28 May 2008NEMO-3 Neutrino081 NEMO-3 A search for double beta decay Robert L. Flack University College London On behalf of the NEMO-3 collaboration

28 May 2008NEMO-3 Neutrino082 Overview NEMO-3 –The collaboration. –The detector. –The sources. –Event reconstruction. –Radon trapping facility (phase 1 and 2 data). Results –Past –Latest The future – SuperNEMO –Comparison with NEMO-3.

28 May 2008NEMO-3 Neutrino083 NEMO3 (Neutrino Ettore Majorana Observatory) 60 physicists, 17 institutions

28 May 2008NEMO-3 Neutrino084 3 m 4 m B (25 G) 20 sectors Source : 10 kg of  isotopes cylindrical, S = 20 m 2, e ~ 60 mg/cm 2 Tracking detector : drift wire chamber operating in Geiger mode (6180 cells) Gas: He + 4% ethyl alcohol + 1% Ar + 0.1% H 2 O Calorimeter : 1940 plastic scintillators coupled to low radioactivity PMTs Magnetic field: 25 Gauss Gamma shield: Pure Iron (e = 18 cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since march 2004: water  boron) Particle ID: e , e ,  and  Fréjus Underground Laboratory : 4800 m.w.e. The NEMO-3 detector

28 May 2008NEMO-3 Neutrino Mo kg Q  = 3034 keV 82 Se kg Q  = 2995 keV 116 Cd 405 g Q  = 2805 keV 96 Zr 9.4 g Q  = 3350 keV 150 Nd 37.0 g Q  = 3367 keV Cu 621 g 48 Ca 7.0 g Q  = 4272 keV nat Te 491 g 130 Te 454 g Q  = 2529 keV  measurement External bkg measurement  search (Enriched isotopes produced by centrifugation in Russia)  decay isotopes in NEMO-3 detector

28 May 2008NEMO-3 Neutrino086 Observables of the final state –Trajectories of the 2 electrons –Energies of the 2 electrons –Time of flight –Curvature of the tracks in a B-field (+ or -). Event reconstruction Source foils Scintillator + PMT Longitudinal view Transverse view Vertex of the e  e  emission

28 May 2008NEMO-3 Neutrino087 1 ton of –50 o C, 9 bars air flux = 150 m 3 /h Input: A( 222 Rn) 15 Bq/m 3 Output: A( 222 Rn) < 15 mBq/m 3 !!! reduction factor of 1000 Phase I : February 2003 – September 2004 (radon background in data) ~ 1  -like event/y/kg with 2.8 < E 1 +E 2 < 3.2 MeV Radon trapping facility Inside the NEMO 3 tent: factor of 100 – 300 Inside NEMO 3: almost factor of 10 A( 222 Rn)  6 mBq/m 3 Phase II : since October 2004 (radon level reduced by a factor of 6) Radon trapping facility (First developed for SuperKamiokande)

28 May 2008NEMO-3 Neutrino088 Cos(  ) Angular distribution events 6914 g 389 days S/B = 40 NEMO Mo E 1 + E 2 (MeV) Sum energy spectrum events 6914 g 389 days S/B = 40 NEMO Mo Background Data-bkg = sig 2  2 Monte Carlo Data-bkg = sig 2  2 Monte Carlo Background T 1/2 (  ) = 7.11  0.02 (stat)  0.54 (syst)  years Number of events Number of events/0.05 MeV 100 Mo 2  results Phys. Rev. Lett (2005) Phase 1: Feb – Dec “High Radon” Now have in excess of 0.5M events and will update later this year.

28 May 2008NEMO-3 Neutrino g 389 days 2750 events S/B = 4 82 Se Results for Phase I data. Additional statistics are being analysed and to be published soon. 82 Se: T 1/2 = [9.6  0.3 (stat)  1.0 (syst) ]  y 116 Cd: T 1/2 = [2.8  0.1 (stat)  0.3 (syst) ]  y  results with other nuclei 454 g 534 days 109 events S/B = Te Preliminary: Result for Phase 1 and 2 data. 130 Te: T 1/2 = [7.6 ± 1.5 (stat) ± 0.8 (syst)]  y  is important: 1) Experimental input to NME calculation 2) Ultimate background for  2) Ultimate background for  NEMO-3

28 May 2008NEMO-3 Neutrino0810 New result: 48 Ca  Cut at 0 Cut at 1.5 MeV E 1 + E 2 (MeV) High bkgs here due to contamination with 90 Sr. Preliminary results: T 1/2 (2  = [ (stat) ± 0.4 (syst)] x y T 1/2 (0  ) >1.3 x10 22 y (90% C.L) < 29.6 eV (90%CL), Eff. 22% refs: E Caurrier et al., Phys. Rev. Lett. 100 (2008) (NME) 133 events S/B days 7g NEMO-3

