“…Several experiments have been done to determine a,(np) directly, by measuring the attenuation of a neutron beam in liquid hydrogen, in good-geometry experiments (Atkinson et al 1961, Ozhdyani et al 1962, Khachaturyan and Pantuyev 1964, Palevsky et al 1964). More recently, experiments of higher statistical accuracy have been carried out for both hydrogen and deuterium (Kreisler et al 1966, Engler et al 1968) and these new data, together with the earlier work, are shown in figure 17(a) and (b).…”