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Calorimetry SuperNemo

Calorimetry SuperNemo. Robert L. Flack University College London On behalf of the SuperNEMO collaboration. Overview. SuperNEMO Neutrino mass Double beta decay The collaboration Results Scintillator blocks Scintillator bars The future Pre-production module Summary.

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Calorimetry SuperNemo

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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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