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Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere

Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere. physics of 0 + → 0 + b transitions recent experimental efforts world data on 0 + → 0 + decay future studies. Bertram Blank, CEN Bordeaux-Gradignan. ISOLDE WS, 12-14 february 2007. Standard model of weak interaction.

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Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere

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  1. Super-allowed 0+ to 0+ beta decay at ISOLDE and elsewhere • physics of 0+→ 0+b transitions • recent experimental efforts • world data on 0+ → 0+ decay • future studies Bertram Blank, CEN Bordeaux-Gradignan ISOLDE WS, 12-14 february 2007

  2. Standard model of weak interaction • SM is theory which describes electro-weak interaction • BUT: parameters have to be determined experimentally • e.g. masses, coupling constants, mixing angles, etc. • nuclear b decay is weak process and may allow for • determination of these parameters • 5 different couplings possible due to Lorentz invariance: • - scalar coupling (S) • - vector coupling (V) • - tensor coupling (T) • - axial-vector coupling (A) • - pseudo-scalar coupling (P) • b decay: mainly vector and axial-vector  V-A theory • weak contribution from other coupling??  scalar, tensor coupling • determination of vector coupling constant: 0+  0+, n decay, p decay • determination of axial-vector coupling constant: neutron decay • SM is theory which describes electro-weak interaction • BUT: parameters have to be determined experimentally • e.g. masses, coupling constants, mixing angles, etc. • nuclear b decay is weak process and may allow for • determination of these parameters • 5 different couplings possible due to Lorentz invariance: • - scalar coupling (S) • - vector coupling (V) • - tensor coupling (T) • - axial-vector coupling (A) • - pseudo-scalar coupling (P) • b decay: mainly vector and axial-vector  V-A theory • weak contribution from other coupling??  scalar, tensor coupling • determination of vector coupling constant: 0+  0+, n decay, p decay • determination of axial-vector coupling constant: neutron decay

  3. K = ft 2 2 2 g 2 g + M M V F A GT K f(Qec) * T1/2 / BR = = ft 2 2 g M V F Beta decay and coupling constants • in general: • for 0+ 0+ transitions: only vector current due to selection rules • experimental quantities: • masses of parent and daughter, half-life, branching ratio • K / (hc)6 = 8120.271(12) * 10-10 GeV-4 s = constant, <MF>2 = T(T+1) - TziTzf • gv can be determined, Vud = gv / gF, quark-mixing matrix element • one high-precision measurement would be enough • BUT…..

  4. K Ft = ft (1 + dR’ ) (1 – dc + dNS) = = constant 2 (1 + DR) 2 g M V F Corrections, CVC, CKM matrix • electromagnetic interactions: e.g. positron - protons, positron - electrons •  radiative correction dR→ dR’ • isospin impurity: binding energy difference, configuration mixing •  Coulomb correction dc = dc1 + dc2 • nuclear structure dependent radiative correction dNS • if these effects corrected: constant ft value •  constant vector current hypothesis (CVC) •  • determination of gv via Ft value: •  many ft values are needed to test CVC and theoretical corrections • from gv: •  determination of Vud matrix element of CKM quark mixing matrix • Vud = gv / gF

  5. inner radiative corrections Jaus & Rasche, 1987

  6. isospin-mixing corrections Towner & Hardy, 2005

  7. isospin-mixing corrections + NS radiative corrections Towner & Hardy, 2005

  8. isospin-mixing corrections

  9. Situation in 2000

  10. overall precision: Ft = (3073.5 ± 1.2) s •  4 * 10-4 •  single measurements: < 10-3 • f: f(QEC5) → DQ < 2 * 10-8 → < 1keV • T1/2: DT < 10-3 • BR: DBR < 10-3 • theoretical corrections: dC, dR~ 1% → < 10% Required precision 9 “classical” cases

  11. Our recent efforts: Q value of Ga-62 • Q value measurements at JYFLTRAP: 62Ga QEC = (9181.07 ± 0.54) keV T. Eronen et al., 2006

  12. Our recent efforts: half-life of Ga-62 • half-life measurement at GSI: • half-life measurement at JYFL: T1/2 = (116.18 ± 0.04) ms B. Blank et al., 2004 T1/2 = (116.12 ± 0.15) ms G. Canchel et al., 2005

  13. 954 – 62Ga 1388 –62Ga 2511- e+e 2228 –62Ga Our recent efforts: branching ratio of Ga-62 • branching ratio measurement at JYFL: A. Bey et al., 2007 BR = (99.905 ± 0.026) %

  14. Decay scheme of Ga-62 62Ga31 (0+,T=1) +Gamow-Teller ~ 0.022% 3638 3180.5 3159 2806 + FermiNonanalog. < 0.014% 0.022(7)% 2374 0.014(5)% 2343.2 2227 1389 1803.5 0.025(7)% 850 + Fermi Analog. (sa)99.902% 953.5 0.078(8)% 953.5 New Ft value for 62Ga 0 62Zn32 (0+,T=1)

