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TY - UNPB AU - Min, C.-K. AU - Cho, M.H. AU - Heo, H. AU - Kang, H.-S. AU - Kim, C. AU - Kim, G. AU - Kim, K. AU - Kim, M.J. AU - Ko, J.H. AU - Na, D.H. AU - Nam, I.H. AU - Oh, B.G. AU - Rah, S.Y. AU - Shim, C.H. AU - Shu, D. AU - Shvyd'ko, Yu. AU - Suh, Y.J. AU - Yang, H. ED - Schaa, Volker R.W. ED - Decking, Winfried ED - Sinn, Harald ED - Geloni, Gianluca ED - Schreiber, Siegfried ED - Marx, Michaela TI - Hard X-Ray Self-Seeding at PAL-XFEL J2 - Proc. of FEL2019, Hamburg, Germany, 26-30 August 2019 CY - Hamburg, Germany T2 - Free Electron Laser Conference T3 - 39 LA - english AB - A hard X-ray self-seeding utilizing time-delayed forward Bragg diffracted photons from thin diamond crystals has been successfully commissioned in a broad spectral range (3.5~14.4 keV), and will be soon provided to user experiments. In the self-seeded mode, the spectral bandwidth is typically 0.2~0.5 eV FWHM in contrast to SASE mode, in which the spectral bandwidth is around 20 eV. This implies that the seeded FEL can be a single longitudinal mode laser since the number of longitudinal mode is 100~200 in the SASE operation. In this case, the photon number of filtered FEL is expected to be fluctuated 100% from the narrow bandwidth filtering out of random and spiky SASE spectra. We found that our energy stability of electron bunches (10⁻⁴) do not degrade much the seeding performance and the large variation of the seeded FEL intensity will be from the seeding probability. The advantages of 30 um thin diamond crystal and diagnostic tool for the self-seeding will be also presented. PB - JACoW Publishing CP - Geneva, Switzerland ER -