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Proposal to join NEMO-3 decay experiment P. Adamson, R. Saakyan, J. Thomas UCL 27 January 2003

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Outline Motivation decay basics Short term future for experiments NEMO-III detector Future experiments Possible UK involvement in NEMO-III Costs

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Motivation Neutrino oscillations 2.5 10 -3 eV 2 5 10 -5 eV 2 2.5 10 -3 eV 2 m scale = 0.01 eVm scale = 0.05 eV

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Motivation neutrino oscillations can not measure: Nature of neutrino mass = bar (Majorana) OR bar (Dirac) Absolute mass scale decay Direct kinematic searches ( 3 H decay)

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UK Involvement. Current Picture

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decay basics T 0.5 ~ 10 20 yrT 0.5 > 10 25 yr Find isotopes where (A,Z) (A,Z+2) is energetically allowed, but forbidden in steps (A,Z) (A,Z+1) (A,Z+2)

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decay basics Average Majorana mass: m depends on sum over U 2 *m If large, could be dominated by U e3 2 m 3 (depends on hierarchy) Majorana CP phases Mixing matrix

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Phase space Nuclear matrix element Q 48 Ca, 76 Ge, 100 Mo, 150 Nd, 136 Xe, 116 Cd, 96 Zr, 82 Se, 130 Te Due to uncertainties in M 0 we have to study as many isotopes as possible! (0.35 – 1 eV) T kin (e - +e - ) (A,Z) (A,Z+2) + e - + e - + bar + bar 2 (A,Z) (A,Z+2) + e - + e - 0 (A,Z) (A,Z+2) + e - + e - + 0 0 (Majoran)

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A look at short term future decay experiments 3 H expts sensitivity in ~ 2008 Future projects: CUORE, Majorana, EXO, etc to have 0.05 eV sensitivity (~ 2008 – 2010) m scale ~ 0.01 – 0.05 eV from oscillation expts

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Short-term future: now - 2007 = 0.4 eV Heidelberg-Moscow Experiment “Evidence” strongly criticized by community Not background free region NEMO-3 CUORICINO by 2007 0.1 – 0.7 eV 130 Te (34%) natural abundance, good bolometric properties

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NEMO-3 Collaboration 50 physicists and engineers 12 Laboratories/Universities 5 Countries

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250ps t timing from plasma propagation in tracker, z = 1cm x, y = 100 m,

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Data taking 2e events

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Data taking Background events 208 Th <.02mBq/kg 214 Bi <.3mBq/kg These have HE electron, but not same topology,or timing Excited states O() less common, used to measure NME

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October visit summary: Significant shortage in manpower for data analysis. We are welcome to start right away Somewhat involved analysis detection (10 5 2 events/y !!! for 100 Mo) BG rejection techniques Source contamination measurements (for future developments) Running since June’02 but only 200 hrs 100 Mo carefully analysed

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Possible UK involvement in data analysis Isotopes “distributed” between institutions We are suggested to take up analysis of 82 Se (NEMO3 upgrade isotope) IsotopeMass, g 100 Mo7200 130 Te1300 82 Se1000 116 Cd600 150 Nd50 96 Zr20 48 Ca10

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NEMO-3 0 sensitivity 5 years 100 Mo 7 kg Q =3.034 MeV External BG: 0 Internal BG: radioactivity < 0.04 event/y/kg = 0.11 event/y/kg T 1/2 > 5 × 10 24 yr < 0.2 – 0.7 eV E = 2.8 – 3.2 MeV 82 Se 1 kg Q =2.995 MeV External BG: 0 Internal BG: radioactivity < 0.01 event/y/kg = 0.01 event/y/kg T 1/2 > 1 × 10 24 yr < 0.6 – 1.2 eV

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Possible UK involvement Upgrade of NEMO-3 12 kg 82 Se Why 82 Se? And theory says there is NO scaling Improve S/B by ~10 Sensitivity ~0.14 eV in 5 yr

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SuperNEMO Sensitivity ~ 0.05 eV in 5 yr ~ 100 kg 82 Se (or other) 4 supermodules, planar geometry Feasible if: a)BG only from 2 (NEMO3) b) E/E = 10-11% at 1 MeV (R&D needed)

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Future projects comparison “Conservative” approach ExperimentSource and Mass Sensitivity to T 1/2 (y) Sensitivity to (eV) * Majorana $50M 76 Ge, 500kg3×10 27 0.03 – 0.07 CUORE $25M,long 130 Te, 750kg(nat) 2×10 26 0.05 – 0.17 EXO (or other Xe-expt) 136 Xe 1 ton 8×10 26 0.05 – 0.12 SuperNEMO $20M 82 Se (or other) 100 kg 2×10 26 0.05 – 0.11 * 5 different latest NME calculations

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SuperNEMO – UK involvement Scintillator R&D Improving E/E from 9% to 6% (at 3 MeV) will reduce BG by a factor of ~ 10 Increase light output Scintillator studies Light collection PMT-scintillator optical coupling PMT studies matches our experience (MINOS)

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Responsibilities 2003-2004 MC of 2e and BG events from 82 Se (Saakyan, New PostDoc) Off-line DA for 82 Se, cross-check with other isotopes (Adamson, NewPostDoc, Saakyan, Thomas) Laser LI calibration/monitoring (Adamson, Thomas) Scintillator R&D for SuperNEMO (Saakyan, Thomas, NewPostDoc, Technician) DAQ/electronics for R&D setup (Adamson, NewPostDoc, Software Engineer) DA from R&D setup (Adamson, NewPostDoc, Saakyan, Thomas)

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Costs Item20032004 Rolling Grant Costs UCL staff Saakyan 05% 30% 05% 30% Extra costs to PPARC Equipment Travel Responsive RA £10K £5K £50K £10K £5K £50K PPARC Fellows Adamson Thomas 30%

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Concluding Remarks is the only practical approach for Majorana ‘s Participation in NEMO-3 is a good opportunity to understand feasibility of this technique… …and to put UK in the DBD arena NEMO-3 will confirm or rule out H-M result (0.1-0.2eV depending on Se availability) Next generation DBD experiments to probe ~ 0.05 eV scale NEMO technology orthogonal to other competitors

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Concluding Remarks II Window of opportunity with MINOS for authors (beam due end of 04) Possibility to analyse data this week! Results will be competitive (many isotopes, orthogonal approach) This proposal does not commit us to Super-NEMO

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