 decay:Present and Future Ruben Saakyan UCL 8 November 2004 Manchester University Particle Physics seminar PREVIEW Motivation Present status Status of “evidence” Future projects UK in NEMO/SuperNEMO

Motivation Neutrino Mixing Observed ! From KamLAND, solar and atmospheric VERY approximately  m 2 LMA ≈ 5×10 -5 eV 2 = (7 meV) 2  m 2 atm ≈ 2.5×10 -3 eV 2 = (50 meV) 2

Neutrino MASS What do we want to know? Relative mass scale ( -osc) Mass hierarchy ( -osc and  ) Absolute mass scale (    ) Dirac or Majorana 1  3 e U e1 2 U e2 2 U e3 2 Mixing Only from  From -osc ~ eV ~ eV preferred by theorists (see-saw) degenerate: > 0.1 eV

 Decay Basics In many even-even nuclei,  decay is energetically forbidden. This leaves  as the allowed decay mode. Q  Endpoint Energy

Double beta decay and neutrino mass  L=0  L=2 ! Q 

Effective Majorana Mass (inverted hierarchy case) U e1 2 m 1 U e2 2 m 2 U e3 2 m 3 min

Isotopes Best candidates: 76 Ge, Q   MeV 48 Ca, Q   MeV 82 Se, Q   MeV 100 Mo, Q   MeV 116 Cd, Q   MeV 130 Te, Q   MeV 136 Xe, Q   2.48 MeV 150 Nd, Q   MeV High Q  is important ( G 0 ~ Q  5, G 2 ~ Q  11 ) In most cases enrichment is a must Different isotopes must be investigated due to uncertainties in NME calculations !

The Experimental Problem ( Maximize Rate/Minimize Background) Natural Activity:  ( 238 U, 232 Th) ~ years Target:  (0  ) > years  Detector Shielding Cryostat, or other experimental support Front End Electronics etc. + Cosmic ray induced activity

A History Plot < 0.35 – 0.9 eV m scale ~ 0.05 eV from oscillation experiments

Hieldeberg-Moscow (Gran Sasso) ( Spokesperson: E. Klapdor-Kleingrothaus, MPI) = 0.4 eV ??? 5 HPGe 11 kg, 86% 76 Ge  E/E  0.2% >10 yr of data taking < 0.3 – 0.7 eV If combine HM and IGEX First claim (end 2001)

Heidelberg claim. Recent developments hep-ph/ , NIMA, Phys. Rev… Data analysed for 1990 – kgyr Data reanalyzed with improved binning/summing Peak visible Effect reclaimed with 4.2 = (0.2 – 0.6) eV, 0.4 eV best fit = (0.1 – 0.9) eV (due to NME) Looks more like 2.5 of effect 214 Bi line intensities do not match  214 Bi unknown Personal view

CUORICINO (bolometer) NEMO-3 (Tracking calorimeter) These two will be determining  fate until ~ Sensitivity ~ 0.2 eV Current Experiments

Located in LNGS, Hall A Cuoricino (Hall A) CUORE R&D (Hall C) CUORE (Hall A) Today:CUORICINO

Incident particle absorber crystal heat bath Thermal sensor Today: CUORICINO 2 modules, 9 detector each, crystal dimension 3x3x6 cm 3 crystal mass 330 g 9 x 2 x 0.33 = 5.94 kg of TeO 2 11 modules, 4 detector each, crystal dimension 5x5x5 cm 3 crystal mass 790 g 4 x 11 x 0.79 = kg of TeO kg total

Today:CUORICINO Operation started early 2003 BG = 0.19 counts/kev/kg/y  E/E = 4 2 MeV Neutrino 2004:  m  < 0.3 – 1.6 eV (all NME)

AUGUST 2001 Today: NEMO-III

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)

Drift distance 100 Mo foil Transverse view Longitudinal view Run Number: 2040 Event Number: 9732 Date: Geiger plasma longitudinal propagation Scintillator + PMT 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 Run Number: 2040 Event Number: 9732 Date: 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)  events selection in NEMO-3 Typical  2 event observed from 100 Mo Trigger: 1 PMT > 150 keV 3 Geiger hits (2 neighbour layers + 1) Trigger rate = 7 Hz  events: 1 event every 1.5 minutes

(Data 14 Feb – 22 Mar. 2004) T 1/2 = 7.72  0.02 (stat)  0.54 (syst)  y 100 Mo 2  2 preliminary results 4.57 kg.y Cos(  ) Angular Distribution Background subtracted 2  2 Monte Carlo Data events 6914 g days S/B = 45.8 NEMO Mo E 1 + E 2 (keV) Sum Energy Spectrum events 6914 g days S/B = 45.8 NEMO Mo Data Background subtracted 2  2 Monte Carlo

Simkovic, J. Phys. G, 27, 2233, 2001 Single electron spectrum different between SSD and HSD 100 Mo 2  2 Single Energy Distribution 2  2 HSD Monte Carlo HSD higher levels Background subtracted Data 2  2 SSD Monte Carlo Background subtracted 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)

Today:NEMO-III Present 90%CL limits from NEMO-III(216.4 days) 82 Se:T 1/2 (  ) > y,  m  < 1.3 – 3.6 eV Simkovic et al., Phys. Rev. C60 (1999) Stoica, Klapdor, Nucl. Phys. A694 (2001) Caurier et al., Phys. Rev. Lett (1996) 100 Mo T 1/2 (  ) > y,  m  < 0.7 – 1.2 eV Simkovic et al., Phys. Rev. C60 (1999) Stoica, Klapdor, Nucl. Phys. A694 (2001) Expected Reach in 5 years after RadonPurification 100 Mo T 1/2 (  ) > y,  m  < 0.2 – 0.35 eV 82 Se:T 1/2 (  ) > y,,  m  < 0.65 – 1.8 eV

