Nuclear Matrix Elements for Rare Decays

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Nuclear Matrix Elements for Rare Decays Jouni Suhonen Department of Physics University of Jyväskylä Neutrinos in Cosmology, in Astro, Particle and

1 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, September, 2009 Contents: Resonant 0νECEC Decays TheRareBetaDecayof 115 In Jouni Suhonen (JYFL, Finland) Erice2009 1/ 17

2 Topic I Resonant 0νECEC Decays Jouni Suhonen (JYFL, Finland) Erice2009 2/ 17

3 The0νECECdecayratecanbeenhancedbythe resonance condition: 1 T 1/2 = ( M) 2 (Q E) 2 + Γ 2 Γ, Q E = degeneracyparameter /4 M = atom-mixing parameter containing the nuclear matrix element Q =M(Z,A) M(Z 2,A) =differencebetweentheinitialand final atomic masses E =E +E H +E H =nuclearexcitationenergy+electronbinding Γ = Γ + Γ H + Γ H =nuclearandatomicradiativewidths Candidates: 74 Se 74 Ge(2 + ), 78 Kr 78 Se(2 + ), 112 Sn 112 Cd(0 + ),... Jouni Suhonen (JYFL, Finland) Erice2009 3/ 17

4 Resonancedecayof 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) Erice2009 4/ 17

5 The Atom-Mixing Parameter with phase-space factor G ECEC 0ν = M =G ECEC 0ν and NUCLEAR MATRIX ELEMENT M ECEC 0ν = a (J + f m,n M ECEC 0ν m ν, ( ) GF cos θ C g 2 A (Zαm e ) 3, R A =1.2A 1/3, 2 2π πr A τ + m τ + nh(r mn,e a )f J (σ m, σ n ) 0 + i ), r mn = r m r n. Hereh(r mn,e a )istheneutrinopotentialcontaining,e.g.,short-range correlations, and f 0 (σ m, σ n ) = σ m σ n (J + f =0 + f ), f 2 (σ m, σ n ) = [σ m σ n ] 2 (J + f =2 + f ), m ν = λ CP j U ej 2 m j. j=light Jouni Suhonen (JYFL, Finland) Erice2009 5/ 17

6 Resonance0νECECdecayof 112 Sn Γ =fewtensofev ; M ECEC 0ν = 4.76 (unitless NME) Q value measured in JYFLTRAP(Phys. Rev. Lett. 103(2009) ) Hence: Q E = 4.5keV for KKcapture = 18.2keV for KLcapture = 40.9keV for LLcapture T 1/2 > ( m ν [ev]) 2years Conclusion: Decay rate much suppressed by the rather large degeneracy parameter Q E Jouni Suhonen (JYFL, Finland) Erice2009 6/ 17

7 Resonancedecayof 74 Se As 41 Q β = kev X L X L kev 0νECEC Se kev Q = (49) kev Ge 42 Jouni Suhonen (JYFL, Finland) Erice2009 7/ 17

8 Resonance0νECECdecayof 74 Se Hence: Γ =fewtensofev ; M ECEC 0ν = (unitless NME) Q value measured in JYFLTRAP(to be submitted) Q E =2.23keVforLLcapture(mostfavourable) T 1/ ( m ν [ev]) 2years Conclusion: Decay rate much suppressed both by the rather large degeneracyparameterq EandtheverysmallNME forthe2 + f finalstate.thesameoccursforthe2νβ β decay (seem.aunolaandj.suhonen,nucl.phys.a602(1996)133) Jouni Suhonen (JYFL, Finland) Erice2009 8/ 17

9 Topic II 115 In:Betadecaywithanultra-lowQ value Jouni Suhonen (JYFL, Finland) Erice2009 9/ 17

10 115 In:Betadecaywithanultra-lowQvalue 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) Erice / 17

11 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) in press. Lowest Q value recorded so far! Previousrecord: 187 ReQ β =2.469(4)keV 1 1 M.S.Basunia,Nucl.DataSheets110(2009)999. Jouni Suhonen (JYFL, Finland) Erice / 17

12 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.MustonenandJ.Suhonen,Phys.Lett.B657(2007)38. Jouni Suhonen (JYFL, Finland) Erice / 17

13 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.RedshawandE.G.Myers,Phys.Rev.Lett.103(2009)inprint Jouni Suhonen (JYFL, Finland) Erice / 17

14 Nuclear wave functions: Naïve picture for protons(in) 1/2 4.5 h / In g 9/2 1p 1/2 0f 5/2 1p 3/2 Jouni Suhonen (JYFL, Finland) Erice / 17

15 Nuclear wave functions: Naïve picture for neutrons (Sn) 82 3/ ps / h 11/2 1d 3/2 2s 1/2 0g 7/2 1d 5/ Sn Jouni Suhonen (JYFL, Finland) Erice / 17

16 Possible sources of the discrepancy Nuclear wave functions? MQPMandpnMQPMtakealsointoaccountthe3-qpdegreesof freedom Relevant states still dominantly 1-qp states Toexplainthediscrepancy,theNMEshouldbewrongbyafactor 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) Erice / 17

17 Conclusions and Outlook Conclusions: The0νECECdecayof 112 SnisNOTOBSERVABLEduetobadly fulfilled resonance condition The0νECECdecayof 74 SeisNOTOBSERVABLEduetobadly fulfilled resonance condition and tiny NME Outlook: 115 Indecaysbyanultra-lowQvalue ATOMICeffects important Other resonant 0νECEC decays should be studied for their Q values using the atom trap techniques Much work needed to chart the magnitudes of the atomic effects inbetadecayswithultra-lowqvalues.onlythenthehuntforthe elusive neutrino mass in these decays is possible. Jouni Suhonen (JYFL, Finland) Erice / 17

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

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,