Stress Induced Birefringence in Atom Trap Viewports

ORAL

Abstract

At TRIUMF Neutral Atom Trap (TRINAT), the current goal is a measurement of the angular asymmetry of beta particles with respect to the nuclear spin, $A_{\beta }$, from the beta decay of $^{\mathrm{37}}$K nuclei. Trapped atoms are spin-polarized by optically pumping with circularly polarized light. We characterize the degree of circular polarization of the light with the Stokes parameter S$_{\mathrm{3}}$; with an S$_{\mathrm{3}}$ value of 0.999 required to spin polarize the atoms to a proportional degree of accuracy of 10$^{\mathrm{-3}}$. One major difficulty we have encountered is stress induced birefringence on the viewports of the atom trap, which alters the S$_{\mathrm{3}}$ value. Fully annealed copper gaskets consistently achieved S$_{\mathrm{3}}$ values of over 0.999 with reproducibility down to 0.9986 and a strong dependence on the torque applied to the bolts sealing the CF flange. Using elastomer o-rings to seal the viewports, we achieved S$_{\mathrm{3}}$ values of over 0.9999, corresponding to a birefringence of $\Delta $n $=$ 3x10$^{\mathrm{-6}}$ [see Solmeyer, Rev. Sci. Instrum$.$ 82 (2011) 066105]. The drawbacks of this method are outgassing and permeation. We achieved 3x10$^{\mathrm{-8}}$ Torr with Viton and Kalrez o-rings, and we are testing Neoflon. In this talk methods of producing and quantifying circularly polarized light will be discussed, as well as techniques for reducing stress-induced birefringence.

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Authors

  • Claire Warner

    University of Waterloo

  • William H. Dowd

    Oregon State University, University of Washington, University of Hong Kong, University of Tennessee, Oak Ridge National Laboratory, University of British Columbia, Univ of Washington, Univ of Cambridge, Michigan State University, Universit\'e de Caen, Argonne National Laboratory, Texas A\&M University -Commerce, Texas A\&M University, Department of Physics, University of Idaho, Moscow, Idaho 83844, USA, Universidad de Salamanca, E-37008 Salamanca, Spain, Department of Physics, Florida State University, Tallahassee, Florida 32306, USA, University of Cambridge, Institute of Astronomy, University of Cambridge, Canadian Institute for Theoretical Astrophysics, University of Toronto, Seoul National University, Chungnam National University, Department of Physics, Oregon State University, TRIUMF, Roosevelt High School, Department of Physics, University of Washington, Oregon State Department of Chemistry, Oregon State School of Electrical Engineering and Computer Science, Oregon State Department of Physics, University of Idaho, Lawrence Livermore National Laboratory, Idaho National Laboratory, Pacific Northwest National Laboratory, Carnegie Institution of Washington, Department of Chemistry, Oregon State University, School of Electrical Engineering and Computer Science, Oregon State University, Washington State University, Harvard University, Idaho Accelerator Center, Idaho Accelerator Center, Idaho State University, 1500 Alvin Ricken drive, Pocatello, ID 83201, USA, CENPA, University of Washington, Physics Division, ANL, NSCL, Michigan State University, Division, ANL, LPC, CAEN, France, Paul Scherrer Institute, US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA, 20192, USA, University of Calgary Department of Physics and Astronomy, University of Calgary Department of Geoscience, None, University of the Fraser Valley, Univ of California, Berkeley, Simon Fraser University, Los Alamos Natl. Lab., University of Science and Technology of China, Hefei, U of Washington, Georgia Institute of Technology, Washington State Univ, National Institute of Standards and Technology and University of Maryland, American University

  • William H. Dowd

    Oregon State University, University of Washington, University of Hong Kong, University of Tennessee, Oak Ridge National Laboratory, University of British Columbia, Univ of Washington, Univ of Cambridge, Michigan State University, Universit\'e de Caen, Argonne National Laboratory, Texas A\&M University -Commerce, Texas A\&M University, Department of Physics, University of Idaho, Moscow, Idaho 83844, USA, Universidad de Salamanca, E-37008 Salamanca, Spain, Department of Physics, Florida State University, Tallahassee, Florida 32306, USA, University of Cambridge, Institute of Astronomy, University of Cambridge, Canadian Institute for Theoretical Astrophysics, University of Toronto, Seoul National University, Chungnam National University, Department of Physics, Oregon State University, TRIUMF, Roosevelt High School, Department of Physics, University of Washington, Oregon State Department of Chemistry, Oregon State School of Electrical Engineering and Computer Science, Oregon State Department of Physics, University of Idaho, Lawrence Livermore National Laboratory, Idaho National Laboratory, Pacific Northwest National Laboratory, Carnegie Institution of Washington, Department of Chemistry, Oregon State University, School of Electrical Engineering and Computer Science, Oregon State University, Washington State University, Harvard University, Idaho Accelerator Center, Idaho Accelerator Center, Idaho State University, 1500 Alvin Ricken drive, Pocatello, ID 83201, USA, CENPA, University of Washington, Physics Division, ANL, NSCL, Michigan State University, Division, ANL, LPC, CAEN, France, Paul Scherrer Institute, US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA, 20192, USA, University of Calgary Department of Physics and Astronomy, University of Calgary Department of Geoscience, None, University of the Fraser Valley, Univ of California, Berkeley, Simon Fraser University, Los Alamos Natl. Lab., University of Science and Technology of China, Hefei, U of Washington, Georgia Institute of Technology, Washington State Univ, National Institute of Standards and Technology and University of Maryland, American University