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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)