Invisibles Workshop, July 17, 2013 Status of Neutrinoless Double Beta Decay Experiments Patrick Decowski decowski@nikhef.nl Wednesday, July 17, 13 1
Double beta decay Isotopes (A,Z+1) (A,Z) ββ even-even (A,Z+2) A second-order process only detectable if first-order beta decay is energetically forbidden Patrick Decowski/Nikhef Wednesday, July 17, 13 2
Neutrinoless Double Beta Decay e - e - ν i ν i M ν 6 = 0 U ei U ei | ∆ L | W - W - = 2 Nuclear Process > > (A, Z) (A, Z+2) • Extremely rare process [W.H. Furry (1939): T 1/2 > 10 16 yr] • Requires massive Majorana neutrino • Lepton Number Violation • Model dependent - Standard interpretation: light Majorana ν + SM interactions Patrick Decowski/Nikhef Wednesday, July 17, 13 3
Neutrinoless Double Beta Decay e - e - ν i ν i M ν 6 = 0 U ei U ei | ∆ L | W - W - = 2 Nuclear Process > > (A, Z) (A, Z+2) • Extremely rare process [W.H. Furry (1939): T 1/2 > 10 16 yr] • Requires massive Majorana neutrino • Lepton Number Violation • Model dependent - Standard interpretation: light Majorana ν + SM interactions Patrick Decowski/Nikhef Wednesday, July 17, 13 3
Candidate 0 ν 2 β Nuclei [Candidates with Q>2 MeV] Candidate Q[MeV] %Abund Candidates are even-even nuclei 48 Ca → 48 Ti 4.271 0.187 76 Ge → 76 Se 2.040 7.8 82 Se → 82 Kr 2.995 9.2 (A,Z+1) 96 Zr → 96 Mo 3.350 2.8 100 Mo → 100 Ru 3.034 9.6 (A,Z) 110 Pd → 110 Cd 2.013 11.8 ββ even-even (A,Z+2) 116 Cd → 116 Sn 2.802 7.5 124 Sn → 124 Te 2.228 5.64 130 Te → 130 Xe 2.530 34.5 136 Xe → 136 Ba 2.479 8.9 150 Nd → 150 Sm 3.367 5.6 Natural abundance of 0 ν 2 β candidates is low → enrichment necessary Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 4
Detecting 0 ν 2 β Decay Without energy resolution 2 ν 2 β 0 ν 2 β � E e /Q • General approach: detect the two final-state electrons • Signature: Two simultaneous electrons with summed energy Q ββ , the Q-value for the ββ decay in the isotope of study Wednesday, July 17, 13 5
Detecting 0 ν 2 β Decay With energy resolution 2 ν 2 β 0 ν 2 β � E e /Q • General approach: detect the two final-state electrons • Signature: Two simultaneous electrons with summed energy Q ββ , the Q-value for the ββ decay in the isotope of study Wednesday, July 17, 13 5
2 ν 2 β has been measured 1 / 2 ) − 1 = G 2 ν ( Q, Z ) | M 2 ν | 2 ( T 2 ν Phase Space Nuclear T 1/22 ν [yr] factor Matrix Element Isotope 48 Ca 4.2±1.0 x 10 19 • Conserves lepton number 76 Ge 1.5±0.1 x 10 21 82 Se 0.92±0.07 x 10 20 • Does not discriminate 96 Zr 2.0±0.3 x 10 19 between Dirac and 100 Mo 7.1±0.4 x 10 18 Majorana neutrinos 116 Cd 3.0±0.2 x 10 19 • Not sensitive to neutrino 128 Te 2.5±0.3 x 10 24 mass scale 130 Te 0.9±0.1 x 10 21 136 Xe 2.172±0.062 x 10 21 • Nevertheless: slow process! 150 Nd 7.8±0.8 x 10 18 238 U 2.0±0.6 x 10 21 Patrick Decowski/Nikhef Wednesday, July 17, 13 6
What mass does 0 ν 2 β measure? 1 / 2 ) − 1 = G 0 ν ( Q, Z ) | M 0 ν | 2 � m ββ ⇥ 2 ( T 0 ν Phase Space factor: Nuclear Matrix Element: Calculable Hard to calculate Effective Majorana mass: � � 3 � � X U 2 h m ββ i = ei m i � � [coherent sum] � � � � i =1 Where U ei elements from the Lepton Mixing Matrix Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 7
What mass does 0 ν 2 β measure? 1 / 2 ) − 1 = G 0 ν ( Q, Z ) | M 0 ν | 2 � m ββ ⇥ 2 ( T 0 ν Phase Space factor: Nuclear Matrix Element: Interesting physics Calculable Hard to calculate Effective Majorana mass: � � 3 � � X U 2 h m ββ i = ei m i � � [coherent sum] � � � � i =1 Where U ei elements from the Lepton Mixing Matrix Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 7
Nuclear Matrix Elements 10 NSM QRPA (Tue) A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 QRPA (Jy) IBM 8 IBM GCM PHFB Pseudo-SU(3) 6 M 0 ν M’ 0 ν 4 2 0 48 Ca 76 Ge 82 Se 96 Zr 100 Mo 110 Pd 116 Cd 124 Sn 130 Te 136 Xe 150 Nd Isotope Past 7-8 years: much better agreements between various models (e.g. NSM and QRPA) Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 8
