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Sun Kee Kim Seoul National University

Highlight of the KIMS research program and plan. Sun Kee Kim Seoul National University. 2 nd China-Korea Workshop on Dark Matter Search Nov. 23-25, Seoul. Brief History. 2000.12.16 Mini-workshop on WIMP search with crystals, Seoul (Henry Wong, Jin Li)

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Sun Kee Kim Seoul National University

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  1. Highlight of the KIMS research program and plan Sun Kee Kim Seoul National University 2nd China-Korea Workshop on Dark Matter Search Nov. 23-25, Seoul

  2. 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

  3. 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? • … Some of these questions can 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-

  4. Composition of Universe Mostly Dark matter, Dark energy Known ~ 4% property of neutrinos not known very well

  5. WIMP Cs I Recoiled nucleus Galactic Dark Matter rotation velocity curve Direct detection of galactic dark matter Recoil energy ~ 10’s keV Event rate < 1/kg/day Density of dark matter around the sun ~ 0.3 GeV /cm3 ~ 5 x 10-28 kg/cm3

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

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

  8. Elastic scattering of SUSY WIMP with ordinary nucleus Spin Dependent Interaction Spin Independent Interaction

  9. Status of Direct Dark Matter Search current best limit(CDMS) only positive result(DAMA) Gaitskell’s summary talk IDM2004

  10. Neutrino oscillation

  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 R = 5% sum electron energy / Q 100 meV energy resolution is very important 25 meV need 1 ton detector 2meV from Ejiri’s talk (IDM2006) S13

  13. Status of DBD searches

  14. 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

  15. Research Program of KIMS • Dark Matter Search • CsI(Tl) crystal detector • Running  result was published  talks today • Ultra-low energyHPGe 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 • Development of Cryogenic Detector • R&D effort is on going  talk tomorrow • Rare event experiment Background reduction is a critical research program Underground laboratory is essential

  16. Yangyang Underground Laboratory

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

  18. 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

  19. Crystals and data taking Pilot run published PLB(2006) published PRL(2007) Engineering run Total crystals 8.7 kg x 12 = 104.4 kg started data taking made of new powder expecting ~ 2cpd

  20. Spin independent limit PRL 99, 091301 (2007) ρD=0.3 GeV/c2/cm3 v0=220km/s vesc=650km/s Systematic uncertainty Fitting, Quenching factor energy resolution... combined in quadrature ~ 15% higher than w/o syst. Nuclear recoil of 127I of DAMA signal region is ruled out unambiguiously

  21. Spin dependent limits PRL 99, 091301 (2007) Pure proton case Pure neutron case

  22. SCIENCE, July 2007

  23. 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 Lin Hau-Bin Li

  24. Liquid Scintilator for 0 NIMA 570, 454(2007) Loading Sn base scintillator: PC+PPO(4g/l)+POPOP(30mg/l) very stable over a year

  25. Liquid Scintilator for 0 1.1 liter 30% Tin-loaded Liquid scintilator 124Sn 124Te + 2b-decay TMSN loading 9 Months data 2287keV T1/2 > 4x1019 yr at 90% C.L previous limit :T1/2 < 2.4x1017 yr at 90% C.L paper in preparation

  26. 0Search with HPGe DBD search with HPGe 124Sn (5.79%)  124Te*  124Te+γ Nucl. Phys. A 793, 171 (2007) 140 hours (TB-Sn) • > 2.31018 y • (2) > 6.71018 y • (3) > 7.91018 y

  27. HPGe + CsI(Tl) 0 Nucl. Phys. A 793, 171 (2007) 332 hours Zn plate : 8cm x 8cm x 1cm > 1.31020 years F.A.Danevich et al., Nucl. Instrum. Meth. A 544, 553 (2005) I.Bikit, et al., Appl. Radiat. Isot. 46, 455 (1995)

  28. Compton edge resolution 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 PSD for alpha/gamma CaMoO4 + LAAPD at -159oC

  29. Sensitivity of CaMoO4 Ca,Mo purification : 0.01 evt/keV/kg/y at 3MeV Active veto(5cm PbWo4(PbMoO4)) + 15cm low bg Pb + 30cm LSC Time correlation , Pulse shape discrimination Mo-100 2nu 10kg (100Mo) 0.01 /kg/keV/year 6% FWHM resolution 5year  8x1024 y(~200 meV) Ca-48 2nu Signal (m=0.3eV) Bi-214 Tl-208 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)

  30. 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 Newest crystal Newer crystals

  31. Underground Lab. Space New Lab. space 40 m x 20 m = 800 m2 Current Lab. ~ 100m2

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

  33. Summary DM/DBD : Hottest research topics KIMS started to produce good physics results A lot of efforts for new detector development Competitive DBD search can be realized rather soon Possibility of larger underground laboratory space at Y2L is being explored Cooperative and harmonious international collaboration will be essential

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