AVERAGE RECOMENDED HALFLIFE VALUES FOR TWO NEUTRINO DOUBLE BETA DECAY: UPGRADE05

1
AVERAGE (RECOMENDED) HALF-LIFE VALUES FOR TWO
NEUTRINO DOUBLE BETA DECAY UPGRADE05

• A.S. Barabash
• Institute of Theoretical and Experimental
  Physics,
• Moscow, Russia

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2?(2?)-decay positive results

• geochemical experiments
• 130Te ( 30 ), 128Te (4), 82Se (20 ),
  96Zr (2), 100Mo (1), 130Ba (1)
• radiochemical experiment
• 238U (1)
• direct (counting) experiments
• 48Ca (3), 76Ge (5), 82Se (3), 96Zr (2),
  100Mo (6),
• 116Cd (4), 130Te (1), 150Nd (3)
• 100Mo 100Ru (0) (3) and 150Nd 150Sm
  (0) (1)

3
In some direct experiments statistical error is
very small 100Mo (NEMO-3) ?
220000 events ( 0.2) 76Ge (G-M)
? 100000 events ( 0.3) But
systematic error usually is gt 10 Good
example 76Ge (G-M) 1.42 ?
0.03(stat) 0.13(syst)?1021 y
(1993)
? 1.77 ? 0.01(stat)
0.13-0.11(syst)?1021 y (1997)
? 1.55 ?
0.01(stat) 0.19-0.15(syst)?1021 y (2001)
?
1.74 ? 0.01(stat) 0.18-0.16(syst)?1021 y
(2003)
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WHY DO WE NEED THE PRECISE VALUES OF HILF-LIVES?

• Nuclear spectroscopy.
• To measure NME(2?) ? to improve quality of
  NME(2?) calculations.
• To check SSD hypothesis (100Mo, 116Cd).

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WHY DO WE NEED THE PRECISE VALUES OF HILF-LIVES?

• 4. To improve quality of NME(0?).
• Precise value of T1/2(2?)
• ?
• Precise value of gpp
• ?
• Precise value of MNE(0?)
• ?
• Precise value of ltm?gt
• (V.A. Rodin, A. Faessler, F. Simkovic and P.
  Vogel, nucl-th/0503063. )

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WAITED AVERAGE PROCEDURE (recommended by
Particle Data Group)

• x ? ?x ? wixi/?wi ? (?wi)-1/2 ,
  (1)
• wi 1/(?xi)2.
• Here xi and ?xi are the value and error reported
  by the i-th experiment, and the sums run over N
  experiments.
• We then calculate ?2 ?wi(x - xi)2 and compare
  it with N-1.
• If ?2/(N-1) lt 1 - no problem
• If ?2/(N-1) gtgt 1 - we may choose not to use
  the average at all
• If ?2/(N-1) gt 1 , but not greatly so, we
  increase our error by a scale
• factor
• S
  ?2/(N-1)1/2
  (2)
• For average we add the statistical and systematic
  errors quadratically and use this combined error
  for ?x.

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1. 48Ca.

• 4.32.4-1.1(stat) ? 1.4(syst)?1019 y
  Moe et al., 1996
• (S/B ? 1/5 N ? 100 events)
• 4.23.3-1.3 ?1019 y
  TGV, 2000
• (S/B ? 5/0 N 5)
• (4 ? 1)1019 y (NEMO-3, preliminary
  result, 2005)
• Average value 4.22.1-1.0 ?1019 y
• (2001 the same value)

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2. 76Ge

• 1. (0.9 ? 0.1)?1021 y
  ITEP-ErPI, 1990
  
• (S/B ? 1/8, N ? 4000)
• 2. 1.10.6-0.3 ?1021 y
  F. Avignone et al.,
  1991
• (S/B ? 1/6, N 758)
• 3. 1.20.2-0.1 ?1021 y (0.930.2 -0.1 ?1021 y)
  F. Avignone et al., 1994
• (S/B ? 4, N 138)
• 4. (1.45 ? 0.15)?1021 y
  IGEX,
  1999
• (S/B ? 1.5, N ? 3000)
• 5. 1.74 ? 0.01(stat) 0.18-0.16(syst)?1021 y
  H-M, 2003
• (S/B ? 1.5, N ? 64000)
• Average value (1.5 ? 0.1) ?1021

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3. 82Se

• 1.080.26-0.06 ?1020 y
  M. Moe, 1992
• (S/B ? 7.8, N 89.6)
• 0.83 ? 0.10(stat) ? 0.07(syst)?1020 y
  NEMO-2, 1998
• (S/B ? 2, N 149)
• 0.96 ? 0.03(stat) ? 0.1(syst)?1020 y
  NEMO-3, 2005
• (S/B ? 4, N 2750)
• (1.3 ? 0.05)1020 y (geochemistry)
• Average value (0.92 ? 0.07) ?1020 y
• 2001 (0.9 ? 0.1) ?1020 y

