1 Current status and future of double  decay experiments Fedor Danevich Institute for Nuclear Research, Kyiv, Ukraine F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

2 content 2  -experiments – current status – projects – normal hierarchy? conclusions F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

3 2  decay - history Ettore Majorana ? Majorana neutrino is identical with its antiparticle  Neutrinoless double beta decay is only possible if neutrino is a massive Majorana particle M. Goeppert–Mayer, Double  –Disintegration Phys. Rev. 48 (1935) 512 G. Racah, Nuovo Cimento. 14 (1937) 322 Paul Adrien Maurice Dirac F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 _

4 2  decay decay modes and channels Two neutrino  decay (A,Z)  (A,Z+2) + e - + e - + e + e conserving lepton number In contrast, the neutrinoless decay (A,Z)  (A,Z+2) + e - + e - violates lepton number by two units and is forbidden in the standard electroweak theory Another decay mode involves the emission of a light neutral boson (s), a Majoron, as postulated in some extensions of the standard electroweak theory (A,Z)  (A,Z+2) + e - + e - +  Decay modes: Decay channels: Double (electron) decay 2  - Double electron capture, electron capture with positron emission, double positron decay 2 ,  +, 2  + F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

5 Half-life of 0 2  (T 1/2 0 ) -1  G 0 2  (Q 2 ,Z)|M 0 2  | 2  m 2   2 G 0 2  (Q 2 ,Z) – phase space integral M 0 2  – nuclear matrix element  m 2   = |  m j U ej 2 | – effective neutrino Majorana mass F. Simkovic et al., PRC 77 (2008) T 1/2 0  yr  m 2   = 0.05 eV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

6 m1m1m1m1 m2m2m2m2 m3m3m3m3 m 3 m 3 m1m1m1m1 m2m2m2m2 m1m1m1m1 m2m2m2m2 m3m3m3m3 normalinverteddegenerated e   atmospheric solar 2  decay and neutrino oscillations F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

7 double  decay Nature of neutrino (Majorana or Dirac particle) Absolute scale of the neutrino mass Lepton number conservation can clarify very important problems of Particle Physics and Cosmology: “Establishing a possible Majorana nature of neutrino would be a fundamental discovery” Neutrino mass hierarchy Status and Perspectives of Astroparticle Physics in Europe, ASPERA Roadmap Phase I, 2007 F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

8 experimental methods Direct registration of  events Geochemical Radiochemical 82 Se 96 Zr 100 Mo 128,130 Te 130,132 Ba (?) 238 U detector = source (calorimetric) detector ≠ source (tracking) F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

9 76 Ge Heidelberg-Moscow Heidelberg-Moscow [1] T 1/2  1.9  yr m  0.35 eV IGEX IGEX [2] T 1/2  1.6  yr m  0.38 eV T 1/2  2  yr  m   eV  m   eV [3] ? 55 kg year 71 kg year F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 [1] H.V. Klapdor-Kleingrothaus et al., EPJA 12 (2001) [3] Mod. Phys. Lett. A. 21 (2006) 1547 [2] C.E. Aalseth et al., PRC 59 (1999) 2108

Xe T 1/2 > 4.4  yr  m <2.2 eV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 R. Luescher et al., PLB 434 (1998) 407

11 The NEMO-3  decay experiment tracking detector 0.96 kg of 97% 82 Se  2.1  yr  m   1.7 – 4.3 eV energy of electrons angular distributions event vertex kg of 91% 150 Nd  1.8  yr  m   1.7 – 2.4 eV 7.1 kg of 97% 100 Mo  5.8  yr  m   0.6 – 1.3 eV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 A. Barabash (for NEMO-3) JPSC 173 (2009)

12 2  decay of 100 Мо to excited level of 100 Ru T 1/2 = (6.5 )  yr ~0.8 kg of 100 Mo yr of measurements by the ultra-low background HP Ge  spectrometer Ge-Multi at LNGS P.Belli et al., in preparation to PRC sample  F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

