The moa bone analysis gave a radiocarbon date of 580 plus or minus 40 years. This application uses a terrestrial calibration curve to calculate the calendar age. To obtain a calendar age for the sample, this radiocarbon age needs to be compared against samples of known age by means of a calibration curve using a specially designed computer software application. The results from the liquid scintillation spectrometer are carefully analysed and provide a radiocarbon age for the sample. The decay events for each sample are measured over a week. In addition to the moa sample, control samples are also measured at the same time. The scintillator chemical butyl-PBD picks up each decay event and emits a tiny flash of light that the spectrometer is programmed to detect and count. ![]() ![]() The C-14 atoms present in the benzene decay at a certain rate. The silica glass vials are loaded into the liquid scintillation spectrometer. Liquid scintillator spectrometer counts the number of decays occurring per minute Special silica glass vials are used to contain the mixture of benzene and PBD. Fiona is wearing an aspirator because of the carcinogenic properties of benzene. Addition of scintillator to benzene sampleĪ scintillator chemical (butyl-PBD) is added to the liquid benzene. This gas is then passed through a vanadium-based catalyst column, which produces liquid benzene (C 6H 6). When all of the carbon dioxide has reacted, distilled water is added to the lithium carbide and a chemical reaction occurs, resulting in the production of acetylene gas. The carbon dioxide formed in the combustion stage is heated in the presence of pure lithium metal, which produces lithium carbide. The carbon dioxide is collected and bubbled through various chemicals in the line, which purify it, and the amount of carbon dioxide that has been collected is measured. It is during this stage that the carbon present in the sample is converted into carbon dioxide. Then a stream of oxygen is added into the system and the sample is combusted. All air is evacuated from the vacuum line because it has C-14 in it and is a potential contaminant. It is a long tube which is hooked up to a vacuum line. The pre-treated sample is loaded onto a quartz silica boat, which is loaded into a combustion tube. Series of chemical reactions to convert all carbon atoms present into benzene After this process, the resulting material has a spongy texture with an off-white colour. The sample is freeze dried to remove excess water. Filtration during this phase allows contaminants to be successfully removed. The remaining material goes through a gelatinisation process to free up the bone protein. ![]() The ground-up bone is treated with hydrochloric acid, which dissolves out the hard part of the bone. Further treatments (weak acid added etc.) The cleaned bone sample is then ground up into smaller pieces to speed up chemical reaction with the acid in the next stage. Once they know that there is sufficient protein remaining, they clean the surface of the bone to remove contaminants like dirt, charcoal or, in some cases, glue that the archaeologists have used to mend the bone fragments Small sample taken and ground into smaller pieces Bone cleanedįirst, the lab will test the bone to see how much protein remains in it, because it’s the protein fraction of the bone that they actually date. Some of these have been sent to the Waikato Radiocarbon Dating Laboratory for analysis. Amongst the artefacts that have been found are ancient moa bones. The Wairau Bar in Blenheim is one of the oldest archaeological sites in New Zealand.
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