First Lasing of the Lcls X-ray Fel at 1.5 Å

The Linac Coherent Light Source (LCLS) is a SASE 1.5-15 Å x-ray Free-Electron Laser (FEL) facility under construction at SLAC [1], and presently in an advanced phase of commissioning. The injector, linac, and new bunch compressors were commissioned in 2007 [2] and 2008 [3], establishing the necessary electron beam brightness at 14 GeV. The final phase of commissioning, including the FEL undulator and the long transport line from the linac, began in November 2008, with first 1.5-Å FEL light and saturation observed in mid-April 2009. We report on the accelerator, undulator, and FEL operations, although prior to the availability of the full x-ray diagnostics suite, which will not be ready until June 2009.