Activities on double beta decay search experiments in Korea 1.Yangyang Underground laboratory 2.Double beta decay search with HPGe & CsI(Tl) 3.Metal Loaded Liquid Scintillators 4.EC/ +, search with 4 CsI(Tl) shielding 5.CaMoO4 Crystal R&D for 0 R&D 6.Prospect H.J.Kim (KyungPook National Univ.) for KIMS The 16th International Conference on Supersymmetry and the Unification of Fundamental Interactions2008/06/17 H.J.Kim, KNU 0-, decay decay 2 nd order beta decay Rare nuclear decay (>10 18 years) decay mass>0 & Majorana particle Majorana particle 2) New Physics e e N N 2 e e N N 0 A B H.J.Kim, KNU Environment Parameters in Y2L DepthMinimum 700 m Temperature20 ~ 25 o C Humidity35 ~ 60 % Rock contents 238 U less than 0.5 ppm 232 Th ppm 40 K 270 ppm Muon flux 2.7 x /cm 2 /s Neutron flux 8 x10 -7 /cm 2 /s 222 Rn in air1~2 pCi/liter Gneiss (2 Gyr ) H.J.Kim, KNU 100% HPGe at Y2L and decay search Background measurement : Cs137,shielding EC+ +, and Excited transition to 2, 0 a) EC+ + of Sn-122, Zn-64 new limits b) Excited transition of Sn-124: new limits H.J.Kim et al., Nuclear Physics A 793 (2007) => Currently working on 0 -EC/EC resonance and EC/ +search Normal Water Ultra pure Pure water NIMA 552(2005) 456 H.J.Kim, KNU 64 Zn EC+ + decay search 64 Zn EC+ + decay search HPGe + Zn(8x8x1cm)+CsI(Tl) crystal Our advantage: 100% of HPGe 10cm Pb, 10cm copper and N2 flowing Calibration by 22 Na ( + radioactive source) Efficiency calculation by Geant4; 3% Result with 2 weeks data; Coincidence cut with 2 sigma ; 1 event 2x10 20 years by 95% CL If I.BIKITs central value is taken, we would observe 100 events (1.1x10 19 y) (1.1x10 19 y) 511keV CsI 7.5x7.5x8 Zn HPGe H.J.Kim, KNU 1.1 liter 30% Tin-loaded Liquid scintillator 124 Sn 124 Te + 2 decay 9Month data at Y2L inside of Pb shielding NIMA 570 (2007) 454 Submitted to Astroparticle phys. 2287keV T 1/2 < 4x10 19 yr at 90% C.LT 1/2 < 2.4x10 17 yr at 90% C.L search with Sn-loaded LSC H.J.Kim, KNU 0,2 EC+ +, + + Experiment at Y2L 2 EC+ +, + + ; No observation yet Interest : 1) Sr-84 : SrCl 2 (7x10 13 yr) 2) Ce-136 : CeBr 3 (4x10 16 yr) 2) Ce-136 : CeBr 3 (4x10 16 yr) 3) Mo-92 : CaMoO4 (2x10 20 yr) 3) Mo-92 : CaMoO4 (2x10 20 yr) 4) Cd-116 : CdWO4 (4x10 20 yr) 4) Cd-116 : CdWO4 (4x10 20 yr) CsI(Tl) 6cm Low background Pb (10cm) EC+ +, + + Crystal keV H.J.Kim, KNU EC setup with 4 CsI crystals at Y2L H.J.Kim, KNU CaMoO 4 & SrCl 2 : 0 EC/ + search 92 Mo Search near 628 keV Very Preliminary limit: 3x10 19 y 84 Sr Search near 765 keV Very Preliminary limit: 1x10 17 y Grown at KNU H.J.Kim, KNU CaMoO4 based 100 Mo Ca(x)MoO 4 scintillation crystal for search -> Active source technique (first presented at new view in particle physics in 2004) First developed 2003 (5x5x5mm 3 ) Difference from other 100 Mo experiment 1) Energy resolution 5% (3.03 MeV) 2) Avalanche photodiode ( 4 times Q.E.) 3) Detection efficiency : ~ 100% 4) Pulse shape discrimination : 238 U, 232 Th background removal H.J.Kim, KNU CaMoO 4 crystal development 12.5 cm 2.2 cm Korea(2004)Ukraine(2006)Russia(2006) Russia (2007), ISTC project 30x30x200mm H.J.Kim, KNU Number of photoelectron from 60keV # of photoelecton from Am-241 Crystals tested 0.6PE/keV : Ukraine 0.6PE/keV : Russia 0.5PE/keV : Korea * The size of crystals are different 0.6 PE/keV => 6% FWHM at 3MeV H.J.Kim, KNU Alpha response of CaMoO 4 and PSD E = 0.2 with 5.5MeV H.J.Kim, KNU Long CaMoO4 crystal test PMT1 PMT2 Attenuation Length >50 cm Size: 30x30x200 mm H.J.Kim, KNU CaMoO4 background measurement at Y2L * Two 22x22x60mm CaMoO4 crystal + RbCs PMT 10 cm Pb shielding Active Veto (4 CsI ) 400Mhz FADC Data taking and analysis on going 238U : 30 ppt(0.4mBq/kg) 231us expected H.J.Kim, KNU 5.3%(FWHM) energy resolution or better at 3 MeV (0 signal) resolution Compton edge 4.7%(11% FWHM) Resolution with CaMoO4 crystal in low temperature(-159C) (11% FWHM) LAAPD H.J.Kim, KNU Backgrounds and signal for 20kg of CaMoO 4 with 5 years data taking (GEANT4) Mo Mo Ca-48 2 Ca-48 2 Tl-208 Bi-214 Signal (m=0.4eV) Sensitivity 10kg ( 100 Mo) 5% FWHM resolution 0.05 mBq/kg for 208 Tl, 214 Bi *5 years 7.1x10 24 y (90% CL) (0.18~0.71 meV) *1.6x10 25 y with Ca depletion *1ton CaMoO 4 : 7 x10 26 y (~0.02eV) (Ca depletion, further bg reduction) Current best limit on 100 Mo : 4.6x10 23 by NEMO3 with 6.9kg 100 Mo Claim by Klapdor-Kleingrothaus et al. ~ 400 meV Assuming optimistic theoretical value 10 significance Conceptual 100 Mo decay experimental setup Ca(x) 100 MoO 4 : 20kg Avalanche photodiode CsI/PbMoO 4 (5cm) Low activity Pb(15cm) Liquid scintilaltor (30cm) (Inside Pb : LN temperature) H.J.Kim, KNU Summary and Prospect Summary and Prospect CaMoO4 R&D CaMoO4 R&D 0.6 PE/keV -> 6% FWHM at Q= 3MeV (5% at low temp) PSD possible, E a/g ratio: 0.2 Currently working on 1) Temperature dependence study with APD 2) Internal background study of CaMoO 4 3) SrMoO4, XMoO4( X= Zn, Ba, Pb etc) R&D 4) Low temperature (LTD) development with CaMoO4 Future Plan : Ukraina, Russia and China collaboration 10kg of Mo-100 enriched CaMoO4 crystals could be installed at YangYang underground Lab in a couple of years. 10kg of Mo-100 enriched CaMoO4 crystals could be installed at YangYang underground Lab in a couple of years. Sensitivity: ~ years by 90% CL with 5 years data taking Sensitivity: ~ years by 90% CL with 5 years data taking 64 Zn: Rule out I.Bikits claim : 2x10 20 year by 95% CL Tin-loaded LSC (33%): 124 Sn : Tin-loaded LSC (33%): 124 Sn : T 1/2 > 4x10 19 yr at 90% C.L 0- EC search with 4 CsI : 92 Mo, 84 Sr -> Promising H.J.Kim, KNU Thank you H.J.Kim, KNU CaMoO 4 2x2x3cm, Cs137 source H.J.Kim, KNU Zn EC+ + decay EC+ + limit ( + -> 2 decay) Positve evidence by I.BIKIT et.al, App. Radio. Isot. 46, 455, 1995 Need to confirm or disprove! 99.7% CL