Scientists at Stanford Linear Accelerator Center (SLAC) have used a high-powered X-ray to read missing text in a 2,000-year-old document by the Greek scientist Archimedes.
Uwe Bergmann, Ph.D., who headed the project, said the scientists used a technique known as X-ray fluorescent imaging to identify iron traces hidden in the document.
Though about 25 percent of the original document had been covered over in gold forgery, Bergmann said he and his colleagues looked for iron because that was the main element in the original ink.
X-ray fluorescent imaging works by using a high-powered X-ray to knock electrons, usually in orbit around an atom's neutron, out of place. If the ray is powerful enough, it can knock out an electron orbiting close to the neutron. This causes one of the electrons in the outer shell to fall in toward the neutron, emitting a so-called "fluorescent'' beam of a frequency unique to the element.
The element-specific fluorescent beams register on a detector, which must be set to pick up a specific element,
Bergmann explained. The detector is tuned to read certain wavelengths that correspond to the energy inherent in the fluorescent rays.
"We are using extremely intense X-rays from our synchrotron, a particle accelerator that produces these intense X-rays,'' Bergmann said.
While scientists have been using this technique for several years, this is the first time it has been used to read a text. Thus far, it has been mainly used in medical applications such as looking for calcification in breast cancer tissue and looking at the distribution of metals in lung tissue.
"Basically it is a way to identify very small quantities of
elements,'' Bergmann said.
The text the scientists will read comes from a document written by Archimedes sometime before his death during the fall of Syracuse in 212 B.C., Bergmann said .
One of the two treatises in the so-called Palimpsest describes how Archimedes combined pure mathematics with his own physical intuition to calculate the center of gravity of objects. The other describes how he learned how to deal with infinite sums.
"You could call it a form of integral calculus, which is usually attributed to (Isaac) Newton,'' Bergmann said. "It is not an exaggeration to say (these theories) were 2,000 years ahead of their time.''