Superallowed Branching Ratio in the $\beta $ Decay of $^{34}$Ar

ORAL

Abstract

Precise \textit{ft}-values for superallowed $0^+\to 0^+ \quad \beta ^{+}$-decays contribute to the most demanding unitarity test of the Cabibbo-Kobayashi-Maskawa matrix. The decays from T$_{z}$=-1 nuclei, like $^{34}$Ar, are particularly valuable because they can constrain the isospin symmetry-breaking corrections that must be applied to the measured \textit{ft}-values. This requires their branching ratios to be determined to $\sim $0.1{\%} or better. We report here on our continuing quest to reach this goal, which most recently has involved better control of our detection geometry (with laser ranging) and continuous monitoring of dead-time. We produced a pure $^{34}$Ar beam at the exit of the MARS recoil separator using a 25A MeV $^{35}$Cl beam from the Texas A{\&}M cyclotron to bombard a hydrogen gas target. The $^{34}$Ar beam was extracted into air, degraded and implanted into the Mylar tape of our fast transport system. In repeated cycles, each $^{34}$Ar sample was collected for 2s and then moved in 175 ms to the center of a well-shielded $\beta -\gamma $ counting station, where $\beta $ singles and $\beta -\gamma $ coincidences were recorded for 2s. The $\beta $'s were detected in a1-mm-thick plastic scintillator, while the $\gamma $'s were detected by our precisely efficiency-calibrated HPGe detector. With the laser sensor we read the tape-to-HPGe distance to a precision better than 0.1mm and recorded it for each cycle. Branching-ratio results will be reported.

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Authors

  • V.E. Iacob

  • Chris Perkins

    Univ. of California at Berkeley, North Carolina Central U. (NCCU), Triangle Universities Nuclear Laboratory (TUNL), Los Alamos National Laboratory, Lawrence Livermore National Laboratory, SJSU, LLNL, United States Naval Academy, Annapolis, USA, University of Dallas, USA, University of Kentucky, USA, ASU, UNC/TUNL, Univ. Tennessee, ORNL/ORAU, ORNL, ORNL/ORAU/Warsaw Univ., Mississippi State Univ., Louisiana State Univ., ORNL/Warsaw Univ., Vanderbilt Univ., UNRIB/ORAU, Vanderbilt Univ./LBNL, Univ. Tennessee/Warsaw Univ., GANIL, CENBG/CNRS/IN2P3, ANL, U. Jyv\"alsky\"a, CENPA, U. Washington, TRIUMF, IFIC, CSIC-Univ. Valencia, Argonne Nat. Lab., The University of Tennessee at Knoxville, Dept. of Physics (TUNL), Duke University, USA, Wright Nucl. Structure Lab., Yale University, USA, Dept. of Nucl. Physics, Australian National University (ANU), Australia, Dept. Chemistry, University of Kentucky, USA, Dept. of Physics and Astronomy, University of Kentucky, USA, Dept. of Physics \& Astronomy and Chemistry, University of Kentucky, USA, Yale University, Bonn University, Germany, Rutgers University, Millsaps College, Texas A\&M University, Oak Ridge National Laboratory, Oregon State University, UC Berkeley, NSCL/MSU, TA\&MU, RIKEN, Japan, University of Tennessee, Knoxville, BHSU, Sanford Lab, UMass Lowell, LSU, UTK, UTK, ORNL, ORNL, ORAU, ORNL, ORAU, UW, Michigan State University, Pacific Northwest National Laboratory, University of Chicago, Osaka U., Tokyo Inst. of Tech., UND, Konan U, Kyoto U., Konan U., Tohoku U., KVI, University of Stuttgart, IFIN-HH, TUNL, University of Kentucky, TU-Darmstadt, Yale, Surrey, Istituto Nazionale Fisica Nucleare Laboratori Nazionali del Sud, Florida State University, University of Jyv\"askyla, NSCL / MSU, Hope College, Central Michigan University, Gettysburg College, Concordia College, Argonne National Laboratory and University of Chicago and JINA, Hebrew University, Argonne National Laboratory and Western Michigan University, Argonne National Laboratory and JINA, Western Michigan University, Argonne National Laboratory, Universidad Nacional Autonoma de Mexico, State Univ. of New York at Oswego, Department of Physics, State University of New York at Oswego, Physics Division, Oak Ridge National Laboratory, CNRS, Indiana University, LANL, CEA-Saclay, FRIB/MSU, Surrey, Mississippi State University, Technische Universitat Munchen, Univ. of Notre Dame, Univ. of Wisconsin - La Crosse, Kocaeli University, Turkey, RIKEN, NSCL, University of Notre Dame, ATOMKI, Hungary, The University of Alabama, Arizona State University, SUNY Stony Brook, United States Naval Research Laboratory, Ruhr-Universit\"at Bochum, UNC-Wilmington, Tulane U., MIT, Waterloo U., NIST, U. 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U., Chung-Ang U., Univ. of Stellenbosch, iThemba LABS, Univ. of Witwatersrand, iThema LABS, Univ. of Cape Town, Univ. of Witwatersand, KVI Univ. of Groningen, NSCL, Michigan State University, East Lansing, MI 48824, USA, Helmholtz-Insitut Mainz, Johannes Gutenberg-Universit\"at Mainz, D-55128 Mainz, Germany, KVI Groningen, U S Naval Academy, University of Surrey, Cyclotron Institute, Texas A\&M University, JIHIR, UNIRIB, ICN-UNAM, FSU, U. of Surrey, NSCL, MSU, Departments of Chemistry and Physics \& Astronomy, University of Kentucky, Lexington, KY 40506, School of Physics, Georgia Institute of Technology, USA, Dept. of Physics, University of Guelph, Canada, Dept. of Chemistry, University of Kentucky, USA, Depts. of Physics \& Astronomy and Chemistry, University of Kentucky, USA, UNIRIB/ORAU, ORAU, U Richmond, WNSL Yale, IKP Univ. Cologne, Univ. 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