Probing Probing neutrinos neutrinos

with with decay decayRuben SaakyanRuben Saakyan

UCLUCLSwanseaSwansea

31 January 200631 January 2006

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Neutrino oscillations, Neutrino oscillations, decay and decay and neutrino massneutrino mass

decay basicsdecay basics Running experimentsRunning experiments Status of “evidence”Status of “evidence” Future projectsFuture projects

Why study neutrinos?Why study neutrinos? Essential part of the Essential part of the

building blocks of building blocks of matter and the Universematter and the Universe

Fundamental for Fundamental for understanding deep understanding deep principles of natureprinciples of nature

In Standard Model In Standard Model assumed to be assumed to be masslessmassless

We now know they We now know they have non-zero masshave non-zero mass

Neutrino mass – Neutrino mass – window beyond window beyond Standard ModelStandard Model

Neutrino oscillationsNeutrino oscillationsSimple case: 2Simple case: 2 vacuum vacuum

oscillationsoscillations

2

1

e

μ

ν

ν

cosθsinθ

sinθcosθ

ν

ν

tiEii

ie0νtν Recall that

e

Consider = 45

Oscillations Oscillations m m 0 0

ijijijij

τττ

μμμ

eee

li

sandcwhere

cs

sc

iδecs

sccs

sc

UUU

UUU

UUU

U

sin,cos

0

010

0

00

010

001

0

0

001

100

0

0

1313

1313

2323

23231212

1212

321

321

321

)E

LΔm.(θ)νP(ν eμ

222 271sin2sin

PMNS matrix (compare CKM matrix for quarks)

from 2from 2 to 3 to 3 oscillations oscillations

PMNS – Pontecorvo-Maki-Nakagawa-SakataCKM – Cabibbo-Kobayashi-Maskawa

First evidence for oscillations fromatmospheric neutrinos

SuperKamiokande detector (Japan)

Solar neutrinos

SNO – Sudbury Neutrino Observatory

Neutrino oscillation Neutrino oscillation summarysummary

e

Ue1 Ue2 Ue3U1 U2 U3

U1 U2 U3

1

2

3

U 0.5 0.87 0

0.61 0.35 0.71

0.61 0.35 0.71

Neutrino Mixing Observed !

From KamLAND, solar and atmospheric

VERY approximately

m2LMA ≈ 5×10-5 eV2 = (7 meV)2

m2atm ≈ 2.5×10-3 eV2 = (50 meV)2

at least one neutrino with mi > 0.05 eV!

Neutrino mass. Neutrino mass. Things we want to know. Things we want to know.

Relative mass scale (Relative mass scale (-oscillations)-oscillations) Mass hierarchy (Mass hierarchy (-oscillations, -oscillations, )) CP-violation (CP-violation (-oscillations, -oscillations, Absolute mass scale (Absolute mass scale (3H-decay, 3H-decay,

cosmology)cosmology) Dirac or Majorana particle (Dirac or Majorana particle (only)only)

L 0? Access to GUT scale (see-saw mechanism)

Important consequences for particle physics, cosmology, nuclear physics

Theorists dream: Theorists dream: is is Majorana particleMajorana particle

MRmL

See-Saw: explains smallness of m

Leptogenesis: may shed light on baryon asymmetry of Universe

2

GUT scale Majorana mass

DL

R

R

mm

M

M

Standard Model 2Standard Model 2 DecayDecay

2+

0+

0+

0+

2-

Ge76

As76

Se76

In many even-even nuclei, decay is energetically forbidden. This leaves as the allowed decay

mode.

Q 1 22 2 2

1/ 2 0(0 0 ) ( , )T G E Z M

Excited statedecays possible

|M| - NME, very hard to calculate but in caseof can be measured experimentally

has been observed for 10 nuclei

Phase space ~Q11

NME

Decay Decay

L = 2!

