  The potential for neutrino telescopes to discover charged stau production in
neutrino-nucleon interactions in Earth depends in part on the stau lifetime and
range. In some supersymmetric scenarios, the next lightest supersymmetric
particle is a stau with a decay length on the scale of 10 km. We evaluate the
electromagnetic energy loss as a function of energy and stau mass. The energy
loss parameter $\beta$ scales as the inverse stau mass for the dominating
electromagnetic processes, photonuclear and $e^+e^-$ pair production. The range
can be parameterized as a function of stau mass, initial energy and minimum
final energy. In comparison to earlier estimates of the stau range, our results
are as much as a factor of two larger, improving the potential for stau
discovery in neutrino telescopes.
