Particle-, Nuclear- and Atomic-Physics Aspects of Rare Weak Decays of Nuclei Jouni Suhonen Department of Physics University of Jyväskylä NCNP2011 - XII th NordicConference onnuclear Physics, Stockholm, Sweden, 13-17 June, 2011 Contents: Intro: 0νββ Decays Resonant 0νECEC Decays Rare Beta Decays Jouni Suhonen (JYFL, Finland) NCNP 2011 1/ 27
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 2011 2/ 27
DoubleBeta Decay(Isobars A = 76) -60.0 Zn A=75-60.0 Zn A=76 Mass excess [MeV] -65.0-70.0 Ga Br Kr Mass excess [MeV] -65.0-70.0 Ga Br Kr Ge As Se Ge As -75.0-75.0 Se 30 31 32 33 34 35 36 Z 30 31 32 33 34 35 36 Z Jouni Suhonen (JYFL, Finland) NCNP 2011 3/ 27
Two-Neutrino Double Beta Decay Nucleus half-life (years) experiments 48 Ca 4.2 10 19 laboratory 76 Ge 1.42 10 21 laboratory 82 Se 9 10 19 laboratory,geochemical 96 Zr 2.1 10 19 laboratory,geochemical 100 Mo 8.0 10 18 laboratory 116 Cd 3.3 10 19 laboratory 128 Te 2.5 10 24 geochemical 130 Te 9 10 20 geochemical 150 Nd 7.0 10 18 laboratory 238 U 2.0 10 21 radio-chemical e 1 - FINAL NUCLEUS p p (Z,N-2) - e 2 2 INTERMEDIATE STATES 1 10 20 years = 10000000000 age of the UNIVERSE n n (Z,N-2) INITIAL NUCLEUS Jouni Suhonen (JYFL, Finland) NCNP 2011 4/ 27
Two-Neutrino DoubleBetaDecay of 76 Ge Virtual (3 - ) (4 - ) (1 + )? (3 - )? (1 - ) (1 + ) (1 + ) (1 + ) transition The decay goes through1 + virtual states 2-0 + 2 - - 76 Ge 76 As 76 Se 0 + Jouni Suhonen (JYFL, Finland) NCNP 2011 5/ 27
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 = 7.67 +0.16 0.19 10 5 ev 2 m 2 atm = 2.39+0.11 0.08 10 3 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 2011 6/ 27
Neutrinoless DoubleBeta Decayof 76 Ge Virtual (3 - ) (4 - ) (1 + )? (3 - )? (1 - ) (1 + ) (1 + ) (1 + ) transition The decay goes throughall J π virtual states 2-0 + 0 - - 76 Ge 76 As 76 Se 0 + Jouni Suhonen (JYFL, Finland) NCNP 2011 7/ 27
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 2011 8/ 27
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 100 1000kg scale andcostabout 100000000 EURO/$ each! Jouni Suhonen (JYFL, Finland) NCNP 2011 9/ 27
Topic I Resonant 0νECEC Decays Jouni Suhonen (JYFL, Finland) NCNP 2011 10/ 27
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 2011 11/ 27
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 2011 12/ 27
Resonant0νECECDecayof 106 Cd X K X K 0 + 2766.26 kev 1 + 1 106 47 Ag 59 0 + 1 R0νECEC Qβ = 202 kev 106 48 Cd 58 4 + 1229.2 kev 0 + 1133.7 kev 2 + 1 1128.0 kev 2 0νβ + EC Q = 2770(7) kev 2 + 1 511.86 kev 0 + gs 106 46 Pd 60 0νβ + β +,0νβ + EC Jouni Suhonen (JYFL, Finland) NCNP 2011 13/ 27
Half-lifeEstimatefor 106 Cd Decay widthof thetwo-hole state: Γ = 10.24eV 10 31 mν = 0.05 ev Half-life (yr) 10 30 10 29 10 28 10 27 mν = 0.3 ev mν = 1.0 ev 10 26 10 25 10 24 10 0 10 1 10 2 10 3 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 2011 14/ 27
Resonant0νECECDecayof 112 Sn X K X K 1 + 1 112 49 In 63 Q β = 658 kev 0 + 4 1924.3 kev 0νECEC 0 + 1 112 50 Sn 62 Q = 1919.82(16) kev 2 + 1 617.516 kev 0 + 1 112 48 Cd 64 Jouni Suhonen (JYFL, Finland) NCNP 2011 15/ 27
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) 042501) Hence: Q E = 4.5 kev for KK capture = 18.2 kev for KL capture = 40.9 kev for LL capture T 1/2 > 5.9 1029 ( m ν [ev]) 2 years Conclusion: Decay rate much suppressed by the rather large degeneracy parameter Q E Jouni Suhonen (JYFL, Finland) NCNP 2011 16/ 27
Resonant0νECECDecayof 74 Se 2 1 74 33As 41 Q β = 1353.1 kev X L X L 2 + 2 1204.31 kev 0νECEC 0 + 1 74 34 Se 40 2 + 1 595.88 kev Q = 1209.171(49) kev 0 + 1 74 32Ge 42 Jouni Suhonen (JYFL, Finland) NCNP 2011 17/ 27
Half-LifeEstimatefor 74 Se Γ = fewtensofev ; M ECEC 0ν < 0.0160 (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 1/2 5 1043 ( 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 2011 18/ 27
Resonant0νECECDecayof 136 Ce 0 + 4 X K X K 1 + 1 2390.20 kev 136 57 La 79 0νECEC 0 + 1 Q β = 460 kev 136 58 Ce 78 2 + 1 818.50 kev Q = 2378.53(27) kev 0 + 1 136 56 Ba 80 Jouni Suhonen (JYFL, Finland) NCNP 2011 19/ 27
Half-LifeEstimatefor 136 Ce Γ = 13.81eV ; M ECEC = 0.250 (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 = 11.67 kev for KK capture = 19.78 kev for KL capture = 51.24 kev for LL capture T 1/2 > 2.26 1033 ( m ν [ev]) 2 years Conclusion: Decay rate much suppressed by the rather large degeneracyparameterq E andtherathersmall NME Jouni Suhonen (JYFL, Finland) NCNP 2011 20/ 27
Topic II 115 In: Beta decay withanultra-low Q value Jouni Suhonen (JYFL, Finland) NCNP 2011 21/ 27
115 In: Beta DecaywithanUltra-Low Q Value First discovered by Cattadori et al. (Nucl. Phys. A 748 (2005) 333) 1/2 4.5 h 0.336 9/2 + 0.000 3/2 + 11 ps 0.497 115 49 In T 1/2 = 4.4 10 14 a 1/2 + 0.000 115 50 Sn stable Suggested as a possible independent experiment to look for the neutrino mass Jouni Suhonen (JYFL, Finland) NCNP 2011 22/ 27
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) 10 20 a b = 1.07(17) 10 6 T partial 1/2 = 4.1(6) 10 20 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) 122501. 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 2011 23/ 27
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 2011 24/ 27
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) 1 0.1 0.01 100 200 300 400 500 Q-value (ev) BJM=B.J.Mount, M.Redshaw and E.G.Myers,Phys. Rev. Lett. 103(2009) 122502 Jouni Suhonen (JYFL, Finland) NCNP 2011 25/ 27
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 2011 26/ 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 2011 27/ 27