Non-gaussian beam tails at the Advanced Light Source
- Author(s): Zholents, A.
- Decking, W.
- et al.
The coordinate and energy distributions of the electron beam density at the Advanced Light Source have been obtained from measurements of the beam lifetime at various storage-ring apertures in the horizontal and vertical planes. It is shown that these distributions have a gaussian core extended approximately up to five rms beam sizes. Beyond this point the electron density is defined by the electron scattering on the residue gas and electron intra-beam scattering and decreases as the cubic of the distance from the beam center. This behavior continues approximately up to ~;30 rms beam sizes in the horizontal plane and ~;60 rms beam sizes in the vertical plane. The horizontal and vertical emittances obtained from the measurements near the beam core suggest a presence of ~; 8.5 percent coupling in the ring at the time of measurements.