Status of decay

Ruben Saakyan

UCL

Outline

Motivation decay basicsResults so farCurrent experimentsFuture projects and sensitivity

Motivation

e

Ue1 Ue2 Ue3U1 U2 U3

U1 U2 U3

123

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

2 5 2 2

2 3 2 2

5 10 (7 )

2.5 10 (50 )

LMA

atm

m eV meV

m eV meV

Neutrino MASSWhat do we want to know?

or

• Relative mass scale (-osc)

• Mass hierarchy (-osc and )

• Absolute mass scale (cosmology)

Dirac or Majorana

1 3e

Ue12 Ue2

2 Ue32

MixingOnly from From -osc

mmin ~ 0 - 0.01 eV mmin ~ 0.03 - 0.06 eV

preferred bytheorists(see-saw)

Decay Basics

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 Endpoint

Energy

Decay Basics

e

e

e

e

n

n n

np

p

p

p

2 and 0

• 2 – Allowed in SM second order weak process. Observed for several isotopes

• 0 – Requires massive Majorana neutrinos (even in presence of alternative mechanisms)

L = 2

Decay Basics. Energy Spectrum

2.01.51.00.50.0Sum Energy for the Two Electrons (MeV)

Two Neutrino Spectrum Zero Neutrino Spectrum

1% resolution(2) = 100 * (0)

Q Endpoint

Energy

76Ge example

Decay Basics. Rates

1 22 2 21/ 2 0(0 0 ) ( , )T G E Z M

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

G – phase space, exactly calculable; G0 ~ Q5, G2 ~ Q

11

M – nuclear matrix element. Hard to calculate. Uncertainties factor of 2-10 (depending on isotope) Must investigate several different isotopes!<m> is effective Majorana neutrino mass

Isotopes of Interest

48Ca, 76Ge, 100Mo, 150Nd,136Xe, 116Cd, 96Zr, 82Se,130Te

Effective Majorana Mass

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

Physics Reach

Normal Hierarchy Inverted Hierarchy Degenerate

m1 ~ 0 meV ~55 meV M ≥ 100 meV

m2 ~ 7 meV ~55 meV M

m3 ~ 55 meV ~0 meV M

<m> ~ 5 meV 28 or 55 meV M/2 or M

m 0.5 2m1 21 0.866 2 m12 m21

2

Solar + KamLAND + Atmospheric (Ue3~ 0)

The Experimental Problem( 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

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

01

04

1

BGMt

m

BGMt

Ebm

live

live

All requirements can NOT be satisfied Red – must be satisfied

Results from previous experiments

<m> < 0.35 – 1.0 eV

mscale ~ 0.01 – 0.05 eV from oscillation experiments

Hieldeberg-Moscow (Gran Sasso)(Spokesperson: E. Klapdor-Kleingrothaus, MPI)

<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

CUORICINO (bolometer)

NEMO-3(Tracking calorimeter)

See Jenny’s talk

Current Experiments

CUORICINO Detector (Gran Sasso)(Milano LNGS, Firenze, Berkeley, S. Carolina)

• High natural abundance of 130Te – 34% (no enrichment)• Good E/E ~0.3% at 2.529 MeV

~ 14 kg 130Te

Spokesperson: E. Fiorini, Milano

CUORICINO Status

T1/2(0) > 5×1023 yr (90%) <m> < 0.8 – 3.2 eV NEMO-3 <m> < 0.9 – 2.1 eV

(Preliminary - TAUP’03, September, Seattle )

•2.26 kg×yr (since Feb’03) • BG 0.2 c/keV/kg/yr

A Great Number of Proposals(Some may start taking data in 2008-2010)

COBRA Te-130,Cd-116 10 kg CdTe semiconductors

DCBA Nd-150 20 kg Nd layers between tracking chambers

SuperNEMO Se-82, Various 100 kg of Se-82(or other) foil

CAMEO Cd-116 1 t CdWO4 crystals

CANDLES Ca-48 Several tons CaF2 crystals in liquid scint.

