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Search for 0-neutrino double beta decay experiments

Search for 0-neutrino double beta decay experiments. Introduction Overview of Double beta decay experiments Sn, Zn double beta search with HPGe & CsI(Tl) Metal Loaded Liquid Scintillators Ca(Sr)MoO4 Crystal R&D Prospect H.J.Kim (KyungPook National U.) for KIMS

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Search for 0-neutrino double beta decay experiments

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  1. Search for 0-neutrino double beta decay experiments Introduction Overview of Double beta decay experiments Sn, Zn double beta search with HPGe & CsI(Tl) Metal Loaded Liquid Scintillators Ca(Sr)MoO4 Crystal R&D Prospect H.J.Kim (KyungPook National U.) for KIMS Underground and Astroparticle Physics Workshop MooJu, 2005/02/17

  2. Double beta decay process (A,Z) -> (A,Z+2) + 2b +2n (A,Z) -> (A,Z-2) + 2b+ +2n EC+b+ ,2EC also is possible (A,Z+1) (A,Z-1) (A,Z) (A,Z) (A,Z+2) (A,Z-2) Excited state g b+-> g g (511 keV) Ground state

  3. Run forever! (Not possible) • Huge mass (If you are rich) • Find large s process (Theoy responsibility) • 100% Efficiency is desired • 0 background (Not possible) Background reduction *Good energy resolution *Low background -> Purification =>Cost optimization is needed Signal: good s Signal: bad s Probability Energy Background

  4. bb material requirements • Matrix elements: Large s (ex: Nd, Gd) ~mn1/2 • Enrichment: Gd, Te ~20%; Zr, Nd -> Difficult ~mn1/2 Mo, Se, Ge, Kr, Xe, (Cd, Sn) ->Easy Expensive : A few hundred $ / 1 g • Efficiency : ~ 100% for active source technique~mn1/2 Mass, time ; ~mn1/4 • Resolution; 2n bb background issue ~mn1/4 • Background; Source impurity (U238,Th232) ~mn1/4Source purification, Time correlation (PSD) Active shielding to reduce backgrounds

  5. Weighted average of all positive results Isotope T1/22n(y) T1/22n(y)calc 48Ca 6 ´ 1018- 5 ´ 1020 (4.2 +2.1-1.0 ) ´ 1019 76Ge 7 ´ 1019- 6 ´ 1022 (1.42 +0.09- 0.07) ´ 1021 82Se (0.9 ± 0.1) ´ 1020 3 ´ 1018- 6 ´ 1021 96Zr 3 ´ 1017- 6 ´ 1020 (2.1+0.8-0.4) ´ 1019 100Mo (8.0 ± 0.7) ´ 1018 1 ´ 1017- 2 ´ 1022 100Mo(0+*) (6.8 ± 1.2) ´ 1020 5 ´ 1019- 2 ´ 1021 (3.3 +0.4-0.3) ´ 1019 116Cd 3 ´ 1018- 2 ´ 1021 128Te (2.5 ± 0.4) ´ 1024 9 ´ 1022- 3 ´ 1025 130Te (0.9 ± 0.15) ´ 1021 2 ´ 1019- 7 ´ 1020 150Nd (7.0 ± 1.7) ´ 1018 6 ´ 1016- 4 ´ 1020 238U (2.0 ± 0.6) ´ 1021 1.2 ´ 1019 2n-DBD Candidate and Experimental results

  6. 0nbb decay half lives uncertainty A VARIETY OF 0n-DBD CANDIDATE NUCLIDES HAS TO BE STUDIED

  7. two neutrino DBD continuum with maximum at ~1/3 Q low energy resolution 2n events can mask 0n ones 1 10-6 Signature: shape of the two electron sum energy spectrum e- low background detector e-   -underground operation • shielding - low radioactivity of materials source R = 5% 10-2 e- e- detector SourceDetector (calorimetric technique) SourceDetector sum electron energy / Q neutrinoless DBD peak enlarged only by the detector energy resolution +event shape reconstruction • low energy resolution • low efficiency +high energy resolution +100% efficiency -no event topology Experimental search for DBD • Two approaches: • If you use the calorimetric approach

