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Neutrino Masses

Dirac. oscillations. double beta decay. Neutrino Masses. Majorana. Oscillations: Kinematics in weak decays: 0 n double beta decay:. Mainz frozen T 2 source, D E=4.8 eV Troitsk gaseous T2 source, D E=3.5 eV Reported anomaly most likely experimental artifact. Katrin (Karlsruhe).

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Neutrino Masses

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  1. Dirac oscillations double beta decay Neutrino Masses Majorana

  2. Oscillations: • Kinematics in weak decays: • 0n double beta decay:

  3. Mainz frozen T2 source, DE=4.8 eV Troitsk gaseous T2 source, DE=3.5 eV Reported anomaly most likely experimental artifact

  4. Katrin (Karlsruhe)

  5. 187Re 187Os + e- + ne E0=2.5 keV, 43 Gyr, abundance 62.8 % mn < 21.7 eV at 90 % CL Milano: 10 AgReO4 crystals (250-300 mg each) as cryogenic bolometers (T=10 mK) DE(FWHM)=28 eV at 2.5 keV

  6. c  e c  e - e c  eR  eL - e Double Beta Decay d(n) u(p) - e W W - e u(p) d(n) d(n) u(p) W W u(p) d(n)

  7. dN dt 2n c0 0n (A,Z+1) 0+ 2+ (A,Z) E0 0+ e-e- (A,Z+2) Eee E0 E0 (MeV) Abundance (%) 48Ca 48Ca 4.271 0.187 dir 76Ge 76Ge 2.040 7.8 dir Popular candidates 82Se 82Kr 2.995 9.2 dir, geo 100Mo 100Ru 3.034 9.6 dir 0.868 128Te 128Xe 31.4 dir, geo 130Te 130Xe 2.533 34.5 dir, geo 136Xe 136Ba 2.479 8.9 dir 150Nd 150Sm 3.367 5.6 dir 232Th 232U 0.858 100 238U 238Pu 1.145 99.3 melking

  8. 76Ge Heidelberg-Moscow (Gran-Sasso) 11 kg of 87 % 76Ge in 5 crystals Energy [keV]

  9. 214Bi bb0n SSE total 71.7 kg yr

  10. bb2n direct geochem. direct Baksan

  11. QRPA Caltech-Tübingen Shell model Strasbourg-Madrid direct -

  12. Next experiments: large mass + low background, better signature, good energy resolution NEMO 10 kg of 100Mo + … in tracking device Majorana 500 kg of 86 % enriched 76Ge 10 cryostats with 21 crystals (2.4 kg each) , segmented readout CUORICINO, 42kg , 760 kg 130Te, 56, 1000 crystals of TeO2, operated as CUORE bolometers (8 mK) GERDA0.1, 1 t, 10 t of 76Ge crystals, immersed in lN2 EXO 200 kg, 1 t, 10 t of 136Xe in TPC

  13. Enriched Xenon Observatoryfor double beta decay 2P1/2 650nm 493nm metastable 47s 4D3/2 2S1/2 Alabama, Caltech, Carleton, Colorado, UC Irvine, ITEP Moscow, Laurentian, Neuchatel, SLAC, Stanford 136Xe: 136Ba++ e- e- final state can be tagged using optical spectroscopy (M.Moe PRC44 (1991) 931) Much improved signature! Ba+ system best studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) Very specific signature “shelving” Single ions can be detected from a photon rate of 107/s

  14. Isotopic enrichment for a gaseous substance like Xe is most economically achieved by ultracentrifugation Russia has enough production capacity to process 100 ton Xe and extract up to 10 ton 136Xe in a finite time This separation step that rejects the light fraction is also very effective in removing 85Kr (T1/2=10.7 yr) that is present in the atmosphere from spent fuel reprocessing

  15. Two detector options under consideration • High Pressure gas TPC • 5-10 atm, 50 m3 modules, • 10 modules for 10 t • Xe enclosed in a non-structural bag • b range ~5-10cm: • can resolve 2 blobs • 2.5m e-drift at ~250kV • Readout Xe scintillation with • WLSB (T0) • Additive gas: quenching and • Ba++ Ba+ neutralization • Steer lasers or drift Ba-ion to • detection region • Liquid Xe chamber • Very small detector (3m3 for 10tons) • Need good E resolution • Position info but blobs not resolved • Readout Xe scintillation • Can extract Ba from hi-density Xe • Spectroscopy at low pressure: • 136Ba (7.8% nat’l) different • signature from natural Ba • (71.7% 138Ba) • No quencher needed, neutralization • done outside the Xe

