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Future Zero-Neutrino Double Beta Decay Experiments

Future Zero-Neutrino Double Beta Decay Experiments. Outline Neutrino Mass and bb General Experimental Issues The Matrix Elements The New Proposals. 3 Complementary Experimental Techniques. Need all three types of experiments to fully understand the nature of the n.

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Future Zero-Neutrino Double Beta Decay Experiments

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  1. Future Zero-Neutrino Double Beta Decay Experiments Outline Neutrino Mass and bb General Experimental Issues The Matrix Elements The New Proposals Steve Elliott, UK Forum 2003

  2. 3 Complementary Experimental Techniques Need all three types of experiments to fully understand the nature of the n. Steve Elliott, UK Forum 2003

  3. Neutrino Masses Direct mass and bb experiments set absolute mass scale. <mb> < 2.2 eV The results of oscillation experiments set the relative mass scale. Sets mn scale > 50 meV bb addresses Dirac/Majorana nature of n. Steve Elliott, UK Forum 2003

  4. bb(2n) vs. bb(0n) bb(2n): Allowed and observed 2nd order weak process. bb(0n): requires massive Majorana neutrinos even in presence of alternative mechanisms. Steve Elliott, UK Forum 2003

  5. Energy Spectrum for the 2 e- Endpoint Energy Steve Elliott, UK Forum 2003

  6. bb Decay Rates G are calculable phase space factors. G0n ~ Q5 |M| are nuclear physics matrix elements. Hard to calculate. mn is where the interesting physics lies. Steve Elliott, UK Forum 2003

  7. What about mixing, mn & bb(0n)? No mixing: virtual n exchange e = ±1, CP cons. Compare to b decay result: real n emission Steve Elliott, UK Forum 2003

  8. Min. <mbb> as a vector sum <mbb> <mbb> is the modulus of the resultant vector in the complex plane. (In this example, <mbb> has a min. It cannot be 0.) min Figure from: PR D63, 073005 Steve Elliott, UK Forum 2003

  9. More General: 3 n (Inverted Heir.) <mbb> 30 meV or few x 1027 yr Plot Thanks to Petr Vogel msmallest Steve Elliott, UK Forum 2003

  10. More General: (Normal Heir.) 30 meV or few x 1027 yr Plot Thanks to Petr Vogel Steve Elliott, UK Forum 2003

  11. Physics Reach Solar + KamLAND + Atmospheric (Ue3~ 0) Steve Elliott, UK Forum 2003

  12. An exciting time for bb! For at least one neutrino: For the next experiments: < mbb> in the range of 10 - 50 meV is very interesting. Steve Elliott, UK Forum 2003

  13. An Ideal ExperimentMaximize Rate/Minimize Background • Large Mass (~ 1 ton) • Good source radiopurity • Demonstrated technology • Natural isotope • Small volume, source = detector • Good energy resolution • Ease of operation • Large Q value, fast bb(0n) • Slow bb(2n) rate • Identify daughter • Event reconstruction • Nuclear theory Steve Elliott, UK Forum 2003

  14. Classes of Background bb(2n) tail Need good energy resolution. Natural U, Th in source and shielding Pure materials, identify bb daughter, pulse shape, timing, position. Cosmic ray activation Store and prepare materials underground. Steve Elliott, UK Forum 2003

  15. bb(2n) as a Background.Sum Energy Cut Only next generation experimental goal Steve Elliott, UK Forum 2003

  16. Natural Activity The Problem: t(U, Th) ~ 1010 years Target: t(bb(0n) ~ 1027 years Detector Shielding Cryostat, or other experimental support Front End Electronics etc. Steve Elliott, UK Forum 2003

  17. Cosmic Ray Induced Activity Material dependent. Need for depth to avoid activation. Need for storage to allow activation to decay. Steve Elliott, UK Forum 2003

  18. Evidence of 68Ge Experimental data from two 1.05 kg natural detectors From: NIM A292 (1990) 337-342. Integral of this spectrum equals integral of this peak. ROI This peak decays with the right half life. Steve Elliott, UK Forum 2003

  19. Matrix Elements There are many calculations. Most authors quote mass limits derived from all or at least representatives of the whole range. How do we interpret the uncertainty associated with the mass due to the nuclear physics? Steve Elliott, UK Forum 2003

