NEMO-III Status and prospects. 12 December 2005 HEP group Christmas meeting Vladimir Vasiliev

Plan decay and neutrino mass decay and neutrino mass experiment experiment what we did in 2005 what we did in 2005 UCL contribution and future prospects UCL contribution and future prospects

decay and neutrino mass decay and neutrino mass L=0 L=2 ! Can happen if neutrino has a mass (proved) neutrino is a Majorana particle (not proved, but highly suspected)

Why to like Majorana? Isnt it just too boring for nature, if all particles are Dirac ones? MRMR mLmL See-Saw: why small m Leptogenesis: why something, not nothing.

Experimental signature a) 2 electrons b) fixed energy Q Until 2009 only 2 big experiments will be running Couricino, b) only NEMO-III, a) and b)

NEMO-III experiment

100 Mo kg Q = 3034 keV decay isotopes in NEMO-3 detector 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 (All the enriched isotopes produced in Russia)

Phase-I ( ) Detector background study Detector background study Precise measurement of Precise measurement of to excited states to excited states

Anti-Radon facility Installed October 2004 Installed October t -45 C 0.5 t -45 C A( 222 Rn) from 20 Bq/m 3 to 0.2 Bq/m 3 A( 222 Rn) from 20 Bq/m 3 to 0.2 Bq/m 3 Should get read of ultimate natural radioactivity BG: 222 Rn Should get read of ultimate natural radioactivity BG: 222 Rn Proof of principle that zero BG experiment is possible Proof of principle that zero BG experiment is possible

Latest results, Mo PRL 95, (2005) T 1/2 = (stat) 0.54 (syst) y, SSD mechanism! T > y, m < eV

Latest results, Se PRL 95, (2005) T 1/2 = (stat) 1.0 (syst) y T > y, m < eV

Latest results, excited states to be published soon T 1/2 (0 - 0)= (stat) 0.6 (syst) y T 1/2 (0 - 2)> y T (0-2)> y, <

NEMO work at UCL Hardware PMT ageing in the helium (R. Saakyan) LED light injection system as alternative to laser (J. Thomas, S. Williamson, R.Saakyan) Data analysis ROOT based framework for analysis (V. Vasiliev) Mo decay to excited states (J. Thomas, S. King, V. Vasiliev) decay of Te and Ca (R. Saakyan, S. King)

Future prospects Analyze low background phase II data. Analyze low background phase II data. Develop full 3D likelihood for search Develop full 3D likelihood for search Try to improve tracking software Try to improve tracking software At present conditions we can reach sensitivity at 0.3 eV in few years. Challenging goal is go down to ~0.2 eV * * Klapdor-Kleingrothaus interval is [ ] eV, best fit 0.44 eV (2004)

WE ARE IN THE MIDDLE OF THE ROAD

EXIT THAT COULD LEAD BEYOND SM