status of bb decay
DESCRIPTION
Status of bb decay. Ruben Saakyan UCL. Outline. Motivation bb decay basics Results so far Current experiments Future projects and sensitivity. Motivation. Neutrino Mixing Observed !. From KamLAND, solar n and atmospheric n. VERY approximately. - PowerPoint PPT PresentationTRANSCRIPT
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Status of decay
Ruben SaakyanUCL
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Outline
Motivation decay basicsResults so farCurrent experimentsFuture projects and sensitivity
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Motivation
e
Ue1 Ue2 Ue3U1 U2 U3U1 U2 U3
123
U 0.5 0.87 0 0.61 0.35 0.710.61 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
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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)
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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
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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
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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
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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 Interest48Ca, 76Ge, 100Mo, 150Nd,136Xe, 116Cd, 96Zr, 82Se,130Te
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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
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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)
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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
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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
041
BGMt
m
BGMtEbm
live
live
All requirements can NOT be satisfied Red – must be satisfied
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Results from previous experiments
<m> < 0.35 – 1.0 eV
mscale ~ 0.01 – 0.05 eV from oscillation experiments
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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
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CUORICINO (bolometer)
NEMO-3(Tracking calorimeter)
See Jenny’s talk
Current Experiments
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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
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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
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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
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COBRA, SuperNEMO
See later talks by Kai Zuber, Ruben Saakyan
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Cryogenic Underground Observatory for Rare Events - CUORE
BerkeleyFirenzeGran SassoInsubria (COMO) LeidenMilanoNeuchatelU. of South CarolinaZaragoza
SpokespersonEttore Fiorini
Milano
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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
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The Majorana ProjectDuke U.North Carolina State U.TUNLArgonne Nat. Lab.JINR, DubnaITEP, MoscowNew Mexico State U.Pacific Northwest Nat. Lab.U. of WashingtonLANLLLNLU. of South CarolinaBrownUniv. of ChicagoRCNP, Osaka Univ.Univ. of Tenn.
Co-SpokespersonsFrank Avignone
Harry Miley
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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
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GErmanium NItrogen Underground Setup - GENIUS
MPI, HeidelbergKurchatov Inst., MoscowInst. Of Radiophysical Research, Nishnij NovgorodBraunschweig und Technische Universität, BraunschweigU. of L'Aquila, Italy Int. Center for Theor. Physics, TriesteJINR, DubnaNortheastern U., BostonU. of Maryland, USAUniversity of Valencia, Spain Texas A & M U.
SpokespersonHans Klapdor-Kleingrothaus
MPI
GENIUS
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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
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Enriched Xenon Observatory - EXO
U. of AlabamaCaltechIBM AlmadenITEP MoscowU. of NeuchatelINFN PadovaSLACStanford U.U. of TorinoU. of TriesteWIPP Carlsbad
SpokespersonGiorgio Gratta
Stanford
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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
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Future projects sensitivity(5 yr exposure)
Experiment Source and Mass
Sensitivity toT1/2 (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
136Xe1 ton
8×1026 0.05 – 0.12
SuperNEMO 82Se(or other)
100 kg2×1026 0.04 – 0.11
* 5 different latest NME calculations
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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
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Things to read…
S.R. Elliott, P. Vogel, Annu. Rev. Nucl. Part. Sci. 52(2002)hep-ph/0202264
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BACKUP SLIDES
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The Controversy.
Locations of claimed peaks
20
15
10
5
0
Cou
nts
20802060204020202000Energy (keV)
16
14
12
10
8
6
4
2
0
Cou
nts
20802060204020202000Energy (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)