CUORE Te-130 750 kg TeO2 bolometers

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

GEM Ge-76 1 ton Ge diodes in liquid nitrogen

GENIUS Ge-76 1 ton Ge diodes in liquid nitrogen

GSO Gd-160 2 t Gd2SiO5:Ce crystal scint. in liquid scint.

Majorana Ge-76 500 kg Ge diodes

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

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

XMASS Xe-136 10 t of liquid Xe

COBRA, SuperNEMO

See later talks by Kai Zuber, Ruben Saakyan

Cryogenic Underground Observatory for Rare Events - CUORE

Berkeley

Firenze

Gran Sasso

Insubria (COMO)

Leiden

Milano

Neuchatel

U. of South Carolina

Zaragoza

SpokespersonEttore Fiorini

Milano

CUORE

CUORICINO×20 270 kg 130Te(~ 750 kg natTe)

0.001 / / /200

CUORICINOBG c keV y kg

Compact: 70×70×70 cm3

5 yr in Gran Sasso: <m> ~ 0.04 eV

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-SpokespersonsFrank Avignone

Harry Miley

Majorana

0.5 ton of 86% enriched 76Ge

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<m> ~ 0.03 eV

GErmanium NItrogen Underground Setup - GENIUS

MPI, Heidelberg

Kurchatov Inst., Moscow

Inst. Of Radiophysical Research, Nishnij Novgorod

Braunschweig und Technische Universität, Braunschweig

U. of L'Aquila, Italy

Int. Center for Theor. Physics, Trieste

JINR, Dubna

Northeastern U., Boston

U. of Maryland, USA

University of Valencia, Spain

Texas A & M U.

SpokespersonHans Klapdor-Kleingrothaus

MPI

GENIUS

GENIUS

1 ton, ~86% enriched 76Ge

Naked Ge crystals in LN Very little material near

Ge. 1.4x106 liters LN 40 kg test facility is

approved. 100% efficient

5 yr in Gran Sasso: <m> ~ 0.02 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

SpokespersonGiorgio Gratta

Stanford

EXO

10 ton, ~70% enriched 136Xe 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.

100-200-kg enrXe prototype (no Ba ID)

Isotope in hand 5 yr in a US underground lab

<m> ~ 0.05 eV

Future projects sensitivity(5 yr exposure)

Experiment Source and

Mass

Sensitivity

to

T1/2 (y)

Sensitivity to

<m> (eV)*

Majorana

GENIUS

76Ge, 500kg

76Ge. 1000kg

3×1027

5×1027

0.03 – 0.07

0.02 – 0.05

CUORE 130Te, 750kg(nat)

2×1026 0.04 – 0.17

EXO

136Xe

1 ton

8×1026 0.05 – 0.12

SuperNEMO 82Se(or other)

100 kg

2×1026 0.04 – 0.11

* 5 different latest NME calculations

Summary

Great progress over past decade: <m> < 0.3-1 eV

Oscillation expts: at least one neutrino 0.05 eV Next generation experiments will reach 0.03

– 0.1 eV (good if inverted hierarchy) Start in ~2008 The next after next generation will address 0.01 eV

Nuclear theory input needed Exciting time for decay

Things to read…

S.R. Elliott, P. Vogel, Annu. Rev. Nucl. Part. Sci. 52(2002)hep-ph/0202264

BACKUP SLIDES

The Controversy.

Locations of claimed peaks

20

15

10

5

0

Co

un

ts

20802060204020202000

Energy (keV)

16

14

12

10

8

6

4

2

0

Co

un

ts

20802060204020202000

Energy (keV)

If one had to summarize the controversy in a short statement:Consider two extreme background models:

1. Entirely flat in 2000-2080 keV region.2. Many peaks in larger region, only peak in small region.

These 2 extremes give very different significances for peak at 2039 keV.KDHK chose Model 2 but did not consider a systematic uncertaintyassociated with that choice.

Mod. Phys. Lett. A16, 2409 (2001)