Recent Results from NEMO 3 Experiment Typical 2 events ~ every 1.5 - PowerPoint PPT Presentation

Recent Results from NEMO 3 Experiment Typical 2νββ events ~ every 1.5 minutes Search for 0νββ events Study neutrino mass H. Ohsumi (Saga U.) @ US-Japan Seminar, September 16-20, 2005, Maui, Hawaii

NEMO3 Collaboration NEMO3 Collaboration CENBG, IN2P3-CNRS Bordeaux University, France Charles University , Praha, Czech Republic CTU , Praha, Czech Republic INEL , Idaho Falls, USA INR , Moscow, Russia IReS , IN2P3-CNRS Strasbourg University, France ITEP , Moscou, Russia JINR , Dubna, Russia Jyvaskyla University, Finland LAL , IN2P3-CNRS Paris-Sud University, France LSCE , CNRS Gif sur Yvette, France LPC , IN2P3-CNRS Caen University, France Manchester University, Great-Britain Mount Holyoke College, USA RRC kurchatov Institute , Moscow, Russia Saga university , Saga, Japon UCL , London, Great-Britain

PLAN PLAN • Introduction • NEMO3 � description, performances � results 2 β 2 ν � results 2 β 0 ν : data phase 1 1.08 year � fight against radon • SuperNEMO (if I have time …a little bit) • Concluding Remarks

Philosophy of NEMO experiment Philosophy of NEMO experiment Neutrinoless Double Beta Decays ( 0νββ) Majorana ν and effective mass <m ν > ? or new physics (SUSY) ? Measure several isotopes ( 0νββ, 2νββ) 100 Mo(~7kg) , 82 Se(~1kg) , 130 Te , 116 Cd, 96 Zr , 48 Ca , 150 Nd Tag and measure all the BG events e - , e + , γ , α , neutron → Tracking chamber+Calorimeter+B-field+Shields “zero background zero background” ” experiment experiment “ 2νββ 0 νββ : 2n → 2p+2e - (∆ L = 2 Process) (Beyond Standard Model) 0νββ (?) 2 νββ : 2n → 2p+2e - +2 ν (Standard Process) ν M E( β 1 + β 2 ) Q ββ

< m > from values of < ν > Expected values of m ν from neutrinos oscillations neutrinos oscillations parameters parameters Expected Pascoli and Petcov, hep-ph/0310003 (best fit ν atm + ν sol ) Search Region of NEMO 3 Quasi-Degenerate (QD): < m ν > > 50 meV Inverted Hierarchy (IH): 15 meV < < m ν > < 50 meV Normal Hierarchy (NH): < m ν > < 5 meV 2 β could give the absolute neutrino mass (hep-ph/0503246 A.Strumia and F.Vissani)

The Location of the NEMO3 The Location of the NEMO3 Frejus Underground NEMO 3 is here ! Laboratory Laboratoire Souterraine de Modane(LSM) (4800 m.w.e.) Italy France NEMO 3

The NEMO3 detector The NEMO3 detector Fréjus Underground Laboratory : 4800 m.w.e. Source : 10 kg of ββ isotopes cylindrical, S = 20 m 2 , e ~ 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 Magnetic field: 25 Gauss Gamma shield: Pure Iron (e = 18cm) Neutron shield: 30 cm water (ext. wall) 40 cm wood (top and bottom) (since march 2004: water + boron) Able to identify e − , e + , γ and α

AUGUST 2001

Cathodic rings Wire chamber PMTs Calibration tube Calibration Source scintillators 207 Bi 2e – (IC) lines ~0.5 ,~1 MeV 90 Sr ββ isotope foils 60 Co

How detect signals and tag the background ? Identification of e, γ , α B=25G � Tracking (Identification e/others) source foil Signal Delayed (<700 µ s) α track ∆ t ~ 0 ns β - β - � Calorimeter ε ( γ )~50% (@0.5MeV) ββ (0 ν ) decay Possible for tagging e γ , e γγ , e γγγ , … γ Internal background Source contaminations ∆ t ~ 0 ns � Time of flight σ t ~300ps(@1MeV) e - β - α External Background rejection ∆ t ~ 0 ns β - � Magnetic Field (Identification e - /e + ) β - ββ (2 ν ) decay 3~5% e - /e + confusion @ 1~7MeV External background ∆ t ≥ 3 ns e - Study of Background Process « Crossing e - » γ � 214 Bi Tagged by e( γ ) α (~164 µ s) γ e - n ∆ t ~ 0 ns ( 214 Bi-> 214 Po-> 210 Pb) e + or e - � 208 Tl e γ , e γγ , e γγγ , with γ (2.6MeV) e + e pairs - or Taggd by e( γ ) α (~300ns) Double Compton Compton + Möller ( 212 Bi-> 212 Po-> 208 Pb) � Neutron Crossing e (4~8MeV)

ββ decay isotopes in NEMO ββ decay isotopes in NEMO- -3 detector 3 detector 05 04 06 03 ββ2ν measurement 02 07 116 Cd 405 g 08 01 Q ββ = 2805 keV 96 Zr 9.4 g 09 00 Q ββ = 3350 keV 150 Nd 37.0 g 19 10 Q ββ = 3367 keV 18 11 48 Ca 7.0 g Q ββ = 4272 keV 17 12 130 Te 454 g 13 16 14 15 Q ββ = 2529 keV External bkg 100 Mo 6.914 kg 82 Se nat Te 491 g 0.932 kg measurement Q ββ = 3034 keV Q ββ = 2995 keV Cu 621 g ββ0ν search (All the enriched isotopes produced in Russia)

