Picosecond Phase Shift Measurements at 358 MHz Using Synchrotron Radiation

Abstract

For our purposes the most important property of synchrotron radiation is the time modulation of the emitted intensity, although it possesses many other qualities, such as broad spectral range, high brightness and 100% polarisation, which are being extensively utilised in many research fields [1,2]. The radiation from, the S.R* is modulated in exactly the same manner in which the electron beam is modulated. The electron pulse or bunch shape is nominally Gaussian [3] and is determined by S.R. parameters. The bunch length increases with stored current, this effect being different from one S.R. to another [4]. The S.R. radio frequency is an integer multiple of the revolution frequency, this being a constant since the electrons are highly relativistic (v/c ≈.9999998). It is possible to have as many electron or positron bunches around the ring as the RF harmonic number, which is 280 in SPEAR. In our experiments SPEAR ran with only one circulating bunch, and we discuss this case.