Te Energy absorber single TeO 2 crystal 790 g, 5 x 5 x 5 cm Thermometer (doped Ge chip) 130 Te 0  MT = 18 kg ( 130 Te)  yr BG = 0.18±0.01 c/keV/kg/y FWHM = 7 keV (average for 790 g detectors)   /2 0 2  > 2.9  yr (90% c.l.) 60 Co sum peak 2505 keV  m   < 0.2 – 0.7 eV  F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 M. Sisi, presentation on TAUP-2009

14 2  experiments with crystal scintillators CdWO 4  106 Cd, 114 Cd, 116 Cd, 180 W, 186 W CaF 2  40 Ca, 48 Ca GSO  160 Gd ZnWO 4  64 Zn, 70 Zn, 180 W, 186 W CeF 3, CeCl 3  136 Ce, 138 Ce BaF 2  130 Ba, 132 Ba SrCl 2  84 Sr CaMoO 4  92 Mo PHYSICAL REVIEW 146 (1966) CaF 2 (Eu), 19 g  T 1/2 0 >2  yr T 1/2 0 > 10 18–23 yr T 1/2 2 = 3  yr (2 2  in 116 Cd) F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

15 48 Ca CaF 2 (Eu) crystal scintillators 1553 kg day kg day of exposure Energy resolution (FWHM): 4.27 MeV Background: 0 events was observed T 1/2 0  > 5.8  yr  m   3.5 – 22 eV PRC 78 (2008) F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

16 Search for 2  decay of 160 Gd 2  160 Gd Q 2  = 1730 keV Yad. Fiz. 58 (1995) 195; NPA 694 (2001) 375 Gd 2 SiO 5 (Ce), 635 g, h  T 1/2 0  1.3  21 yr T 1/2 2  1.9  19 yr 160 Gd is interesting candidate for high sensitive 2  experiment due to the large natural abundance (21.86%) and promising theoretical estimations of the matrix elements at 90 % C.L. F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

17 2  decay of 116 Cd Plastic active shield CdWO 4 Plastic light guide The main results: T 1/2 2 = 2.9  19 yr T 1/2 0  1.7  23 yr  m   1.7 eV 116 CdWO 4 crystal ~0.5 kg PRC 68 (2003) F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

18 best 0 2  - experiments [1] S. Umehara et al., PRC 78 (2008) [2] H.V. Klapdor-Kleingrothaus et al., EPJA 12 (2001) 147 [3] C.E. Aalseth et al., PRC 59 (1999) [4] H.V. Klapdor-Kleingrothaus, I. Krivosheina, Mod. Phys. Lett. A. 21 (2006) 1547 [5] A. Barabash, JPSC 173 (2009) [6] F.A. Danevich et al., PRC 68 (2003) [7] M. Sisi, presentation on TAUP-2009 [8] R. Luescher et al., PLB 434 (1998) 407 Nuclide Experimental limits T 1/2 (yr) Limits  m  (eV) Ref. 48 Ca > 5.8 ×10 22 < (3.5 – 22) [1] 76 Ge > 1.9×10 25, > 1.6×10 25 = 2.2  < ( ) = [2,3] [4] 82 Se > 2.1×10 23 < ( ) [5] 100 Mo × > 5.8×10 23 < ( ) [5] 116 Cd > 1.7×10 23 < 1.7 [6] 130 Te > 2.9×10 24 < ( ) [7] 136 Xe > 4.4×10 23 < 2.2 [8] 150 Nd > 1.8 ×10 22 < ( ) [5] F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

19 2 ,  +, 2  + processes  Half-lives for 0  + decay depend strongly on whether the decay is dominated by the mass mechanism or right-handed weak current [1] M. Hirsch et al., Z. Phys. A 347 (1994) 151 Search for the 0 modes of 2 ,  + and 2  + processes could help for a refined investigation of the neutrino nature and weak interaction Search for the 0 modes of 2 ,  + and 2  + processes could help for a refined investigation of the neutrino nature and weak interaction [1] F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

