The word cathode refers to the value obtained for the measurement of a carbon AMS target. We use the abstraction of a run to refer to a single exposure of the target to cesium. Typically there are 8 two minute exposures of the target to cesium, so the value for a cathode is obtained by averaging 8 runs. We also use the abstraction of a sample to refer to the average value of several cathodes of the same material. This is most often used for standards and backgrounds.

We use avg and sig for average and uncertainty (sigma). R0 and R1 refer to 14C/12C and 13C/12C ratios respectively. When a B or S is inserted before the R it refers to that ratio for the Background or Standard.

In this notation the formula for the background and fractionation corrected quantity F14C for a run is