Characteristics are described for the collection of cyclotron beams in a conducting medium separated from the accelerator by an insulating window. The measured current can be interpreted in terms of an absolute beam current if charge displacement within the insulator is taken into account. Collection of the beam in this manner is particularly advantageous in a region external to the cyclotron magnetic field where stray currents due to air ionization and secondary electron emission are pronounced. A comparison is made between particle energies determined by the charge‐input method and by calorimetry. A simplified arrangement for particle range determination is described.