  8. Experiment Isotope T1/20n (y) <mn>* (eV) Range <mn> 6.0 48Ca > 1.8 ´ 1022 Ogawa I. et al., submitted 2002 76Ge > 1.9 ´ 1025 0.35 < 0.3 - 2.5 Klapdor-Kleingrothaus et al. 2001 > 1.57 ´ 1025 0.38 < 0.3 - 2.5 Aalseth et al 2002 > 5.5 ´ 1022 4.8 < 1.4 - 256 100Mo Ejiri et al. 2004* 1.9 < 1.8 - 6.2 116Cd > 1.3 ´ 1023 Zdenko et al. 2002 128Tegeo > 7.7 ´ 1024 1.0 < 1.0 - 4.4 Bernatowicz et al. 1993 130Te > 2.1 ´ 1023 1.5 < 0.9 - 2.1 Mi DBD n 2002 136Xe > 7 ´ 1023 1.8 < 1.4 - 4.1 Belli et al. The Best 0n-DBD results with different nuclei * 100Mo : 3.5x1023 years by NEMO3, 2004

  9. 20 sectors Source: 9,5 kg of  isotopes (20 m2 with 60 mg/cm2 thickness) Tracking detector: 6180 cells in Geiger mode t=5 mm, z≤1 cm (vertex) Calorimeter: 1940 plastic scintillators coupled to low radioactivity PMs : E/E (FWHM): 14 to 16% at 1 MeV Time : =250 ps at 1 MeV Magnetic field: 25 Gauss differentiate between (e-e-) and (e+e-) Shielding: -18 cm iron (rayt ) -30 cm water -28 cm wood Best candidate? 100Mo (6,9 kg) 82Se(0,93 kg) Cu (0,62 kg) 116Cd (0,40kg) 130Te (0,45 kg) 150Nd (36,5 g) 96Zr (9,43 g) 48Ca (6,99g) natTe (0,61 kg) (neutrons) NEMO3 detector Installed at the Frejus Underground Laboratory (4800 m.w.e)

  10. Entries=13824 Data 2+ expected background simulations T1/2 =(8.40.1(stat)1.3(syst)).1018 years Consistent with world average: T1/2 =(8.00.7).1018 years 22 0 1000 2000 3000 4000 5000 0 region No event E=[2700-3200] keV Data analysis ~ 890 hours Iron shielding+B=30 Gauss   - 100Mo Expected background in  channel during 890 hours (simulations) ~ 79 events In  channel : Signal/Noise ~ 170 Very preliminary!

  11. Double beta decay

  12. 0 nbb evidence? Now claiming 4s significance By H.V.Klapdor At 2038.5keV 2004 NIM

  13. * Staudt, Muto, Klapdor-Kleingrothaus Europh. Lett 13 (1990) 31 Technology Mass [ton] present bkg [c/keV kg y] old/future bkg Sensitivity (10y) GENIUS GEM MAJORANA HD-M partially tested HD-M partially tested IGEX mature 1 – 10 1 nat – enr 0.5 0.06 0.06 1500 300 150 2.3 1028 y 2 - 6 1028 y 0.1 – 1 1028 y 0.4 1028 y CUORE MI-DBD tested 0.8 nat 0.33 330 5 1027 y 1 1027 y EXO XMASS Gotthard Xe challenging DAMA - Xe tested 1 – 10 10nat– 1.6enr 0.025 0.06 1000 10 2.2 1028 y 0.9 - 13 – 1027 0.5 - 1 1027 y MOON ELEGANT standard 34 nat ~ 0.02 300 1.3 1028 y 1 1027 y CAMEO INR - Kiev needs confirm. 0.1 - 1 0.03 600 4.9 1027 y 0.1 - 1 1027 y Future projects (2)

  14. Klapdor-Kleingrothaus HV hep-ph/0103074 Aalseth CE et al. hep-ex/0201021 Zdesenko Y et al. nucl-ex/0106021 GENIUS – MAJORANA - GEM M =1 (10?),0.5,1 ton (86% enriched 76Ge) 0n-DBD sensitivity T10y ~ 2,0.4,1·1028 y <mn> ~ 10–80meV Assumed bkg: ~ 0.04, 0.4, 0.2 count/keV ton y

  15. Cubic structure, ideal for active shielding no more inert Cu plates facing crystals Special dilution refrigerator Each tower is a CUORICINO-like detector CUORE M = 0.76ton natural TeO2 0n-DBD sensitivity (1 c/keV ton y) T10y ~ 1027 y <mn> ~ 30 – 50 meV

  16. Danilov M. et al. Phys. Lett. B480 (2000) 12 Moriyama S., XENON01 proc. Zdesenko Y., XENON01 proc. Large 136Xe TPC(1 – 10 ton) with single Ba+-ion detection via laser tagging (optical spectr.) 5 c/keV ton y Almostno BKGexcept 2n-DBD Ton~1027 y<mn>  20 meV IF 10 ton T0n > 1.3 x 1028 y (90% C.L.) – <mn> < 13 - 40 meV in 10 y EXO – XMASS 10 ton nat. or 1.6 ton enriched