Strategy for future. An Ideal Experiment  Large Mass (  0.1t)  Good source radiopurity  Demonstrated technology  Natural isotope  Small volume, source = detector  Tracking capabilities  Good energy resolution or/and Particle ID  Ease of operation  Large Q value, fast  (0 )  Slow  (2 ) rate  Identify daughter  Event reconstruction  Nuclear theory  All requirements can NOT be satisfied  Red – must be satisfied

A Great Number of Proposals ( Some may start taking data in ) DCBANd kg Nd layers between tracking chambers SuperNEMOSe-82, Various100 kg of Se-82(or other) foil COBRA CAMEO Te-130,Cd-116 Cd-116 CdTe semiconductors 1 t CdWO 4 crystals CANDLESCa-48Several tons CaF 2 crystals in liquid scint. CUORETe kg TeO 2 bolometers EXOXe-1361 ton Xe TPC (gas or liquid) GEMGe-761 ton Ge diodes in liquid nitrogen GERDAGe ton Ge diodes in LN 2 /LAr GSOGd-1602 t Gd 2 SiO 5 :Ce crystal scint. in liquid scint. MajoranaGe kg Ge diodes MOONMo-100Mo sheets between plastic scint., or liq. scint. XeXe t of Xe in liq. Scint. XMASSXe t of liquid Xe

GERDA. 76 Ge Phase I: collect 76 Ge detectors from HM(11kg)+IGEX(8kg) 15kg  c/keV/kg/y  sens-ty: 3·10 25 y, eV Confirm Klapdor with 5  OR rule out at 98% Phase II:enlarge to ~35-40 kg BG < c/keV/kg/y within 4 yr ~ 100 kg  y  2·10 26 y, eV Phase III: ton Possible merge with Majorana ~ 0.03 eV “Naked” 76 Ge detectors in LN 2 /LAr Original idea from GENIUS (Klapdor)

Cryogenic Underground Observatory for Rare Events - CUORE Berkeley Firenze Gran Sasso Insubria (COMO) Leiden Milano Neuchatel U. of South Carolina Zaragoza Spokesperson Ettore Fiorini Milano

CUORE CUORICINO×20  270 kg 130 Te (~ 750 kg nat Te) Compact: 70×70×70 cm 3 5 yr in Gran Sasso: ~ 0.04 eV APPROVED !

The Majorana Project Duke U. North Carolina State U. TUNL Argonne Nat. Lab. JINR, Dubna ITEP, Moscow New Mexico State U. Pacific Northwest Nat. Lab. U. of Washington LANL LLNL U. of South Carolina Brown Univ. of Chicago RCNP, Osaka Univ. Univ. of Tenn. Co-Spokespersons Frank Avignone Harry Miley

Majorana 0.5 ton of 86% enriched 76 Ge Very well known and successful technology Segmented detectors using pulse shape discrimination to improve background rejection. Prototype ready to go this autumn/winter. (14 crystals, 1 enriched) 100% efficient Can do excited state decay. 5 yr in a US undegr lab ~ 0.03 eV

Enriched Xenon Observatory - EXO U. of Alabama Caltech IBM Almaden ITEP Moscow U. of Neuchatel INFN Padova SLAC Stanford U. U. of Torino U. of Trieste WIPP Carlsbad Spokesperson Giorgio Gratta Stanford

EXO 10 ton, ~70% enriched 136 Xe 70% effic., ~10 atm gas TPC or LXe chamber Optical identification of Ba ion. Drift ion in gas to laser path or extract on cold probe to trap. 200-kg enr Xe prototype (no Ba ID) being built Isotope in hand 5 yr in a US underground lab ~ 0.05 eV

Cadmium-Telluride O-neutrino double-Beta Research Apparatus COBRA Sussex Oxford Dortmund Warwick Project Leader Kai Zuber Sussex CdTe or CdZnTe semiconductor detectors Good  E/E Two isotopes 116 Cd and 130 Te Operate at room temperature New approach Large R&D programme needed If successful can get to ~10-20 meV in ~ 20yr

SuperNEMO UCL Manchester IC LAL, Orsay Bordeaux Strasbourg Prague ITEP (Moscow) JINR (Dubna) Saga Univ. (Japan) INEEL (USA) MHC (USA) NEMO3 x 10 + better  E/E robust and developed technology quick start (100 kg of isotope) F ~ (  E /E) 6

Isotopes in SuperNEMO IsotopeQ, MeV 100 Mo Se Cd Te2.529 Factor of 10 lower BG for 82 Se Can be produced in centrifuge - $30K-$50K/kg

SuperNEMO 4 supermodules Planar geometry 100 kg 82 Se (Q  = 3 MeV, large T 1/2 2  Sensitivity ~0.04 eV in 5 yr Feasible if Zero BG experiment: 1) No BG from radioactivity the only possible BG from 2 tail (NEMO-III) 2) Improve  E/E from existing (14%-16%)/  E to (8%-10%)/  E Demonstrated (UCL+ Dubna) Boulby mine is an attractive experimental site

SuperNEMO. Time Scale 2004 – 2005 scintillator R&D Attempt to reach 5-6% : Design study proposal (PPRP, Dec-Feb) Prototype submodule in Boulby : Production : Start taking data 2014: planned sensitivity ~0.04 eV Excellent chance to be the first to reach meV

Concluding Remarks Very exciting time for neutrino physics in general and 0  in particular From oscillations: positive signal is a serious possibility “Good value”: ~$50M for the great potential scientific gain Several experiments with different isotopes are needed (recall NME uncertainties)