4 for ββ • 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) CaMoO4 + LAAPD at -159oC

  41. 40Ca100MoO4 Ca-48 Depletion needed First 40Ca100MoO4 crystal after big bang Mo-100 2nβ Ca-48 2nββ Signal (m=0.4eV) Bi-214 Tl-208 SB28 CMO-3 S35 D44 mmxL51mm~300g

  42. Cryogenic Detector 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) 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)

  43. Cryogenic Detector Energy absorption  Heat (Temperature) , , , etc. Thermometer Absorber Thermal link Heat sink < 100 mK • Choice of thermometers • Thermistors (doped Ge, Si) • TES (Transition Edge Sensor) • MMC (Metallic Magnetic Calorimeter ) • STJ, KID etc. Example

  44. Metallic Magnetic Calorimeter (MMC) g = 6.8 Field coil Magnetic material (Au:Er) in dc SQUID • Au:Er(10~1000ppm) • paramagnetic system • metallic host: fast thermalization ( ~ 1ms) • Can control heat capacity by magnetic field junctions 5 mT  Δε= 1.5 eV 1 keV 109spin flips U. of Heidelberg

  45. Experimental setup at KRISS with MMC ~ 500 m thick brass crystal size ~ 1 cm  0.7 cm  0.6 cm base temperature : 13 ~ 100 mK 45

  46. Performance of CMO+MMC Astroparticle Physics, 2011 5.5 MeV alpha FWHM = 11.2 keV high energy resolution suitable to search for Mo-100 0νββ Emission line of Mo : 18keV 42 keV FWHM = 1.7 keV 60keV gamma low energy threshold suitable to search for WIMP

  47. CaMoO4DBD Sensitivity Scintillation technique 5% FWHM resolution Cryogenic detector 0.5% FWHM15 keVFWHM 5 years, 100 kg 40Ca100MoO4 7.0x1026 years -> 20 – 70 meV

  48. Dark matter sensitivity of CaMoO4 cryogenic experiment Eth=10 keV (5 and 100 kg year) CaMoO4 CDMS 2008 SuperCDMS 25kg XENON10 2007 Bottino et al XENON100 6000 kgd Eth=1 keV (5 and 100 kg year) Trotta et al CMSSM, Ellis et al Ellis et al CMSSM, Markov chain Trotta et al Effective MSSM, Bottino et al

  49. AMoRE Collaboration 4 countries 8 institutions 69 collaborators 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, GulRooh, 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)

  50. 국가대형연구시설구축지도(National Facility Road Map (NFRM)) 21개 S군에 선정됨 (NFRM에는 282 제안 중 69 선정, 69개는 다시 S,A,B군으로 분류)

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