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Set-up, optimization and first set of samples at the radiocarbon laboratory in Lebanon

Baydoun R., El Samad O., Aoun M., Nsouli B., Younes G.

Geochronometria

2014

Vol. 41, no. 1

87--91

A new radiocarbon laboratory has been established recently at the Lebanese Atomic Ener-gy Commission. This laboratory consists of benzene synthesis line and a low background liquid scin-tillation counter, Tri-Carb 3180 TR/SL for measurements with Bismuth Germanate (BGO) guard de-tector. The effectiveness of the benzene line was tested firstly by preparing benzene from a wood sample after carbide and acetylene receiving. Normalization and standardization of the liquid scintil-lation counter was carried out, as well as the Factor of Merit (E2/B) was determined for three differ-ent counting regions. To assure accuracy and reliability of results, reference materials were used. Based on z-score and u-score evaluation, as well as Student's t-test, acceptable data were obtained from travertine and wood samples available through the International Atomic Energy Agency (IAEA-C2 and IAEA-C5), and humic acid (U) and murex shell (R) from the Fifth International Radiocarbon Intercomparison (VIRI). After that, a preliminary study was done, which is the base for future re-search in order to assess the anthropogenic impact and degree of environmental pollution in terms of radiocarbon isotope ratio (Δ14C) deduced from the Percent Modern Carbon or PMC. This work repre-sents the results of four reference materials and those of five green grass samples. The Δ14C of green grass samples collected from two different clean zones were found to be 50‰ and 52‰, while the values of those collected from different polluted zones were 23‰, 7‰ and 15‰.