Measurement of the Charged Kaon Mass Using the MIPP RICH

The current charged kaon mass of $493.677$ MeV $\pm26$ parts per million (ppm) is dominated by two measurements of kaonic atom x-ray energies. These measurements have precisions of 14 and 22 ppm, respectively, and differ by 122 ppm. Given its importance in measurements of $V_{us}$ from $K^{+}$ decay, resolution of the ambiguity in charged kaon mass measurements is needed. This talk describes a method for making a measurement with 40 ppm statistical precision from the correlation between $p$, $\pi$, and $K$ RICH radii and precisely known values of proton and pion masses. Analysis of data from the Main Injector Particle Production (MIPP) experiment taken during spring 2006 at Fermilab is presented.