Probing neutrinos with  decay Ruben Saakyan UCLSwansea 31 January January 2006

Preview Neutrino oscillations,  decay and neutrino mass Neutrino oscillations,  decay and neutrino mass  decay basics  decay basics Running experiments Running experiments Status of “evidence” Status of “evidence” Future projects Future projects

Why study neutrinos? Essential part of the building blocks of matter and the Universe Essential part of the building blocks of matter and the Universe Fundamental for understanding deep principles of nature Fundamental for understanding deep principles of nature In Standard Model assumed to be massless In Standard Model assumed to be massless We now know they have non-zero mass We now know they have non-zero mass Neutrino mass – window beyond Standard Model Neutrino mass – window beyond Standard Model

Neutrino oscillations Simple case: 2 vacuum oscillations Recall that e   Consider  = 45 

Oscillations  m  0 PMNS matrix (compare CKM matrix for quarks) from 2 to 3 oscillations PMNS – Pontecorvo-Maki-Nakagawa-Sakata CKM – Cabibbo-Kobayashi-Maskawa

First evidence for oscillations from atmospheric neutrinos

SuperKamiokande detector (Japan)

Solar neutrinos SNO – Sudbury Neutrino Observatory

Neutrino oscillation summary 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  at least one neutrino with m i > 0.05 eV!

Neutrino mass. Things we want to know. Relative mass scale ( -oscillations) Relative mass scale ( -oscillations) Mass hierarchy ( -oscillations,  ) Mass hierarchy ( -oscillations,  ) CP-violation ( -oscillations,  CP-violation ( -oscillations,  Absolute mass scale (  3H-decay, cosmology) Absolute mass scale (  3H-decay, cosmology) Dirac or Majorana particle (  only) Dirac or Majorana particle (  only)  L  0? Access to GUT scale (see-saw mechanism) Important consequences for particle physics, cosmology, nuclear physics

Theorists dream: is Majorana particle MRMR mLmL See-Saw: explains smallness of m Leptogenesis: may shed light on baryon asymmetry of Universe

Standard Model 2  Decay In many even-even nuclei,  decay is energetically forbidden. This leaves  as the allowed decay mode. Q  Excited state decays possible |M| - NME, very hard to calculate but in case of  can be measured experimentally  has been observed for 10 nuclei Phase space ~Q  11 NME

 Decay  L = 2! Phase space ~Q  5 NME Q  But there are other mechanisms which could generate  (V+A, Majoron emission, leptoquarks, extra-dimensions, SUSY, H -- …)  spectra. E e1 + E e2

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

Recent developments in NME calculations Rodin, Faessler, Simcovic, Vogel, PRC 68 (2003) nucl-th/ g pp fixed from experimentally measured   Different calculations converge Underlines the importance of 2  precise measurements Error bars are from experimental errors on Workshop on NME in Durham, May 2005 K. Zuber, nucl-ex/

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 Extremely radiopure materials + underground Lab

Experimental approaches to direct searches Two approaches for the detection of the two electrons: e-e- e-e- Source  Detector (calorimetric technique)   scintillation  cryogenic macrocalorimeters (bolometers)  solid-state devices  gaseous detectors high efficiency and energy resolution e-e- e-e- source detector Source  Detector   scintillation  gaseous TPC  gaseous drift chamber  magnetic field and TOF event reconstruction  signature

A History Plot < 0.35 – 0.9 eV m scale ~ 0.05 eV from oscillation experiments Current best limit comes from 76Ge experiments: Heidelberg-Moscow and IGEX

Hieldeberg-Moscow (Gran Sasso) = 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) Until ~2008 results are only from these two Sensitivity ~ 0.2 eV – 0.6 eV Current Experiments

Located in LNGS, Hall A 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  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 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

Latest results, 100 Mo PRL 95, (005) T 1/2 = 7.11  0.02 (stat)  0.54 (syst)  y, SSD mechanism! T  > 4.6  y, m  < 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 DCBANd kg Nd layers between tracking chambers SuperNEMO Se-82, Various 100 kg of Se-82(or other) foil COBRACAMEOTe-130,Cd-116Cd-116 CdTe semiconductors 1 t CdWO 4 crystals CANDLESCa-48 Several tons CaF 2 crystals in liquid scint. CUORETe kg TeO 2 bolometers EXOXe ton Xe TPC (gas or liquid) GEMGe-76 1 ton Ge diodes in liquid nitrogen GERDAGe ton Ge diodes in LN 2 /LAr GSOGd t Gd 2 SiO 5 :Ce crystal scint. in liquid scint. MajoranaGe kg Ge diodes MOONMo-100 Mo sheets between plastic scint., or liq. scint. XeXe t of Xe in liq. Scint. XMASSXe t of liquid Xe

Clean room lock Vacuum insulated copper vessel Water tank / buffer/ muon veto Liquid N/Ar Ge Array “Naked” 76 Ge detectors in LN 2 /LAr Original idea from GENIUS (Klapdor) GERDA. 76 Ge.

