Radiocarbon dating programme at the Birbal Sahni Institute of Paleobotany

Sample combustion is described in a pure oxygen stream to obtain CO2, and the subsequent conversion to CH4 proceeding for 8 to 12 hours. A low-background proportional counter with an in-built anticoincidence counter was used in measurement. The shielding box consisted of 10 cm lead layers and of a 2 cm mercury layer with a 10 cm paraffine wax layer in between. The circuit diagram is shown. The detector background was 1.4 imp/min. The Laboratory is involved in Quaternary research applied to paleobotany and palynology. The application is described of 14C dating in determining the vegetation, climatic and agricultural history and geomorphological future. 14C dating applications in archeology and in determining the post-growth factor are shown. (J.P.)