TY - CPAPER AU - Decker, F.-J. AU - Colocho, W.S. AU - Ding, Y. AU - Iverson, R.H. AU - Loos, H. AU - Sheppard, J. AU - Smith, H. AU - Turner, J.L. TI - Photon Energies beyond the Selenium K-Edge at LCLS J2 - Proc. of FEL2015 AB - The Linac Coherent Light Source (LCLS) was designed for a photon energies of 830 eV to 8.3 keV. This range was widened and up to 11.2 keV photons were already delivered for users. The Selenium K-edge at 12.6578 keV is very interesting since Selenium can replace Sulfur in biological structures and then that structure could be precisely measured. To reach this the electron energy would need to be raised by about 6% which initially didn't seem possible. The trick is to change the final compression scheme from a high correlated energy spread and moderate R56 in the compression chicane to moderate energy spread and high R56. The same bunch length can be achieved and RF energy is freed up, so the overall beam energy can be raised. Photons up to an energy of 12.82 keV (1.3% above the K-edge) with a pulse intensity of 0.93 mJ were achieved. The photon energy spread with this setup is wider at around 40-50 eV FWHM, since less correlated energy spread is left after the compression. PB - JACoW CY - Geneva, Switzerland SP - 630 EP - 633 KW - FEL KW - photon KW - electron KW - operation KW - linac DA - 2015/12 PY - 2015 SN - 978-3-95450-134-2 DO - 10.18429/JACoW-FEL2015-WEP022 UR - http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/wep022.pdf ER -