28 May 2008NEMO-3 Neutrino0811 New result: 96 Zr  Preliminary result: 96 Zr: T 1/2 (2νββ) = [2.3 ± 0.2(stat) ± 0.3(syst) ]  y T 1/2 (2νββ) = 8.6  y (90% C.L) < eV (90%CL), Eff. 19% Refs for NME : Simkovic, et al., Phys. Rev. C 77 (2008) Kortelainen and Suhonen, Phys. Rev. C 76 (2007) days S/B g NEMO-3

28 May 2008NEMO-3 Neutrino0812 Recent result: 150 Nd  Moriond  37g Preliminary results: 150Nd: T 1/2 (2νββ) = [ (stat) ± 0.62 (syst)] x y T 1/2 (0νββ) = 1.45 x y (90% C.L.) < eV (90%CL), Eff. 19% Ref for NME : V. A. Rodin et al., Nucl. Phys. A 766 (2006)107

28 May 2008NEMO-3 Neutrino days of data Phase I + Phase II 693 days of data Phase I + Phase II  of 100 Mo and 82 Se 100 Mo 82 Se T 1/2 > 2.1 × % C.L.  m  < (1.4 – 2.2) eV [1-3] (To be updated) [1] M.Kortelainen and J.Suhonen, Phys.Rev. C 75 (2007) (R). [2] M.Kortelainen and J.Suhonen, Phys.Rev. C 76 (2007) [3] V.A.Rodin et al., Nucl.Phys. A 793 (2007) 213. NME: Data until spring 2006 T 1/2 > 5.8 × % C.L.  m  < (0.8 – 1.3) eV [1-3] NEMO-3

28 May 2008NEMO-3 Neutrino0814 From NEMO-3 to SuperNEMO 7 kg kg isotope mass M 18 % ~ 30 % isotope 100 Mo 82 Se - baseline ( 150 Nd if it can be enriched) T 1/2 (  ) > ln 2  M    T obs N 90 N A A  NEMO-3 SuperNEMO internal contaminations 208 Tl and 214 Bi in the  foil 208 Tl: < 20  Bq/kg 214 Bi: < 300  Bq/kg 208 Tl   Bq/kg if 82 Se: 214 Bi  10  Bq/kg T 1/2 (  ) > 2 x y < 0.3 – 0.9 eV T 1/2 (  ) > y < eV energy resolution (FWHM) 3 MeV efficiency  See SuperNEMO poster

28 May 2008NEMO-3 Neutrino0815 NEMO’s Tracking + Calorimetry approach is unique –Good rejection of backgrounds –Choice of isotopes –Reconstruction of kinematics NEMO3 is taking data –2  factory: precise life-time measurements for 7 isotopes (out of 9 main candidates). –New results for 48 Ca and 96 Zr. –Data taking until end 2010: meV. SuperNEMO: 3 year Design Study addresses most critical issue –Based on design study results full proposal for 100+ kg detector in – 82 Se – baseline, 150 Nd possible. –First module 2010/11. –All 20 modules ~2013. Target sensitivity: meV by 2016 Summary

28 May 2008NEMO-3 Neutrino0816 Backup slides

28 May 2008NEMO-3 Neutrino0817 SuperNEMO Design Study Schedule Summary NEMO3 Running Running full detector in 2014 Target sensitivity ( eV) in 2016 construction of 20 modules SuperNEMO modules installation at new LSM Preparation of new LSM site BiPoinstallation BiPo1Canfranc/LSMBiPoconstruction BiPo Canfranc 1-5 SuperNEMO modules running at Canfranc running at Canfranc SuperNEMO 1 st module construction 2014

28 May 2008NEMO-3 Neutrino0818 Choice of Isotope Criteria of choice: - High Q bb value - Phase space G 0n - 2nbb half-life - natural abundance - enrichment possibilities. Purification of 4kg of 82 Se underway (INL, US). Enrichment of 150 Nd possible. 82 Se obtained by centrifugation. Impossible for 150 Nd, only laser enrichment.

28 May 2008NEMO-3 Neutrino0819 Background. ββ decay is about background suppression Natural radioactivity: T 1/2 ( 238 U, 232 Th) ~ yr T 1/2  > yr 238 U and 232 Th produce 214 Bi (Q  = 3.27 MeV) and 208 Tl(Q  = 4.99 MeV) Radon! Cosmogenic activitity Underground is a must Due to tracking, for SuperNEMO the main focus is on source (foil) purity. Must be super-duper-ultra low < 10  Bq/kg! (For reference humans Bq/kg typical materials ~ 1Bq/kg) But how to measure these levels?!

28 May 2008NEMO-3 Neutrino0820 Choice of site Canfranc –2500 m.w.e LS Modane –4800 m.w.e Boulby –2800 m.w.e Canfranc Boulby