Reconsideration of the Electron-Neutron Scattering Length As Measured by the Scattering of Thermal Neutrons by Noble Gases

Our value for the electron-neutron scattering length has been corrected on the basis of new measurements of some neutron scattering lengths and now is (-1.30±{}0.03) ×{}10^-16 cm, which is 3% lower than our original result. (The equivalent figure in the Fermi convention is -3630±{}70 eV and at $q=0$, dGEndq²=0.0189±0.0004 fm².) A check on the worrisome possibility of an H₂ impurity in the scattering gases showed that is quite unlikely to be a significant source of error. The difference between our result and the Munich measurement and also the Foldy calculation thus continues unexplained.