Comparison of air fluorescence and ionization measurements of E.M.   shower depth profiles: test of a UHECR detector technique
  Measurements are reported on the fluorescence of air as a function of depth in electromagnetic showers initiated by bunches of 28.5 GeV electrons. The light yield is compared with the expected and observed depth profiles of ionization in the showers. It validates the use of atmospheric fluorescence profiles in measuring ultra high energy cosmic rays. 
J.Belz, Z.Cao, P.Huentemeyer, C.C.H.Jui, K.Martens, J.Matthews,   M.Maestas, J.Smith, P.Sokolsky, R.W.Springer, J.Thomas, S....