1 20 0 0 21/ 2 0(0 0 ) ( , )T G E Z M m

Phase space ~Q5 NME

Q

But there are other mechanisms whichcould generate (V+A, Majoron emission,leptoquarks, extra-dimensions, SUSY, H--…)

spectra. Ee1 + Ee2

Effective Majorana MassEffective Majorana Mass(inverted hierarchy case)(inverted hierarchy case)

2 222 2 i

N N

ei i ei ii i

m U m U e m

Ue12 m1

Ue22 m2

Ue32 m3

<mee>

min

IsotopesIsotopes Best candidates: Best candidates:

7676Ge, QGe, Q2.038 MeV2.038 MeV 4848Ca, QCa, Q 4.272 MeV 4.272 MeV 8282Se, QSe, Q 2.995 MeV2.995 MeV 100100Mo, QMo, Q 3.034 MeV 3.034 MeV 116116Cd, QCd, Q 2.804 MeV 2.804 MeV 130130Te, QTe, Q 2. 528 MeV 2. 528 MeV 136136Xe, QXe, Q 2.48 MeV2.48 MeV 150150Nd, QNd, Q 3.368 MeV 3.368 MeV

High QHigh Q is important ( is important (GG00 ~ Q ~ Q55, G, G22 ~ Q ~ Q

1111)) In most cases enrichment is a mustIn most cases enrichment is a must Different isotopes must be investigated due Different isotopes must be investigated due

to uncertainties in NME calculations !to uncertainties in NME calculations !

Recent developments in NME calculationsRecent developments in NME calculations

Rodin, Faessler, Simcovic, Vogel, PRC 68 (2003) 044303 nucl-th/0503063.

gpp fixed from experimentally measured

Different calculations converge Underlines the importance of 2 precise measurements

Error bars are fromexperimental errors on 2

1/ 2T

Workshop on NME in Durham, May 2005K. Zuber, nucl-ex/0511009

The Experimental ProblemThe Experimental Problem(( Maximize Rate/Minimize Background) Maximize Rate/Minimize Background)

Natural Activity:

(238U, 232Th) ~ 1010 yearsTarget: (0) > 1025 years

DetectorShielding

Cryostat, or other experimental supportFront End Electronics

etc.+

Cosmic ray induced activity

Extremely radiopure materials + underground Lab

Experimental approaches to direct searchesExperimental approaches to direct searches

Two approaches for the detection of the two electrons:

e-

e-

Source Detector(calorimetric technique)

scintillation cryogenic macrocalorimeters (bolometers) solid-state devices gaseous detectors

high efficiency and energy resolution

e-

e-

source

detector

detector

Source Detector

scintillation gaseous TPC gaseous drift chamber magnetic field and TOF

event reconstruction signature

A History PlotA History Plot

<m> < 0.35 – 0.9 eV

mscale ~ 0.05 eV from oscillation experiments

Current best limit comesfrom 76Ge experiments:Heidelberg-Moscow andIGEX

Hieldeberg-Moscow (Gran Hieldeberg-Moscow (Gran Sasso)Sasso)

<m> = 0.4 eV ???

• 5 HPGe 11 kg, 86% 76Ge• E/E 0.2%• >10 yr of data taking

<m> < 0.3 – 0.7 eV If combine HM and IGEX

First claim (end 2001)

Heidelberg claim. Heidelberg claim. Recent developmentsRecent developments

hep-ph/0403018, NIMA, Phys. Rev…Data analysed for 1990 – 2003

71.7 kgyr

• Data reanalyzed with improved binning/summing • Peak visible• Effect reclaimed with 4.2• <m> = (0.2 – 0.6) eV, 0.4 eV best fit<m> = (0.1 – 0.9) eV (due to NME)

• Looks more like 2.5 of effect•214Bi line intensities do not match

214Bi214Bi

unkn

own

Personal view

CUORICINO (bolometer)

NEMO-3(Tracking calorimeter)

Until ~2008 results are only from these twoSensitivity ~ 0.2 eV – 0.6 eV

Current ExperimentsCurrent Experiments

Located in LNGS, Hall ALocated in LNGS, Hall A

Cuoricino (Hall A)

CUORE R&D (Hall C)

CUORE (Hall A)

