Particle-, Nuclear- and Atomic-Physics Aspects of Rare Weak Decays of Nuclei

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Particle-, Nuclear- and Atomic-Physics Aspects of Rare Weak Decays of Nuclei Jouni Suhonen Department of Physics University of Jyväskylä NCNP2011 - XII th

1 Particle-, Nuclear- and Atomic-Physics Aspects of Rare Weak Decays of Nuclei Jouni Suhonen Department of Physics University of Jyväskylä NCNP XII th NordicConference onnuclear Physics, Stockholm, Sweden, June, 2011 Contents: Intro: 0νββ Decays Resonant 0νECEC Decays Rare Beta Decays Jouni Suhonen (JYFL, Finland) NCNP / 27

INTRO: Neutrino Properties from Experiments Neutrino Properties from Oscillation Experiments: From solar, atmospheric, accelerator and reactor-neutrino data (SuperKamiokande, SNO, KamLAND, etc.

2 INTRO: Neutrino Properties from Experiments Neutrino Properties from Oscillation Experiments: From solar, atmospheric, accelerator and reactor-neutrino data (SuperKamiokande, SNO, KamLAND, etc.): Squaredmass differences m 2 of neutrinos Matrix elements of the neutrino mixing matrix flavor eigenstates in terms ofmass eigenstates: ν e ν i ν µ ν j ν e ν k ν µ Complementary Experiments: Tritium beta decay(absolute neutrino mass), KATRIN Double beta decay(nature, absolute mass and hierarchy of neutrinos) Jouni Suhonen (JYFL, Finland) NCNP / 27

3 DoubleBeta Decay(Isobars A = 76) Zn A= Zn A=76 Mass excess [MeV] Ga Br Kr Mass excess [MeV] Ga Br Kr Ge As Se Ge As Se Z Z Jouni Suhonen (JYFL, Finland) NCNP / 27

4 Two-Neutrino Double Beta Decay Nucleus half-life (years) experiments 48 Ca laboratory 76 Ge laboratory 82 Se laboratory,geochemical 96 Zr laboratory,geochemical 100 Mo laboratory 116 Cd laboratory 128 Te geochemical 130 Te geochemical 150 Nd laboratory 238 U radio-chemical e 1 - FINAL NUCLEUS p p (Z,N-2) - e 2 2 INTERMEDIATE STATES years = age of the UNIVERSE n n (Z,N-2) INITIAL NUCLEUS Jouni Suhonen (JYFL, Finland) NCNP / 27

5 Two-Neutrino DoubleBetaDecay of 76 Ge Virtual (3 - ) (4 - ) (1 + )? (3 - )? (1 - ) (1 + ) (1 + ) (1 + ) transition The decay goes through1 + virtual states Ge 76 As 76 Se 0 + Jouni Suhonen (JYFL, Finland) NCNP / 27

6 Neutrinoless Double Beta Decay 0νββ Decay isable to: Reveal if the neutrino is a Majorana particle Probe the neutrino effective mass m ν = P j=light λcp j U ej 2 m j Probe the degenerate or inverted mass hierarchies(next-generation experiments!) Probe possibly the CP phases (nuclear matrix elements are critical!) (ν τ ) ν 3 } m 2 atm (ν µ ) ν 2 } m 2 (ν e ) ν 1 Normal hierarchy ν 2 ν 1 } ν 3 Inverted hierarchy m 2 = ev 2 m 2 atm = ev 2 [Global 3ν oscillation analysis (2008)] } m 2 m 2 atm e 1 - MASS MODE: T 1/2 m ν 2 p n FINAL NUCLEUS p (Z,N-2) e 2 - helicities L=2 m =0 INTERMEDIATE STATES helicities n INITIAL NUCLEUS (Z,N-2) Jouni Suhonen (JYFL, Finland) NCNP / 27

7 Neutrinoless DoubleBeta Decayof 76 Ge Virtual (3 - ) (4 - ) (1 + )? (3 - )? (1 - ) (1 + ) (1 + ) (1 + ) transition The decay goes throughall J π virtual states Ge 76 As 76 Se 0 + Jouni Suhonen (JYFL, Finland) NCNP / 27

8 About Experiments UNDERGROUND LABORATORIES protect from COSMIC RAYS and their secondary particles Canfranc (Spain) Kamioka (Japan) Boulby(England) Gran Sasso(Italy) Pyhäsalmi (Finland) Baksan(Ukraine) Modane(France-Italy) Sudbury(Canada) Jouni Suhonen (JYFL, Finland) NCNP / 27