  20. Consider a 100 meV result. Statistical contribution to uncertainty. Matrix Element contribution to uncertainty. Would this exclude the inverted hierarchy with small msmallest? Need improvement in the Theory. Steve Elliott, UK Forum 2003

  21. “Found” Peaks Need more than one experiment PR D45, 2548 (1992) A 2527-keV Ge-det. peak that was an electronic artifact. NP B35 (Proc. Supp.), 366 (1994). A ~2528-keV Te-det. peak that was a 2s Statisticalflucuation. Steve Elliott, UK Forum 2003

  22. A Great Number of Proposed Experiments Steve Elliott, UK Forum 2003

  23. Potential Large-Mass (~1 ton) Future Experiments Experiments in Europe CUORE, GENIUS NUSEL Candidates EXO*,MAJORANA,MOON Smaller Mass and Development Experiments Cobra*, DCBA, NEMO*, CAMEO, CANDLES, GSO… Steve Elliott, UK Forum 2003

  24. The MOON Collaboration: • H.Ejiri, Y. Itahashi, N. Kudomi, M. Nomachi, T. Shima • RCNP, Osaka Univ. Japan • R. Hazama, K. Matsuoka, Y. Sugaya, S. Yoshida • Phys. Dept. Osaka Univ. Japan • K. Fushimi, K. Ichihara, Y. Shichijo • University of Tokushima, Japan • P.J. Doe, V. Gehman, R.G.H. Robertson, O. E. Vilches, J.F. Wilkerson, D.I. Will • CENPA, Univ. Washington Seattle, USA • S.R. Elliott, • LANL, USA • J. Engel • Univ. North Carolina, USA • A. Para, • FNAL, USA • M. Greenfield, • International Christian Univ., USA • M. Finger • Phys. Dept., Charles Univ., Prague, Czech Republic • A. Gorin, I.Manouilov, A. Rjazantsev • Inst. High Energy Physics, Protvino, Russia • K. Kuroda, P. Kavitov, V. Vatulin, • VNIIEF, Sarov, Russia • V. Kekelidze, V. Kutsalo, G. Shirkov, A. Sisakian, • A. Titov, V. Voronov, • JINR, Dubna, Russia In Association with: The Majorana Collaboration C. Aalseth, F. Avignone, S.R. Elliott, H. Miley…... Steve Elliott, UK Forum 2003

  25. MOON is 4 experiments… 100Mo 0.168 0  100Tc 100Mo 16 s 1.00 x 1019 y -3.034 CC Solar n 100Ru -3.034 100Ru ? 100Mo -1.293  H. Ejiri et al. PRL 85 (2000) 2917 6.1 x 1020 y -1.904 100Ru Steve Elliott, UK Forum 2003 Hamish Robertson APS, April 5, 2003

  26. MOON Overview 3.3 tons 100Mo, 34 tons Mo Doesn’t require enriched material (but would probably want it). Scintillator/source sandwich Position and single Eb data play big role in bb(2n) and U, Th rejection. Or possibly bolometer 14% efficiency ELEGANTS is precursor. Steve Elliott, UK Forum 2003

  27. Detection Techniques under Consideration: • Scintillator Mo Foil Sandwich • Mo loaded liquid scintillator • Cryogenic calorimeter One possible configuration scintillator Readout fibers Mo foil • 1 module: • Mo foil, 6m x 6m x 0.05 gm/cm • Scintillator 6m x 6m x 0.25cm • 222 wavelength shifting fibers • Super module (detector) • 1950 Modules • 6m x 6m x 5m • 34 t nMo (3 t 100Mo) • 13600, 16-anode PMT readout Steve Elliott, UK Forum 2003

  28. MOON Prototype Steve Elliott, UK Forum 2003

  29. Cryogenic UndergroundObservatory for Rare Events - CUORE Spokesperson Ettore Fiorini Milano Berkeley Firenze Gran Sasso Insubria (COMO) Leiden Milano Neuchatel U. of South Carolina Zaragoza Steve Elliott, UK Forum 2003

  30. CUORE Overview 0.21 ton, 34% natural abundance 130Te TeO2 bolometers, 750 g crystals Doesn’t require enriched material. 1020 5x5x5 cm3 crystals 25 towers of 10 layers of 4 crystals Gran Sasso Laboratory CUORICINO is an approved prototype (1 tower). CUORICINO began operation in Feb. 2003 Steve Elliott, UK Forum 2003

