US Geological Survey, Menlo Park, California, Radiocarbon Measurements I

Abstract

A radiocarbon laboratory at the US Geological Survey Western Regional Headquarters in Menlo Park, California was established in temporary rooms in March, 1976. In August, 1976 the laboratory was dismantled and moved into a new building that was designed specifically for the facility. This list contains results of operations in the temporary laboratory, which was located in the basement of a two-story building. The counter shield was 15cm lead and 5cm borated paraffin with an additional 5cm of lead above the counters. The anticoincidence ring consisted of copper tubes, 5cm in diameter, mounted around a copper tube with an inside diameter of 15cm. Installed in the anticoincidence ring were the four sample counters, whose characteristics are shown in Table 1. The counting electronics unit, which is designed to service five sample counters, follows the design of Gulliksen (1972) in most respects. The sample counters were constructed of copper and quartz; their design is described in detail by Robinson (1977). The CO2 counting gas was purified by recirculation over copper and silver at ca 450°C. Wood samples were typically pretreated by leaching for 24 hours alternately in 1N sodium hydroxide and hydrochloric acid solutions at 70°C.