High precision study of the decay of 42Ti

Vud matrix element and nuclear physics

Experimental and theoretical precisions

New cases: goals and challenges

Experimental requirementsKVI PAC meeting, 25 november 2005(spokesperson B.Blank)

CKM mixing matrixcoupling quark states in the Standard Modelunitarity condition

Vud ~ 95 %Vus ~ 5 %Vub ~ 0 %Vud nuclear 0+ g 0+ decaysneutron decay Part. Data Group (2004) Serebrov et al. (2005)pion beta decay(larger uncertainty)

VusKX decays + form factor Leutwyler-Roos (1984) Cirigliano et al. (2005)

the situation todayMass crises? W. Marciano @ NUPAC ISOLDESavard et al. PRL 95, 102501 (2005)

deviation tounitarityVudnuclear0+ g 0+tnpdg 04tnSe 05VusK decay: pdg04+ LR 84~ 2s~ 2sokK: all results+ LR 84okok~ 2sK: all results+ Ci 05~ 2s~ 2sok

matrix element

coupling constantFermi decay and CVCCorrection termsfor T = 1 statesthen ft = constant for given isospinFermi 0+ g 0+ transitions and CVC hypothesisg radiative correctionsDRnucleus independent (~ 2.4 %)dRnucleus dependent (~ 1.5 %)

g isospin symmetry breaking

dC ~ 0.5 %

nuclear structure insight: dC - dNS

Experimental ft measurementsprecision measurements requiredto test Ft value ~10-3

QECmass measurementsf ~ QEC5

T1/2, BRb-decay studiest = T1/2 / BRStatus in 2005 9 best cases10C, 14O, 26mAl, 34Cl, 38mK, 42Sc, 46V, 50Mn, 54Co many recent results22Mg T1/2, BRTexas A&MQECANL, ISOLDE

34Ar T1/2, BRTexas A&MQECISOLDE62Ga T1/2, BR GSI, Jyvskyl,Texas A&M74Rb T1/2 ,BRTRIUMF, ISOLDEQECISOLDE

46VQECCPT Argonne

Average Ft valueFt = 3074.4 1.2 s10-3 ~ 10-2~ 10-1~ 10-0

Further experimental directionsbest casessame theo. and exp. errorfew improvements(10C, 14O)

TZ = -1 nuclei, sd/f shellsbranching ratio exp. test of dIM

TZ = 0 nuclei, Z > 30decay, masses dC increases with Z

Theoretical correctionsCoulomb correctiondC = dIM + dRO

dIMisospin mixingcan be tested with non analoguebranching ratios

dROradial overlap

challenges for TZ = -1 nucleiHardy, Towner 2004similar T1/2 of parent and daughterprecise determination is difficult

branching ratio < 100 %:BR determination requires very precise gamma efficiencycalibration (

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 MeVPresent letter of intentWhy KVI? Ti refractiveClean production (inverse kinematics)3He(40Ca,42Ti)1n or 12C(40Ca,42Ti)12BFavorable yields

Best 0+ g 0+ decay casesExperimental precision reaches theoretical calculations level

Theoretical corrections should be calculated in different formalisms(currently mainly shell model)46V mass recentlyre-measured(JYFL, ANL)10C branching ratio14O branching ratio:only from b G.S. feedingHardy, Towner 2004

Detection requirementsa Low Energy Facility is obviously the best suited for this kind of measurements.

which kind of equipment ?

QECgmass measurements (Z > 30)(Penning) trapmost sophisticated equipment, but appears in all physicscase conclusions

T1/2 , BR gdecay studies

short half-lives (

Experimental test of correctionsneed for wider range of experimental data to test theoretical correctionsassuming a constant Ft value

Hardy, Towner 2004heavier TZ = 0 nucleifurther from stabilitylower production rates

lower proton binding energy higher radial overlap correction

high charge Zstronger isospin mixing effects

important Coulomb correction dChigher shells involvedg theoretical uncertaintiesrecent measurementsfor 62Ga and 74Rb

ConclusionCKM 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