Double%20Beta%20Decay%20Present%20and%20Future

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Double Beta Decay Present and Future

• Jenny Thomas
• Rencontres du Vietnam, 2004

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Preview

• Introduction why search for 0nbb decay?
• Status of the search today 3 experiments
• Cuoricino
• NEMO-III
• Heidleberg-Moscow signal!
• Look at parameter space for 0nbb experiments
• Highlights of a few experiments on the horizon
• Conclusions

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Introduction oscillations

• The neutrino mixing matrix looks like this
• From KamLAND, SNO, Super-K (Gonzales-Garcia NOON)

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Introductionoscillations
mmin 0.03 - 0.06 eV
mmin 0 - 0.01 eV
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Introductiondouble beta decay

• Large number of even-even nuclei undergo
  double-beta decay, but not single-beta decay
• Standard Model process of 2nbb is also allowed of
  course
• Enrichment procedure in place for about 10
  isotopes
• You do not search for peaks in unknown places
  you always know where to look
• Q value of the decay is well known (difference in
  energy between two isotopes)

2nbb 0nbb
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Introductiondouble beta decay
76Ge example
Qbb Endpoint Energy
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Introductionthe experiments

• Two classes of approach to the experiment
• Detector IS the isotope
• Ionisation detectors
• Bolometer detectors
• TPCs
• Detector Contains the isotope(s)
• Tracking detectors
• Measure half life, infer mn
• Half life sensitivity given by experimental
  details
• G-phase space, exactly calculableG0n Qbb5
• M0n-Nuclear Matrix Element, hard to calculate
• Uncertain to factor 2-10, isotope dependent
• Motivation to measure several isotopes

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Introductionthe isotopes

• What are the usable bb decay isotopes?
• 76Ge, Q2.038MeV MG 7.3 0.6 -0.6 x 10 -14
• 48Ca,Q 4.272MeV MG 5.43.0-1.4 x 10 -14
• 82Se, Q 2.995MeV MG 1.70.4-0.3 x 10 -13
• 100Mo, Q 3.034MeV MG 1.00.3-0.3 x 10 -12
• 116Cd,Q 2.804MeV MG 1.30.7-0.3 x 10 -13
• 130Te,Q 2.528MeV MG 4.20.5-0.5 x 10 -13
• 136Xe,Q 2.481MeV MG 2.80.4-0.4 x 10 -14
• 150Nd,Q 3.368MeV MG 5.71.0-0.7 x 10 -12
• These can all be enriched by standard processes

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A History Plot
TeO2
mscale 0.01 0.05 eV from oscillation
experiments
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Where are we today?

• People have been searching for double beta decay
  for many years first suggested in 1937
• Presently three experiments taking data
• CUORICINO Bolometer
• NEMO-III Tracking
• HEIDLEBERG-MOSCOW Ionization Ge detector
• New improved Heidelberg-Moscow result shows 4.2s
  effect!
• Cuoricino and NEMO-III will reach this sensitivity

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TodayCUORICINO

• Located in LNGS, Hall A

CUORE RD (Hall C)
CUORE (Hall A)
Cuoricino (Hall A)
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Today CUORICINO
40.7kg total 34 natural abundance
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 g 4 x 11 x 0.79
34.76 kg of TeO2
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TodayCUORICINO
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TodayCUORICINO

• 130Te crysals in LNGS
• Q 2.528MeV
• Operation started early 2003
• Background 0.19 counts/kev/kg/y
• Energy resolution 4eV at 2MeV
• T1/2gt7.5x1023 years
• ltmngt0.3-1.6eV indicates large range of NME
  calculations available!

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Today NEMO-III
AUGUST 2001
Located in Frejus Underground Lab
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bb decay isotopes in NEMO-3 detector
116Cd 405 g Qbb 2805 keV
96Zr 9.4 g Qbb 3350 keV
150Nd 37.0 g Qbb 3367 keV
48Ca 7.0 g Qbb 4272 keV
130Te 454 g Qbb 2529 keV
External bkg measurement
100Mo 6.914 kg Qbb 3034 keV
82Se 0.932 kg Qbb 2995 keV
natTe 491 g
Cu 621 g
(All the enriched isotopes produced in Russia)
Dominique Lalanne for the NEMO-3 Collaboration
ICHEP 2004 Beijing August 16-21,
2004
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bb events selection in NEMO-3
Typical bb2n event observed from 100Mo
Run Number 2040 Event Number 9732 Date
2003-03-20
Vertex emission
Vertex emission
Deposited energy E1E2 2088 keV Internal
hypothesis (Dt)mes (Dt)theo 0.22 ns Common
vertex (Dvertex)? 2.1 mm
(Dvertex)// 5.7 mm
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100Mo 2?2? preliminary results
(Data 14 Feb. 2003 22 Mar. 2004)
Sum Energy Spectrum
Angular Distribution
145 245 events 6914 g 241.5 days S/B 45.8
145 245 events 6914 g 241.5 days S/B 45.8
NEMO-3
NEMO-3
100Mo
100Mo
2?2? Monte Carlo
Background subtracted
2?2? Monte Carlo
Background subtracted
Cos(?)
E1 E2 (keV)
T1/2 7.72 0.02 (stat) 0.54 (syst) ? 1018 y
4.57 kg.y
Dominique Lalanne for the NEMO-3 Collaboration
ICHEP 2004 Beijing August 16-21,
2004
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100Mo 2?2? Single Energy Distribution
Single electron spectrum different between SSD
and HSD
Simkovic, J. Phys. G, 27, 2233, 2001
Esingle (keV)
NEMO-3
4.57 kg.y E1 E2 gt 2 MeV
4.57 kg.y E1 E2 gt 2 MeV
NEMO-3
2?2? SSD Monte Carlo
2?2? HSD Monte Carlo
SSD Single State
HSD higher levels
Background subtracted
Background subtracted
?2/ndf 139. / 36
?2/ndf 40.7 / 36
Esingle (keV)
Esingle (keV)
HSD T1/2 8.61 0.02 (stat) 0.60 (syst) ?
1018 y SSD T1/2 7.72 0.02 (stat) 0.54
(syst) ? 1018 y
100Mo 2?2? single energy distribution in favour
of Single State Dominant (SSD) decay
Dominique Lalanne for the NEMO-3 Collaboration
ICHEP 2004 Beijing August 16-21,
2004
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TodayNEMO-III

