Journal of large-scale research facilities, 2, A96 (2016) http://dx.doi.org/10.17815/jlsrf-2-92 Published: 25.11.2016 The crystal monochromator beamline KMC-1 at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientist: - Dr. Franz Schäfers, Helmholtz-Zentrum Berlin für Materialien und Energie, phone +49 30 8062 –12946, email: franz.schaefers@helmholtz-berlin.de Abstract: The KMC-1 is a soft x-ray double crystal monochromator beamline for the energy range be- tween 2 and 12 keV. The bending magnet beamline as well as the experiment are under UHV-condition. It incorporates high indexed Si-crystals for high resolution and it is primarily used for HAXPES exper- iments employing the HIKE (High Kinetic Energy Photoelectron Spectroscopy) chamber. 1 Introduction The crystal monochromator beamline KMC-1 (Schaefers et al., 2007) at a BESSY II bending magnet covers the energy range from soft (2 keV) to hard x-rays (12 keV) employing the n,-n double crystal arrangement with constant beam o�set. The monochromator is equipped with three sets of crystals, Si (111), Si (311) and Si (422) which are exchangeable in-situ. Beamline and monochromator have been optimized for high �ux and high resolution. The beamline and experiment are under UHV-condition. The multipurpose beamline is used for techniques such as hard x-ray high kinetic photoelectron spec- troscopy (HIKE or HAXPES), (Bio)-EXAFS, NEXAFS, absorption, re�ection and �uorescence spec- troscopy. Due to the windowless UHV-setup the k-edges of the technologically and biologically im- portant elements such as P, and S are accessible. The photon �ux is in the 1011–1012 photons/s range and a resolving powers E/∆E of more than 100.000 has been measured at selected energies. Thus, HAX- PES with a total instrumental resolution of about 150 meV is possible at selected energies. The beamline is not permanently equipped with a particular experimental station but rather varying user experiments are connected to it according to the beamtime schedule. Based on the allocated beam- time the HIKE end station is the main user of the KMC-1 beamline (Gorgoi et al., 2009). *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2016). The crystal monochromator beamline KMC-1 at BESSY II. Journal of large-scale research facilities, 2, A96. http://dx.doi.org/10.17815/jlsrf-2-92 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-2-92 http://dx.doi.org/10.17815/jlsrf-2-92 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A96 (2016) http://dx.doi.org/10.17815/jlsrf-2-92 Figure 1: Top-view of beamline KMC-1. 2 http://dx.doi.org/10.17815/jlsrf-2-92 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-2-92 Journal of large-scale research facilities, 2, A96 (2016) 2 Instrument Applications Typical applications are: • HAXPES (Hard X-Ray Photoelectron Spectroscopy) • EXAFS, NEXAFS, XANES • Di�ractometry • Re�ectometry 3 Source The source is the bending magnet D1.1 with the following parameters: Electron energy [GeV] 1.7 Magnetic �eld [T] 1.3 Bending radius [m] 4.35 Power on 1st optical element (300 mA) [W] 45 Critical energy [keV] 2.5 Source horizontal size (σ 4x) [µ m] 96 vertical size (σ y) [µ m] 47 Source hor. divergence (σ x) [µ rad] 300 vert. divergence (σ y) [µ rad] 20 Table 1: BESSY II source characteristics of the dipole section DIP 1.1. 4 Optical Design The beamline and the double crystal monochromator KMC-1 have been optimized for highest possible �ux and high resolution (Schaefers et al., 2007). This was achieved by (1) a windowless setup under ultrahigh-vacuum (UHV-) conditions up to the experiment, (2) by the use of only three optical ele- ments to minimize re�ection losses, (3) by collecting an unusually large horizontal radiation fan from the bending magnet (6 mrad) with the one and only toroidal mirror, and (4) the optimization of the crys- tal optics to the soft x-ray range necessitating quasi-backscattering crystal geometry (θ Bragg,max=82°) delivering crystal limited resolution. 5 Technical data Location 3.1 Source D1.1 Monochromator KMC-1 Energy range 2 – 12 keV Polarisation horizontal Divergence horizontal 3 mrad Divergence vertical 0.2 mrad Focus size (hor. x vert.) 0.4 x 0.6 mm Distance Focus/last valve 670 mm Height Focus/�oor level 1728 mm Free photon beam available Yes Fixed end station No Table 2: Technical data of Beamline KMC-1. 3 http://dx.doi.org/10.17815/jlsrf-2-92 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A96 (2016) http://dx.doi.org/10.17815/jlsrf-2-92 Figure 2: Optical layout of beamline KMC-1. Figure 3: Photon �ux at the sample position, normalized to 100 mA ring current. Typically BESSY-II runs with 300 mA. 4 http://dx.doi.org/10.17815/jlsrf-2-92 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-2-92 Journal of large-scale research facilities, 2, A96 (2016) Figure 4: Energy resolution of the KMC-1 beamline for the di�erent crystals. References Gorgoi, M., Svensson, S., Schäfers, F., Öhrwall, G., Mertin, M., Bressler, P., . . . Eberhardt, W. (2009). The high kinetic energy photoelectron spectroscopy facility at BESSY progress and �rst results. Nu- clear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 601(1–2), 48 - 53. http://dx.doi.org/10.1016/j.nima.2008.12.244 Schaefers, F., Mertin, M., & Gorgoi, M. (2007). KMC-1: A high resolution and high �ux soft x-ray beamline at BESSY. Review of Scienti�c Instruments, 78(12). http://dx.doi.org/10.1063/1.2808334 5 http://dx.doi.org/10.17815/jlsrf-2-92 http://dx.doi.org/10.1016/j.nima.2008.12.244 http://dx.doi.org/10.1063/1.2808334 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument Applications Source Optical Design Technical data