9 Experiments Searching for 0νββ Decays: Major Running Experiments: Heidelberg Moscow( 76 Ge)(ceased,claim of detectionbutresult still controversial) NEMO3( 76 Ge 82 Se 96 Zr 100 Mo 116 Cd...) runningin Modane Cuoricino ( 128,130 Te) running in Gran Sasso Future Experiments: SUPERNEMO ( 82 Se 100 Mo...), GERDA ( 76 Ge), MAJORANA ( 76 Ge), CAMEOII,III ( 116 Cd), CUORE ( 128,130 Te), MOON ( 100 Mo), EXO ( 136 Xe), COBRA ( 70 Zn 106,114,116 Cd 128,130 Te),ZORRO( 96 Zr) Theseare in kg scale andcostabout EURO/$ each! Jouni Suhonen (JYFL, Finland) NCNP / 27

10 Topic I Resonant 0νECEC Decays Jouni Suhonen (JYFL, Finland) NCNP / 27

11 Two-Neutrino Double Electron Capture Final nucleus (Z 2, N + 2) n (Z 2, N) n H H ν e ν e e bound p (Z 2, N) p e bound Initial nucleus (Z, N) Jouni Suhonen (JYFL, Finland) NCNP / 27

12 Neutrinoless Double Electron Capture Radiative 0νECEC Final nucleus (Z 2, N + 2) n (Z 2, N) n H H Resonant 0νECEC Final nucleus (Z 2, N + 2) n (Z 2, N) n H H γ ν e = ν e ν e = ν e e bound p (Z 2, N) p e bound e bound p (Z 2, N) p e bound Initial nucleus (Z, N) Initial nucleus (Z, N) Jouni Suhonen (JYFL, Finland) NCNP / 27

13 Resonant0νECECDecayof 106 Cd X K X K kev Ag R0νECEC Qβ = 202 kev Cd kev kev kev 2 0νβ + EC Q = 2770(7) kev kev 0 + gs Pd 60 0νβ + β +,0νβ + EC Jouni Suhonen (JYFL, Finland) NCNP / 27

14 Half-lifeEstimatefor 106 Cd Decay widthof thetwo-hole state: Γ = 10.24eV mν = 0.05 ev Half-life (yr) mν = 0.3 ev mν = 1.0 ev x (ev) (x/γ) 2 +1/4 T 1/2 = ln2g ECEC [M ECEC ] 2 m ν Γ, x = Q E (degeneracyparameter) 2 Jouni Suhonen (JYFL, Finland) NCNP / 27

15 Resonant0νECECDecayof 112 Sn X K X K In 63 Q β = 658 kev kev 0νECEC Sn 62 Q = (16) kev kev Cd 64 Jouni Suhonen (JYFL, Finland) NCNP / 27

16 Half-LifeEstimatefor 112 Sn Γ =few tensof ev ; M ECEC 0ν = 4.76 (unitless NME) Q value measured in JYFLTRAP (S Rahaman, V.-V. Elomaa, T. Eronen, J. Hakala, A. Jokinen, A. Kankainen, J. Rissanen, J. Suhonen, C. Weber, and J. Äystö, Phys. Rev. Lett. 103 (2009) ) Hence: Q E = 4.5 kev for KK capture = 18.2 kev for KL capture = 40.9 kev for LL capture T 1/2 > ( m ν [ev]) 2 years Conclusion: Decay rate much suppressed by the rather large degeneracy parameter Q E Jouni Suhonen (JYFL, Finland) NCNP / 27

17 Resonant0νECECDecayof 74 Se As 41 Q β = kev X L X L kev 0νECEC Se kev Q = (49) kev Ge 42 Jouni Suhonen (JYFL, Finland) NCNP / 27

18 Half-LifeEstimatefor 74 Se Γ = fewtensofev ; M ECEC 0ν < (unitless NME) Q value measured in JYFLTRAP(V.S. Kolhinen, V.-V. Elomaa, T. Eronen, J. Hakala, A.Jokinen,M.Kortelainen, J.Suhonen and J.Äystö,Phys. Lett. B684 (2010) 17) Hence: Q E = 2.23keV forllcapture (mostfavorable) T 1/ ( m ν [ev]) 2 years Conclusion: Decay rate much suppressed both by the rather large degeneracyparameterq E andtheverysmall NME forthe2 + f final state. Thesame occurs forthe 2νβ β decay (seem.aunola and J.Suhonen, Nucl. Phys. A602(1996)133) Jouni Suhonen (JYFL, Finland) NCNP / 27

19 Resonant0νECECDecayof 136 Ce X K X K kev La 79 0νECEC Q β = 460 kev Ce kev Q = (27) kev Ba 80 Jouni Suhonen (JYFL, Finland) NCNP / 27

