Carbon-14 activities in recently fallen meteorites and Antarctic meteorites

摘要: This paper reports {sup 14}C measurements in meteorites using an extraction method which employs RF melting of samples as small 0.1 g. A study cosmic-ray-produced Bruderheim gave levels between 38 and 60 dpm/kg for had been preheated air 250 700{degree}C, with a mean value 46.8 {plus minus} 1.4 dpm/kg. range values 35 59 was found other falls saturated to 500{degree}C. The preheating step is shown be effective removing terrestrial carbon contamination. series previously dated by 81}Kr having ages 120-310 kyr <0.16 0.37 0.10 These are consistent situ production cosmic rays at the Earth's surface.