Presentation on theme: "Center for Underground Physics, IBS"— Presentation transcript:
1 Center for Underground Physics, IBS Dark MAtters and Neutrino Projects at the Center for Underground Physics.Yeongduk KimCenter for Underground Physics, IBSSejong UniversityAKPA
2 Center for Underground Physics (CUP) CUP began on July 2013 as a headquarter center.Now, 17 Ph.Ds, 15 students, 3 technicians, 2 administrations.Research Area : Dark Matter, Double Beta Decay, Sterile neutrino search, Low temperature Detector Development.
4 More quantitative evidence : cosmic microwave background
5 Particle candidates Many particle candidates are proposed with many orders of magnitude of mass.Who will be the hero ?OrNone of them.K.Y. Choi, JKPS 63, 1685(2013)
6 Weakly Interacting Massive Particle (WIMP) increasingWIMP is a massive new particle having a right <sv> value for the current dark matter density. So it is a good candidate for dark matter particles.
7 WIMP DETECTION c q (Accelerator Search) Production (Indirect Search) AnnihilationWIMP scattering(Direct Search)
8 Detection Principle of Direct Search DetectorWIMPNucleusWIMP-Nucleus elastic scatteringEvent rate :ExperimentMeasure thisSUSY modelsLimit of R Limit of s
9 What is the direct signal for WIMPs ? Recoil energy spectrum as expected at low energy.Annual modulation.Directional asymmetry.A2 dependence (Spin-independent)Yearly revolution annual modulationDaily rotation direction changeEarth velocity (30km/s)
10 DAMA/LIBRA experiment 250 kg NaI(Tl) crystals coupled with PMTs.Observed clear annual modulation for 13 years.PMT+HVdivider
12 YangYang(Y2L) Underground Laboratory (Upper Dam)YangYang PumpedStorage Power PlantSeoulY2L1000m700mRENO(Power Plant)(Lower Dam)KIMS (Dark Matter Search)AMoRE (Double Beta Decay Experiment)Minimum depth : 700 m / Access to the lab by car (~2km)
13 KIMS-NaI Experiment @ CUP To verify the DAMA result using same NaI(Tl) crystals.Our strategy : Achieve lower background level and lower energythreshold than DAMA by factor 2.We can clarify the origin of the annual modulation unambiguously.NaI(Tl) CrystalCsI Detector
14 Background rates – We are getting there. Low threshold down to 1 keV is possible.Background reduction expected by further purification.
18 Search for Neutrinoless double beta decay (0nbb) eventObservation of 0nbb will prove
19 Neutrino mass from 0nbb experiment Half-lifves of 0nbb inversely proportional to mass2Half-lifeMeasuredNeutrinoMass
20 Elliott & Vogel, Ann, Phys. (2002) Moore’s law for 0nbb ?Elliott & Vogel, Ann, Phys.(2002)76Ge, Gerda (0.3)136Xe, EXO (0.26)136Xe, KAMLAND-ZEN (0.19)
21 Overview of AMoRE-200kg Scintillating Bolometer : 40Ca100MoO4 + MMC Light sensorMMCphononsensor<10-50 mK>216 g<2018><Now, 2013>AMoRE-200 is the most massive experiment with enriched isotope having Q value > 3MeV.
22 MMC (Metallic Magnetic Calorimeter) paramagnetic sensor:Au:Er수정Mass 수정 216g
23 Energy resolution data CaMoO4(natural) with a phonon sensor only.<2013 KRISS>FWHM = 9 keV, Goal = 5 keV
24 Crystal Growing Facility Motivation : difficulty to find a reliable and economical company.Will develop chemical purification and crystallization ourself inside the center. (4 furnaces)
28 Weakly Interacting Massive Particles (WIMP) 이휘소, 와인버거 박사의 1977 논문“Cosmological Lower Bound on Heavy-Neutrino Mass” (무거운 중성미자 질량에 대한 우주론적인 하한값)암흑물질의 후보로서의 약하게 상호작용하는 윔프와 같은 무거운 입자의 가능성을 거론.빅뱅이후 약하게 상호작용하는 안정적인 입자가 생성되어 Freeze out 되어 남게 되면 Dark Matter가 될수 있다.M(wimp)>2GeV
29 KIMS-CsI annual modulation data 2 Jun.TimeBackground Level12 crystals (104.4kg).2.5 year data (Sep. 2009–Feb. 2012)Background Level : 2~3 cpd/kg/keVThe mean amplitude from 3 keV to 6 keV is ± cpd/kg/keV
32 PMT noise reduction in background data. DAMA/LIBRA reported PMT noise reduction by introducing charge ratio parameters. KIMS-NaI obtained the same results as DAMA.X1X2DAMA, E=2-4 keVKIMS-NaI, E=2-4 keVPMT noiseReal signals
33 Supersymmetric particles Q|fermion> = |boson>particle super particleR parity = 1 for ordinary particles= -1 for SUSY partnersIf R parity is conserved, LSP ( Lightest SUSY Partner) will be stable and a strong candidate of WIMP.
34 Toward lower neutrino mass AMoRE 10AMoRE 200Effective Neutrino mass (eV)Lightest neutrino mass (eV)Toward lower neutrino mass
35 Pulse Shape Discrimination and events show different pulse shapes in phonon signals.Beta-AlphaGammaMuonAlpha
36 Phonon sensor for AMoRE MMCPhonon collectorPatterned gold filmGold filmGold wires(thermal connection)216 g CaMoO4rise-time: ~ 0.5msWe measure both thermal and athermal phonons.<Heat flow optimization>