  15. Our recent efforts: Q value and half-life of Ca-38 • Q value measurements at ISOLTRAP: e.g. 38Ca • half-life measurements at ISOLDE using REXTRAP: e.g. 38Ca Dm = (-22058.01±0.65) keV S. George et al., 2007 T1/2 = (450.0±1.6) ms B. Blank et al., 2007 T1/2 = (450.0  1.6) ms

  16. The REXTRAP facility A longitudinal Penning trap filled with Ne as buffer gas Superconducting magnet 3T PNe ~10-4 mbar in the trapping area DE Buffer gas cooling Accumulation Cooling Ejection – TOF selection

  17. Our recent efforts: Q value and half-life of Ca-38 • Q value measurements at ISOLTRAP: e.g. 38Ca • half-life measurements at ISOLDE using REXTRAP: e.g. 38Ca Dm = (-22058.01±0.65) keV S. George et al., 2007 T1/2 = (450.0±1.6) ms B. Blank et al., 2007 T1/2 = (450.0  1.6) ms

  18. Recent experimental efforts: Texas A&M • branching-ratio measurement: 22Mg • half-life measurement: 34Ar • other measurements: 62Ga BR = (53.15 ± 0.12) % J. Hardy et al., 2003 T1/2 = (843.8 ± 0.4) ms V. Iacob et al., 2006

  19. Recent experimental efforts: TRIUMF • branching-ratio measurement: 62Ga • other measurements: 18Ne , 74Rb BR = (99.861 ± 0.011) % B. Hyland et al., 2006

  20. Experimental results after 2000 14O T1/2 Leuven, Auckland, Berkeley QEC Auckland 18Ne T1/2 TRIUMF QEC ISOLDE 22Mg T1/2, BR Texas A&M QEC CPT Argonne, ISOLDE 26Si QEC JYFL 26Alm QEC JYFL 34Ar T1/2, BR Texas A&M QEC ISOLDE 38Ca QEC, T12 ISOLDE QEC MSU 38Km T1/2 Auckland 42Sc QEC JYFL 42Ti QEC JYFL 46V QEC JYFL, CPT Argonne 50Mn QEC JYFL T1/2 Auckland 62Ga T1/2, BR GSI, JYFL, TRIUMF, Texas A&M QEC JYFL 74Rb T1/2 ,BR TRIUMF, ISOLDE QEC ISOLDE

  21. Summary of experimental and theoretical results <Ft> = (3074.4 ± 1.2) s  gv = 1.1358(4)  Vud = 0.9736(4)

  22. Error budget • CVC accepted • measurement • of ft • testdc - dNS • from theoretical • models

  23. ft (1 + dR’ ) (1 – dc + dNS) Test of nuclear corrections • ft value + QED corrections • ft value with all corrections  Ft •  nuclear corrections seem to be • okey, but they have large • uncertainties • new calculations needed • + measurements for nuclei • with large corrections

  24. CKM quark mixing matrix • coupling of quark weak eigen states to mass eigen states in the Standard Model unitarity condition: Vud = 0.9736(4) ~ 95 % Vus = 0.2254(21) ~ 5 % Vub = 0.00367(47) ~ 0 %   Vui² = 0.9987(12)  • the situation today Vud 0+g 0+b decays: 0.9736(4) neutron decay: 0.9741(20)  Part. Data Group (2004) (Serebrov et al. (2005) not included) pion beta decay: 0.9728(30) larger uncertainty Vus KX decays + form factor  Leutwyler-Roos (1984)  Cirigliano et al. (2005) Severijns, Beck, Naviliat-Cuncic, 2006

  25. 1 (1 + <b’F>) K 2 GF2 Vud2 (1 + DVR) The standard model and beyond • limit on induced scalar currents: • fs = -0.00005(130) or |fs|  0.0013 • limit for fundamental scalar current: • |Cs / Cv |  0.0013 • limit for Fierz interference term: • bF = 0.0001(26) • Ft = • limits on right-handed currents: • -0.0005 <  < 0.0015 (90% C.L.) • W1 = WL cos - WR sin • W2 = WL sin + WR cos • unitarity of first column of CKM matrix: •  Vid = 0.9985(54) • best limits from all approaches Ft value for fs =  0.002 Hardy & Towner, 2005

