Display the Report for S823, report 200512S

Experiment: S823

Pure Fermi Decay in Medium Mass Nuclei (74Rb,74Kr,62Ga)

by the Exotic Nuclear Studies Group group

Active (Stage 2)
Spokespersons:
G. Ball (TRIUMF)

Progress Report for EEC meeting 200512S

Table of Contents

Detailed Information

Proposal/Report S823_proposal.pdf (179.94 kB)

Beam Shift Summary

12-hr ShiftsBeam Line / channelPolarized Primary BeamPriority
New Beam Requests
 20 8π No
Committee Recommendations
 20 No H
The group is proposing to revisit the 74Rb decay branching ratio determination to bring the precision of the determination of the Ft value to the level of the nine well-studied low-Z cases. The interest is that the structure dependent corrections are much larger, and such a high precision measurement would test the theoretical approach used for all the cases studied. ISAC has the highest yield of 74Rb in the world; the lifetime was already measured by this group to the required precision; TITAN is the best facility to get the Q value for this short lived isotope; and, the 8π spectrometer supplemented by the SCEPTAR and PACES arrays can be used to improve the branching ratio measurement by a factor of 3 as was demonstrated already in the studies of 62Ga. The Committee recommends pursuing this objective.
Beam Shifts Used
 20 ISAC No

Shifts scheduled on Schedule 109.


Membership

G. Ball TRIUMF Research Scientist 0 % Spokesperson
A. Andreyev TRIUMF Research Associate %  
A.A. Phillips University of Guelph Student (Graduate) %  
A.C. Morton TRIUMF Research Scientist %  
B. Hyland University of Guelph Student (Graduate) %  
C. Andreoiu Simon Fraser University Assistant Professor %  
C.E. Svensson University of Guelph Professor %  
C.J. Pearson TRIUMF Research Associate %  
C.Y. Wu Lawrence Livermore National Laboratory Research Scientist %  
D. Bandyopadhyay University of Guelph PDF %  
E.F. Zganjar University of Louisiana Professor Emeritus %  
G. Hackman TRIUMF Research Scientist %  
G.F. Grinyer University of Guelph Student (Graduate) %  
I.A. Towner Queen Associate Professor %  
J. Dilling TRIUMF Research Scientist %  
J.A. Becker Lawrence Livermore National Laboratory Research Scientist %  
J.L. Wood Georgia Tech Professor %  
J.R. Leslie Queens Professor Emeritus %  
M. Dombsky TRIUMF Senior Research %  
M.A. Schumaker University of Guelph Student (Graduate) %  
P. Bricault TRIUMF Senior Research %  
P. Finlay University of Guelph Student (Graduate) %  
P.E. Garrett University of Guelph Associate Professor %  
R. Kanungo Saint Mary’s University Assistant Professor %  
R.A.E. Austin McMaster University Student (Graduate) %  
W.D. Kulp Georgia Institute of Technology Research Scientist %  

Basic Information

Date Submitted
2005-08-18 14:33:57
Date Experiment Ready
0000-00-00
Projected Completion Date
0000-00-00
Summary *
Precision measurements of the ft values for superallowed 0+ →0+ Fermi β decay between isobaric analogue states provide demanding tests of the Standard Model description of the electroweak interaction. Presently, superallowed ft values have been determined at the ± 0.1% level for nine nuclei between 10C and 54Co [Har05]. Once corrected for small radiative and isospin symmetry breaking effects, their consistency has confirmed the conserved vector current (CVC) hypothesis at the level of 3 x 1 0. From these studies, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element, Vud, can be derived by comparing the β-decay data with pure leptonic muon decay. Combining the results from superallowed Fermi beta decay with the recommended [PDG04J values of Vus and Vub, indicates a violation of CKM unitarity at the 98% confidence level [Har05]. Although recent measurements [She03, Ale04] indicate the accepted value of Vus may be the cause of this discrepancy, these results are still under intense scrutiny. With a number of new experiments in progress (E865, KLOE, NA4812 and CMD2) [Dur03] the present uncertainty in the value of is expected to be resolved in the coming years. Nevertheless, continued effort to reduce the uncertainty in Vud remains a high priority since the unitarity test of the elements in the first row of the CKM matrix is, at the present time, the most precise unitarity test that can be applied to the CKM matrix. In this regard, it is important to note that the error in Vud is predominately associated with uncertainties in the calculated theoretical corrections. Since the leading terms in the radiative corrections are so well founded, attention has focused on the nuclear structure dependent corrections. To remove the uncertainties in the calculated Coulomb corrections, it is essential to extend the precision β-decay measurements to heavier (A 62, T = 0) odd-odd nuclei where these corrections are predicted to be much larger. This is the subject of E823 which has been discussed in more detail in previous EEC reports (e.g. Nov 1999, 2003).
Plain Text Summary *
Primary Beam Line
Primary Beam and Target
Secondary Channel
Secondary Beam
TRIUMF Support (Resources Needed)
Other Funding
Safety Issues

Proposals and Progress Reports

200712S
200512S
200312S
200012S
199912S
199905S
199806S
199712S
199707S (Original Proposal)