Scientists Use AMS to Date Human Remains

Laboratory scientists from the joint NSU Laboratory of Radiocarbon Methods analyzed the human remains that were found in Novosibirsk, during excavations on the spot of a former NKVD prison functioning in 1929-1951. Our scientists report that the remains belong to the period before 1955. It is the first time when the radiocarbon method using accelerator mass-spectrometry has been applied in criminal science in Russia.

The old building at the cross-section of Narymskaya and 1905 Streets, which was to be redeveloped, used to house a transit NKVD prison in 1929-1951 and later a psychoneurologic dispensary. In 2012, when it was wrecked, some human remains were found on the spot. Activists from Memorial, a Russian historical and civil rights society, asked for dating them in the Laboratory.

Radiocarbon method is used for determining the age of an object containing organic material by using the properties of radiocarbon (14C), a radioactive isotope of carbon. Accelerator mass-spectrometry (AMS) is a very effective modern method for counting the radiocarbon atoms in a substance. There are essentially two parts in the process of radiocarbon dating through accelerator mass spectrometry. The first part involves accelerating the ions to extraordinarily high kinetic energies, and the subsequent step involves mass analysis. AMS separates rare isotopes from the neighboring mass and counts them rather than analyzes the decay rate. The greatest advantage that AMS radiocarbon dating has over radiometric methods is small sample size. Accelerator mass spectrometers need only as little as 20 milligrams and as high as 500 milligrams for certain samples whereas conventional methods need samples of much bigger sizes. Accelerator mass spectrometry also takes less time to analyze samples for carbon 14 content compared to radiometric dating methods that can take one or two days. An accelerator mass spectrometer has a run time of a few hours per sample. Lastly, AMS measurements usually achieve higher precision and lower backgrounds than common radiometric dating methods. The scientists from the joint NSU Laboratory used AMS to date the remains found. The experiment was conducted by Ekaterina Parkhomchuk, an associated professor at NSU and a senior research scientist at the Boreskov Institute of Catalysis, Petr Kalinkin, a senior instructor at NSU, and Sergey Rastigeev, a senior research scientist at BINP.

After a special chemical pre-treatment, the scientists analyzed six samples for residual radiocarbon concentration in the remains given. The samples coded CN 653, CN 654, CN 655, CN 656, CN 657, CN 658 had the isotope abundance of 0,97; 0,97; 0,97; 0,97; 1,01; 0,98 correspondingly, with 2% possible error of the indication. Such data mean that the people died not later than in 1955.

Accelerator Mass Spectrometry Radiocarbon Dating is widely used abroad for archaeological and geological samples as well as in other fields like biomedical research and ocean sciences research. Our joint laboratory has used AMS radiocarbon dating for criminal science for the first time in Russia.

The joint Laboratory of Radiocarbon Methods has been launched at Novosibirsk State University according to the Program 5-100. The Laboratory is headed by Prof. Vasily Parkhomchuk, a corresponding member of RAS. The research is conducted on the unique AMS system developed by the specialists from BINP SB RAS.