20 Half-LifeEstimatefor 136 Ce Γ = 13.81eV ; M ECEC = (unitlessnme) Q value measured in JYFLTRAP(V.S. Kolhinen, T. Eronen, D. Gorelov, J. Hakala, A. Jokinen, A. Kankainen, J. Rissanen, J. Suhonen and J. Äystö, Phys. Lett. B 697 (2011) 116) Hence: Q E = kev for KK capture = kev for KL capture = kev for LL capture T 1/2 > ( m ν [ev]) 2 years Conclusion: Decay rate much suppressed by the rather large degeneracyparameterq E andtherathersmall NME Jouni Suhonen (JYFL, Finland) NCNP / 27

21 Topic II 115 In: Beta decay withanultra-low Q value Jouni Suhonen (JYFL, Finland) NCNP / 27

22 115 In: Beta DecaywithanUltra-Low Q Value First discovered by Cattadori et al. (Nucl. Phys. A 748 (2005) 333) 1/2 4.5 h / / ps In T 1/2 = a 1/ Sn stable Suggested as a possible independent experiment to look for the neutrino mass Jouni Suhonen (JYFL, Finland) NCNP / 27

23 Experimental Results LNGS(C.M. Cattadori et al.) first observation b = 1.18(31) 10 6 HADES JYFLTRAP T partial 1/2 = 3.73(98) a b = 1.07(17) 10 6 T partial 1/2 = 4.1(6) a Q β = 0.35(17) kev J.S.E.Wieslander,J.Suhonen, T.Eronen,M.Hult, V.-V.Elomaa, A.Jokinen,G. Marissens, M. Misiaszek, M.T. Mustonen, S. Rahaman, C. Weber and J. Äystö, Phys. Rev. Lett. 103 (2009) Lowest Q value recorded so far! Previousrecord: 187 ReQ β = 2.469(4) kev 1 1 M.S.Basunia, Nucl. Data Sheets 110(2009) 999. Jouni Suhonen (JYFL, Finland) NCNP / 27

24 Theory 2nd-forbiddenunique 115 In(9/2 + ) 115 Sn(3/2 + )decay dependent on only one nuclear matrix element(nme) M T 1/2 = 1 M 2 f K (w 0,Z f,r) wave functions from the proton-neutron microscopic quasiparticle-phonon model(pnmqpm) pnmqpm was previously successfully applied to the 4th-forbiddennon-unique 115 In(9/2 + ) 115 Sn(1/2 + )g.s.-to-g.s. decay(logft, half-life, electronspectrum) 2 2 M.T.Mustonenand J.Suhonen, Phys. Lett. B 657(2007) 38. Jouni Suhonen (JYFL, Finland) NCNP / 27

25 Experiments Meet Theory 10 Beta decay of 115 In g.s. to the lowest excited state of 115 Sn BJM JYFLTRAP Half-life (10 20 y) Q-value (ev) BJM=B.J.Mount, M.Redshaw and E.G.Myers,Phys. Rev. Lett. 103(2009) Jouni Suhonen (JYFL, Finland) NCNP / 27

26 Possible Sources of Discrepancy Nuclear wave functions? MQPM andpnmqpm takealso intoaccount the3-qp degreesof freedom Relevant states still dominantly 1-qp states Toexplain thediscrepancy,thenmeshouldbewrongby afactor of5ormore! Maybe the problem lies in the lepton wave functions... Atomic effects for ultra-low Q values electron screening(not estimated for forbidden decays) atomic overlap (previous approximations break down) exchange effects(contradictory results for low Q values) final-state interactions (estimates only for tritium beta decay) Jouni Suhonen (JYFL, Finland) NCNP / 27

27 Conclusions and Outlook Conclusions: The0νECECdecaysof 112 Snand 136 CeareNOT OBSERVABLEdueto badly fulfilled resonance condition The0νECECdecayof 74 Seis NOT OBSERVABLEduetobadlyfulfilled resonance condition and tiny NME 115 Indecaysby anultra-low Q value ATOMICeffectsimportant Outlook: Other resonant 0νECEC decays should be studied for their Q values using the atomtraptechniques, e.g. 106 Cd Muchwork neededto chartthe magnitudes ofthe atomic effectsinbeta decayswithultra-low Qvalues. Only thenthe hunt forthe elusive neutrino mass in these decays is possible. Jouni Suhonen (JYFL, Finland) NCNP / 27

Nuclear Matrix Elements for Rare Decays

Nuclear Matrix Elements for Rare Decays Jouni Suhonen Department of Physics University of Jyväskylä Neutrinos in Cosmology, in Astro, Particle and Nuclear Physics, Erice, Sicily, 16-24 September, 2009