NEMO-3 bb experiment First Results and Future Prospects Ruben Saakyan, UCL UK HEP Neutrino Forum The Cosener’s House, Abingdon
Outline n n n Why NEMO-3 ? The Detector First results Sensitivity by 2007 Towards Super. NEMO
Currently Active Experiments CUORICINO NEMO-3 (bolometer) (Tracking calorimeter) <m > = 0. 4 e. V ? ? ? Heidelberg-Moscow exp is still running
Why NEMO-3 ? n n One of the two experiments to improve <m > sensitivity before 2007/2008 (0. 15 0. 5 e. V) for a few isotopes Well known (for us) technique orthogonal to other approaches Excellent chance to understand nitty gritty of bb experiment…. . and choose a project to attack n× 10 -2 e. V scale
Neutrino Ettore Majorana Observatory 50 physicists and engineers 13 Laboratories/Universities 7 Countries
UK NEMO team (so far) n n Phil Adamson, Leo Jenner, Ruben Saakyan, Jenny Thomas (all UCL) Received approval from PPRP 27 Jan 03 Main involvement: data analysis. . but also some hardware tasks (PMT helium tests, light injection optimization)
• From scintil detector: st = 250 ps • From tracker: s||= 1 cm s = 0. 45 mm (using timing information on plasma propagation) Calibration: • Laser survey • neutron Am/Be for s||, s , e+ signature • e- 207 Bi, 90 Sr for energy calibration • 60 Co for time alignment Trigger: 1 scintillator hit > 150 ke. V + 1 track: few Geiger planes (flexible 3 – 7 Hz)
Pure materials: Source foils measured with the NEMO-3 detector • 208 Tl < 2 m. Bq/kg • 214 Bi < 2 m. Bq/kg • neutrons < 10 -9 n cm-2 s-1 Radon in the detector • 222 Rn ~ 20 m. Bq/m 3 • 220 Rn ~ 1. 6 m. Bq/m 3 to be improved with new anti-radon system
Data taking n n n June 2002: start with all 20 sectors, iron shielding, neutron shielding but… …still a lot of debugging (both tracking detector and calorimeter) 14 February 2003: start of routine data taking
NEMO bb events 3 D pictures Ø study single electron spectra Ø study angular distributions Ø Detailed 2 information Ø O (105) 2 100 Mo events/yr ! Ø 7 isotopes Ø
NEMO background events e +e - e- (~7 Me. V) from n
NEMO-3 First Results 100 Mo 1200 h 2 : T 1/2=[7. 4± 0. 05(stat)± 0. 8(sys)]× 1018 yr (19000 events; S/B 50) 0 : 1 event in 2. 8 – 3. 2 Me. V region T 1/2 > 1023 yr 90% CL <m > < 0. 9 – 2. 1 e. V World’s best result for 100 Mo
Single State Dominance (SSD) VS Higher order State Dominance (HSD) Simkovic, Domin, Semenov nucl-th/0006084, Phys. Rev. C HSD 1+ 100 Tc 0+ SSD 100 Mo 0+ 1. 2. 3. 4. 100 Ru single e- spectrum Shape of 2 b spectrum Angular distribution ~ 20% difference in T 1/2 100 Mo + NEMO-like detector can test it experimentally !
NEMO-3 First Results 100 Mo 1200 h single e- spectrum Angular distribution between two e- Preliminary: SSD is preferred
NEMO-3 First Results Other Isotopes 82 Se 116 Cd 150 Nd T 1/2=[8. 2± 0. 4(stat)± 0. 8(sys)]× 1019 T 1/2=[7. 0± 0. 7(stat)± 0. 7(sys)]× 1018 T 1/2=[3. 9± 0. 3(stat)± 0. 4(sys)]× 1019 T 1/2 > 4 × 1022 y 90% CL World’s best result ! T 1/2 > 7. 7 × 1020 y T 1/2 > 1. 0 × 1022 y 90% CL
NEMO-3 0 bb sensitivity 5 years 100 Mo E = 2. 8 – 3. 2 Me. V 82 Se 7 kg Qbb =3. 034 Me. V 1 kg Qbb =2. 995 Me. V T 1/2 > 3 × 1024 yr <m > < 0. 2 – 0. 5 e. V T 1/2 > 1 × 1024 yr <m > < 0. 6 – 1. 2 e. V External BG: 0 Internal BG: radioactivity < 0. 04 event/y/kg 2 bb = 0. 11 event/y/kg In case of full load of 82 Se External BG: 0 Internal BG: radioactivity < 0. 01 event/y/kg 2 bb = 0. 01 event/y/kg (~14 kg) <m > < 0. 15 – 0. 3 e. V
Super. NEMO (not an official proposal yet) ~ 100 kg 82 Se (or other) §Sensitivity <m > ~ 0. 05 e. V in 5 yr 4 supermodules, planar geometry Feasible if: a) BG only from 2 (NEMO 3) b) DE/E = 10 -11% at 1 Me. V (R&D needed)
Future bb projects comparison Experiment Majorana $50 M Source and Mass Sensitivity to T 1/2 (y) 76 Ge, 500 kg 3× 1027 130 Te, CUORE 2× 1026 750 kg(nat) $25 M 136 Xe EXO 8× 1026 $50 M-100 M 1 ton Super. NEMO 82 Se(or other) 2× 1026 $20 M 100 kg * 5 different latest NME calculations Sensitivity to <m > (e. V)* 0. 03 – 0. 07 0. 05 – 0. 12 0. 05 – 0. 11
Concluding Remarks n 1200 h, T 1/2(2 ) for 4 isotopes; World’s best results for T 1/2(0 ) for 100 Mo, 82 Se By 2007/2008 n n n NEMO-3 to reach <m > < 0. 15 - 0. 5 e. V (depending on 82 Se availability) Several isotopes will be investigated Unprecedented high 2 statistics with detailed information (single e- spectra, angular distributions) for 7 isotopes Experimental input to NME calculation
Concluding Remarks II n n n NEMO-3 will test experimentally feasibility of Super. NEMO If yes 0. 05 e. V is achievable at relatively low cost and with very well known technology If not will not waste time and money and do something else
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