Ancient Lead Can Help Experimental Physics

Scientists from the National University of Science and Technology MISIS measured the number of trace impurities in the ingots of ancient lead from the sunken ship of the ancient Romans, using a novel technology. It was shown that lead, which stayed underwater for 1500 years, contains such a small amount of radioactive elements — Uranium and Thorim, that it can be used without any purification in one of the most “demanding” areas — Nuclear physics — in the study of elementary particles. The experiment on the selection and determination of micro-impurities was carried out in cooperation with colleagues from the Joint Institute for Nuclear Research and the National Center for Scientific Research (France). An article about the development published in the journal Talanta.

The more precise and efficient modern devices become, the more pure materials are required to construct them. These are so-called high-purity materials, which contain impurities in so small amounts that they cannot influence the specific properties of the studied objects. One of the most “demanding” spheres where high-purity materials can be used is Nuclear physics. For instance, particle accelerators, which are already built underground to protect the experiments from cosmic rays, still require additional radiation protection from special shields made of ultra-pure lead. An example of such an accelerator is the Large Hadron Collider in CERN.

High-purity lead is produced in several stages, such as the dissolution of ore, smelting, separation of the alloy into component parts, alkali purification, and separation of each impurity. When many stages of purification are performed, it is needed to analyze a probe of the high-purity lead. The permissible maximum of radioactive impurities should not exceed 0,0000000001% (one ten-billion %) of the total mass. With this amount of radioactive impurities (or lower), lead can be used to protect high-precision equipment. However, even the most modern methods of direct elemental analysis do not allow to determine such small amounts of impurities in the main component — lead.

Scientists of NUST MISIS laboratory for separation and concentration in chemical diagnostics of functional materials and objects of the environment, led by Professor Pyotr Fedotov, Sc.D. in Chemistry, suggested a new technology to separate impurities for further analysis. The experiment was conducted on the probes of ancient lead — more than 1500 years old ingots. Centuries ago, this lead was mined by the ancient Romans in the mines, located on the territory of modern England. When transporting lead ore ship sank, and was discovered only at the end of the 20th century off the coast of France.