20 2  decay of 106 Cd TGV experiment to search for 2  decay of 106 Cd in the Modane UL T 1/2 0 EC/EC > 6.5  yr T 1/2 2 EC/EC > 1.7  yr JINR Dubna; CSNSM Orsay Paris; IEAP Prague N.I. Rukhadze et al., Bull. Rus. Acad. Sci.: Phys. 73 (2009) 741 F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

21 Search for 2  decay of 64 Zn ZnWO 4  0.7 kg Polystyrene Light-guide Low BG PMT DAMA R&D, Gran Sasso INFN Roma 1 & 2; LNGS; INR Kyiv; ISMA Kharkov DAMA R&D, Gran Sasso P. Belli et al., PLB 658 (2008) 193 P. Belli et al., NPA 825 (2009) 256 in particular: T 1/2 2 2K ≥ 6.2 × yr T 1/2 0 2  ≥ 1.1 × yr T 1/2 2  + ≥ 7.0 × yr T 1/2 0  + ≥ 4.3 × yr at 90% C.L. Limits on T 1/2 relatively to 2  processes in 70 Zn, 180 W, 186 W on the level of yr F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

22 2  -decay of 96 Ru limT 1/2 2   y 158 h, 483 g of Ru y ? y P.Belli et al., Eur. Phys. J (corr. proof) F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 Resonant 0 2  is possible

23 Some best 2 ,  +, 2  + experiments NuclideChannel Experimental limits T 1/2 (yr) Technique 40 Ca 22 > (3-6) ×10 21 CaF 2 (Eu) scintillators 54 Fe 22 > (4-5) ×10 20 HPGe  spectrometry 58 Ni 2 ,  + > (0.2-7)×10 20 HPGe  spectrometry 64 Zn 2 ,  + > (0.06-7)×10 20 ZnWO 4 scintillators 78 Kr 2 ,  +, 2  + > (1-5× > (1-5)×10 21 Gaseous detector 92 Mo 2 ,  + > (0.06-9)×10 20 HPGe  spectrometry 96 Ru 2 ,  +, 2  + > ( × > ( )×10 19 HPGe  spectrometry 106 Cd 2 ,  +, 2  + > (0.01-4)×10 20 HPGe  spectrometry, NaI(Tl)  spectrometry CdWO 4 scintillators CdZnTe semiconductor 130 Ba 2 ,  +, 2  + > 4×10 21 = (2.2 ± 0.5) ×10 21 Geochemical 132 Ba 22 > 2.2×10 21 Geochemical F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

24 Search for 2  decay of 106 Cd Crystal boule 231 g  27  60 mm (87% of mass of initial material) enriched in 106 Cd to 66% 106 CdWO CdWO 4 F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 Attenuation length 60 cm newer reported FWHM=10% Excellent optical and scintillation properties thanks to special R&D to purify raw materials P.Belli et al., submitted to NIMA

25 The White King awaits messengers from the White Queen. He asks Alice: Lewis Carroll “Through the Looking Glass” “Just look along the road, and tell me if you can see either of them.” “I see nobody on the road,” said Alice. “I only wish I had such eyes,” the King remarked in a fretful tone. “To be able to see Nobody! And at the distance too! Why, it's as much as I can do to see real people, by this light!” F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct  experiments only wish to have better sensitivity Sir Charles Lutwidge Dodgson “Lewis Carroll”) (“Lewis Carroll”) Alice's Adventures in Wonderland “ Alice's Adventures in Wonderland ” Sir John Tenniel Sir John Tenniel Illustrator of Alice’s Adwentures

26 2  projects F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

27 GERDA 20 kg of enriched HP 76 Ge detectors from H-M and IGEX Background expected ~0.01 cnt/(yr kg keV) 76 Ge LNGS, Italy T 1/2 ~ 2  yr,  m  ~ 0.3 − 0.9 eV Phase I 100 kg  yr exposition100 kg  yr exposition BG ~0.001 cnt/(yr kg keV) T 1/2 ~ 2  yr,  m  ~ 0.09 − 0.29 eV Phase II hep-ex/ Phase III 1 t of 76 Ge1 t of 76 Ge  m  ~ 0.01 eV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 Important advantage: good energy resolution ~ 2-3 keV (0.1%)

