3 BROOKHAVEN SCIENCE ASSOCIATES Higher harmonic interference: use QEPU Source polarization: linear (horiz., vert. or any angle in between), circular, or elliptical
4 BROOKHAVEN SCIENCE ASSOCIATES Proposed NSLS-II soft x-ray undulator beamlines High resolution Soft x-ray resonant magnetic and inelastic scattering (XRMS, RIXS) High flux Soft x-ray imaging and coherent scattering XRMS RIXS Imaging Coherent Source: Two 2m-long EPUs (EPU42 or EPU45) located in a 5m NSLS-II straight section. Operating modes: (1) uncanted and phased as a single 4m-long EPU, or (2) canted, by ~0.25 mrad, for fast-switching polarization capability.
5 BROOKHAVEN SCIENCE ASSOCIATES High resolution soft x-ray undulator beamline : XRS, XRMS XRS, XRMS (x-ray resonant [magnetic] scattering) endstation Scientific themes / drivers: 1.Ordering Phenomena in Correlated Electron Materials 2.Magnetic multilayers, superlattices & spintronic materials / devices 3.Nanomagnetism: patterned & self-assembled 4.“Soft” materials (e.g. complex polymers; C, N, O K-edges) Beamline requirements - small spot size >4 m spot overfills ~100 m crystal at critical angle of ~4° (h =700eV) - high energy resolution (select different multiplet states) - high flux (detect weak, diffuse features in scattered beam) Comparable endstations (incomplete list) 1. NSLS X1B, X13A, U4B 2. ALS BL APS 4-ID-C 4. ESRF ID-08 (N. Brookes), Rogalev BL, XMaS 5. Diamond: Peter Hatton endstation, BLADE 6. BESSY-II: Helmut Zabel endstation 7. Pohang LS: J-H Park BL 8. Swiss Light Source 9. Spring-8
6 BROOKHAVEN SCIENCE ASSOCIATES High resolution soft x-ray undulator beamline : RIXS RIXS (resonant inelastic x-ray scattering) endstation Scientific themes / drivers: 1.Correlated Electron Materials low energy excitations (excitions, orbitons, HT c “stripe” formation, etc.) field- and temperature-driven phase transitions bulk sensitivity 2.Organic molecules (incl. fullerenes, nanotubes) Beamline requirements - Small spot size (collect large solid angle, possibly no entrance slit) - Very good energy resolution (precise selection of initial state) - Highest flux possible (very low inelastic cross section) Comparable endstations (incomplete list) 1.NSLS X1B (commercial Scienta analyzer) 2.MAX-III (J. Nordgren program) 3.ALS beamlines 7.0.1, 8.0.1, MERLIN (lower energy) 4.ESRF: AXES instrument (U. of Milan) 5.Swiss Light Source: SAXES 6.ELETTRA: ComIXS, BACH beam line
7 BROOKHAVEN SCIENCE ASSOCIATES High flux soft x-ray undulator beamline : Coherent Scattering Techniques: scattering, diffraction, coherent SAXS, diffraction imaging, holography,… Scientific themes / drivers: image the mesoscopic non-crystalline world (few x 10nm resolution), e.g. large cells, magnetic domains, … measure time-dependent fluctuations in materials (correlated spectroscopy) 3D imaging of granular materials (with grains around 30 nm) Eisebit & Luening, Nature 432, (2004) Beamline requirements (with 2013-state-of-the-art optics) -flux > photons/s on sample -beam size ~few m on pinhole -resolving power ~10 4 Comparable endstations (incomplete list) ALS – Cryo-capable Diffraction and Topography (transmission and reflectivity) ALS – Steve Kevan’s Flange-o-Saurus SSRL – speckle; EPU BESSY ESRF - Goedkoop; Van der Laan NSLS - CCD based (transmission)
8 BROOKHAVEN SCIENCE ASSOCIATES High flux soft x-ray undulator beamline : Microscopy Techniques: STXM, phase contrast scope, full field scope, PEEM, spectro- scopy, … Scientific themes / drivers: Imaging nano- and mesoscopic world, simultaneous spectroscopic measurements Imaging of single nano-elements, nano-contacts, or nano-magnets, to understand isolated behavior (no collective phenomena) Structural and electronic information, differences between boundaries/interfaces and bulk. Magnification Acceleration, focusing and magnification Energy and angle selection Beamline requirements (with 2013-state-of-the-art optics) -resolving power ~10 4 -STXM: flux > photons/s on sample, beam size 10 m x 10 m on Fresnel zone plate (full transverse coherence), <10nm x <10nm on sample -PEEM: flux > few x photons/s on sample, beam size ~few m on sample Comparable endstations (incomplete list) NSLS/CFN, ALS, BESSY, ESRF, SLS, Trieste, Spring8, Pohang Light Source, Diamond, Soleil, HASYLAB, … PEEM
9 BROOKHAVEN SCIENCE ASSOCIATES Soft x-ray beamline design: VLS PGM illuminated by collimated light Side View Horizontal Focusing by M :1 Rapid Switching: change M2 and M4 Possible planarM1 BeamlineHigh resolution High flux Source to M127m30m M1 to M21m M2 to M3PGM design M2 to grating~2m Grating to exit slit20m10m Exit slit to M41.85m M4 to M50.5m M5 to sample1.0m Total53.35m46.35m
10 BROOKHAVEN SCIENCE ASSOCIATES Sample spot size 100nrad RMS planes 0.5 rad RMS Elliptical, cylinder meridional h =200eV: h =2.3 m, v =1.1 m h =1000eV: h =2.1 m, v =1.1 m h =200eV: h ’=1.1mrad, v ’=0.44mrad h =1000eV: h ’=0.8mrad, v ’=0.3mrad Req’d figure error and divergence
11 BROOKHAVEN SCIENCE ASSOCIATES Calculated flux & resolving power Higher resolution beamline rp; rp Higher flux beamline 10 4 rp; 10 3 rp Each soft x-ray undulator beamline would be equipped with at least 3 gratings, interchangeable under computer control
13 BROOKHAVEN SCIENCE ASSOCIATES M2 RCP LCP M1 M3 M5 Side view Single beam mode M5 Top view Single beam mode M1 M3 Top view Fast switching mode M1 M3 Planar gratings M4 RCP LCP Planar gratings M4 M2 Planar gratings RCP LCP RCP LCP M2 M5 M4 Mechanical Chopper Canted undulator optical schematic, polarization switching Exit slit
14 BROOKHAVEN SCIENCE ASSOCIATES h =200eV: h =2.2 m, v =1.1 m h =1000eV: h =2.4 m, v =1.1 m h =200eV: h =2.6 m, v =1.1 m h =1000eV: h =2.0 m, v =1.1 m Spot sizes on sample, dual (canted) undulator beams Near, e.g. LCP, beam Far, e.g. RCP, beam To ensure complete overlap, defocus and/or trim with baffles
15 BROOKHAVEN SCIENCE ASSOCIATES Comparisons of selected soft x-ray beamlines in the US
16 BROOKHAVEN SCIENCE ASSOCIATES NSLS-II soft x-ray undulator beamlines High-resolution, high-flux, polarization-switchable, soft x-ray beamline design, well matched to the high- brightness NSLS-II accelerator design Example soft x-ray scientific programs well matched to this beamline design: XRMS, RIXS, imaging, coherent scattering Actual buildout of soft x-ray beamlines will be based on the NSLS-II scientific program, including input from all stakeholders (NSLS-II staff, EFAC, NSLS-II users, …).