Third-generation electron beams at the accelerator test facility for JLC

The purpose of the ATF is to develop beams with very small transverse and longitudinal emittances. A 1.37 nm horizontal emittance was confirmed by emittance measurements using wire scanners in the extraction line and a measurement of the horizontal spacial coherence using an SR interferometer. This paper reports on the transverse emittance ratio and gives a discussion on an extreme intra-beam scattering effect. It also describes some problems which should be overcome.