Neutrinoless double beta decay experiments Marisa Pedretti Lawrence - PowerPoint PPT Presentation

Lawrence Livermore National Laboratory Neutrinoless double beta decay experiments Marisa Pedretti Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA 94551 This work performed under the auspices of the U.S. Department of Energy by LLNL-PRES-414948 Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Neutrino and Double Beta Decay (DBD) 3 mass eigenstates M 1 , M 2 , M 3 but ν -oscillations measure only the Δ M ij 2 =M i 2 -M j 2 What we don’t know • the mass hierarchy • the nature of ν  ν e 2 ν DBD: (A,Z) → (A,Z+2) + 2e - + 2 allowed by SM  new physics beyond the SM 0 ν DBD: (A,Z) → (A,Z+2) + 2e - neutrinoless double beta decay 2 ν DBD 0 ν DBD peak spread only by the detector energy resolution Lawrence Livermore National Laboratory 2 Option:UCRL# Option:Additional Information

How 0 ν DBD is connected to neutrino mixing matrix and to neutrino masses? Neutrinoless Phase Nuclear Effective Double Beta Decay space matrix elements Majorana mass rate 1/ τ = G(Q,Z) |M nucl | 2 〈 M ββ 〉 2 what the experimentalists parameter containing try to measure the physics what the nuclear theorists try to calculate Lawrence Livermore National Laboratory 3 Option:UCRL# Option:Additional Information

How 0 ν DBD is connected to neutrino mixing matrix and to neutrino masses? Neutrinoless Phase Nuclear Effective Double Beta Decay space matrix elements Majorana mass rate 1/ τ = G(Q,Z) |M nucl | 2 〈 M ββ 〉 2 what the experimentalists parameter containing try to measure the physics what the nuclear theorists try to calculate 2 M 3 | 〈 M ββ 〉 || U e1 | 2 M 1 + e i α 1 | U e2 | 2 M 2 + e i α 2 | U e3 | U ei are the elements of the first row of neutrino mixing matrix M i are the neutrino mass eigenvalues Lawrence Livermore National Laboratory 4 Option:UCRL# Option:Additional Information

〈 M ββ 〉 || U e1 | 2 M 1 + e i α 1 | U e2 | 2 M 2 + e i α 2 | U e3 | 2 M 3 | Quasi Degenerate Inverted Hierarchy Normal Hierarchy Lawrence Livermore National Laboratory 5 Option:UCRL# Option:Additional Information

76 Ge claim Quasi Degenerate Inverted Hierarchy Normal Hierarchy Lawrence Livermore National Laboratory 6 Option:UCRL# Option:Additional Information

76 Ge claim excluded by CUORICINO , NEMO3 Quasi Degenerate Inverted Hierarchy Normal Hierarchy Lawrence Livermore National Laboratory 7 Option:UCRL# Option:Additional Information

3 different value of neutrino mass can be seen as future milestones: 500 meV Quasi Degenerate 50 meV Inverted Hierarchy 15 meV Normal Hierarchy Lawrence Livermore National Laboratory 8 Option:UCRL# Option:Additional Information

3 different value of neutrino mass can be seen as future milestones: enriched natural Counts/y/ton Ge TeO 2 500 meV Nucl. Phys. A 434 575 729, 867 (2003) Quasi Degenerate 50 meV Inverted Hierarchy 15 meV Normal Hierarchy Lawrence Livermore National Laboratory In order to give an idea of the amazing challenge of the future sensitivity target: 9 Option:UCRL# Option:Additional Information

3 different value of neutrino mass can be seen as future milestones: 500 meV Quasi Degenerate enriched natural Counts/y/ton Ge TeO 2 50 meV Nucl. Phys. A 4.3 5.7 Inverted Hierarchy 729, 867 (2003) 15 meV Normal Hierarchy Lawrence Livermore National Laboratory In order to give an idea of the amazing challenge of the future sensitivity target: 10 Option:UCRL# Option:Additional Information

3 different value of neutrino mass can be seen as future milestones: 500 meV Quasi Degenerate 50 meV Inverted Hierarchy enriched natural Counts/y/ton 15 meV Ge TeO 2 Nucl. Phys. A 0.39 0.52 729, 867 (2003) Normal Hierarchy The order magnitude of the Bkg is ≤ 1 c / y ton Lawrence Livermore National Laboratory In order to give an idea of the amazing challenge of the future sensitivity target: 11 Option:UCRL# Option:Additional Information

Requirements for a 0 ν DBD experiment sensitivity S 0 ν : lifetime corresponding to the minimum detectable number of events over background at a given confidence level source mass live time background level energy resolution  large source (many nuclei under observation)  long time measurements  good energy resolution  low background Lawrence Livermore National Laboratory 12 Option:UCRL# Option:Additional Information

0 ν DBD experiments Name Nucleus Method Location Status Cuoricino 130 Te bolometric LNGS Completed Nemo-3 82 Se tracking Frejus Taking data until end 2010 CUORE 130 Te bolometric LNGS Funded – in construction GERDA 76 Ge ionization LNGS Funded (I & II) – in construction SNO+ 150 Nd scintillation SNOLAB Funded (natural Nd) SuperNEMO 82 Se/ 150 Nd tracking Frejus R&D and demonstrator funded MAJORANA 76 Ge ionization SUSEL R&D and demonstrator funded EXO 136 Xe tracking WIPP R&D and demonstrator funded To define the timeline of the above experiments is difficult Lawrence Livermore National Laboratory 13 Option:UCRL# Option:Additional Information

