Study of the Fluorescence Yield for Electrons between 0.5 2.2 MeV

The fluorescence yield in air is an important parameter for the reconstruction of air showers events. The new generation of air fluorescence experiments demands for a better precision of the fluorescence yield, and several efforts are being done to get it. We present some preliminary results of measurements performed at University of Campinas. Using 90 Sr as source of electrons and a prototype chamb er we obtained firsts measurements of the fluorescence light produced in nitrogen and in dry air. The analysis is aided by a detailed Monte Carlo simulation