Nuclear Matrix Elements 10 NSM QRPA (Tue) A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 QRPA (Jy) IBM 8 IBM GCM PHFB Pseudo-SU(3) 6 M 0 ν M’ 0 ν 4 2 0 48 Ca 76 Ge 82 Se 96 Zr 100 Mo 110 Pd 116 Cd 124 Sn 130 Te 136 Xe 150 Nd Isotope Past 7-8 years: much better agreements between various models (e.g. NSM and QRPA) Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 8
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) Normal Inverted θ 12 = 33.58 0 δ θ 13 = 0 0 δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) θ 13 non-zero Normal Inverted θ 12 = 33.58 0 θ 12 = 33.58 δ δ θ 13 = 0 0 θ 13 = 8.33 δ δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) Planck, KATRIN Normal Inverted θ 12 = 33.58 0 θ 12 = 33.58 δ δ θ 13 = 0 0 θ 13 = 8.33 δ δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) KKDC claim in 76 Ge Planck, KATRIN Normal Inverted θ 12 = 33.58 0 θ 12 = 33.58 δ δ θ 13 = 0 0 θ 13 = 8.33 δ δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) KKDC claim in 76 Ge Next-generation of 0 ν 2 β expt: few 100kg Planck, KATRIN Normal Inverted θ 12 = 33.58 0 θ 12 = 33.58 δ δ θ 13 = 0 0 θ 13 = 8.33 δ δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Effective Majorana Mass S. Elliot, Mod. Phys. Lett. A 27, 1230009 (2012) KKDC claim in 76 Ge Next-generation of 0 ν 2 β expt: few 100kg Future 0 ν 2 β expt: ton-scale Planck, KATRIN Normal Inverted θ 12 = 33.58 0 θ 12 = 33.58 δ δ θ 13 = 0 0 θ 13 = 8.33 δ δ Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 9
Osc Params in ⟨ m ββ ⟩ determination 1 1 ∆ m 2 A c 2 13 cos 2 θ 12 M. Lindner, A. Merle, W. Rodejohann, Phys.Rev. D73 (2006) 053005 m 0 ∆ m 2 A c 2 13 0.1 0.1 m 312 0 eV eV 0.01 0.01 1 − t 2 12 − 2 s 2 13 m 0 m ee m ee 1+ t 2 12 m 312 0 m 1 c 2 12 c 2 0.001 0.001 13 ∆ m 2 + m 2 1 s 2 12 c 2 − 13 ∆ m 2 s 2 12 c 2 13 ∆ m 2 1 s 2 A + m 2 − 13 ∆ m 2 A s 2 ± 13 0.0001 0.0001 0.0001 0.0001 0.001 0.001 0.01 0.01 0.1 0.1 1 1 m eV m eV [And, if sterile ν s exist, this diagram is no longer correct!] Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 10
Osc Params in ⟨ m ββ ⟩ determination 1 1 ∆ m 2 A c 2 13 cos 2 θ 12 M. Lindner, A. Merle, W. Rodejohann, Phys.Rev. D73 (2006) 053005 m 0 ∆ m 2 A c 2 13 0.1 0.1 m 312 0 eV eV 0.01 0.01 1 − t 2 12 − 2 s 2 13 m 0 m ee m ee 1+ t 2 12 m 312 0 m 1 c 2 12 c 2 0.001 0.001 13 ∆ m 2 + m 2 1 s 2 12 c 2 − 13 ∆ m 2 s 2 12 c 2 13 ∆ m 2 1 s 2 A + m 2 − 13 ∆ m 2 A s 2 ± 13 0.0001 0.0001 0.0001 0.0001 0.001 0.001 0.01 0.01 0.1 0.1 1 1 m eV m eV [And, if sterile ν s exist, this diagram is no longer correct!] Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 10
θ 12 Matters! m 3 = 0.001 eV 0.1 Adapted from A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 σ IH, 3 IH, BF ⟨ m ββ ⟩ [eV] meff 0.01 0.28 0.3 0.32 0.34 0.36 0.38 s12 +3 σ sin 2 θ 12 Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 11
θ 12 Matters! m 3 = 0.001 eV 0.1 Adapted from A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 σ IH, 3 IH, BF ⟨ m ββ ⟩ [eV] meff 0.01 0.28 0.3 0.32 0.34 0.36 0.38 s12 -3 σ +3 σ sin 2 θ 12 Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 11
θ 12 Matters! m 3 = 0.001 eV 0.1 Adapted from A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 σ IH, 3 IH, BF ⟨ m ββ ⟩ [eV] meff Factor 2! 0.01 0.28 0.3 0.32 0.34 0.36 0.38 s12 -3 σ +3 σ sin 2 θ 12 Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 11
θ 12 Matters! m 3 = 0.001 eV 0.1 Adapted from A. Dueck, W. Rodejohann and K.Zuber, Phys.Rev. D83 (2011) 113010 σ IH, 3 IH, BF ⟨ m ββ ⟩ [eV] meff Factor 2! 0.01 0.28 0.3 0.32 0.34 0.36 0.38 s12 -3 σ +3 σ sin 2 θ 12 Better measurement of θ 12 required: similar impact as NME uncertainty for a given isotope Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 11
Experimental sensitivity 1 / 2 ∝ ✏ a No experimental T 0 ν AMt background: Detector Isotopic Mass Fraction Detector Running Efficiency Time � 1 / 2 ∝ � a Mt With experimental T 0 ν background: A b ∆ E Detector Atomic Resolution Mass Background Rate Patrick Decowski/University of Amsterdam Wednesday, July 17, 13 12
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