  17. Ejiri H. et al. Phys. Rev. Lett. 85 (2000) 2917 passive source for 0n2b target for solar neutrinos 100Mo 34 ton nat. (3.3 ton 100Mo) Supermodule of scintillator and Mo ensembles BKG from 214Bi and 2n-DBD ~ 0.07 c/ keV ton y Ton~1027 y<mn>  30 meV 1 module prototype MOON

  18. DB experiment R&D in Korea (4 years) • Low Cost is highly required (Experimentalist problem) • New method is desired • Other DB Elements ( Theoretical uncertainty) • Unexpected surprise (Unlikely but who knows) • New method for double beta decay R&D -> Metal-Loaded Liquid scintillator (No experiment yet) -> New scintillation crystal (CaMoO4 etc) • Good News : KIMS experiment experience -> YangYang Underground lab and shielding -> Background reduction technique for Cs -> Experience with Crystal( CsI) and Liquid scintillator

  19. Double beta; HPGe with CsI crystal • HPGe a) EC+b+ , b+b+ ; No observation yet b) Excited transition to 2nu, 0nu; Mo, Nd (new) • HPGe + CsI ( top only) ; Under study (Zn,Sn, Zr) • HPGe + Full CsI cover ; Improve sensitivity 1 order? => Confirm Nd and try for Zr,Sn excited transition => Uses 12 6x6x30cm existing crystal using existing RbCs PMT • HPGe + Active detector( Sn-LSC, CaMoO4....)

  20. Sn-124, Sn-122 0-,2-nbb limit * World best limit on Sn-124 (E.Norman PLB 195,1987) • Test of TBSN for a week at CPL , Preliminary results 450cm3 HPGe, 140 hours , 1.0liter TBSN : 400g of Sn • 2+ (603keV) 3.8x1018 year (4.0x1019 year) • 0+ (1156) 1.1x1019 year (2 -n theory : 2.7x1021) • 0+ (1326) 1.3x1019 year (2.2x1018 year) * Sn-122 EC+b+ decay ; 1.5x1018 year (6.1x1013)

  21. Zn EC+b+ decay EC+b+ limit ( b+ -> 2 g decay) 99.7% CL Positve evidence by I.BIKIT et.al, App. Radio. Isot. 46, 455, 1995 <= 25% HPGe + NaI(Tl) with 350g Zn at surface with shielding. -> Need to confirm or disprove!

  22. 511keV g 511keV g Zn EC+b+ decay HPGe + Zn(8x8x1cm)+CsI(Tl) crystal Our advantage: • 100% of HPGe • 350m underground • 10cm low background lead, • 10cm copper and N2 flowing Calibration by Na22 (b+ radioactive source) Efficiency calculation by Geant4; 3% Very Preliminary result with 1 week data; Coincidence cut with 2 sigma range ; 1 event • 2x1020 year by 95% CL • If I.BIKIT’s central value is taken, we would observe 100 events (1.1x1019 y) CsI 7.5x7.5x8 Zn HPGe

  23. Energy dist at HPGe

  24. Why metal loaded liquid scintillator? • Advantage a) high-Z can be loaded to LS (>50% or more) b) Fast timing response (few ns) c) Low cost of LS, Large volume is possible d) U/Th/K background for LS is low and purification is known e) Some elements can’t be made to Scintillator • Disadvantage a) Bigger volume is necessary (C,H in LS, low density) b) Lowerlight output (>15% of NaI(Tl))

  25. LSC test sample HV + LSC Setup VME

  26. Zr2EH + LSC (50% ->Zr 3%) Nd2EH + LSC (50%->Nd 6.25%) TetraButhyl Tin + LSC (50%->Sn 20%) TetraMethyl Tin + LSC (50%->Sn 40%)

  27. Double beta decay detector Quartz glass Plastic Dimension R = 5cm H = 15.2cm V = 1.18L Teflon

  28. 214Bib-decay g214Poa-decay s -> T 1/2 = 0.166ms (0.163 ms exp.) U-238 decay chain

  29. 212Bib-decay g212Poa-decay -> T 1/2 = 300ns Th-232 Decay chain

  30. TMSN50% Energy Spectrum pol3 + gaus fitting Ee(keV) Ee(keV)

  31. Current Sn-124 Results * TMSN50% by 500MHz FADC -> 33 days T1/2 = 3.41x1019 year by 90% C.L World best limit = 2.4x1017 years by M.I. Kalkstein * More data taking is on-going More R&D …… Zr, Nd and Gd loaded LSC Purification

  32. Scintillation Crystals for bb (Calorimeter technique) • 300g CdWO4bb search by Ukrine group; >0.7x1023 year Enrichment, PSD, active shielding -> successful • CaMoO4 (PbMoO4 , SrMoO4...) ; Mo, Ca bb search 1) Similar to CdWO4 but no hazard with Cd. and low Z 2) Light output; 20% at 20o, increase with lower temp 3) Decay time; 16 micro sec 4) Wavelength; 450-650ns-> RbCs PMT or APD 5) Pulse shape discrimination • GSO, ZnSe, CaF2 • New Crystal R&D : NdCl3(X), GdCl3(?) New idea?? • New Method R&D : LSC + CaF2 powder (?)