• Present 90CL limits from NEMO-III(216.4 days)
• 82SeT1/2(bb0n) gt 1.9 1023 y, ?mn? lt 1.3 3.6 eV
• Simkovic et al., Phys. Rev. C60 (1999)
• Stoica, Klapdor, Nucl. Phys. A694 (2001)
• Caurier et al., Phys. Rev. Lett. 77 1954 (1996)
• 100Mo T1/2(bb0n) gt 3.5 1023 y, ?mn? lt 0.7 1.2
  eV
• Simkovic et al., Phys. Rev. C60 (1999)
• Stoica, Klapdor, Nucl. Phys. A694 (2001)
• Expected Reach in 5 years after RadonPurification
• 100Mo T1/2(bb0n) gt 4.0 1024 y, ?mn? lt 0.2 0.35
  eV
• 82SeT1/2(bb0n) gt 8.0 1023 y,,?mn? lt 0.65 1.8 eV

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Today Heidelberg-Moscow

• Enriched Germanium ionisation detector

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Today Heidelberg-Moscow

• New analysis provides evidence of a peak at the
  expected value
• Total 71.7kgy of data
• Significance is 4.2 s
• mn 0.24-0.58eV
• Corresponds to quasi-degenerate neutrino masses

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Present Cuoricino/NEMO-III region
Possible evidence (best value 0.39 eV)
quasi degeneracy
m1? m2 ? m3
Inverse hierarchy
?m212 ?m2atm
Direct hierarchy
?m212 ?m2sol
Cosmological disfavoured Region (WMAP)
Feruglio F. , Strumia A. , Vissani F.
hep-ph/0201291
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Future Plans

• Only a few approaches
• Bolometers Isotope is the detector
• Tracking Isotope inside the detector
• Ionisation Isotope is the detector
• Simple formula relates experimental parameters to
  half life reach background or no background
• a-isotopic abundance,b-background/Kev/kg/y,e-effic
  iency,dE-energy resolution,t-time,W-molecular
  weight,m-mass

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Future Plans

• There are presently 16 projects in various stages
  of planning/approval in Italy,Japan,US,France and
  perhaps other places, target 0.02-0.05eV in mass
  

• Ionisation
• Cobra, CdTe
• GEM
• GENIUS
• Majorana
• MPI

• Scintillator
• CAMEO Cd
• GANDLES Ca
• CARVEL Cd
• GSO Gd
• Xe Xe.

• Tracking, TPC, Drift
• DCBA Nd
• MOON Mo
• Super-NEMO Mo,Se,Nd
• EXO Xe

• Highlight reach of a few
• CUORE, 720kg TeO2, bolometers
• EXO, 1Tonne Xenon, TPC amd Ba identification
• MAJORANA, 500kg Ge, ionization
• Super-NEMO several isotopes, tracking

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Future Plans CUORE

• First fully-funded next generation experiment
• Based on CUORICINO technology, 130TeO2
• Located at LNGS
• Target background 0.001c/kev/kg
• 720kg of TeO2

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Future Plans EXO

• High Pressure Xe TPC with laser tagging of Ba
  daughter for background-free measurement
• 2 Tonne of 136Xe at 10Atm or Liq Xe with
  cold-finger tagging
• Energy resolution 2 at 2.5MeV
• 200kg prototype of Liq Xe funded by DoE (no
  tagging) will be built at WIPP, New Mexico.
• 200kg isotope already in hand

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Future Plans Majorana/MPI

• 500kg enriched segmented conventional Ge detector
• Feasability has been demonstrated, waiting for
  approval
• Will use pulse-shape information to reduce
  background
• Based on theory that dominant background is 68Ge
  from cosmogenics

• MPI-Ge experiment also proposed
• Uses Ge mono-crystal in Liquid N or Ar for
  passive/active shielding
• Based on theory that dominant background is from
  Cu etc external to Ge

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Future Plans Super-NEMO

• Based on NEMO-III technology,SM only background
• study Se,Nd,Mo, low SM background
• Design study will start 2005

• Feasible if
• BG only from 2n bb
• (NEMO3)
• b) DE/E 10 at 1 MeV
• (8 has already been demonstrated in recent RD)

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Future Plans

• Certain factors dominate reach
• Some factors are instrinsic to a particular
  isotope (M), others to the experimental approach
• T01/2 given by experimental parametersbackground,
  resolution,efficiency
• The larger M, the lower the reach in mn

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Future Plans Summary
weighted world average NMEs a la Frank Avigone,
Neutrino 2004
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Conclusions

• Very exciting time for neutrino physics in
  general and 0nbb in particular
• A positive signal is now a serious possibility in
  light of oscillation results
• Costs of experiemnts all in the 50M range this
  is small potatoes for the potential scientific
  gain
• In light of large NME uncertainties, several
  isotopes should be measured to avoid
  disappointment