ZSJ IFD UW Zenon Janas Poszukiwanie podwójnego bezneutrinowego rozpadu beta w eksperymentach NEMO-3 i SuperNEMO Kraków,

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 Neutrinoless  decay rate M

Tracking + calorimeter Both techniques are complementary !! only total energy measured high energy resolution good efficiency compact detectors 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 cylindrical, S = 20 m 2, 60 mg/cm 2 Tracking detector : 6180 drift wire chamber operating in Geiger mode Gas: He + 4% ethyl alcohol + 1% Ar Calorimeter : 1940 plastic scintillators low radioactivity PMTs NEMO-3 detector © S. Julian, LAL Ability to identify e , e ,  and 

NEMO-3 sector R. Arnold et al., NIM A536 (2005) 79  foil PMT Scint.

NEMO-3 detector

Deposited energy: E 1 +E 2 = 2088 keV Common vertex: (  vertex)  = 2.1 mm vertex emission (  vertex) // = 5.7 mm vertex emission Transverse view Longitudinal view Typical 2  event 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

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 background measurement  search  sources in NEMO-3 detector

2  decay of 100 Mo T 1/2 = 7.1 ± 0.6  y 2 2 sim. bgnd cos(  ee ) E 1 + E 2 (MeV) evnts 6914 g 389 days evnts 6914 g 389 days 2 sim. bgnd Sum Energy SpectrumAngular Distribution T 1/2 > 1.5  y 00

MeV range N observed = 7 events bgnd = 8.1 ±  decay of 100 M o (Q  = 3034 keV) R. Arnold et al., PRL 95 (2005) T 1/2 > 5.8  y  m   < 0.7 – 2.8 eV 0 0  for T 1/2 = 5  y

 decay of 82 Se (Q  = 2995 keV) R. Arnold et al., PRL 95 (2005) T 1/2 > 2.1  y  m   < 1.4 – 2.2 eV 0 0  for T 1/2 = 5  y   82 Se T 1/2 = 9.6 ± 1.3  y 2 2 sim. bgnd

Effective mass and neutrino mass scale degenerate Normal hierarchy Inverse hierarchy Ge M-H NEMO-3 S-NEMO

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

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

NEMO-3 SuperNEMO From NEMO-3 to SuperNEMO 7 kg 100 kg Mass of isotope Efficiency  (  ) = 8 %  (  ) ~ 30 % Isotope 100 Mo T 1/2 (  ) = 7 x y 82 Se T 1/2 (  ) = 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 ~ 8 % at 3 MeV ~ 4 % at 3 MeV 208 Tl and 214 Bi int. contamin. 208 Tl < 2  Bq / kg 214 Bi < 10  Bq / kg 208 Tl < 20  Bq / kg 214 Bi < 300  Bq / kg

Detector for purity control of drift cells 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

L xy =115 mm  t= 5  s Example: 214 Po  -decay CCD PMT

222 Rn 3.8 d 218 Po 3.1 m 214 Pb 27 m 210 Pb 22.3 y 214 Bi 20 m 214 Po 164  s 210 Tl 1.3 m Pb stable 210 Po 138 d 210 Bi 5 d 206 Tl 4.2 m 5.30 MeV Rn decay products Radon Q  = 3.3 MeV

220 Rn 56 s 216 Po 145 ms 212 Pb 10.6 h 208 Pb stable 212 Bi 61 m 212 Po 300 ns 208 Tl 3 m MeV Rn decay products Thoron Q  = 5 MeV

ms 5  s Search for 220 Rn -  216 Po  decay - two triggers within 300 ms gate 9 cm 220 Rn 216 Po

220 Rn -  Po -  decay (300 ms gate)

 SuperNEMO aims to reach  m   ~ 50 meV  R&D programme focused on: Conclusions - calorimeter energy resolution - source isotope - radiopurity  first SuperNEMO module in 2010  NEMO-3 will reach  m   ~ 300 meV  all 20 module in 2013

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

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

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

Summary  observation of 0  decay  Majorana neutrinos physics beyond SM  complementary experiments needed and planned  measurement of T 1/2 (0  ) nuclear matix element absolute mass scale mass hierarchy 

Neutrino mixing atmospheric angle reactor angle and CP phase solar angle sin 2  12 = 0.31±0.03 sin 2  23 = 0.50±0.06 sin 2  13 < Maki-Nakagawa-Sakata-Pontecorvo (MNSP) matrix U =U =

tritium decay: m  < 2.3 eV Neutrino mass cosmology: m 1 + m 2 + m 3 < 1.7 eV oscillation exp.: m 2 2 – m 1 2 = 7.9 ± 0.3  eV 2  m 3 2 – m 1 2  = 2.2 ± 0.4  eV 2 Mass hierarchy Normal Inverted m2m2 m12m22m32m12m22m32 Degnerate ?

Questions absolute mass scale ? mass hierarchy ? CP symmetry violation ? Dirac (  ) or Majorana (  ) particles ?

