Measurement of the imaginary part of the<i>I=1</i><i>N¯N S</i>-wave scattering length

Abstract

The survival time spectrum of slow antineutrons produced in a liquid-hydrogen target has been measured. From these data the imaginary part of the I=1 spin-averaged S-wave antineutron proton scattering length has been deduced to be Im${a}_{1}$=-0.83\ifmmode\pm\else\textpm\fi{}0.07 fm. The result lies within the range of values calculated from current potential models. In addition, by combining ${a}_{1}$ with the antiproton-proton scattering length deduced from antiprotonic atoms, the imaginary part of the I=0 spin-averaged N\ifmmode\bar\else\textasciimacron\fi{}N scattering length was calculated to be Im${a}_{0}$=-1.07\ifmmode\pm\else\textpm\fi{}0.16 fm.