Warsaw - NEMO initiative group Zenon Janas for Search for neutrinoless double  decay in NEMO-3 and SuperNEMO experiments Warszawa,

Warsaw - NEMO initiative group W. Dominik, IFD UW Z. Janas, IFD UW T. Matulewicz, IFD UW M. Pfutzner, IFD UW E. Rondio, SINS

Double beta decay Main  decay modes: (A, Z)  (A, Z+2) + 2e   2   0  (A, Z)  (A, Z+2) + 2 e  + 2 e (A, Z) (A, Z+1) (A, Z+2)  L = 0L = 0 L = 2L = 2

Energy spectra of emitted electrons arbitrary units (Q  ~ MeV) Neutrinoless  decay rate

Motivation of 0  decay studies neutrino nature: Dirac or Majorana ? absolute neutrino mass scale neutrino mass hierarchy Majoron emission ?

Tracking + calorimeter Both techniques are complementary !! only total energy measured high energy resolution good efficiency compact detectors (  10 m) very pure crystals source specific Experimental approaches in  decay studies Calorimeter HPGe – Te bolometers NEMO individual electrons observed modest energy resolution small efficiency large detector size (  50 m) background measured universal

3 m 4 m B (25 G) 20 sectors Location: Fréjus Underground Lab m.w.e. Source : 10 kg of  isotopes (100Mo) cylindrical, S = 20 m 2, 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 NEMO-3 detector Ability to identify e , e ,  and  © S. Julian, LAL

Criteria to select  events 2 tracks with charge < 0 2 PMT, each > 200 keV PMT-Track association Common vertex Internal hypothesis (external event rejection) No other isolated PMT (  rejection) No delayed track ( 214 Bi rejection) Deposited energy: E 1 +E 2 = 2088 keV Internal hypothesis: (  t) mes –(  t) theo = 0.22 ns Common vertex: (  vertex)  = 2.1 mm Vertex emission (  vertex) // = 5.7 mm Vertex emission Transverse view Longitudinal view Typical 2  event observed from 100 Mo isotope Trigger: at least 1 PMT > 150 keV  3 Geiger hits (2 neighbour layers + 1) Trigger rate = 5.8 Hz  events: 1 event every 2.5 minutes

2  decay of 100 Mo T 1/2 ( 100 Mo,2  ) = [ 7.11 ± 0.02 (stat) ± 0.54 (syst) ]  y cos(  ee ) E 1 + E 2 (MeV) evnts 6914 g 389 days evnts 6914 g 389 days 2 sim. bgnd Data Sum Energy SpectrumAngular Distribution 2 sim. bgnd Data

MeV range N observed = 7 events bgnd = 8.1 ±  decay of 100 Mo T 1/2 ( 100 Mo,0  ) > 4.6  y < 0.7 – 2.8 eV T 1/2 ( 100 Mo,0  ) > 4.6  y < 0.7 – 2.8 eV R. Arnold et al., PRL 95 (2005)

Plane geometry, 20 modules Top view 5 m 1 m 1 module: source: 3  4 m 2  40 mg/m 2 of enriched isotope tracking volume: ~ 3000 drift chamber cells calorimeter: ~ 1000 scintillators + PMTs SuperNEMO - preliminary design © S. Julian, NEMO-3 collaboration

NEMO-3 SuperNEMO From NEMO-3 to SuperNEMO 7 kg 100 kg Mass of isotope Efficiency  (  ) = 8 %  (  ) ~ 20 % Isotope 100 Mo T 1/2 (  ) = 7 x y 82 Se T 1/2 (  ) = y ~ 1 evt/ 100 kg / y ~ 1 evt / 7 kg / y T 1/2 (  ) > 2 x y < 0.3 – 1.3 eV T 1/2 (  ) > 2 x y < 0.04 – 0.1 eV SENSITIVITY after 5 years Resolution ~ 11 % at 3 MeV ~ 7 % at 3 MeV 208 Tl and 214 Bi background

Most promissing 0  projects A.S. Barabash, arXiv:hep-ex/

R&D program construction of the SuperNEMO module with 5 kg 82 Se construction and installation of the 20 modules, start taking data with delivered modules full SuperNEMO running with 100 kg of 82 Se Plans for SuperNEMO

SuperNEMO collaboration Kurchatov Inst. Moscou, Russia Karkhov Ukraine Manchester University, UK UCL London, UK INL Idaho Falls, USA MHC Massachusets, USA Saga Univ., Japan Texas Univ. Austin, USA CENBG Bordeaux, France IReS Strasbourg, France LAL Orsay, France LPC Caen, France LSCE Gif sur Yvette, France FNSPE Prague Univ., Czech Rep. ITEP Moscow, Russia JINR Dubna, Russia R&D tasks in the SuperNEMO collaboration SuperNEMO R&D Source Enrichment Purification Foils prod. Calorimeter Scintillators PMT Drift Chamb Prototype Autom. wiring Radiopurity HPGe spectr BiPo det. Radon det. MechanicsComputing Simulation Electronics Calorimeter Drift chamb Trigger © S. Julian, LAL

Possible contribution of Polish group: - data analysis NEMO-3 - modeling and simulations - main detector design and construction - data analysis - detector for purity control of drift chamber gas SuperNEMO

Detector for purity control of drift chamber gas a possibility: O ptical T ime P rojection C hamber gas CCD PMT drift 1  s/cm amp. WLS  ee M. Ćwiok et al., IEEE TNS, 52 (2005) 2895

Performance of the OTPC 13 O p  K. Miernik et al.

Water shield ( 2 ktons) Source foil 14 m Needed cavity: ~60 x 15 x 15 m Location: Modane, Gran Sasso …? Full detector 3,75 m © S. Julian, LAL 20 modules: 100 kg of enriched isotope

100 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 (all enriched isotopes produced in Russia) 100 Mo purified in INL (USA) and ITEP (Russia)  sources in the NEMO-3 detector