3 ms·

I was very curious about "the only approved outdoor LINAC...". I presume it's what this article describes? http://galprop.stanford.edu/elibrary/icrc/2011/pape

• batbomb 11y ago
  Yep, that's it. We used to calibrate with laser shots into the night sky, but direct excitation of the sky with the LINAC is much better, because you are directly measuring fluorescence.