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2?2? preliminary results for other nuclei
82Se T1/2 0.96 0.03 (stat) 0.1 (syst)
? 1020 y 116Cd T1/2 2.8 0.1 (stat) 0.3
(syst) ? 1019 y (SSD) 150Nd T1/2 9.7 0.7
(stat) 1.0 (syst) ? 1018 y 96Zr T1/2
2.0 0.3 (stat) 0.2 (syst) ? 1019 y
Background subtracted
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4. 96Zr

• 2.10.8-0.4(stat) ? 0.2(syst)?1019 y
  NEMO-2, 1999
• (S/B ? 2, N 26.7)
• 2.0 ? 0.3(stat) ? 0.2(syst)?1019 y
  NEMO-3, 2005
• (S/B ? 0.9, N 72)
• (3.9 ? 0.9)?1019 y (geochemistry) A.
  Kawashima et al., 1993
• (0.94 ? 0.32)?1019 y (geochemistry)
  M. Wieser, 2001
• Average value (2.0 ? 0.3) ?1019 y
• 2001 (2.10.8-0.4) ?1019 y

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5. 100Mo

• 1. 11.63.02.0 ?1018 (S/B ? 1/7,
  N ? 500)
  ELEGANT-V, 1991
• 2. 9.5 ? 0.4(stat) ? 0.9 (syst)?1018 y
  (S/B ? 3, N 1433) NEMO-2,
  1995
• 8.1 ? 0.35(stat) ? 0.8 (syst)?1018 y
  HSD
• 7.3 ? 0.35(stat) ? 0.8 (syst)?1018 y
  SSD
• 3. 7.62.2 1.4 ?1018 y (S/B ? 1/2, N
  175)
  Si-detectors, 1997
• 4. 6.750.370.42(stat) ? 0.68(syst) ?1018 y
  (S/B ? 10, N 377) M. Moe et al., 1997
• 5. 7.5 ? 1.1(stat) ? 1.5(syst) ?1018 y
  (S/B ? 1/9, N ? 800) Liq. Ar,
  2001
• 6. 7.11 ? 0.02(stat) ? 0.54 (syst)?1018 y
  (S/B ? 40, N 219000) SSD NEMO-3, 2005
• (2.1 ? 0.3)?1018 y (geochemistry 1-3
  billion years minerals)

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100Mo 2?2? preliminary results
(Data Feb. 2003 Dec. 2004)
Angular Distribution
Sum Energy Spectrum
219 000 events 6914 g 389 days S/B 40
219 000 events 6914 g 389 days S/B 40
NEMO-3
NEMO-3
100Mo
100Mo
E1 E2 (keV)
Cos(?)
T1/2 7.11 0.02 (stat) 0.54 (syst) ? 1018 y
7.37 kg.y
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Single electron spectrum different between SSD
and HSD
F. Simkovic et al., J. Phys. G 27 (2001) 2233
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
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6. 100Mo- 100Ru (0 1130.29 keV).

• 6.11.8-1.1 ?1020 y (S/B ? 1/6, N
  66) SOUDAN, 1995
• 9.32.8 1.7 (stat) ? 1.4(syst) ?1020 y (S/B
  ? 1/3, N 76)
• 
  MODANE,
  1999
• 5.91.71.1(stat) ? 0.6(syst) ?1020 y (S/B ?
  8/1, N 19.5)
• 
  ITEP-TUNL, 2001
• Average value (6.8 ? 1.2) ?1020 y
• 2001 the same value

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7. 116Cd

• 1. 2.60.9-0.5 ?1019 y (S/B ? 1/4, N ?
  180) ELEGANT-V, 1995
• 2. 2.9 ? 0.06(stat) 0.4-0.3(syst)?1019 y
  (S/B ? 3/1, N ? 9850) KIEV, 2003
• 3. 3.75 ? 0.35(stat) ? 0.21(syst)?1019 y
  (S/B ? 4/1, N 174.6)
• 
  
  NEMO-2, 1996
• 3.2 ? 0.3(stat) ? 0.2(syst)?1019 y
• 4. 2.8 ? 0.1(stat) ? 0.3(syst)?1019 y (S/B
  ? 7.5 , N ? 1370) SSD
• 3.1 ? 0.1(stat) ? 0.3(syst)?1019 y
  (S/B ? 7.5 , N ? 1370) HSD
• 
  
