Double beta decay, neutrino and Majorana theory

Transcription

1 Double beta decay, neutrino and Majorana theory 1.The birth of double beta decay 2. From low energy nuclear physic to neutrino mass and properties 3. Experimental approaches and difficulties 4. Present experimental status 5. The nightmare of nuclear matrix elements 6. The future 7. News on Nuclear Matrix Elements 8. Majorana theory in solid states 10.Conclusions 1

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3 Double beta decays 1935 M.Goeppert-Mayer, P.R. 48 (1935) 512 T>10 20 Majorana, Nuovo Cimento 14 (1937) 171 Symmetric Theory of Electron and Positron G. Racah, Nuovo Cimento 14 (1937) 322 W.H. Furry Lepton number nonconservation 1967: 130 Te, Geochemical Ogata and Takaoka, Kirsten et 1987: 82 Se, Direct counting Moe et al : Source=detector 48 Ca, 76 Ge 3

4 1. (A,Z) => (A,Z+2) + 2 e n e Two neutrino double beta decay Allowed by the standard model Found in eleven nuclei to ground state and in two to excited state 2. (A,Z) => (A,Z+2) + 2 e - + c ( 2,3 c) Emission of a massless Goldston boson named Majoron (Gelmini and Roncadelli) 3. (A,Z) => (A,Z+2) + 2 e - Neutrinoless double beta decay. The two electrons share the total transition energy E 1 + E 2 => DE => a peak should appear in the sum spectrum of the two electrons Other possible DL=2 decays - Double positron decay => b + b + - Positron decay + Electron Capture => EC- b + - Double electron capture => EC-EC 4

5 Two neutrino and neutrinoless double beta decay Measurement of the CP phase in the 0n bb-decay 5

6 Cloud chambers Emulsions? Experimental challenges Many types of detectors Bubble chambers (yes for Dark Matter) Scintillators Double state liquids Time projectrion chambers Imagining devices Single atom counters 136 Xe => 136 Ba Bolometers Hybrid devices 6

7 How to search for bb decay Geochemical experiments 82 Se = > 82 Kr, 96 Zr = > 96 Mo, 128 Te = > 128 Xe, 130 Te = > 130 Te Radiochemical experiments 238 U = > 238 Pu (non confirmed) Direct experiments Source = detector Source detectors e - e - 7

8 Thermal detectors DT Q C V Thermal sensor C V 1944 v v m ( T ) 3 J/K absorber crystal Incident particle Energy resolution <1 ev ~ 6 kev ~10 ev 2 MeV 8

9 A first bb experiment 9

10 RARE events One of the main problem => background Cosmic rays => underground physics 10

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12 The Jin Ping Laboratory (700 m.w.e) INO 12

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14 Radioactivity 14

15 CUORICINO 15

16 The second mystery of Ettore Majorana In 1937, Majorana theoretically showed that the conclusions of the theory of β decay remain unchanged under the assumption of the existence of only onetype of the neutrino having no antiparticle (i.e., ν ν). 16

17 Dirac or Majorana neutrino? n: n: LEFT RIGHT <= => Majorana =>

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19 Neutrino oscillations Sterile neutrinos LSND,Miniboon,Gallex,reactors) 19

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22 Bracking news => 0nbb in 76 Ge <m n > ~ 0.34eV 22

23 Present results on neutrinoess DBD 23

24 BUT => GERDA 24

25 Future experiments on DBD 25

26 GERDA Majorana Supernemo Ettore Fiorini Brussel May

27 Brussel May

28 Ettore Fiorini Brussel May

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31 NEXT 31

32 CUORICINO CUORE0 CUORE 32

33 New CUORE0 =>T on 1/2 > 2.7 x % c.l. CUORE+CUORICINO =>T on 1/2 > 4 x % c.l. 33

34 The future => Hybrid techniques 34

35 Now a competitor AMORE Advanced Mo based Rare process Experiment 35

36 The past Brussel May

37 Robertson Brussel May

38 Bracking news unpleasant F.Iachello => S.Dell Oro and F.Vissani A.Faessler et al. J.Phys. G35 (2008) Quenching g A from 2n bb decay and one n b decay 38

39 The first strike by Brutus 39

40 The final strike by Brutus - Impressive progress by cosmology on neutrino mass. - Recent data by Planck - A detailed analysis of cosmological results possibly favoring the direct hierarchy (Palanque Delabrouille) Sm n < 0.17 ev or Amicus Plato, sed magis amica veritas Platus is a friend.but truth even more 40

41 Majorana => can a ½ spin particle be its own antiparticle? So far application to neutrino Conventional Cooper excitons are bosons and not Majorana particles In superconductors Cooper pairs, being boson like particle, form condensates respecting Pauli principle How to produce excitons which are Majorana particles Cooper pairs can be added to holes producing spin ½ exitons. Superconductors can contain magnetic wires acting as quasiparticles Form magnetic flux tubes ( vortices) 41

42 Bi 2 Te 3 on a superconductor NbSe 2 In normal superconductors Scanning with a tunneling microscope and sepctrocope one can find explicity a single Majorana mode. Common opinion: Majorana theory can be as impoortnt in solid state like it is In elementary particle physics Brussel May

43 Conclusions Massive detectors (now expensive) of unique sophistication Reduction of background which could hide neutrinoless bb events has reached an unprecedented sensistivity The quenching of g A reduces the matrix would ref+duce sensitivity oon neutrino mass limit by a factor 4 to 5. If so no present hope to reach the inverse hierarchy region The validity to extend to neutrinoless DBD the g A obtained from two neutrino and single beta decay should be justified The sophistication reached and to be reached in serches for DBD could have appplications in other fields of science Aplication to solid state physics of the Maiorana theory could bring to results as important as in solid state physics 43

44 There are more things in Earth and Heaven, Polonius, that can be dreamt of by your Philosophy Hamlet 44