Today:CUORICINOToday:CUORICINO

Incident particle

absorber crystal

heat bath

Thermal sensor

Today: CUORICINO

2 modules, 9 detector each,crystal dimension 3x3x6 cm3

crystal mass 330 g

9 x 2 x 0.33 = 5.94 kg of TeO2

11 modules, 4 detector each,crystal dimension 5x5x5 cm3

crystal mass 790 g4 x 11 x 0.79 = 34.76 kg of

TeO2

40.7kg total

Today:CUORICINOToday:CUORICINO

• Operation started early 2003• BG = 0.19 counts/kev/kg/y• E/E = 4 eV @ 2 MeV

m < 0.3 – 1.6 eV (all NME)

AUGUST 2001

Today: NEMO-III

100Mo 6.914 kg Q= 3034 keV

decay isotopes in NEMO-3 detector

82Se 0.932 kg Q= 2995 keV

116Cd 405 g Q= 2805 keV

96Zr 9.4 g Q= 3350 keV

150Nd 37.0 g Q= 3367 keV

Cu 621 g

48Ca 7.0 g Q= 4272 keV

natTe 491 g

130Te 454 g Q= 2529 keV

measurement

External bkg measurement

search (All enriched isotopes produced in Russia)

Drift distance

100Mo foil100Mo foil

Transverse view Longitudinal view

Run Number: 2040Event Number: 9732Date: 2003-03-20

Geiger plasmalongitudinalpropagation

Scintillator + PMT

Deposited energy: E1+E2= 2088 keVInternal hypothesis: (t)mes –(t)theo = 0.22 nsCommon vertex: (vertex) = 2.1 mm

Vertexemission

(vertex)// = 5.7 mm

Vertexemission

Transverse view Longitudinal view

Run Number: 2040Event Number: 9732Date: 2003-03-20

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 (214Bi rejection)

events selection in NEMO-3

Typical 2 event observed from 100Mo

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, Latest results, 100100Mo Mo PRL 95, 182302 (005)PRL 95, 182302 (005)

T1/2 = 7.11 0.02 (stat) 0.54 (syst) 1018 y, SSD mechanism!T > 4.6 1023 y , m< 0.7-2.8 eV

Strategy for future.Strategy for future.An Ideal ExperimentAn Ideal Experiment

Large Mass (Large Mass (0.1t)0.1t) Good source radiopurityGood source radiopurity

Demonstrated technology Demonstrated technology Natural isotopeNatural isotope

Small volume, source = detectorSmall volume, source = detector Tracking capabilitiesTracking capabilities

Good energy resolution or/and Good energy resolution or/and Particle IDParticle ID

Ease of operationEase of operation Large Q value, fast Large Q value, fast (0(0))

Slow Slow (2(2) rate) rate Identify daughterIdentify daughter

Event reconstructionEvent reconstruction Nuclear theoryNuclear theory

01

04

1

BGMt

m

BGMt

Ebm

live

live

All requirements can NOT be satisfied Red – must be satisfied

A Great Number of A Great Number of ProposalsProposals

DCBADCBA Nd-150Nd-150 20 kg Nd layers between tracking 20 kg Nd layers between tracking chamberschambers

SuperNEMSuperNEMOO

Se-82, Se-82, VariousVarious

100 kg of Se-82(or other) foil 100 kg of Se-82(or other) foil

COBRA COBRA

CAMEOCAMEOTe-130,Cd-Te-130,Cd-116116

Cd-116Cd-116

CdTe semiconductorsCdTe semiconductors

1 t CdWO1 t CdWO44 crystals crystals

CANDLESCANDLES Ca-48Ca-48 Several tons CaFSeveral tons CaF22 crystals in liquid crystals in liquid scint.scint.

CUORECUORE Te-130Te-130 750 kg TeO750 kg TeO22 bolometers bolometers

EXOEXO Xe-136Xe-136 1 ton Xe TPC (gas or liquid)1 ton Xe TPC (gas or liquid)

GEMGEM Ge-76Ge-76 1 ton Ge diodes in liquid nitrogen1 ton Ge diodes in liquid nitrogen

GERDAGERDA Ge-76Ge-76 0.5-1 ton Ge diodes in LN0.5-1 ton Ge diodes in LN22/LAr/LAr

GSOGSO Gd-160Gd-160 2 t Gd2 t Gd22SiOSiO55:Ce crystal scint. in :Ce crystal scint. in liquid scint.liquid scint.

