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Advancements in Neutrino Mass: Calorimetry Studies

Explore findings on neutrino mass in Double Beta Decay through Calorimetry, Majorana masses, and nuclear matrix elements. Discover the SuperNEMO project's research and R&D in calorimeter technology for precise measurements.

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Advancements in Neutrino Mass: Calorimetry Studies

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  1. CalorimetrySuperNemo Robert L. Flack University College London On behalf of the SuperNEMO collaboration Calorimetry-TIPP09

  2. Overview • SuperNEMO • Neutrino mass • Double beta decay • The collaboration • Results • Scintillator blocks • Scintillator bars • The future • Pre-production module • Summary Calorimetry-TIPP09

  3. What is the absolute mass scale? How far above zero is the pattern? Oscillation data Cosmological data Calorimetry-TIPP09

  4. Do neutrinos have Majorana masses? Majorana masses for quarks and charged leptons are forbidden due to charge conservation. If neutrinos do have Majorana masses then they must have a very different origin to quark and charged lepton masses. Calorimetry-TIPP09

  5. 2νββ decay • Standard model process; • Valuable measurement in its own right; • Input into nuclear matrix element (NME) calculations; • Accurate estimates of NMEs are crucial in the analysis of 0νββ decay data. Calorimetry-TIPP09

  6. DL = 2! Phase space Half-life νe effective mass Nuclear matrix element 0νββ decay • - Beyond SM: Total lepton number • violation; • - Most sensitive way to establish • Majorana/Dirac nature of neutrino; • - Most sensitive way to measure • absolute ν mass in a lab environment • (for Majorana ν’s); • - Possible access to ν mass hierarchy • and Majorana CP-violation phases; • Link to matter-antimatter asymmetry (leptogenesis). Calorimetry-TIPP09

  7. SuperNEMO simulations and physics reach Se82 “Conservative” scenario Nd150 Sensitivity 82Se: T1/2(0n) =(1-2) 1026 yr depending on final mass, background and efficiency <mn>  0.06 – 0.1 eV (includes uncertainty in T1/2) – MEDEX’07 NME 150Nd: T1/2(0n) =5 1025 yr <mn>  0.045 eV (but deformation not taken into account) Calorimetry-TIPP09

  8. Calorimeter R&D at SuperNEMO . M. t e A ln2 N kC.L. (y) . . NBkg.DE > by Matthew Kauer Good energy resolution is a must! M mass (g) e efficiency kC.L. confidence level NAvogadro number t time (y) NBkg background events (keV-1.g-1.y-1) DE energy resolution (keV) Even with ideal M, Nbkg, e 2n and 0n mix at low DE 8% FWHM 12% FWHM Calorimetry-TIPP09

  9. Calorimeter R&D at SuperNEMO • SuperNEMO ~ 90 physicists, 12 countries • currently on 3 year R&D phase (ends late ’09) • R&D on: • Isotope enrichment • Drift cell tracker • Software • Calorimeter UCL London CENBG Bordeaux, LAL Orsay INR Kiev, ISMA Kharkov JINR Dubna Univ. Texas Austin Isotope Isotope Mass M Efficiency e Internal Bkgs Energy Resolution Sensitivity 82Se (and/or 150Nd if enrichment possible) 100 - 200 kg ~ 30 %  10 mBq/kg 4% FWHM @ 3 MeV T1/2(0nbb) > 1026 y <mn> < 0.04 - 0.11 eV Calorimetry-TIPP09

  10. SuperNEMO base design (Energy resolution ~ 7%) Single sub-module with ~5-7 kg of isotope ~20 sub-modules for 100+ kg of isotope surrounded by water shielding Foil Total: ~ 40-60k geiger channels for tracking ~ 10-20k PMTs Shielding Problem with the low radio-purity of the glass of the PMTs Calorimetry-TIPP09

