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

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

Motivation Neutrino oscillations 2.5  eV 2 5  eV  eV 2 m scale = 0.01 eVm scale = 0.05 eV

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)

UK Involvement. Current Picture

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

 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

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)

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

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

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

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

Data taking 2e events

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

October visit summary: Significant shortage in manpower for data analysis. We are welcome to start right away Somewhat involved analysis  detection ( 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

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 Mo Te Se Cd Nd50 96 Zr20 48 Ca10

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 × 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 × yr  < 0.6 – 1.2 eV

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

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)

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

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)

Responsibilities 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)

Costs Item 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%

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 ( eV depending on Se availability) Next generation DBD experiments to probe ~ 0.05 eV scale NEMO technology orthogonal to other competitors

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