CUORE (Cryogenic Underground Observatory for Rare Event) → 130 Te Q ββ = 2527 keV ~ 34% natural abundance Detector: array of 988 5x5x5 90 cm cm 3 TeO 2 bolometers @ ~ 10 mK (total mass = 741 kg) Energy resolution: 0.28% @ Qvalue Location: Hall A at LNGS (Italy) 19 towers Cuoricino-like Background Sensitivity Effective Majorana Mass 0.01 c/keV/kg/y (realistic) T 1/20 ν = 2.1 · 10 26 y 23 - 82 meV 0.001 c/keV/kg/y (aggressive) T 1/20 ν = 6.5 ·10 26 y 11 - 57 meV Lawrence Livermore National Laboratory 14 Option:UCRL# Option:Additional Information

SNO + → 150 Nd Q ββ = 3368 keV Natural Nd (a.i. 150 Nd = 5.6%) Detector: refill SNO detector with liquid scintillator (linear alkylbenzene - LAB) loaded at 0.1% Nd if m ν =100 meV (not enough light output in SNO+ if using 1% Nd loading) 56 kg of 150 Nd Location: Sudbury (Canada) En resolution: 6.4% @ Qvalue Lawrence Livermore National Laboratory 15 Option:UCRL# Option:Additional Information

Conclusions The future scenarios can be divided in possible steps: • I step [100-500 meV]: to test of HM claim and to probe the QD region of neutrino mass SuperNEMO, CUORE, GERDA, EXO-200, SNO++ if the neutrino mass is in this range different experiment could see it with different isotopes. Precision measurement era for 0nDBD • II step [15-50 meV]: to probe the IH region of neutrino mass. 1 ton scale and 10 y SuperNEMO (especially with 150Nd), CUORE (especially if enriched), GERDA-III, SNO++ (enriched) discovery in 3-4 isotopes is necessary to confirm the observation Lawrence Livermore National Laboratory 16 Option:UCRL# Option:Additional Information

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→ 100 Mo Q ββ = 3034 keV Detector: tracking detector with different sources Energy resolution: 8% @ Qvalue Location: Modane Underground Laboratory (France) Multi-source detector ββ ββ sources ( thickness ∼ 60 60 mg/cm 2 ) Other sources ββ (2 ν ) Bckg 82 Se (0,93 kg) 18 18

1 Source plane 2 Tracking volume (3-D readout wire drift chamber with 6180 cells) 3 Calorimeter volume (1940 plastic scintillator block) E 1 ββ ββ event e - 2 ν Vertex spectrum e - E 1 +E 2 = 2088 keV Δ t= 0.22 ns ( Δ vertex) ⊥ = 2.1 mm E 2

Expansion of NEMO-3 → 82 Se Q ββ = 2995 keV → 150 Nd Q ββ = 3367 keV Detector: tracking detector with different sources Location: Modane (Fr) / Canfranc (SP) Top view Tracking: drift chamber ~3000 cell (Gaiger mode) 1m Calorimeter: scintillators + PM ~ 1000 if sc. blocks ~ 100 scint. bars 5 m

Improvement with respect to NEMO-3: NEMO-3 SuperNEMO 100 Mo Choice of isotope 150 Nd or 82 Se 7 kg Isotope Mass 100 -200 kg 8% Efficiency 30% 208 Tl < 20 mBq/Kg 208 Tl < 2 mBq/Kg Internal contamination 214 Bi < 300 mBq/Kg 214 Bi < 10 mBq/Kg 8% @ 3MeV Energy resolution 4% @ 3MeV 0 ν (y) ~ 2 × 10 24 y 0 ν (y) ~ 10 26 y τ 1 /2 τ 1 /2 SENSITIVITY <m> ~ 0.3 -1.3 eV <m> ~ 50 meV

→ 136 Xe Q ββ = 2458 keV 200 kg of Xe enriched to 80% in 136 Detector: TPC of enriched liquid Xenon able to reconstruct the event position and topology. In this phase the Ba tagging technique (for the reduction of the background) will not be used GOALS - search for 0nDBD with competitive sensitivity (and test the claim) - measure 2 ν DBD half life (best limit currently set by Bernabei et al. 1x10 22 y) - Understand the operation of a large LXe detector • Understand bkg / characterize detectors materials • Learn about large scale Xe enrichment • Understand Xe handling, purification

Low but finite radioactive background: 20 counts/ year in ±2 σ interval centered around the 2.458 MeV endpoint No Ba tagging capability Negligible background from 2 ν DBD (T 1/2 > 1·10 22 yr R.Bernabei et al. measurement) Rodin et al Phys Rev C 68(2003)044302 Courier et al. Nucl Phys A 654 (1999) 973c In case that the Klapdor’s claim is correct EXO-200 in 2 year will see: - 15 events on top of 40 events of bkg in the worst case (QRPA – upper limit) -> 2 σ - 162 events on top of 40 of bkg in the best case (NSM, lower limit) -> 11 σ