Sources preparation

NEMO-3 Opening Day, July 2002 Start taking data 14 February 2003 Water tank wood coil Iron shield

ββ events selection in NEMO ββ events selection in NEMO- -3 3 Typical ββ 2 ν event observed from 100 Mo Transverse view Transverse Run Number: 2040 Run Number: Longitudinal Longitudi Event Number: 9732 2040 view view nal Date: 2003-03-20 Event Number: view 9732 Date: 2003-03-20 Vertex 100 Mo foil 100 Mo foil emissi Geiger plasma on longitudinal propagation Vertex emissi Drift distance on Deposited energy: E 1 +E 2 = 2088 keV Internal hypothesis: ( ∆ t) mes –( ∆ t) theo = 0.22 ns ( ∆ vertex) // = Scintillator Common vertex: 5.7mm ( ∆ vertex) ⊥ = 2.1 mm + PMT Criteria to select ββ Trigger : 1 PMT > 150 keV events: 3 Geiger hits (2 neighbour layers + 1) • 2 tracks with charge < 0 • Internal hypothesis (external event rejection) • 2 PMT, each > 200 keV Trigger rate = 7 Hz • No other isolated PMT ( γ rejection) ββ events: 1 event every 1.5 minutes • PMT-Track association • No delayed track ( 214 Bi rejection) • Common vertex

Background events observed by NEMO- -3 3… … Background events observed by NEMO Electron + α delay track (164 µ s) 214 Bi → 214 Po → 210 Pb Electron crossing > 4 MeV Neutron capture → Electron + N γ ’s 208 Tl (E γ = 2.6 MeV) Electron – positron pair B rejection

Performance of the detector Performance of the detector ββ events from the foil Tracking Detector: Calorimeter: � 99.5 % Geiger cells ON β � 97% of the PMTs+scintillators are ON - � Vertex resolution : � Energy Resolution : ∆ Verte 2 e − channels (482 and 976 keV) using 207 Bi sources calibration runs (every ~ 40 days) with 207 Bi x at 3 well known positions in each sector sources β σ ⊥ ( ∆ Vertex) = 0.6 cm Ext. Wall Int.Wall External Background - 5" PMTs 3" PMTs σ // ( ∆ Vertex) = 1.3 cm (Z=0) � e + /e − separation with a magnetic field of 25 G FWHM (1 MeV) 14% 17% ∆ Vertex = distance between the two ~ 3% confusion at 1 MeV � Daily Laser Survey to control gain stability of each PM vertex ( ∆ t mes – ∆ t calc ) internal hypo. (ns) Time Of Flight: 976 keV � Time Resolution ( ββ channel) ≈ 250 ps at 1 MeV 207 Bi ToF (external crossing e − ) > 3 ns ) Expected Performance of the detector s n ( 2 conversion e − . o p y h l a n has been reached external crossing e − totaly rejected r e 482 keV and 976 t x e ) ∆ t calc keV – ∆ t mes ( FWHM = 135 keV 482 (13.8%) keV

2 β β 2 2 ν ν decay results in NEMO decay results in NEMO- -3 3 2

100 Mo 2 β 2 ν preliminary results (Data Feb. 2003 – Dec. 2004) Angular Distribution Sum Energy Spectrum 219 000 events 219 000 events NEMO-3 NEMO-3 6914 g 6914 g 100 Mo 100 Mo 389 days 389 days S/B = 40 S/B = 40 • Data 2 β 2 ν • Data Monte Carlo 2 β 2 ν Background subtracted Monte Carlo Background subtracted Cos( θ ) E 1 + E 2 (keV) T 1/2 = 7.11 ± 0.02 (stat) ± 0.54 (syst) × 10 18 y 7.37 kg.y

2 β 2 ν preliminary results for other nuclei NEMO-3 932 g T 1/2 = 9.6 ± 0.3 (stat) ± 1.0 (syst) × 10 19 y 82 Se 389 days 2750 events T 1/2 = 2.8 ± 0.1 (stat) ± 0.3 (syst) × 10 19 y 116 Cd 82 Se S/B = 4 150 Nd T 1/2 = 9.7 ± 0.7 (stat) ± 1.0 (syst) × 10 18 y • Data T 1/2 = 2.0 ± 0.3 (stat) ± 0.2 (syst) × 10 19 y 96 Zr 2 β 2 ν Monte Carlo Background subtracted Background subtracted E 1 +E 2 (keV) NEMO-3 NEMO-3 37 g 405 g NEMO-3 5.3 g 168.4 days 168.4 days 168.4 days 116 Cd 96 Zr 150 Nd 1371 events 449 events 72 events S/B = 7.5 S/B = 2.8 S/B = 0.9 Data Data Data ββ2ν ββ2ν ββ2ν simulation simulation simulation E 1 +E 2 (MeV) E 1 +E 2 (MeV) E 1 +E 2 (MeV)