Measurement of the beam bunch length in an electron storage ring using an avalanche photodiode

A simple method of measurement of the beam bunch length in an electron storage ring has been proposed. It measures the time profile of synchrotron radiation using an avalanche photodiode and, assuming a Gaussian profile for the bunch, the length σ L has been determined by fitting an equation representing the order dependence of the amplitude of the harmonics to the observed one, with the result that σ L =52 mm under normal operation condition. This value is in a fair agreement with that determined by the conventional method using a streak camera.