Double Beta Decay Present and Future Jenny Thomas

Double Beta Decay Present and Future Jenny Thomas Rencontres du Vietnam, 2004 Jenny Thomas

Preview Introduction: why search for 0 nbb decay? Status of the search today: 3 experiments Cuoricino NEMO-III Heidleberg-Moscow : signal! Look at parameter space for 0 nbb experiments Highlights of a few experiments on the horizon Conclusions J. Thomas, UCL

Introduction: oscillations The neutrino mixing matrix looks like this: From Kam. LAND, SNO, Super-K (Gonzales-Garcia NOON) J. Thomas, UCL

Introduction: oscillations mmin ~ 0. 03 - 0. 06 e. V mmin ~ 0 - 0. 01 e. V J. Thomas, UCL

Introduction: double beta decay Large number of even-even nuclei undergo double-beta decay, but not single-beta decay Standard Model process of 2 nbb is also allowed of course Enrichment procedure in place for about 10 isotopes You do not search for peaks in unknown places: you always know where to look Q value of the decay is well known (difference in energy between two isotopes) 2 nbb J. Thomas, UCL 0 nbb

Introduction: double beta decay 76 Ge example Q Endpoint Energy J. Thomas, UCL

Introduction: the experiments Two classes of approach to the experiment: Detector IS the isotope Ionisation detectors Bolometer detectors TPCs Detector Contains the isotope(s) Tracking detectors Measure half life, infer mn Half life sensitivity given by experimental details G-phase space, exactly calculable: G 0 n ~ Qbb 5 M 0 n-Nuclear Matrix Element, hard to calculate Uncertain to factor 2 -10, isotope dependent Motivation to measure several isotopes J. Thomas, UCL

Introduction: the isotopes What are the usable bb decay isotopes? Q=2. 038 Me. V : MG = 7. 3 +0. 6 -0. 6 x 10 -14 48 Ca, Q = 4. 272 Me. V : MG = 5. 4+3. 0 -14 x 10 -1. 4 82 Se, Q = 2. 995 Me. V : MG = 1. 7+0. 4 -13 x 10 -0. 3 100 Mo, Q = 3. 034 Me. V : MG = 1. 0+0. 3 -12 x 10 -0. 3 116 Cd, Q = 2. 804 Me. V : MG = 1. 3+0. 7 -13 x 10 -0. 3 130 Te, Q = 2. 528 Me. V : MG = 4. 2+0. 5 -13 x 10 -0. 5 136 Xe, Q = 2. 481 Me. V : MG = 2. 8+0. 4 -14 x 10 -0. 4 150 Nd, Q = 3. 368 Me. V: MG = 5. 7+1. 0 -12 -0. 7 x 10 76 Ge, These can all be enriched by standard processes J. Thomas, UCL

A History Plot Te. O 2 mscale ~ 0. 01 – 0. 05 e. V from oscillation experiments J. Thomas, UCL

Where are we today? People have been searching for double beta decay for many years : first suggested in 1937 Presently three experiments taking data CUORICINO : Bolometer NEMO-III: Tracking HEIDLEBERG-MOSCOW : Ionization Ge detector New improved Heidelberg-Moscow result shows 4. 2 s effect! Cuoricino and NEMO-III will reach this sensitivity J. Thomas, UCL

Today: CUORICINO Located in LNGS, Hall A CUORE R&D (Hall C) CUORE (Hall A) Cuoricino (Hall A) J. Thomas, UCL

Today: CUORICINO 40. 7 kg total 2 modules, 9 detector each, crystal dimension 3 x 3 x 6 cm 3 crystal mass 330 g 9 x 2 x 0. 33 = 5. 94 kg of Te. O 2 34% natural abundance heat bath Thermal sensor 11 modules, 4 detector each, absorber crystal dimension 5 x 5 x 5 cm 3 crystal mass 790 g 4 x 11 x 0. 79 = 34. 76 kg of Te. O 2 Incident particle J. Thomas, UCL