  33. Czochralski(CZ) Crystal Growing for DB • Russia, Ukrine • PSU (Crystal Bank) • KNU (small one for R&D)

  34. CaMoO4 R&D Crystals PSU crystals in Korea: CaMoO4, 5x5x6mm, 8x7x11mm 8x6x10mm CaMoO4from Russia 18x18x35mm, 10x10x10mm

  35. CaMoO4 R&D Crystal from Crystal Bank in PSU New One 14.3x15x13.7mm 10.73g (small) 20x20x20mm 24.27g (middle) 24.8x30x40.8mm 93.13g (large)

  36. CaMoO4 Pulse shape with 500MHz FADC 60keVg 5.5MeVa

  37. Number of photoelectron from 60keV g # of photoelecton from Am-241 Energy distribution # of photoelectron : 0.6 PE/keV => 6% FWHM at 3MeV at 25deg

  38. CaMoO4 2x2x3cm, Pulse Shape discrimination

  39. CaMoO4 2x2x3cm, 1Month data!

  40. Various Backgrounds and signal estimation with 20kg of CaMoO4 with 5 years data taking (GEANT4) Mo-100 2nu Ca-48 2nu Signal (m=0.3eV) Bi-214 Tl-208

  41. Backgrounds & signal with CaMoO4 (GEANT4 simulation) 5s significance All Backgrounds Signal

  42. 10kg Mo-100 CaMoO4 8x1024년 (0.2eV) (현재 3.5x1023 년) 10% 10kg Ca-48 1.5x1024년 (0.6eV) (현재 2x1022 년) 1톤 Mo-100 CaMoO4 8x1026년 (0.02eV) 이론 예측: 0.01-1.0 eV 결정섬광 검출기를 이용한 0-n bb실험 CaMoO4 (PbMoO4, SrMoO4, ZnMoO4) ; Mo, Ca 0-n bb탐색 <= 새로운 아이디어

  43. 감사합니다

  44. CaMoO4 sensitivity and prospect • Ca,Mo purification : 0.01 evt/keV/day/kg at E=3MeV • Active veto (6cm CsI) + 15cm low bg Pb + 30cm LSC • Time correlation , Pulse shape discrimination • 4% FWHM . • 10kg Mo-100 enriched CaMoO4 with 5 years data Sensitivity: 1025 years by 90% CL (0.15 eV) <- 5 sigma significance if Klapdor claim is right (Current best limit: 3.5x1023 years by NEMO3, 2004) • 100kg Mo-100 enriched CaMoO4 with further background 10 reduction 1026 years (0.05 eV) sensitivity <- next generation experiment

  45. CaMoO4 R&D Summary and Plan • CaMoO4 (18x18x30mm) :0.6 PE/keV -> 6% FWFM at Q= 3MeV Decay time : g ; 16.5 +-0.5 ms, a ; 15.5 +-0.5 ms at 4.5MeV a • PSD possible:Th232, U238 background reduction • Ea/gratio:0.2 • Currently working on • Temperature dependence • Background reduction study of powder, Crystal growing (Russia) • Internal bkg study 2x2x3cm CaMoO4 at Y2L shielding * Study of internal bkg (U238,Th232-> timing correlation, alpha) • Future Plan : 10kg of Mo-10 enriched CaMoO4 crystals installed at YangYang underground Lab in Korea in two years. Sensitivity: 1025 years by 90% CL(0.15eV) with 5 years data taking <- 5 sigma significance if Klapdor claim is right

  46. Large area with high efficiency R&D 4x4 1.5cm Photodiode ->noise problem Large Area avalanche photodiode (1.6cm diameter) • Large ared : 5x5cm • Noise : a few hundred RMS noise • High quantum efficiency : 80% (PMT: 15% ) Silicon Drift sensor

  47. CdWO4 experiment (Zdsenko) Double beta decay

  48. (A,Z+1) (A,Z) (A,Z+2) 0 -, 2-n bb decay processes (A,Z) -> (A,Z+2) + 2b +(2n)

  49. CaMoO4 2x2x3cm, Cs137 source

  50. Alpha response of CaMoO4 Ea/g = 0.2 with 5.5MeV a particle

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