  NEMO-3, 2005
• Average value (3.1 ? 0.2) ?1019 y
  HSD
• (2.9 ?
  0.2) ?1019 y SSD
• 2001 3.30.4-0.31019 y

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8. 150Nd

• 1.880.69-0.39(stat) ? 0.19(syst)?1019 y (S/B
  ? 1.8, N 23)
• 
  ITEP-TPC,
  1995
• 6.750.37-0.42(stat) ? 0.68(syst)?1018 y (S/B
  ? 6, N 414)
• 
  M.Moe-TPC,
  1997
• 9.7 ? 0.7(stat) ? 1.0(syst)?1018 y (S/B ?
  2.8, N 449)
• 
  NEMO-3,
  2005
• Average value (7.8 ? 0.7)?1018 y
• 2001 (7.0 ? 1.7) ?1020 y

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9. 150Nd- 150Sm (0 740.4 keV).

• 1.40.4 0.2 (stat) ? 0.3(syst) ?1020 y
  (S/B ? 1/5, N 186)
• 
  MODANE, 2004
• Recommended value
• 1.40.5-04?1020 y

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10. 238U

• (2.0 ? 0.6)?1021 y (radiochemistry)
• This is the only one measurement!

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11. 128Te and 130Te

• T1/2 (130)/T1/2 (128) (3.52 ? 0.11)?10-4 (no
  gas retention age
• 
  problem!)
• There are two groups of results
• I.
• 130Te ? (2.55 ? 0.2)?1021 y
  (T.Kirsten83 internally dated ores)
• (2.7 ? 0.1)?1021 y
  (T.Bernatowicz93)
• 128Te ? gt 5?1024 y
  (T.Kirsten86 internally dated ores)
• (7.7 ? 0.4)?1024 y
  (T.Bernatowicz93)
• II.
• 130Te ? (7.9 ? 1.0)?1020 y
  (N.Takaoka96 young ores)
• 8?1020 y
  (O.Manuel91)
• 128Te ? (1.8 ? 0.7)?1024 y
  (W.Lin88)
• 2?1024 y
  (O.Manuel91)

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• There are a few measurements with minerals which
  contain Te and Se
• T1/2(130)/T1/2(82) 7.3 ? 0.9
  12.5 ? 0.9 9.7 ? 2
• Average 9.9 ?
  0.6
• Using the present 82Se half-life value T1/2
  (0.92 ? 0.07) ?1020 y one can estimate the
  present 130Te half-life value ?
• T1/2 (130Te ) (0.9 ?
  0.1) ?1021 y
• 
  ?
• using T1/2 (130)/T1/2 (128)
  (3.52 ? 0.11)?10-4
• 
  ?
• T1/2 (128Te ) (2.5 ? 0.3)
  ?1024 y

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130Te direct experiment

• C. Arnaboldi et al., Phys. Lett. B 557 (2003)
  167.
• T1/2 gt 3.81020 y (conservative approach)
• T1/2 (6.1 ? 1.4(syst) 2.9-3.5)1020 y

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12. 130Ba ECEC(2?)

• Geochemistry
• A. Meshik et al., 2001
• T1/2 (2.2 0.5)1021 y
• A. Barabash and R. Saakyan, 1996
• T1/2 gt 41021 y
• and T1/2 2.13.0-0.8)1021 y

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Recommended values for half-lives

• 128Te(geo) (2.5 ? 0.3)?1024 y
• 130Te(geo) (0.9 ? 0.1)?1021 y
• 150Nd - (7.8? 0.7)?1018 y
• 150Nd 150Sm (01)
• (1.40.5-0.4)1020 y
• 238U(rad) - (2.0 ? 0.6)?1021 y
• ECEC(2?)
• 130Ba(geo) - (2.2 ? 0.5)?1021 y

• 48Ca - (4.2 2.1-1.0)?1019 y
• 76Ge (1.5 ? 0.1)?1021 y
• 82Se (0.92? 0.07)?1020 y
• 96Zr (2.0 ? 0.3)?1019 y
• 100Mo (7.1 ? 0.4)?1018 y
• 100Mo 100Ru (01)
• (6.8 ? 1.2)?1020 y
• 116Cd (3.1? 0.2)?1019 y

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Future improvements

• 1. NEMO-3 48Ca, 82Se, 96Zr, 100Mo, 116Cd,
• 130Te, 150Nd
• - accuracy can be 3-5 (using
• calibration)
• - ratios will be known with even better
• accuracy ( 1-2)
• - T1/2(130Te) ? T1/2(128Te).
• 2. CUORICINO 130Te
• T1/2(130Te) ? T1/2(128Te)
• 3. TGV-II 48Ca
• 4. EXO-I 136Xe