We report a precise, model-independent determination of the age and age spread of CO2 in air trapped in ice. A large pulse of atmospheric radiocarbon, generated in the atmosphere by nuclear tests, peaked in the early-to-mid 1960's. We measure the profile of the radiocarbon ''bomb spike'' in firm air and ice bubbles from high snow-accumulation sites drilled in 1987 and 1993 on Law Dome, East Antarctica, by employing high precision AMS (Accelerator Mass Spectrometry). Large 14C atmospheric growth rates and a high signal-to-noise ratio lead to a direct and precise determination of the CO2 age and age-spread in the ice. A least-squares comparison with the atmospheric history gives a mean CO2 age of 8.9¿0.5 years at the bottom of the firn (where vertical gas diffusion ceases) with an age spread in the ice (full width of a moving average smoothing window) of 12.5¿1.5 years. These results confirm the possibility of examining decadal trace gas variations prior to direct instrumental measurements.