Improved Single Ion Cyclotron Resonance Mass

We have improved the state of the art for precision mass spectroscopy of a mass doublet to below one part in 1010. By alternately loading single ions into a Penning trap, we have determined the mass ratio M(CO+)/M(N2+) = 0.999 598 887 74(11), an accuracy of 1 x 10-1°. This is a factor of 4 improvement over our previous measurement, and a factor of 10 better than the 1985 atomic mass table adjustment [WAA85a]. We have rebuilt much of our apparatus, increasing the signal-to-noise ratio and im-proving the reliability of the machine. We have also reduced the typical time needed to make and cool a single ion from about half an hour to under 5 minutes. This was done by a combination of faster ion-making and a much faster procedure for driving out ions of the wrong species. The improved SIN, in combination with a much better signal processing algorithm to extract the ion phase and frequency from our data, has substantially reduced the time required for the actual measurements. This is important now that the measurement time is a substantial fraction of the cycle time (the time to make a new ion and measure it)