Fractal approach in petrology: combining ultra small angle, small angle and intermediate angle neutron scattering

Ultra small angle neutron scattering (USANS) instruments have recently cove red the gap between the size resolution available with conventional interme diate angle neutron scattering and small angle neutron scattering (SANS) in struments on one side and optical microscopy on the other side. New fields of investigations are now open and important areas of material science (cer amics, glass fibers, natural materials) and fundamental physics (phase tran sition, phase separation and critical phenomena) can be studied in bulk sam ples with an accuracy previously unobtainable owing to a combination of fav ourable features of the neutron-matter interaction: high penetrability of n eutrons, even cold neutrons, ability to easily manipulate local scattering amplitudes by means of isotopic substitution methods, small absorption for most nuclei and hardly any radiation damage. In particular, neutrons see ro cks as two-phase systems, and therefore the data analysis is enormously sim plified. Rocks showing fractal behavior in over two decades of momentum tra nsfer and seven orders of magnitude of intensity are examined and fractal p arameters are extracted from the combined USANS, SANS and intermediate angl e neutron scattering curves.