In his postdoctoral studies, David Haas set out to reduce radiation damage to protein crystals during X-ray crystallography. In 1970, he published a paper on his invention of macromolecular cryocrystallography – freezing crystals to extend their lifetime in the X-ray beam. The widespread use of the synchrotron beginning in the 1970s made cryo-cooling essential, and today nearly all protein crystal structures deposited in the international Protein Data Bank use this method.