Today: CUORICINO J. Thomas, UCL

Today: CUORICINO 130 Te crysals in LNGS Q = 2. 528 Me. V Operation started early 2003 Background 0. 19 counts/kev/kg/y Energy resolution ~ 4 e. V at 2 Me. V T 1/2>7. 5 x 1023 years <mn>=0. 3 -1. 6 e. V : indicates large range of NME calculations available! J. Thomas, UCL

Today: NEMO-III AUGUST 2001 Located in Frejus Underground Lab J. Thomas, UCL

decay isotopes in NEMO-3 detector 2 measurement 116 Cd 405 g Qbb = 2805 ke. V 96 Zr 9. 4 g Qbb = 3350 ke. V 150 Nd 37. 0 g Qbb = 3367 ke. V 48 Ca 7. 0 g Qbb = 4272 ke. V 130 Te 454 g Qbb = 2529 ke. V 100 Mo 6. 914 kg Qbb = 3034 ke. V 82 Se 0. 932 kg Qbb = 2995 ke. V 0 search Dominique Lalanne for the NEMO-3 Collaboration nat. Te 491 g Cu 621 g External bkg measurement (All the enriched isotopes produced in Russia) J. Thomas, UCL ICHEP 2004 Beijing August 16 -21, 2004

events selection in NEMO-3 Typical 2 event observed from 100 Mo Run Number: 2040 Event Number: 9732 Date: 2003 -03 -20 Vertex emission Deposited energy: E 1+E 2= 2088 ke. V Internal hypothesis: (Dt)mes –(Dt)theo = 0. 22 ns Common vertex: (Dvertex) = 2. 1 mm (Dvertex)// = 5. 7 mm J. Thomas, UCL

100 Mo 2 2 preliminary results (Data 14 Feb. 2003 – 22 Mar. 2004) Sum Energy Spectrum NEMO-3 100 Mo Angular Distribution 145 245 events 6914 g 241. 5 days S/B = 45. 8 NEMO-3 100 Mo • • Data 2 2 Monte Carlo Background subtracted Cos( ) E 1 + E 2 (ke. V) 4. 57 kg. y T 1/2 = 7. 72 ± 0. 02 (stat) ± 0. 54 (syst) 1018 y Dominique Lalanne for the NEMO-3 Collaboration J. Thomas, UCL ICHEP 2004 Beijing August 16 -21, 2004

100 Mo 2 2 Single Energy Distribution Single electron spectrum different between SSD and HSD, higher levels contribute to the decay 1+ 100 Tc SSD, 1+ level Simkovic, J. Phys. G, 27, 2233, 2001 dominates in the decay (Abad et al. , 1984, Ann. Fis. A 80, 9) 0+ 100 Mo Esingle (ke. V) NEMO-3 4. 57 kg. y NEMO-3 E 1 + E 2 > 2 Me. V • HSD higher levels 2/ndf = 139. / 36 E 1 + E 2 > 2 Me. V • Data 2 2 HSD Monte Carlo SSD Background subtracted Single State Dominique Lalanne for the NEMO-3 Collaboration 2 2 SSD Monte Carlo Background subtracted 2/ndf = 40. 7 / 36 Esingle (ke. V) HSD: T 1/2 = 8. 61 ± 0. 02 (stat) ± 0. 60 (syst) 1018 y SSD: T 1/2 = 7. 72 ± 0. 02 (stat) ± 0. 54 (syst) 1018 y Data Esingle (ke. V) 2 2 single energy distribution in favour of Single State Dominant (SSD) decay J. Thomas, UCL 100 Mo ICHEP 2004 Beijing August 16 -21, 2004

Today: NEMO-III Present 90%CL limits from NEMO-III(216. 4 days) 82 Se: T 23 y, m < 1. 3 – 3. 6 e. V ( 0 ) > 1. 9 10 1/2 Simkovic et al. , Phys. Rev. C 60 (1999) Stoica, Klapdor, Nucl. Phys. A 694 (2001) Caurier et al. , Phys. Rev. Lett. 77 1954 (1996) 100 Mo T 1/2( 0 ) > 3. 5 1023 y, m < 0. 7 – 1. 2 e. V Simkovic et al. , Phys. Rev. C 60 (1999) Stoica, Klapdor, Nucl. Phys. A 694 (2001) Expected Reach in 5 years after Radon. Purification T 1/2( 0 ) > 4. 0 1024 y, m < 0. 2 – 0. 35 e. V 82 Se: T ( 0 ) > 8. 0 1023 y, , m < 0. 65 – 1. 8 e. V 1/2 100 Mo J. Thomas, UCL