  11. Alternative design using scintillator bars (Energy resolution ~ 10%) • To overcome the radio-purity problem the number of PMTs is halved and they are situated away from the main detector volume. • Only ~7,600 3″ or 5″ instead of 15,000 8″ in baseline. • Other advantages are: • Much more compact: 19 m2 floor area will accommodate ~100 kg of isotope (20 mg/cm2) • External walls as active shielding by anti-coincidences • Reduced cost of PMTs 8.5M€ - baseline, 1.25M€ - bars (if 3”) • More options for external bkg suppression, TOF can be relaxed (possibly). Hence may try smaller scintillator-foil gap  higher efficiency Active shielding (10cm) Foil Bars (2.5cm) Active shielding Calorimetry-TIPP09

  12. Programme followed for Calorimeter R&D • Energy resolution is a combination of energy losses in foil and calorimeter DE/E • Two routes pursued • 8″ PMT + plastic block • 2m plastic scintillator bars. • PMTs • Working closely with Hamamatsu • Real breakthrough in high-QE PMTs of 43% QE • First large (8″) high-QE Hamamatsu PMT was delivered to UCL for testing last year • Involvement in ultra-low background PMT development. • Enhanced specular reflectors available, 98% reflectivity instead of usual 93%. • Decision on calorimeter design in June 2009. Calorimetry-TIPP09

  13. Calorimeter R&D at SuperNEMO Significant improvements on PM QE! by Matthew Kauer Calorimetry-TIPP09

  14. 1800 Volts 1900 Volts Matthew Kauer 8″ Hamamatsu SBA Characterization 33% QE (eventually UBA ~ 45%) 8 dynode chain linearity > 3000 Npe Calorimetry-TIPP09

  15. Excellent first result with plastic scintillator Using 207Bi source by Matthew Kauer 976keV DE/E = 6.5% at 1 MeV  3.8% at 3 MeV 207Bi conversion electron source BC404 scintillator wrapped in Teflon Hamamatsu high-QE PMT Calorimetry-TIPP09

  16. More realistic setup Optical contact Matthew Kauer Point-to-point ~ 25.5 cm Side-to-side ~ 22 cm Min depth ~ 10 cm Max depth ~ 18 cm Surface area ~ 420 cm2 EJ200 ~ BC408 Glycerol Containment Ring Cargille silica fluid reacts with the PVT! Hamamatsu R5912-MOD Super-Bialkali 8 Dynodes Can try 2-propanol R-index = 1.37 @ 400nm Calorimetry-TIPP09

  17. 8″ PMT @ 1650 V – 25.5x22x10cm HexEJ200~BC408 ESR sides, Mylar face, Glycerol coupling fluid Tested hexagonal and cylindrical shape and got similar results For mechanical reasons we will use hexagonal Calorimetry-TIPP09

  18. Matthew Kauer Tested using 90Sr source @ 1MeV 7.6% !! Calorimetry-TIPP09

  19. Scintillator bars • Scintillator bars from ELJEN, Texas: • EJ-200 (analogue of BC408); • 200cm length x 10cm width, tapered at ends to 6.5cm width to fit 3” PMTs at 45° angle; • 3″ Hamamatsu SBA-select tubes (~ 40% QE) • Wrapped ReflecTech ESR: • Thickness: 100μm; • Surface density: 11.9mg/cm2 • 15 - 20 keV loss in ESR Calorimetry-TIPP09

  20. Scintillator bars Calorimetry-TIPP09

  21. Top: Bottom: +20cm 0cm -20cm +80cm -40cm +60cm -60cm +40cm -80cm +20cm Laboratory setup Plastic tube acts as guide for the ESR “pipe” wrapping inside Holes to introduce the radioactive source Calorimetry-TIPP09

  22. Tests of mechanical structure and optical contact of the PMTs in differing orientations Calorimetry-TIPP09

  23. Summary • SuperNEMO: 3 year Design Study nearly finished • For the baseline: • PVT blocks with 8″ PMTs • 40% High-QE PMTs • 98% specular reflectors • 10K photons/MeV scintillator (low Z) • Unprecedented resolution for low Z scintillator (~7% FWHM 1MeV) • Alternative design using 2m scintillator bars • 10% resolution • 450 ps timing resolution, • want to reduce this ~250ps • We will achieve the target sensitivity of 50-100 meV Calorimetry-TIPP09

