Experimental Studies
The threshold displacement energies have been studied extensively with electron irradiation experiments. Electrons with kinetic energies of the order of hundreds of keVs or a few MeVs can to a very good approximation be considered to collide with a single lattice atom at a time. Since the initial energy for electrons coming from a particle accelerator is accurately known, one can thus at least in principle determine the lower minimum threshold displacement energy by irradiating a crystal with electrons of increasing energy until defect formation is observed. Using the equations given above one can then translate the electron energy E into the threshold energy T. If the irradiation is carried out on a single crystal in a known crystallographic directions one can determine also direction-specific thresholds .
There are several complications in interpreting the experimental results, however. To name a few, in thick samples the electron beam will spread, and hence the measurement on single crystals does not probe only a single well-defined crystal direction. Impurities may cause the threshold to appear lower than they would be in pure materials.
Read more about this topic: Threshold Displacement Energy
Famous quotes containing the words experimental and/or studies:
“If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning, concerning matter of fact and existence? No. Commit it then to flames: for it can contain nothing but sophistry and illusion.”
—David Hume (1711–1776)
“The conduct of a man, who studies philosophy in this careless manner, is more truly sceptical than that of any one, who feeling in himself an inclination to it, is yet so over-whelm’d with doubts and scruples, as totally to reject it. A true sceptic will be diffident of his philosophical doubts, as well as of his philosophical conviction; and will never refuse any innocent satisfaction, which offers itself, upon account of either of them.”
—David Hume (1711–1776)