  16. Grenoble-Neuchâtel-Padova-Zurich (Bugey reactor) e grid 1 m CH2+B reactor 18 m liquid scintillator (veto+anti-Compton) steel vessel PMT vD=2.3 cm/s e- anode (20 m) qreac CF4 gas at 3 bar 1 cm acrylic vessel +field shaping rings cathode (-45 kV) Pb potential (100 m) x - y plane

  17. M U N U  - proton EM shower

  18. M U N U x 5cm y 5cm DX,Y = 1.7mm DZ = 1.7mm 20cm z 870 keV electron MUNU measures qreacand Te

  19. s(E)/E=0.13 % at 2.48 MeV ! Energy resolution F=0.19, W=22 eV Gotthard 5 bar xenon a (from cathode), 210Po (238U chain) quenching (a/e-)=1/6.5 s(E)/E=1.1 % at 2.48 MeV ! e-, 232Th s(E)/E=3.4 % at 1.59 MeV s(E)/E= 2.7 % at 2.48 MeV

  20. Micromegas Woven mesh stainless steel Anode with spacers Fe Fe Neuchâtel-CERN: CF4 Ag pulser pulser Ag 0 10 20 30 40 E(keV) 0 10 20 30 E(keV) 1 bar 2 bar

  21. ITEP-Moscow, Kharkov, Neuchâtel Light detection (electroluminescence)in xenon (+CF4?) e- track Grid (metallic cloth) Multianode photomultiplier UV photons Anode (charge) Two gap scheme: Grid (metallic cloth) Optical fibers x-y Doped fibers : 1 step WLS UV (180 +/-20nm) to blue or 2 step WLS with coated fibers anode Fibers (250 mm)

  22. Found a clear (anti)correlation between ionization and scintillation 1 kV/cm ~570 keV Major effort now: liquid xenon

  23. Have demonstrated that we can get sufficient energy resolution in LXe to separate the 2νfrom the 0νmodes We can do ionization measurements as well as anyone Resolutions at 570 keV Now we turn on our new correlation technique… 3.3%@570keV or 1.6%@2.5MeV

  24. Fishing ions in LXe

  25. Prototype Scale • 200 Kg enriched 136Xe • All functionality of EXO except Ba identification • Operate in WIPP for ~two years • Prototype Goals • Test all technical aspects of EXO (except Ba id) • Measure 2n mode • Set decent limit for 0n mode (probe Heidelberg-Moscow)

  26. Massive materials qualification program led by Alabama with contributions from Carleton, Laurentian and Neuchatel • Approximate detector simulation with material properties to • establish target activities • NAA whenever possible (MIT reactor + Alabama) • Direct Ge counting at Neuchatel, Alabama and soon Canada • High sensitivity mass spectroscopy starting in Canada • Alpha counting at Carleton and Stanford • Rn outgassing measurements starter at Laurentian (Xe plumbing) • Full detector simulation in progress

  27. Pb Plombum VG2 13 days 34 kg Vue-des-Alpes 400 cc germanium 2614 keV 208Tl (232Th chain)

  28. Detector (356 on each side, 16 mm diameter 120 % QE in UV))

  29. APD plane below crossed wire array 100 APD channels (7 APD grouped together) provide light and t0 200 ionization channels (groups of wires 100 x +100 y) Can define fiducial volume

  30. Drift trajectories – crossed wires

  31. Cryostat Cross Section Outer Door Condenser FC-87 Xenon Chamber Inner Door Xenon Chamber Support Xenon Heater should be on this area FC-87 1” thick Thermal Insulation (MLI-vacuum), not shown to scale Inner Copper Vessel Outer Copper Vessel

  32. Full detector view With Pb shielding

  33. DoE’s Waste Isolation Pilot Plant (WIPP), Carlsbad NM

  34. Assuming 1) that the Xe chamber + Ba tagging gives 0 background from radioactivity... 2) that the energy resolution is s(E)/E=2 % (2nbb!) Background <m > (eV) <m > (eV) T Mass Enrichment Eff. Time 0 n n n 1/2 (kg) (%) (%) (yr) (events) (yr) QRPA SM 1000 90 70 5 0.3 0.05 0.08 2*10 27 28 10000 90 70 10 5.5 0.02 0.03 1.3*10 Conclusion: With a coordinated effort, the meV region is within reach!

  35. Status • Enriched Xe in hand. • Clean rooms in commercial production. • WIPP agreement, including Environmental Impact, complete. • Cryostat being designed. • Xe purification and refrigeration issues being finalized • Detector vessel, readout, and electronics being engineered.

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