  24. Backup slides Calorimetry-TIPP09

  25. Schedule Summary 2010 2011 2007 2008 2009 2012 2013 BiPo construction 2014 NEMO3 Running SuperNEMO Design Study BiPo1 Canfranc/LSM BiPo installation BiPo running @ Canfranc SuperNEMO 1st module construction Preparation of new LSM site construction of 20 modules 1-5 SuperNEMO modules running at Canfranc Running full detector in 2014 Target sensitivity (0.05-0.1 eV) in 2016 SuperNEMO modules installation at new LSM Calorimetry-TIPP09

  26. Choice of Isotope • Criteria of choice: • High Qbb value • Phase space G0n • 2nbb half-life • natural abundance • enrichment possibilities. Purification of 4kg of 82Se underway (INL, US). Enrichment of 150Nd possible. 82Se obtained by centrifugation. Impossible for 150Nd, only laser enrichment. Calorimetry-TIPP09

  27. Qββ for some isotopes Q-values: 48Ca, 4.27MeV 150Nd, 3.37MeV 100Mo, 3.03MeV 82Se, 3.00MeV 136Xe, 2.48MeV 76Ge, 2.04MeV Calorimetry-TIPP09

  28. ββdecay is about background suppression Background. Natural radioactivity: T1/2(238U, 232Th) ~ 1010 yr T1/2(0nbb) > 1025 yr 238U and 232Th produce 214Bi (Qb = 3.27 MeV) and 208Tl(Qb = 4.99 MeV) Radon! Cosmogenic activitity Underground is a must Due to tracking, for SuperNEMO the main focus is on source (foil) purity. Must be super-duper-ultra low < 10 mBq/kg! (For reference humans 10-100 Bq/kg typical materials ~ 1Bq/kg) But how to measure these levels?! Calorimetry-TIPP09

  29. SuperNEMO NEMO-3 isotope 82Se - baseline (150Nd if it can be enriched) 100Mo isotope massM 100-200 kg 7 kg 208Tl mBq/kg if 82Se: 214Bi  10 mBq/kg 208Tl: < 20 mBq/kg 214Bi: < 300 mBq/kg internal contaminations 208Tl and 214Bi in the bb foil energy resolution (FWHM) 8% @ 3MeV 4%@ 3 MeV T1/2(0nbb) > 2 x 1024 y <mn> < 0.3 – 0.9 eV T1/2(0nbb) > 1026 y <mn> < 0.04 - 0.11 eV From NEMO-3 to SuperNEMO NA Me Tobs T1/2 (bb0n) > ln 2   A N90 18 % efficiency  ~ 30 % Calorimetry-TIPP09

  30. Choice of site • Canfranc • 2500 m.w.e • LS Modane • 4800 m.w.e • Boulby • 2800 m.w.e Boulby Canfranc Calorimetry-TIPP09

  31. SuperNEMO preliminary design Single module (baseline design) Planar geometry. 20 modules for 100+ kg Source (40 mg/cm2) 12m2 , tracking volume (~2-3k Geiger channels). calorimeter (0.5-1k ch) Total: ~ 40-60k geiger channels for tracking ~ 10-20k PMTs (3k if scintillator bars design) 4 m 1 m 5 m Top view Calorimetry-TIPP09 Side view

  32. Energy resolution is a combination of energy losses in foil and calorimeter DE/E Goal: 7-8%/√E  4% at 3 MeV (82Se Qbb) Studies: Material: organic (plastic or liquid) Geometry and shape (block, bar) Size Reflective coating PMT High QE Ultra-low background Calorimeter R&D Factor of 2 compared to NEMO3! Calorimetry-TIPP09

  33. Quick Comment on Radio-purity by Matthew Kauer Barium salt used to make glass is chemically same as Radium Ra226  Rn222 into the tracker volume  Bi214 (Qb ~ 3.3MeV) Calorimetry-TIPP09

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