28Majorana 500 kg of Ge, isotopically enriched to 86% in 76 Ge, in the form of ~200 segmented detectors, equipped by pulse shape analysis electronics 76 Ge At present the collaboration working on a 60 kg prototype set-up material selection detector segmentation pulse shape analysis electro-formation of copper parts and granularity T 1/2 ~ 4  yr  m  ~ 0.03 − 0.04 eV hep-ex/ F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 good energy resolution ~ 2-3 keV (0.1%)

29 EXO The EXO 136 Xe  decay project using laser tagging PLB 480 (2000) Xe F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 facet 1: EXO-200 is prototype to develop techniques of working with liquid xenon in a time projection chamber (200 kg of enriched to 80% 136 Xe) with a goal to detect 2 mode and to set a competitive limit on neutrinoless double beta decay facet 2: EXO - a ton scale experiment using 136 Xe to search for 0 2  decay Large Time Projection Chamber or Scintillation Detector Detecting Ba + ions in the final state of 136 Xe T 1/2  8  yr (1 t of 136 Xe)  m   0.05 eV Good possibilities to enrich 136 Xe low energy resolution ~ 5-7%

30 From CUORICINO to CUORE ( Cryogenic Underground Observatory for Rare Events ) Each tower is a CUORICINO-like detector Special dilution refrigeratorCUORE 130 Te F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 CUORE = closely packed array of 988 detectors 19 towers - 13 modules/tower - 4 detectors/module M = 741 kg  ~ Te nuclides Compact structure, ideal for active shielding good energy resolution ~ 5-7 keV (0.3%)

31 SuperNEMO 82 Se ( 150 Nd) A half-life sensitivity is predicted: T 1/2  2  yr  m   0.05 eV 82 Se foil Track volume Calorimeter 100 kg of enriched 82 Se ( 150 Nd) foil, track reconstruction 20 modules ~5 kg of 82 Se each Radiopurity of 82 Se at the level of a few Bq/kg ~4% of energy resolution at 3 MeV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 A track experiment expected energy resolution ~4%, detection efficiency (~30%)

32 Design Concepts of CANDLES Undoped CaF 2 Scintillator CaF 2 (Pure) Long Attenuation Length Double Beta Decay Source 48 Ca (Q  =4.27MeV) Peak Emission at UV Region (280nm) ↓ Wave Length Shifter Liquid Scintillator Wave Length Shifter 4  Active Shield Large Photomultiplier Tube Large Photomultiplier Tube Signals from both scintillators are detected simultaneously Active Shielding TechniqueActive Shielding Technique Different Time Constants CaF 2 (pure) : ～ 1  sec Liquid Scintillator : a few 10 nsec Courtesy Prof. Saori Umehara F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct Ca High Q  energy (4.27 MeV) large mass, low isotopic abundance of 48 Ca (0.187%)

33 SNO++ 2  decay of 150 Nd with Nd-loaded liquid scintillator 0.1% Nd in 1000 tons of natural Nd loaded liquid scintillator  56 kg of 150 Nd F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 low energy resolution ~ 6-7%, too large mass ~1 kt 150 Nd

34 Advancement of 116 Cd experiment Energy resolution 3.9% at 2.6 MeV An excellent pulse-shape discrimination  42×39 mm NIMA 569 (2006) 743; NIMA 556 (2006) 259 F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 R&D to produce kg of enriched 116 CdWO 4 crystals is in progress in collaboration with the DAMA group, ITEP (Moscow, Russia), NIIC (Novosibirsk, Russia)

35 Results on the first array of CdWO 4 crystals Background-Free area 2615 keV 208 Tl  The MC simulation predicts a background level of c/keV/kg/y in the region of interest 44 days background Courtesy Dr. Stefano Pirro, INFN - Sezione di Milano Bicocca  particles

