In September 2022, a scientific conference was held in Zurich (Switzerland). The conference presented results fr om an 鈥渋nternational test鈥� for AMS laboratories that was launched by the University of Glasgow in the summer of 2021. 70 of 140 international accelerator mass spectrometers participated in the competition and 55 laboratories passed the test. Among the successful laboratories was The Center for Collective Use AMS NSU-NSC (CCUAMS NSU-NSC). Radiocarbon dating data from 17 different GIRI-specimens showed a 100% hit for corresponds to testing targets.
Ekaterina Parkhomchuk, PhD and Director CCU AMS NSU-NSC, described the test,
We processed, prepared, and analyzed 17 samples (barley husk, wood, cellulose, individual annual rings, whale bone, humic acids) for international cross-testing in three independent series of experiments. This involved a combination of preparation for AMS targets by Russian (ACS) and Swiss (AGE-3) graphitization bench. It also involved conducting an experiment on the INP SB RAS AMS and a foreign AMS (MICADAS): 1) AGE-3 + MICADAS, 2) ACS + MICADAS, 3) AGE-3 + AMS INP. In all three experiments the results differed within the error allowed for the radiocarbon dating method.
In one of the experiments (ACS + MICADAS), our scientists used an absorption-catalytic graphitization setup. This included catalytic combustion of the sample, selective sorption of CO2 and removal of other gases by vacuum, followed by reduction of CO2 with hydrogen to graphite. This method of carburization is well known to physical chemists in the process of obtaining hydrogen, but Novosibirsk scientists were the first in the world to apply it to radiocarbon dating.
Parkhomchuk provided more detail about their approach,
It was important to provide process parameters that would give the required quantity and quality of graphite for AMS analysis with the highest possible carbon conversion. The quality of graphite is determined not only by its purity, the absence of external impurities, but also by its ability to be pressed into tablets that then act as AMS targets. We conducted a whole scientific study to sel ect the parameters for the process, components for the stand, and to automate it. The result turned out to be unexpectedly good at a significantly lower cost for the Russian installation in comparison to the most common CHNS-method for AMS analysis of graphite fr om two installations that give close dates. The disadvantage is the need for regular installation maintenance, replacement of consumables and components. If this is not done, then the quality of the graphite obtained and the reliability of dating drops sharply since the contribution of background pollution and isotope fractionation increases. In other words, the human factor is very important here.
In all three experiments, the results differed within the error allowed for a radiocarbon dating method. For example, wood, which scientists identified by optical microscopy as larch, showed an age of 1) 4550 卤 32 years, 2) 4553 卤 72 years, 3) 4530 卤 70 years, and whale bone - 1) 12809 卤 40, 2) 12894 卤 150, 3) 12503 卤 150. The "correct answers" for these samples are 4526 卤 47 and 12745 卤 99. This means that the chemical laboratory for sample preparation at the Institute of Archeology and Ethnography SB RAS, the unique AMS scientific installation assembled at the Budker Institute of Nuclear Physics SB RAS, and the method of absorption-catalytic graphitization developed at the Institute of Catalysis SB RAS all confirmed their viability experimentally.
The Director added,
The results of the analysis of GIRI facilities showed the viability of the Research Center as a whole. All multi-stage procedures that involved many scientists were conducted accurately and the team was able to complete all chemical, physical, and analytical work in a short period of time. In addition, specific devices created by Russian scientists under challenging conditions, as well as the method of absorption-catalytic graphitization for radiocarbon dating, have been recognized. Now all these internationally recognized achievements need to be converted into sustainable developments.
Aleksey Petrozhitsky, a researcher at the Institute of Nuclear Physics SB RAS, spoke about plans for the further development of accelerator mass spectroscopy. He noted that in addition to automating the facility, wh ere the CCUAMS NSU-NSC is able to study 1500 samples per year, the team plans to develop a new ion source, implement a beam diagnostics system, and create a reliable power supply system.
Petrozhitsky explained,
With the increased availability of C14 analysis, new users appear meaning the technology itself generates a market. If earlier this method was in demand primarily by archaeologists, it is now actively used for drug testing, and is important not only for fundamental science, but for the applied sector. This field is intensively developing around the world and we need to develop together with it. Therefore, the creation of a low-voltage machine similar to the Swiss one is one of our goals. We are already working on a prototype and plan to create it by 2026.