MajoranaMajorana Ge-76Ge-76 500 kg Ge diodes500 kg Ge diodes

MOONMOON Mo-100Mo-100 Mo sheets between plastic scint., Mo sheets between plastic scint., or liq. scint.or liq. scint.

XeXe Xe-136Xe-136 1.56 t of Xe in liq. Scint.1.56 t of Xe in liq. Scint.

XMASSXMASS Xe-136Xe-136 10 t of liquid Xe10 t of liquid Xe

Clean roomlock

Vacuum insulated copper vessel

Water tank / buffer/ muon veto

Liquid N/Ar

Ge Array

“Naked” 76Ge detectors in LN2/LArOriginal idea from GENIUS (Klapdor)

GERDA. 76Ge.

GERDA. GERDA. 7676GeGe Phase IPhase I: collect : collect 7676Ge detectors from HM(11kg)Ge detectors from HM(11kg)

+IGEX(8kg)+IGEX(8kg) 15kg15kgy+BG@0.01 c/keV/kg/yy+BG@0.01 c/keV/kg/y sens-ty: 3·10sens-ty: 3·102525 y, 0.24-0.77 eV  y, 0.24-0.77 eV Confirm Klapdor with 5Confirm Klapdor with 5 OR OR rule out rule out

Phase II:Phase II: increase to ~35-40 kg increase to ~35-40 kg BG < 10BG < 10-3 -3 c/keV/kg/yc/keV/kg/y within 4 yr ~ 100 kgwithin 4 yr ~ 100 kgyy 2·102·102626 y, 0.09-0.29 eV  y, 0.09-0.29 eV 

Phase IIIPhase III: : 0.5 -1 ton0.5 -1 ton Possible merge with MajoranaPossible merge with Majorana >10>102727 y, ~ 0.03 eV- 0.09 eV y, ~ 0.03 eV- 0.09 eV

GERDA Phase I and Phase II approved

Site: Gran SassoMostly European project

CUORE. CUORE. 130130TeTe

New 130Te experiment, evolution of CUORICINO Closely packed array of 988 bolometers at 10 mK19 towers - 13 modules/tower - 4 detectors/moduleM = 741 kg ~ 265 kg of 130Te

Compact structure, ideal for active shielding

Each tower is a CUORICINO-like detector

Special dilution refrigerator

Site: Gran SassoEuope +US

CUORE CUORE

Current CUORICINO background 0.2 Current CUORICINO background 0.2 c/keV/y/kgc/keV/y/kg

Two scenarios:Two scenarios: I: BG down to 0.01 c/keV/y/kgI: BG down to 0.01 c/keV/y/kg II: BG down to 0.001 c/keV/y/kgII: BG down to 0.001 c/keV/y/kg

Sensitivity I: 2Sensitivity I: 2×10×102626 y, 0.03 – 0.1 eV y, 0.03 – 0.1 eV Sensitiviry II: 6.5×10Sensitiviry II: 6.5×102626 y, 0.017 – 0.06 y, 0.017 – 0.06

eV eV

5 yearexposure

Approved

SuperNEMO SuperNEMO (UK, France, Russia, Spain, US, Czech Rep…)(UK, France, Russia, Spain, US, Czech Rep…)

Evolution of NEMO 3 same technique, larger mass, lower background better efficiency, higher energy resolution

82Se experiment (high Q, slower 2 rate) as baseline. Basic points:

Planar geometry

Modular structure

Isotope Mass 100-200 kg

Instrumentation ~20 submodules, 40,000 – 60,000 tracking channels ~ 5,000 – 20,000 PMTs (depending on the design)

Sensitivity T1/2: 2 x1026 y

M < 40 - 70 meV

Top viewSide view

5 m

1 m 4 m

source

tracker

calorimeter

SUPERNEMO. Tracking calorimeterSUPERNEMO. Tracking calorimeter

Majorana. Majorana. 7676GeGe 0.5 ton of 86% enriched 0.5 ton of 86% enriched

7676GeGe Very well known and Very well known and

successful technologysuccessful technology Segmented detectors Segmented detectors

using pulse shape using pulse shape discrimination to discrimination to improve background improve background rejection.rejection.