GERDA. 76 Ge Phase I: collect 76 Ge detectors from HM(11kg)+IGEX(8kg) Phase I: collect 76 Ge detectors from HM(11kg)+IGEX(8kg) 15kg  c/keV/kg/y 15kg  c/keV/kg/y  sens-ty: 3·10 25 y, eV sens-ty: 3·10 25 y, eV Confirm Klapdor with 5  OR rule out Phase II: increase to ~35-40 kg Phase II: increase to ~35-40 kg BG < c/keV/kg/y BG < c/keV/kg/y within 4 yr ~ 100 kg  y within 4 yr ~ 100 kg  y  2·10 26 y, eV 2·10 26 y, eV Phase III: ton Phase III: ton Possible merge with Majorana Possible merge with Majorana >10 27 y, ~ 0.03 eV eV >10 27 y, ~ 0.03 eV eV GERDA Phase I and Phase II approved Site: Gran Sasso Mostly European project

CUORE. 130 Te New 130 Te experiment, evolution of CUORICINO Closely packed array of 988 bolometers at 10 mK 19 towers - 13 modules/tower - 4 detectors/module M = 741 kg ~ 265 kg of 130 Te Compact structure, ideal for active shielding Each tower is a CUORICINO-like detector Special dilution refrigerator Site: Gran Sasso Euope +US

CUORE Current CUORICINO background 0.2 c/keV/y/kg Current CUORICINO background 0.2 c/keV/y/kg Two scenarios: Two scenarios: I: BG down to 0.01 c/keV/y/kg I: BG down to 0.01 c/keV/y/kg II: BG down to c/keV/y/kg II: BG down to c/keV/y/kg Sensitivity I: 2×10 26 y, 0.03 – 0.1 eV Sensitivity I: 2×10 26 y, 0.03 – 0.1 eV Sensitiviry II: 6.5×10 26 y, – 0.06 eV Sensitiviry II: 6.5×10 26 y, – 0.06 eV 5 year exposure Approved

SuperNEMO (UK, France, Russia, Spain, US, Czech Rep…) Evolution of NEMO 3  same technique, larger mass, lower background better efficiency, higher energy resolution 82 Se experiment (high Q , slower 2 rate) as baseline. Basic points: Planar geometry Modular structure Isotope Mass kg Instrumentation ~20 submodules, 40,000 – 60,000 tracking channels ~ 5,000 – 20,000 PMTs (depending on the design) Sensitivity T 1/2 : 2 x10 26 y  M   < meV

Top view Side view 5 m 1 m 4 m source tracker calorimeter SUPERNEMO. Tracking calorimeter

Majorana. 76 Ge 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 (14 crystals, 1 enriched) Possible merger with GERDA at later stage Sensitivity: T 1/2 ~ 3×10 27 y ~ 0.03 – 0.09 eV Mostly US

EXO. 136 Xe 1-10 ton, ~80% enriched 136 Xe 1-10 ton, ~80% enriched 136 Xe Gas TPC or LXe chamber Gas TPC or LXe chamber Optical identification of Ba ion. Optical identification of Ba ion. Drift ion in gas to laser path or extract on cold probe to trap. Drift ion in gas to laser path or extract on cold probe to trap. 200-kg enr Xe prototype (no Ba ID) being built 200-kg enr Xe prototype (no Ba ID) being built Isotope in hand Isotope in hand Sensitivity with 1 ton: 8×10 26 y 0.04 – 0.08 eV Mostly US

Cadmium-Telluride O-neutrino double-Beta Research Apparatus. COBRA SussexOxfordDortmundWarwick CdTe or CdZnTe semiconductor detectors Good  E/E Two isotopes 116 Cd and 130 Te Operate at room temperature New approach

Experiment Source and MassSensitivity to T 1/2 (y) to T 1/2 (y) Sensitivity to (eV) GERDA/Majorana$50M-100M 76 Ge, 500kg 3× – 0.09 CUORE$30M 130 Te, 750kg(nat) 2× – 0.1 EXO$50M-100M 136 Xe 1 ton 8× – 0.08 SuperNEMO$40M 82 Se (or other) 100 kg (1-2)× – 0.08 Next generation experiments Plan to reach this sensitivity by ~2015

 [eV]  M   [eV]  M   [eV] Strumia-Vissani hep-ph/  degeneracy will be deeply probed  inverted hierarchy will be soon attacked (HM,CUORICINO, NEMO3) COSMOLOGYCOSMOLOGY SINGLESINGLE DOUBLEDOUBLE Neutrino mass scale Expected limits from 0 -DBD A. Giulliani, Neutrino mass scale Expected limits from 0 -DBD A. Giulliani, 1 st Astroparticle EU town meeting Munich, Nov PLANCK + larger surveys KATRIN, MARE CUORE, GERDA, SUPERNEMO,... KDHK claim

Concluding Remarks Very exciting time for neutrino physics in general and 0  in particular Very exciting time for neutrino physics in general and 0  in particular From oscillations: positive signal is a serious possibility From oscillations: positive signal is a serious possibility “Good value”: ~$50M for great potential scientific gain “Good value”: ~$50M for great potential scientific gain At least one measurement which must be done but can not be done by any other approach (nature of mass) At least one measurement which must be done but can not be done by any other approach (nature of mass) Several experiments with different isotopes are needed (recall NME uncertainties) Several experiments with different isotopes are needed (recall NME uncertainties)