Setting limits on different Majoron modes of 150Nd

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Setting limits on different Majoron modesof
150Nd

• Nasim Fatemi-Ghomi

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Half-life eff x Number of atoms x ln2 x data
taking time/ (Nexp-Nbgr)
Systematic considered on the half-life

• Signal 2???
  other backgrounds
• Eff 5 5 5
  
• Act x x
  2.7
• Stat x 2.6 x

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Limits For different majoron modes

• Normalization factor used to normalise the 2???
• background

• half-life
  majoron mode
• Esumlt2.0 MeV 9.370.27 - 0.25 X1018
  1
• Esumlt1.5 MeV 9.31 0.37 - 0.32 X1018
  2,3
• Esumgt2.1 MeV 8.84 0.79 - 0.67 X1018
  7

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Results

• Eff N Half-life (year)
• M1 8.25 lt13.99 gt 1.55 x 1021
• M2 7.95 lt36.19 gt 5.79 x 1020
• M3 5.68 lt57.54 gt 2.61 x1020
• M7 3.84 lt266.72 gt 3.80 X1019

The efficiency all are found in the energy
interval Where the limit has been set
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In comparison with Helene method

• Helene Equation (without considering the
  uncertainties)
• M1 2.0-3.19 MeV gt8.06 X 1020 year
• M2 1.5-3.19 MeV gt5.35 X 1020 year
• M3 1.5-3.19 MeV gt3.08 X1020 year
• M7 0.5-2.1 MeV gt8.70 X 1019 year

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Future work

• Have to think about a method to set a stronger
  limit on M7!
• There is no energy region where that the
  distribution of 2??? background does not depend
  on the distribution of this mode!