Prototype ready (14 Prototype ready (14 crystals, 1 enriched)crystals, 1 enriched)

Possible merger with Possible merger with GERDA at later stageGERDA at later stage

Sensitivity:T1/2 ~ 3×1027 y

<m> ~ 0.03 – 0.09 eV

Mostly US

EXO. EXO. 136136XeXe 1-10 ton, ~80% 1-10 ton, ~80%

enriched enriched 136136XeXe Gas TPC or Gas TPC or LXe LXe

chamberchamber Optical identification Optical identification

of Ba ion.of Ba ion. Drift ion in gas to laser Drift ion in gas to laser

path or extract on cold path or extract on cold probe to trap.probe to trap.

200-kg 200-kg enrenrXe prototype Xe prototype (no Ba ID) being built(no Ba ID) being built

Isotope in handIsotope in hand

Sensitivity with 1 ton: 8×1026 y 0.04 – 0.08 eV

Mostly US

CCadmium-Telluride admium-Telluride OO--neutrino double-neutrino double-BBeta eta RResearch esearch AApparatus. pparatus.

COBRACOBRA

SussexSussex

OxfordOxford

DortmuDortmundnd

WarwicWarwickk

• CdTe or CdZnTe semiconductor detectors• Good E/E• Two isotopes 116Cd and 130Te• Operate at room temperature• New approach

ExperimentExperiment Source and Source and

MassMassSensitivitySensitivity

to Tto T1/21/2 (y) (y)Sensitivity Sensitivity to<mto<m>(eV)>(eV)

GERDA/GERDA/MajoranaMajorana

$50M-100M$50M-100M

7676Ge, 500kgGe, 500kg 3×103×102727 0.03 – 0.090.03 – 0.09

CUORECUORE

$30M$30M

130130Te, Te, 750kg(nat)750kg(nat)

2×102×102626 0.03 – 0.10.03 – 0.1

EXOEXO

$50M-100M $50M-100M

136136XeXe

1 ton 1 ton 8×108×102626 0.04 – 0.080.04 – 0.08

SuperNEMOSuperNEMO

$40M$40M

8282SeSe(or other)(or other)

100 kg100 kg(1-2)×10(1-2)×102626 0.04 – 0.080.04 – 0.08

Next generation experiments

Plan to reach this sensitivity by ~2015

[e

V]

M

[eV

]

M

[eV

]

Str

umia

-Vis

sani

hep

-ph/

0503

246

degeneracy will be deeply probed

inverted hierarchy will be soon attacked

(HM,CUORICINO, NEMO3)

COSMOLOGY

SINGLE

DOUBLE

Neutrino mass scaleNeutrino mass scaleExpected limits from 0Expected limits from 0-DBD-DBDA. GiullianiA. Giulliani, , 1st Astroparticle

EU town meetingMunich, 23-25 Nov

PLANCK + larger surveys

KATRIN, MARE CUORE, GERDA, SUPERNEMO, ...

KDHKclaim

Concluding RemarksConcluding Remarks

Very exciting time for neutrino physics in Very exciting time for neutrino physics in general and 0general and 0 in particular in particular

From oscillations: positive signal is a serious From oscillations: positive signal is a serious possibilitypossibility

““Good value”: ~$50M for great Good value”: ~$50M for great potential potential scientific gainscientific gain At least one measurement which must be done but At least one measurement which must be done but

can not be done by any other approach (nature of can not be done by any other approach (nature of mass)mass)

Several experiments with different isotopes Several experiments with different isotopes are needed (recall NME uncertainties)are needed (recall NME uncertainties)