"X-rays bounce off electrons, and so scatter much more spectacularly from heavier elements that have many electrons than from lighter ones, such as hydrogen, which has only one. It has been estimated that, as a result, the placement of about half of the hydrogen atoms in published protein structures derived from X-ray studies are not known."
"Neutrons can also probe magnetic moments in solids and phenomena such as high-temperature superconductivity."
"Oak Ridge was built in 1943 to produce uranium and plutonium for the Manhattan Project, and a major new facility hasn't been added since the high-flux isotope reactor was built in 1966."
Nature, p730-731, Vol438, 8Dec2005