An improved method for the measurement of alpha‐ray sources, using the luminescence of fluorescent screens, is described. The improvements consist of the use of a multiplier photo‐tube and long lived non‐emanating alpha‐standards. The chief advantage of the multiplier photo‐tube is its great flexibility, allowing quite an extensive range of measurements. Alpha‐ray sources, ranging from110&mgr;Cup to a few curies, can thus be measured, in a much quicker fashion than either the ionization or calorimetric method would permit. The standardization procedure of the photo‐tube for measurements of absolute intensity is described in detail, the accuracy of the results being estimated at 5 percent. New applications of this method to the preparation of photometric standards and to the measurements of strong neutron sources are suggested.