Today: Heidelberg-Moscow Enriched Germanium ionisation detector J. Thomas, UCL

Today: Heidelberg-Moscow New analysis provides evidence of a peak at the expected value Total 71. 7 kgy of data Significance is 4. 2 s mn =0. 24 -0. 58 e. V Corresponds to quasidegenerate neutrino masses J. Thomas, UCL

Present Cuoricino/NEMO-III region Possible evidence (best value 0. 39 e. V) “quasi” degeneracy m 1 m 2 m 3 Inverse hierarchy m 212= m 2 atm Direct hierarchy m 212= m 2 sol Cosmological disfavoured Region (WMAP) Feruglio F. , Strumia A. , Vissani F. hep-ph/0201291 J. Thomas, UCL

Future Plans Only a few approaches Bolometers: Isotope is the detector Tracking : Isotope inside the detector Ionisation : Isotope is the detector Simple formula relates experimental parameters to half life reach: background or no background: a-isotopic abundance, b-background/Kev/kg/y, e-efficiency, d. Eenergy resolution, t-time, W-molecular weight, m-mass J. Thomas, UCL

Future Plans There are presently 16 projects in various stages of planning/approval in Italy, Japan, US, France and perhaps other places, target 0. 02 -0. 05 e. V in mass Tracking, TPC, Drift Ionisation DCBA Nd Cobra, Cd. Te MOON Mo GEM Super-NEMO Mo, Se, Nd GENIUS EXO Xe Majorana MPI Scintillator CAMEO Cd GANDLES Ca CARVEL Cd GSO Gd Xe Xe……. Highlight reach of a few CUORE, 720 kg Te. O 2, bolometers EXO, 1 Tonne Xenon, TPC amd +Ba identification MAJORANA, 500 kg Ge, ionization Super-NEMO several isotopes, tracking J. Thomas, UCL

Future Plans : CUORE First fully-funded next generation experiment Based on CUORICINO technology, 130 Te. O 2 Located at LNGS Target background 0. 001 c/kev/kg 720 kg of Te. O 2 J. Thomas, UCL

Future Plans : EXO High Pressure Xe TPC with laser tagging of +Ba daughter for background-free measurement 2 Tonne of 136 Xe at 10 Atm or Liq Xe with cold-finger tagging Energy resolution 2% at 2. 5 Me. V 200 kg prototype of Liq Xe funded by Do. E (no tagging) will be built at WIPP, New Mexico. 200 kg isotope already in hand J. Thomas, UCL

Future Plans : Majorana/MPI 500 kg enriched segmented conventional Ge detector Feasability has been demonstrated, waiting for approval Will use pulse-shape information to reduce background Based on theory that dominant background is 68 Ge from cosmogenics MPI-Ge experiment also proposed Uses Ge mono-crystal in Liquid N or Ar for passive/active shielding Based on theory that dominant background is from Cu etc external to Ge J. Thomas, UCL

Future Plans : Super-NEMO Based on NEMO-III technology, SM only background study Se, Nd, Mo, low SM background Design study will start 2005 Feasible if: a) BG only from 2 n bb b) (NEMO 3) b) DE/E = 10% at 1 Me. V (8% has already been demonstrated in recent R&D) J. Thomas, UCL

Future Plans Certain factors dominate reach Some factors are instrinsic to a particular isotope (M), others to the experimental approach T 01/2 given by experimental parameters: background, resolution, efficiency The larger M, the lower the reach in mn J. Thomas, UCL

Future Plans : Summary J. Thomas, UCL

Conclusions Very exciting time for neutrino physics in general and 0 nbb in particular A positive signal is now a serious possibility in light of oscillation results Costs of experiemnts all in the $50 M range: this is small potatoes for the potential scientific gain In light of large NME uncertainties, several isotopes should be measured to avoid disappointment J. Thomas, UCL