  26. Improvements between 1990 and 2005 • uncertainty on <Ft> : • 3073.3(35) s  3074.4(12) s==>> 30 % due to more and more precise exp. data • Fierz term : • 0.0010(30)  0.0001(26)==>> strongly reduced value due to better exp. data • Vud : • 0.9740(10)  0.9736(4)==>> slight change, factor 2.5 • unitarity test of first row of CKM matrix: •  Vui = 0.9970(21)  Vui = 0.9987(12) ==>> change mainly due to Vus, improved precision from Ft • unitarity test of first column of CKM matrix: •  Vid = 0.9985(54) ==>> not evaluated in 1990 • right-handed currents: • Re(alr) = -0.0004(6)==>> not evaluated in 1990

  27. Present and future efforts • Tz = -1 nuclei:10C, 18Ne, 22Mg, 26Si, 30S, 34Ar, 38Ca, 42Ti • - major problems: • T1/2 of daughter nuclei • BR with precision of 10-3 → absolute g efficiency with < 10-3 • → knowledge of source strength • - solutions: • trap-assisted spectroscopy for half-life measurements • high-precision efficiency calibration of single-crystal Germanium • ion counting → experiments on separators like • MARS (Texas A&M), LISE3 (GANIL), TRmMP (KVI) • Tz = 0 nuclei:66As, 70Br, 78Y, 82Nb, 86Tc, …, 98In • - major problem: • production rates, for some isomers, excited 0+ states • - solution: • future facilities like EURISOL, maybe SPIRAL2,ISOLDE • theoretical corrections: • - new approaches needed for nuclear corrections • - higher-order calculations for QED corrections

  28. Our next projects • half-life of 38Ca at ISOLDE • half-life of 26Si at JYFL • half-life of 42Ti at JYFL or at KVI • calibration of a HP germanium • - branching ratio of 10C, 26Si, • 38Ca, 42Ti

  29. Conclusions • interesting physics case with strong implications • beyond nuclear physics • lively field with world-wide activities • high-intensity beams of nuclei of interest are already available • trap-assisted spectroscopy becomes more and more important, • ISOLDE is a very good place • LISE3/GANIL and TRImP/KVI could be a prominent place for • new branching ratio measurements • in Europe: ISOLDE, JYFL, LISE3, TRImP,LIRAT/DESIR can play an • important role

  30. Recent experimental efforts: ISOLDE • Q value measurements at ISOLTRAP: e.g. 38Ca • half-life measurements at ISOLDE: e.g. 38Ca • other measurements: 18Ne, 22Mg, 34Ar, 74Rb S. George et al., 2007 T1/2 = (451.8±1.6) ms B. Blank et al., 2007

  31. Recent experimental efforts: MSU • Q value measurements at MSU trap: 38Ca • Dm = 280 eV G. Bollen et al., 2006

  32. Recent experimental efforts: JYFL • Q value measurements at JYFLTRAP: e.g. 62Ga • half-life and branching-ratio measurements: • other measurements: 26Alm, 26Si, 42Ti, 42Scm, 46V, 50Mn QEC = (9181.07 ± 0.54) keV T. Eronen et al., 2006 T1/2 = (116.12 ± 0.15) ms G. Canchel et al., 2005 A. Bey et al. , 2007

  33. Recent experimental efforts: Argonne • Q value measurements at CPT at Argonne: 46V • other measurements: 22Mg G. Savard et al., 2005

  34. Recent experimental efforts: GSI • half-life measurement: 62Ga • branching-ratio measurement: 62Ga T1/2 = (116.18 ± 0.04) ms B. Blank et al., 2004 G. Savard et al.

  35. Recent experimental efforts: LEUVEN • half-life measurement: 14O T1/2 = (70.560 ± 0.049) s M. Gaelens et al., 2001

  36. Recent experimental efforts: Auckland • half-life measurement: 50Mn • other measurements: 14O, 38Km T1/2 = (283.10 ± 0.14) ms P.H. Barker et al., 2006

  37. Recent experimental efforts: Berkeley • half-life measurement: 14O T1/2 = (70.696 ± 0.052) s J.T. Burke et al., 2006

  38. A possible program for GANIL • half-life measurements: • - only nuclei without “daughter half-life problem” • e.g. 10C, 14O, 18Ne, 30S, ….. 66As, 70Br ?? • on LIRAT2 or SIRa • branching ratio measurements • - top candidates: 18Ne, 26Si, 38Ca, where half-life and QEC are measured • production rates at LISE3: 18Ne: 6000pps with 3mA of 20Ne, 100% pure • 26Si: 3000pps with 3mA of 32S, 100% pure • 38Ca: 2500pps with 3mA of 40Ca, 100% pure • - others which are feasible: 10C, 14O,22Mg, 30S, 34Ar, (42Ti)

  39. Determination of branching ratios • integration of decay time • spectrumto yield source strength • (a few percent error) • intensity of g rays • (statistical and systematic error) •  branching ratios with large error bars (~ 1%) • acceptable for very small branching ratios

  40. SISSI target Primary beam spectrometer LISE3 : degrader Be Wien filter Setup for branching-ratio measurements

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