Re-evaluation of a precise measurement of h/m(n)

At the high-flux reactor of the Institut Laue-Langevin in Grenoble the fine -structure constant a was determined by measuring the quotient of the Planc k constant and the neutron mass him,. The results have already been publish ed. In order to evaluate the measurement data, the lattice parameters of se veral silicon crystals must be known very accurately. As these parameters c an now be determined in a more direct way than in the past, the results of the experiment have been re-evaluated. The values obtained by the re-evalua tion are h/m(n) = 3.956 033-285 (287) x 10(-7) m(2) s(-1) (relative standar d uncertainty 7.26 x 10(-8)) and alpha(-1) = 137.036 01144(498) (relative s tandard uncertainty 3.64 x 10(-8)), the uncertainties being one-standard-de viation estimates. These values differ from those obtained in the first eva luation by only about 15 % of their uncertainties.