36 ZnSe – an extremely interesting compound Courtesy Dr. Stefano Pirro, INFN - Sezione di Milano Bicocca

37 ZnMoO 4 – A promising Molibdate A 22 g ZnMoO 4 crystal was grown by Institute for Scintillation Materials (Kharkov, Ukraine) in collaboration with Institute for Nuclear Research (Kiev, Ukraine) 226 Ra, 222 Rn, 218 Po, 214 Bi- 214 Po (56 mBq/kg) 210 Pb (360 mBq/kg) Courtesy Dr. Stefano Pirro, INFN - Sezione di Milano Bicocca 

38 Li 2 MoO 4 ZrO 2 Good Scintillation light Poor Scintillation light No Scintillation light MgMoO 4 TeO 2 Scintillators for double  decay search ZnSe PbMoO 4 SrMoO 4 CdMoO 4 CdWO 4 CaF 2 CaMoO 4 Li 2 Zn 2 (MoO 4 ) 3 Courtesy Dr. Stefano Pirro, INFN - Sezione di Milano Bicocca ZnMoO 4 The energy resolution needed to go towards normal hierarchy can be achieved only by bolometers and semiconductors Different nuclei can be studied

39 Normal hierarchy? Is it possible to go toward normal hierarchy? Is it possible to go toward normal hierarchy?  m   – eV Т 1/2  yr F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

40 Energy resolution Should be better than ~1% (FWHM) Y.G. Zdesenko et al., J. Phys. G, 30 (2004) 971 HPGe, cryogenic bolometers F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

41 Exposition Y.G. Zdesenko et al., J. Phys. G, 30 (2004) 971 Mass of detector t Time of experiments 10 years Detection efficiency → 100% F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

42 Background 0 counts / (10 yr  10 t  30 keV) ~ cnt / (yr keV kg) At present achieved background counting rate:  cnt / (yr keV kg) 48 Ca, CaF(Eu)  0.01 cnt / (yr keV kg) 136 Xe, TPC  0.04 cnt / (yr keV kg) 116 CdWO 4, Solotvina  0.1 cnt / (yr keV kg) HP 76 Ge, H-M, IGEX (no PSA)  0.2 cnt / (yr keV kg) Te0 2, CUORICINO Problems and possible solutions: 2 -mode – energy resolution only U, Th, Radon – < ( – ) g/g, «wise» detector (pulse shape analysis, etc) Cosmogenic activation: choice of nuclei (high Q  ), production of detector deep underground Background from neutrino: minimal volume of detector, energy resolution Special “radiopure” technology is needed F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

43 conclusions I 0 2  experiments can: measure  m   0.01 – 0.1 еВ and establish hierarchy of the neutrino mass measure  m   0.01 – 0.1 еВ and establish hierarchy of the neutrino mass determine nature of neutrino (Dirak or Majorana) determine nature of neutrino (Dirak or Majorana) test lepton number conservation test lepton number conservation The most sensitive 2  - experiments give limits on half-lives of nuclei ( 48 Ca, 76 Ge, 82 Se, 100 Mo, 116 Cd, 130 Te, 136 Xe, 150 Nd) and on the effective neutrino Majorana mass: Т 1/2  yr  m   0.3 – 3 eV F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009 The best 2 ,  +, 2  + experiments give only limits on half-lives of nuclei ( 40 Ca, 54 Fe, 58 Ni, 78 Kr, 92 Mo, 96 Ru, 106 Cd, 130 Ba, 132 Ba): Т 1/2  yr Even 2 mode is still not detected clearly. Further development of experimental methods is required

44 conclusions II  100 кг 0 2  -experiments ( 48 Ca, 76 Ge, 82 Se, 130 Te, 136 Xe, 100 Mo, 116 Cd, 150 Nd, …) to test inverted hierarchy of neutrino mass is in preparation to test inversed hierarchy of the neutrino mass Т 1/2  yr  m   0.1 – 0.05 эВ 0 2  -experiment able to detect  m  of the normal hierarchy should have a sensitivity Т 1/2  – yr Background of a detector looks the most complicated and exciting problem F.A. Danevich Workshop on Double Beta Decay Search, SNU15 Oct 2009

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