On the coherent scattering length of natural gadolinium

Using the reflection of thermal neutrons from the surface of plane sample the coherent scattering length of natural gadolinium was measured. Due to the closeness of resonances in radiation capture cross section the imaginary part of coherent scattering length strongly depends on neutron wavelength. Its real part can be expressed as a sum of Re(b)=b sub 0 + b(lambda). For the constant component of the real part we experimentally obtained the value b sub 0 =(11.5+-0.7)Fm. This result should be considered as a preliminary.