We describe a simple closed loop system for beam position stabilization on an electron storage ring. The system using a differential photoresistive cell for the beam position detector reacts on the beam through appropriate dipole correctors. Typical lsensitivity of this cell is 10 mV per micron with less than one mV noise. Results obtained on ACO show that the position of a beam could be stabilized by a few microns and that the efficiency of the system is determined only by the quality of the cell and the mechanical stability of its support. A set of four identical systems will be installed on DCI which operation in space charge compensation implies a good steering of orbits in the common parts of the machine. Preliminary tests on DCI are reported. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.
