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Precision Study of Beta Decay in 42Ti and Nuclear Physics Challenges

This study explores the precise beta decay of 42Ti, Vud matrix element, and nuclear physics challenges. It discusses experimental and theoretical precisions in CKM mixing matrix and Fermi decay, emphasizing goals, challenges, and the current experimental requirements.

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Precision Study of Beta Decay in 42Ti and Nuclear Physics Challenges

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  1. High precision study of the  decay of 42Ti  Vud matrix element and nuclear physics  Experimental and theoretical precisions  New cases: goals and challenges  Experimental requirements (spokesperson B.Blank) KVI PAC meeting, 25 november 2005

  2. CKM mixing matrix Mass crises? W. Marciano @ NUPAC ISOLDE Savard et al. PRL 95, 102501 (2005) coupling quark states in the Standard Model unitarity condition Vud ~ 95 % Vus ~ 5 % Vub ~ 0… % the situation today Vud nuclear 0+g 0+ decays neutron decay  Part. Data Group (2004)  Serebrov et al. (2005) pion beta decay (larger uncertainty) Vus KX decays + form factor  Leutwyler-Roos (1984)  Cirigliano et al. (2005)

  3. Fermi 0+g 0+ transitions and CVC hypothesis Fermi decay and CVC matrix element coupling constant for T = 1 states thenft = constant for given isospin Correction terms g radiative corrections DR nucleus independent (~ 2.4 %) dR nucleus dependent (~ 1.5 %) g isospin symmetry breaking dC ~ 0.5 % nuclear structure insight: dC - dNS

  4. 0+ T1/2 QEC BR 0+ Experimental ft measurements precision measurements required to test Ft value ~10-3 QEC mass measurements f ~ QEC5 T1/2, BR b-decay studies t = T1/2 / BR Status in 2005  9 best cases 10C, 14O, 26mAl, 34Cl, 38mK, 42Sc, 46V, 50Mn, 54Co  many recent results 22Mg T1/2, BR Texas A&M QEC ANL, ISOLDE 34Ar T1/2, BR Texas A&M QEC ISOLDE 62Ga T1/2, BR GSI, Jyväskylä, Texas A&M 74Rb T1/2 ,BR TRIUMF, ISOLDE QEC ISOLDE 46V QEC CPT Argonne

  5. Average Ft value ~ 10-0 ~ 10-1 10-3 ~ 10-2 Ft = 3074.4 ± 1.2 s

  6. Further experimental directions best cases same theo. and exp. error few improvements (10C, 14O) TZ = -1 nuclei, sd/f shells branching ratio  exp. test of dIM TZ = 0 nuclei, Z > 30 decay, masses  dCincreases with Z

  7. Theoretical corrections Coulomb correction dC = dIM + dRO dIM isospin mixing can be tested with non analogue branching ratios dRO radial overlap

  8. challenges for TZ = -1 nuclei Hardy, Towner 2004  need for decay studies similar T1/2 of parent and daughter precise determination is difficult branching ratio < 100 %: BR determination requires very precise gamma efficiency calibration (<10-3 !!!)

  9. Present letter of intent • Study of 42Ti • production rates required: • ~103 ions/sec • Proposed measurements: • T1/2 study with a gas detector, a tape transport system • and NaI detectors to tag with the 611 keV  of the 42Ti decay • branching ratio measurement with one Germanium detector • calibrated with a precision of 0.1% • Beam time requirements: • 6 shifts of a 40Ca beam on target at 10 MeV • 6 shifts of a 40Ca beam on target at 45 MeV Why KVI? Ti refractive Clean production (inverse kinematics) 3He(40Ca,42Ti)1n or 12C(40Ca,42Ti)12B Favorable yields

  10. Best 0+g 0+ decay cases 10C branching ratio Hardy, Towner 2004 46V mass recently re-measured (JYFL, ANL) 14O branching ratio: only from b G.S. feeding Experimental precision reaches theoretical calculations level Theoretical corrections should be calculated in different formalisms (currently mainly shell model)

  11. Detection requirements a Low Energy Facility is obviously the best suited for this kind of measurements. which kind of equipment ? QECgmass measurements (Z > 30) (Penning) trap most sophisticated equipment, but appears in all physics case conclusions T1/2 , BR gdecay studies short half-lives ( <100 ms ) fast tape transport system precision: mainly statistics (production rates) branching ratios ( for TZ=-1, non analogue decay branches ) need for very precise g intensities: efficient and very precise gamma detection g no need for segmentation: simple but efficient detectors to reach 10-3 precision level in absolute efficiency calibration

  12. Experimental test of corrections assuming a constant Ft value… need for wider range of experimental data to test theoretical corrections

  13. heavier TZ = 0 nuclei further from stability lower production rates lower proton binding energy  higher radial overlap correction high charge Z stronger isospin mixing effects  important Coulomb correction dC higher shells involved g theoretical uncertainties Hardy, Towner 2004 recent measurements for 62Ga and 74Rb

  14. Conclusion CKM matrix unitarity: still an open question - neutron decay half-life - form factor calculation in Vus determination - weak interaction Nuclear Physics: Fermi 0+g 0+ transitions - CVC hypothesis confirmed at the level of 3x10-4 - many joint theoretical and experimental efforts Experimental challenges - masses of heavier TZ=0 nuclei - branching ratios for TZ = -1 nuclei

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