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

Feynman diagram for 2  decay arbitrary units (Q  ~ MeV) Energy spectrum of emitted electrons

2   decay rate - phase space factor - nuclear matrix element

Double beta decay  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

(V+A) current Light neutrino exchange Majoron emission M Mechanisms of 0  decays

Energy spectra of electrons emitted in  decay M

0   decay rate - effective Majorana mass - phase space factor - nuclear matrix elements

- neutrino potential (A, Z) (A, Z+1) 0+0+ (A, Z+2) Nuclear matrix elements in 0 

JJ V.A. Rodin et al., nucl-th/ Example QRPA calculations for 100 Mo

Nuclear Matrix Elements calculations

 source Scint. PMTs calibration tube cathodic rings NEMO-3 sector

water+ B (30 cm) iron (18 cm) wood (40 cm) magnetic coil (25 Gauss) Shielding of the NEMO detector

Tracking detector: vertex resolution:   = 0.6 cm  // = 1.3 cm e + /e - separation with a magnetic field of 25 G ~ 3% confusion at 1 MeV Calorimeter: energy resolution: FWHM (1 MeV) = 14 – 17 % time resolution FWHM (1 MeV)  250 ps Performance of the NEMO-3

Neutron capture Electron crossing > 4 MeV Electron – positron pair B rejection  Background events in NEMO-3

208 Tl  208 Pb electron + 3  ’s 214 Bi  214 Po  210 Pb electron +  delay (164  s) Background events in NEMO U 214 Bi (19.9 mn) 210 Tl (1.3 mn) 214 Po 210 Pb 22.3 y 0.021%   MeV (164  s)

Criteria to select  events 2 tracks with charge < 0 common vertex 2 PMT – associated with tacks no other isolated PMT (  rejection ) TOF condition (external event rejection) no delayed track ( 214 Bi rejection)

Effective mass and neutrino mass scale degenerate Normal hierarchy Inverse hierarchy Ge M-H NEMO-3

© S. Julian, LAL 2004 : tent surrounding the detector + air purification system Radon level 25 mBq/m 3  3 mBq/m 3

What one can measure with OTPC ? - length and position on XY plane (from camera picture) - length of projection on Z axis (from the length of the PMT signal) - no Z coordinate - energy (from the total track length) - charge of the particle (from the energy loss) - time and position correlation between succesive  -decays - no sensitivity for electrons

Simkovic, J. Phys. G, 27, 2233, 2001 Single electron spectrum different between SSD and HSD 2  2 HSD Monte Carlo HSD higher levels Background Data 2  2 SSD Monte Carlo Background Data SSD Single State HSD: T 1/2 = 8.61  0.02 (stat)  0.60 (syst)  y SSD: T 1/2 = 7.72  0.02 (stat)  0.54 (syst)  y 100 Mo 2  2 single energy distribution in favour of Single State Dominant (SSD) decay 4.57 kg.y E 1 + E 2 > 2 MeV 4.57 kg.y E 1 + E 2 > 2 MeV HSD, higher levels contribute to the decay SSD, 1  level dominates in the decay (Abad et al., 1984, Ann. Fis. A 80, 9) 100 Mo 00 100 Tc 11   /ndf = 139. / 36   /ndf = 40.7 / 36 NEMO-3 E single (keV) 100 Mo 2  2 Single Energy Distribution

Two tracks of negative charge associated to isolated PM Energy deposit in each scintillator E > 200 keV. Event vertex is inside the foil Distance track-to-vertex:  XY < 4 cm,  Z<8 cm; TOF cut: internal hypothesis probality > 4%, external hypothesis probability<1%; Reject events with the alpha particle found using alpha_search means: if only 1 extra hit in the tracking detector  t > 40  sec  xy < 4 cm  Z < 10 cm if at least 2 hits search for a short track  t > 2  sec only but all hits on time Reject events with two tracks at one side of the foil and a geiger hit in time at the opposite side fo the foil close to the vertex: M ö ller scattering of  decay in gas (Radon). vertex Event selection criteria

arbitrary units (Q  ~ MeV)

CENBG, IN2P3-CNRS et Université de Bordeaux, France IReS, IN2P3-CNRS et Université de Strasbourg, France LAL, IN2P3-CNRS et Université Paris-Sud, France LPC, IN2P3-CNRS et Université de Caen, France LSCE, CNRS Gif sur Yvette, France Fes University, Marocco FNSPE, Prague University, Czech Republic INEEL, Idaho Falls, USA ITEP, Moscou, Russia JINR, Dubna, Russia JYVASKYLA University, Finland KURCHATOV Institute, Russia MHC, Massachusets, USA Saga University, Japan UCL London, UK N eutrino E ttore M ajorana O bservatory NEMO collaboration

H.V. Klapdor-Kleingrothaus et al., Phys. Lett. B586 (2004)  Heidelberg - Moscow experiment 11 kg 76 Ge calorimeter, 71.7 kg·y exposure 214 Bi

N eutrino E ttore M ajorana O bservatory NEMO collaboration: 11 countries, 27 laboratories USA MHC INL U. Texas Japan U. Saga KEK U Osaka France CEN Bordeaux IReS Strasbourg LAL ORSAY LPC Caen LSCE Gif/Yvette UK UC London U. Manchester IC London Finland U. Jyvaskyla Russia JINR Dubna ITEP Mosow Kurchatov Institute Ukraine INR Kiev ISMA Kharkov Czech Charles U. Praha IEAP Praha Marocco Fes U. Slovakia U. Bratislava Spain U. Valencia U. Zarogoza U. Barcelona

J. Suhonen et al., Phys. Rep. 300 (1998) 123 Nuclear matrix element in 2  (A, Z) (A, Z+1) 0+0+ (A, Z+2) GT

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