  31. CUORE Detector Detector Damping Suspension Dilution Unit Thermal Shields Steve Elliott, UK Forum 2003

  32. CUORICINO IS OPERATING FIRST PULSE. Data runs began In Feb. 2003 Steve Elliott, UK Forum 2003

  33. Enriched Xenon Observatory - EXO Spokesperson Giorgio Gratta Stanford U. of Alabama Caltech IBM Almaden ITEP Moscow U. of Neuchatel INFN Padova SLAC Stanford U. U. of Torino U. of Trieste WIPP Carlsbad Steve Elliott, UK Forum 2003

  34. EXO Overview (latter talk) 10 ton, ~70% enriched 136Xe 70% effic., ~10 atm gas TPC or LXe chamber Optical identification of Ba ion. Drift ion in gas to laser path or extract on cold probe to trap. TPC performance similar to that at Gottard. 100-kg enrXe prototype (no Ba ID) Isotope in hand Steve Elliott, UK Forum 2003

  35. The Majorana Project Co-Spokespersons Frank Avignone Harry Miley Duke U. North Carolina State U. TUNL Argonne Nat. Lab. JINR, Dubna ITEP, Moscow New Mexico State U. Pacific Northwest Nat. Lab. U. of Washington LANL LLNL U. of South Carolina Brown Univ. of Chicago RCNP, Osaka Univ. Univ. of Tenn. Steve Elliott, UK Forum 2003

  36. Majorana Overview 0.5 ton of 86% enriched 76Ge Segmented detectors using pulse shape discrimination to improve background rejection. Prototype ready to go this fall/winter. (14 crystals, 1 enriched) 100% efficient Can do excited state decay. IGEX is precursor Steve Elliott, UK Forum 2003

  37. Majorana Layout Steve Elliott, UK Forum 2003

  38. AGe + fast n -> 68Ge + X 288d 68Ge 68Ga 68Zn 2.9 MeV 68Ge is the dominate background. For 500-kg enriched detector, initially expect ~500 68Ge decays/day. t1\2 = 288 d The naturally occurring 40K in the human body decays at a rate of 12000 decays/second. Steve Elliott, UK Forum 2003

  39. Why Segmentation and Pulse Shape Analysis? bb is pointlike. b+ or Compton scattered g rays deposit energy in multiple locations. Segmentation and PSD help reduce these Backgrounds. Steve Elliott, UK Forum 2003

  40. Recent Crystal Packaging Test (MEGA) Steve Elliott, UK Forum 2003

  41. GErmanium NItrogen Underground Setup - GENIUS MPI, Heidelberg Kurchatov Inst., Moscow Inst. Of Radiophysical Research, Nishnij Novgorod Braunschweig und Technische Universität, Braunschweig U. of L'Aquila, Italy Int. Center for Theor. Physics, Trieste JINR, Dubna Northeastern U., Boston U. of Maryland, USA University of Valencia, Spain Texas A & M U. Spokesperson Hans Klapdor-Kleingrothaus MPI GENIUS Steve Elliott, UK Forum 2003

  42. GENIUS Overview 1 ton, ~86% enriched 76Ge Naked Ge crystals in LN Very little material near Ge. 1.4x106 liters LN 40 kg test facility is approved. 100% efficient Heid.-Moscow experiment is precursor GENIUS Steve Elliott, UK Forum 2003

  43. GENIUS Layout Clean Room Data Acquisition Insulation Liquid Nitrogen Setup for operation of three 'naked’ Germanium detectors in liquid nitrogen. Steel Vessel 12 m GENIUS Steve Elliott, UK Forum 2003

  44. The Controversy. Locations of claimed peaks Mod. Phys. Lett. A16, 2409 (2001) If one had to summarize the controversy in a short statement: Consider two extreme background models: 1. Entirely flat in 2000-2080 keV region. 2. Many peaks in larger region, only bb peak in small region. These 2 extremes give very different significances for peak at 2039 keV. KDHK chose Model 2 but did not consider a systematic uncertainty associated with that choice. Steve Elliott, UK Forum 2003

  45. Summary of Proposals The <mbb> limits depend on background assumptions and matrix elements which vary from proposal to proposal. Steve Elliott, UK Forum 2003

  46. Conclusions Research and Development are needed for all the future proposed detectors. UG Lab space will be needed for some of that R&D. The next generation bb experiments have a good possibility of reaching an interesting <mbb> region. Steve Elliott, UK Forum 2003

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