EXPLORING A CALIBRATION DISCREPANCY AT SAGE & GALLEX : 51 51 THE DIRECT Q-VALUE MEASUREMENT OF Cr(e, νe) V AT TITAN T.D. Macdonald, A.T. Gallant, J. Dilling Department of Physis & Astronomy, The University of British Columbia, Vancouver, Canada TRIUMF, 4004 Wesbrook Mall, Vancouver, Canada A. Chaudhuri, A. Grossheim, A.A. Kwiatkowski, B.E. Schultz, M.C. Simon TRIUMF, 4004 Wesbrook Mall, Vancouver, Canada C. Andreoiu, J.C. Bale Department of Chemistry, Simon Fraser University, Burnaby, Canada U. Chowdhury Department of Physics, University of Manitoba, Winnipeg, Canada TRIUMF, 4004 Wesbrook Mall, Vancouver, Canada D. Frekers, A. Lennarz Institut fur¨ Kernphysik, Westfalishe¨ Wilhelms-Universitat,¨ Munster,¨ Germany V.V. Simon Max Planck Institute for Nuclear Physics, Heidelberg, Germany TRIUMF, 4004 Wesbrook Mall, Vancouver, Canada

TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) uses Penning trap mass spectrometry to probe nuclear structure, nuclear astrophysics, and the fundamental symmetries of nature. Measurements were recently per- formed to address uncertainties in the nuclear structure of isotopes that were used in the solar neutrino experiments SAGE and GALLEX. These experiments used gallium neutrino detectors to detect the first low-energy solar neutri- nos and confirm low-energy neutrino oscillations [1]. However, there is an unresolved discrepancy in the calibration 51 51 of these detectors; the calibration measurements using Cr(e,νe) V do not agree with theoretical expectations [2]. Penning trap mass spectrometry is the most accurate and precise method available for performing direct mass mea- 51 51 surements on nuclides [3], and most recently a Q-value measurement of the calibration reaction Cr(e,νe) V was performed. The results will rule out whether or not the discrepancy at SAGE and GALLEX was caused by an imprecise Q-value determination. An overview of the TITAN facility and the preliminary results will be provided.

[1 ] J. Bahcall, et al, Phys Rev C, 56 3391 (1997) [2 ] J.N. Abdurashitov, et al, Phys Rev C, 80 015807 (2009)

[3 ] K. Blaum, Phys Rep, 425 1 (2006)