Measurement of the parity-violating triton emission asymmetry in the reactionLi6(n,α)H3with polarized cold neutrons

Abstract

We describe measurements of the parity-violating ($P\text{\ensuremath{-}}\mathrm{odd}$) triton emission asymmetry coefficient ${a}_{P\text{\ensuremath{-}}\mathrm{odd}}$ in the $^{6}\mathrm{Li}$$(n,\ensuremath{\alpha})$$^{3}\mathrm{H}$ reaction with polarized cold neutrons. Experiments were carried out at the Petersburg Nuclear Physics Institute (Gatchina, Russia) and at the Institut Laue-Langevin (Grenoble, France). We employed an ionisation chamber in a configuration allowing us to suppress the left-right asymmetry well below ${10}^{\ensuremath{-}8}$. An additional test for a false asymmetry due to eventual target impurities (``zero test'') resulted in ${a}_{0\text{\ensuremath{-}}\mathrm{test}}=(0.0\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$. As final result of this series of experiments we obtained ${a}_{P\text{\ensuremath{-}}\mathrm{odd}}=(\ensuremath{-}8.8\ifmmode\pm\else\textpm\fi{}2.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$.