Neutron scattering on nuclei.

Very small angle neutron scattering studies have been made on intact nuclei under a variety of solution conditions. Scattering maxima are observed at 30 to 40 nm and at 18 nm in most environments. Although the spacing, intensity and presence of the maximum near 40 nm varies considerably with environment the 18 nm is rather constant. The 30 to 40 nm maximum appears to be best interpreted by the presence of 35 to 50 nm diameter fibers in nuclei. An important result is that no scattering maximum was observed near 11 nm, suggesting that a tightly super coiled nucleofilament with such a pitch is not present.