Measurement of the Coherent Neutron Scattering Amplitude of Deuterium, Mercury, and Fluorine by Mirror Reflection

The bound coherent neutron-scattering amplitudes of deuterium, mercury, and fluorine have been measured by the mirror-reflection method. The measured values are $a_{\mathrm{D}}=+6.21\mathrm{}\pm 0.04$ F, $a_{\mathrm{Hg}}=+12.67\mathrm{}\pm 0.13$ F, and $a_{\mathrm{F}}=+5.83\mathrm{}\pm 0.17$ F. The mercury and fluorine values are in agreement with presently accepted values. The deuterium value departs seriously from most previously reported measurements. This value implies + 6.13±0.04 F for the quartet scattering amplitude, + 0.13±0.05 F for the doublet scattering amplitude, and 3.15±0.04 b for the free-atom scattering cross section of deuterium.