Electron-Capture Branch of 100Tc _Alejandro Garcia et al._

							Electron-Capture Branch of 100Tc                                               (Alejandro Garcia et al.)




                                           •        Overview
                                           •        The 1993 measurement
                                           •        The 2005 measurement
                                           •        Why the change?
                                           •        Summary

 CENPA                                                                         J.F. Wilkerson on behalf of Alejandro Garcia
                                                                                    Neutrino Nuclear Responses Workshop
 Center for Experimental Nuclear Physics and Astrophysics
 University of Washington                                   December 4, 2005                          CAST/SPring-8, Japan
     Electron-Capture Branch of 100Tc                                (A. Garcia et al.)




                            5 measurable observables in addition
                            to energy of Giant Resonance:
                            1) 100Mo 100Ru(g.s.)          (known)
                            2) 100Mo 100Ru(1130 keV) (known)
                            3) 100Tc 100Ru(g.s.)          (known)
                            4) 100Tc 100Ru(1130 keV) (known)
                            5) 100Tc 100Mo (difficult to measure)


Electron Capture in 100Tc            December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     EC Branch of 100Tc 1993 Publication                                (A. Garcia et al.)


    Phys. Rev. C 47 2010 (1993)

          LBNL 88” cyclotron
          100Mo(p,n)100Tc

          97.4% 100Mo




Electron Capture in 100Tc         December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     EC Branch of 100Tc 1993 Publication                                              (A. Garcia et al.)




                            The Tc and Nb x-ray peaks are mainly due to IC of 140-keV
                            transition in 99Tcm and the 743 keV transition in 97Nbm

Electron Capture in 100Tc                       December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     EC Branch of 100Tc 1993 Publication                                              (A. Garcia et al.)




  Substantial
  Backgrounds




                            The Tc and Nb x-ray peaks are mainly due to IC of 140-keV
                            transition in 99Tcm and the 743 keV transition in 97Nbm

Electron Capture in 100Tc                       December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     EC Branch of 100Tc 1993 Publication (A. Garcia et al.)
       Many long-lived contaminants from (p,n) and (p,alpha) reactions
       on other Mo isotopes.




            1993 Result
            B(GT , 0+ 1+) = 0.66 ±0.33

Electron Capture in 100Tc                 December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
 New 2005 Result EC Branch of 100Tc (S. Sjue et al.)
     100Tc         Production at IGISOL facility at Jyväskylä




Electron Capture in 100Tc            December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
 New 2005 Result EC Branch of 100Tc (S. Sjue et al.)
     100Tc         Production at IGISOL facility at Jyväskylä
                                                                               100Mo(p,n)100Tc

                                                                               (97.4%-enriched
                                                                               100Mo)




Electron Capture in 100Tc            December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
 New 2005 Result EC Branch of 100Tc (S. Sjue et al.)
     100Tc         Production at IGISOL facility at Jyväskylä
                                                                               100Mo(p,n)100Tc

                                                                               (97.4%-enriched
                                                                               100Mo)




 Select A=100
 component of the ion
 beam using a magnet
 with a resolution of
 M/ΔM ≈ 250




Electron Capture in 100Tc            December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     New 2005 Result EC Branch of 100Tc (S. Sjue et al.)

     IGISOL facility at the
     University of Jyväskylä.

     Ions are implanted onto an
     aluminized Mylar tape.

     Tape is moved after counting
     to remove long-lived 99Tc
     Contaminant




Electron Capture in 100Tc         December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     2005 Result - EC Branch of 100Tc (S. Sjue et al.)




                            New measurement: (Sjue et al, To be published)
                                 B(GT , 0+ 1+) = 2.01 ± 0.45 +.02/-.10
                                        log ft = 3.96 +0.11/−0 .09

Electron Capture in 100Tc                   December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     Why the Change ?
       AG as yet has been unable to pinpoint an error in the 1993 result.
       Looks like too much background subtracted in 1993 analysis.



                            ?                                                            ?


Electron Capture in 100Tc            December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan
     Summary - EC Branch of 100Tc
      New result based on isotope separator has substantially reduced backgrounds
      compared to the 1993 result.
      This result is in better agreement with the QRPA calculation.
      The new value has substantial implications on sensitivities to solar neutrinos.
      A paper describing the new measurement is nearing completion.
      For future experiments, considering measurements using an ion trap.



                            QRPA (Griffiths-Vogel, PRC 46, 181 (1992)) :
                            B(GT, 0+ 1+) = 1.75
                            1993 measurement: (Garcia et al, PRC 47, 2910 (1993))
                            B(GT , 0+ 1+) = 0.66 ±0.33

                            New measurement: (Sjue et al, To be published)
                            B(GT , 0+ 1+) = 2.01 ±0.45 +.02/-.10


Electron Capture in 100Tc                       December 4, 2005   On Behalf of Alejandro Garcia NNR05, CAST/SPring-8, Japan