SuperNEMO Thoughts about next generation NEMO experiment Ruben Saakyan UCL

Outline Motivation Possible Scheme R&D needed Sensitivity Time scale

Motivation Need to access < 0.1 eV scale Realistic project with sensitivity  0.05 eV with “modest” cost (~$15-20M) NEMO technology very well known/understood Measure background/source purity with NEMO Feasibility estimate based on NEMO-3 results

The Idea NEMO3×10 = SuperNEMO  ~100 kg Candidate Isotopes: 100 Mo, 82 Se, 116 Cd, 130 Te Modular structure Improve energy resolution (see later) Time resolution 250ps, vertex: 1cm (1  ) – as in NEMO3 Improve efficiency to from 12% to ~ 20% No B-field ? (check with NEMO3) Better geometry Thinner wires in tracking detector Improved event selection

Which Isotope? IsotopeQ, MeV 100 Mo Se Cd Te2.529 Factor of 10 lower BG for 82 Se Can be produced in centrifuge - $30K-$50K/kg

Possible Layouts “Clone” structure 10×NEMO3 “Large scale” structure Source diameter – 25m (passive shielding: 29m) “Intermediate” 4 cylinders with source diameter ~ 7m NEMO-3 like 2.5 m

Possible Layouts Low BG (NEMO) PMTs – 5000 (2.5×NEMO3) 30×30 ×10 cm 3 scint blocks 30,000 Geiger cells (5×NEMO3) Passive shielding: 20cm Fe cm antineutron shield Space needed: 30 ×12 ×6m 3 New Lab, Boulby? (visited on 17-July-03) Planar Geometry (preferred) 4 supermodules 25 kg each

Energy Resolution 2  – the only BG (check with 3MeV:  E /E) = 3.5-4%(NEMO3) (  E /E) = 2.5-3% (SuperNEMO)  Gains factor of ~7 F ~ (  E /E) 6

Energy Resolution Scintillator R&D Optimise: Optical coupling to PMT Surface treatment Scint-r size PMT size New scintillator? Combination of organic/non-organic scintillator? MC input UK contribution (MINOS scintillator experience) 207 Bi 482 keV 976 keV There are a few NEMO3 scint blocks with  E /E  4.5% 3 MeV

SuperNEMO advantages Well known technology “Smart” detector (tracking) High Q-value Feasibility checked by NEMO-3 BG only from 2 (for 82 Se and 100 Mo)  E /E  4.5% at 1 MeV (R&D) Modular structure One supermodule even simpler than NEMO3 100kg of isotope “only” Modest price ~ $15M (isotope: $5-7M)

SuperNEMO disadvantages Big detector Energy resolution (can be improved further?) Detection Efficiency

Sensitivity calculation Assumptions:  E /E = 1MeV  = 20% Isotope purity: 214 Bi: < 50  Bq/kg 208 Tl < 5  Bq/kg T measur = 5 yr

Sensitivity Isotope Q, MeV Rad BG 2  BG T 1/2, yr, eV 82 Se ~ × Mo ~ × Cd ~ × Te ~ ×

Time Scale 2-4 December 2003 – first meeting (LAL) to discuss R&D plans and proposal submission  E/E (UK) Efficiency BG Isotope production/purification 2006: NEMO-3 upgrade with kg of 82 Se and run  ~0.1 eV 2008: Start SuperNEMO installation (new Frejus lab, Boulby?) 2010: Start taking data

Future  projects sensitivity (5 yr exposure) ExperimentSource and Mass Sensitivity to T 1/2 (y) Sensitivity to (eV) * Majorana $50M GENIUS $100M 76 Ge, 500kg 76 Ge. 1000kg 3× × – – 0.05 CUORE $25M 130 Te, 750kg(nat) 2× – 0.17 EXO $50M-100M 136 Xe 1 ton 8× – 0.12 SuperNEMO $15M 82 Se (or other) 100 kg 2× – 0.11 * 5 different latest NME calculations

Concluding Remarks NEMO-3 will test experimentally feasibility of SuperNEMO First step: kg 82 Se from kg 82 Se  ~0.04 eV is achievable at relatively low cost (~$15M) and with very well known technology Could measure other isotopes Collaborators welcome 2-4 December 1 st meeting at LAL(Orsay)