Neutrino Masses double beta decay oscillations Majorana Dirac

1)Oscillations: 2)Kinematics in weak decays: 3) 0 double beta decay:

Mainz frozen T 2 source,  E=4.8 eV Troitsk gaseous T2 source,  E=3.5 eV Reported anomaly most likely experimental artifact

Katrin (Karlsruhe)

187 Re 187 Os + e - + e E 0 =2.5 keV, 43 Gyr, abundance 62.8 % Milano: 10 AgReO4 crystals (  g each) as cryogenic bolometers (T=10 mK)  E(FWHM)=28 eV at 2.5 keV m  < 21.7 eV at 90 % CL

Double Beta Decay - - d(n) u(p) e c e e W W d(n)u(p) c e e - c eReR W d(n) u(p) W e - eLeL

E ee dN dt    E0E0 (A,Z) 0+ (A,Z+1) (A,Z+2) E0E0 e-e-e-e- Popular candidates E 0 (MeV)Abundance (%) Ca 76 Ge Se 82 Kr Mo 100 Ru Te 128 Xe Te 130 Xe Xe 136 Ba Nd 150 Sm Th 232 U 238 U 238 Pu dir dir, geo dir dir, geo dir melking dir

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

 214 Bi total 71.7 kg yr SSE

NucleusQRPA Caltech Shell model Strasbourg- Madrid exp 48 Ca x Ge x Se x Mo x Te x Te X Te x Xe<1.0<2.6>8.1 x direct geochem.  Baksan

QRPA Caltech-Tübingen Shell model Strasbourg-Madrid - direct

Next experiments: large mass + low background, better signature, good energy resolution NEMO 10 kg of 100 Mo + … in tracking device Majorana 500 kg of 86 % enriched 76 Ge 10 cryostats with 21 crystals (2.4 kg each), segmented readout CUORICINO, 42kg, 760 kg 130 Te, 56, 1000 crystals of TeO 2, operated as CUORE bolometers (8 mK) GERDA 0.1, 1 t, 10 t of 76 Ge crystals, immersed in lN 2 EXO 200 kg, 1 t, 10 t of 136 Xe in TPC

Enriched Xenon Observatory for double beta decay Alabama, Caltech, Carleton, Colorado, UC Irvine, ITEP Moscow, Laurentian, Neuchatel, SLAC, Stanford Ba+ system best studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) Very specific signature “shelving” Single ions can be detected from a photon rate of 10 7 /s 2 P 1/2 4 D 3/2 2 S 1/2 493nm 650nm metastable 47s Much improved signature! 136 Xe: 136 Ba++ e- e- final state can be tagged using optical spectroscopy (M.Moe PRC44 (1991) 931) optical spectroscopy (M.Moe PRC44 (1991) 931)

Isotopic enrichment for a gaseous substance like Xe is most economically achieved by ultracentrifugation This separation step that rejects the light fraction is also very effective in removing 85 Kr (T 1/2 =10.7 yr) that is present in the atmosphere from spent fuel reprocessing Russia has enough production capacity to process 100 ton Xe and extract up to 10 ton 136 Xe in a finite time

Two detector options under consideration High Pressure gas TPC High Pressure gas TPC 5-10 atm, 50 m 3 modules, 5-10 atm, 50 m 3 modules, 10 modules for 10 t 10 modules for 10 t Xe enclosed in a non-structural bagXe enclosed in a non-structural bag  range ~5-10cm:  range ~5-10cm: can resolve 2 blobs can resolve 2 blobs 2.5m e-drift at ~250kV2.5m e-drift at ~250kV Readout Xe scintillation withReadout Xe scintillation with WLSB (T0) WLSB (T0) Additive gas: quenching andAdditive gas: quenching and Ba ++ Ba + neutralization Ba ++ Ba + neutralization Steer lasers or drift Ba-ion toSteer lasers or drift Ba-ion to detection region detection region Liquid Xe chamber Liquid Xe chamber Very small detector (3m 3 for 10tons)Very small detector (3m 3 for 10tons) Need good E resolutionNeed good E resolution Position info but blobs not resolvedPosition info but blobs not resolved Readout Xe scintillationReadout Xe scintillation Can extract Ba from hi-density XeCan extract Ba from hi-density Xe Spectroscopy at low pressure:Spectroscopy at low pressure: 136 Ba (7.8% nat’l) different 136 Ba (7.8% nat’l) different signature from natural Ba signature from natural Ba (71.7% 138 Ba) (71.7% 138 Ba) No quencher needed, neutralizationNo quencher needed, neutralization done outside the Xe done outside the Xe

x - y plane anode (20  m) potential (100  m) grid 1 cm liquid scintillator (veto+anti-Compton) PMT CF 4 gas at 3 bar acrylic vessel +field shaping rings steel vessel e cathode (-45 kV) reactor 18 m  reac e-e- v D =2.3 cm  s CH 2 +B Pb 1 m Grenoble-Neuchâtel-Padova-Zurich (Bugey reactor)

MUNUMUNU   -  protonEM shower

x y  cm z  cm 870 keV electron  X,Y = 1.7mm  1.7mm MUNUMUNU MUNU measures  reac  and T e

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

Micromegas Woven mesh stainless steel Neuchâtel-CERN: CF 4 1 bar 2 bar E(keV) Ag FeFe FeFe pulser E(keV) Anode with spacers

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

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

Have demonstrated that we can get sufficient energy resolution in LXe to separate the 2 ν from the 0 ν modes We can do ionization measurements as well as anyone Now we turn on our new correlation technique… Resolutions at 570 keV or

Fishing ions in LXe

Prototype Scale –200 Kg enriched 136 Xe –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 2 mode –Set decent limit for 0 mode (probe Heidelberg- Moscow)

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

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

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

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

Drift trajectories – crossed wires

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

Full detector view With Pb shielding

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

Assuming 1) that the Xe chamber + Ba tagging gives 0 background from radioactivity... 2) that the energy resolution is  (E)/E=2 % (2  !) Conclusion: With a coordinated effort, the meV region is within reach! MassEnrichmentEff.Time Background (kg)(%) (yr)(events)(yr)QRPASM T 1/2 0 <m > (eV)<m > (eV) 2* *10 28

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.