3 Higher harmonic interference: use QEPU Source polarization: linear (horiz., vert. or any angle in between), circular, or elliptical
4 Proposed NSLS-II soft x-ray undulator beamlines High fluxSoft x-ray imaging and coherent scatteringHigh resolutionSoft x-ray resonant magnetic and inelastic scattering (XRMS, RIXS)CoherentXRMSImagingRIXSSource: 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 High resolution soft x-ray undulator beamline : XRS, XRMS XRS, XRMS (x-ray resonant [magnetic] scattering) endstationScientific themes / drivers:1. Ordering Phenomena in Correlated Electron Materials2. Magnetic multilayers, superlattices & spintronic materials / devices3. Nanomagnetism: patterned & self-assembled4. “Soft” materials (e.g. complex polymers; C, N, O K-edges)Beamline requirements- small spot size>4 mm spot overfills ~100 mm 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, U4B2. ALS BL 4.0.13. APS 4-ID-C4. ESRF ID-08 (N. Brookes), Rogalev BL, XMaS5. Diamond: Peter Hatton endstation, BLADE6. BESSY-II: Helmut Zabel endstation7. Pohang LS: J-H Park BL8. Swiss Light Source9. Spring-8
6 High resolution soft x-ray undulator beamline : RIXS RIXS (resonant inelastic x-ray scattering) endstationScientific themes / drivers:1. Correlated Electron Materialslow energy excitations (excitions, orbitons, HTc “stripe” formation, etc.)field- and temperature-driven phase transitionsbulk sensitivity2. 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: SAXES6. ELETTRA: ComIXS, BACH beam line
7 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)Beamline requirements (with 2013-state-of-the-art optics)flux > 1013 photons/s on samplebeam size ~few m on pinholeresolving power ~104Comparable endstations (incomplete list)ALS – Cryo-capable Diffraction and Topography (transmission and reflectivity)ALS – Steve Kevan’s Flange-o-SaurusSSRL – speckle; EPUBESSYESRF - Goedkoop; Van der LaanNSLS - CCD based (transmission)Eisebit & Luening, Nature 432, (2004)
8 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 measurementsImaging 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.Beamline requirements (with 2013-state-of-the-art optics)resolving power ~104STXM: flux > 1012 photons/s on sample, beam size 10m x 10m on Fresnel zone plate (full transverse coherence), <10nm x <10nm on samplePEEM: flux > few x 1013 photons/s on sample, beam size ~few m on sampleMagnificationAcceleration, focusingand magnificationEnergy and angle selectionComparable endstations (incomplete list)NSLS/CFN, ALS, BESSY, ESRF, SLS, Trieste, Spring8, Pohang Light Source, Diamond, Soleil, HASYLAB, …PEEM
9 Soft x-ray beamline design: VLS PGM illuminated by collimated light Possible planarM1Rapid Switching: change M2 and M4Side ViewBeamlineHigh resolutionHigh fluxSource to M127m30mM1 to M21mM2 to M3PGM designM2 to grating~2mGrating to exit slit20m10mExit slit to M41.85mM4 to M50.5mM5 to sample1.0mTotal53.35m46.35mHorizontal Focusing by M :1
11 Calculated flux & resolving power Higher resolution beamline105 rp; 104 rpHigher flux beamline2104 rp; 5103 rpEach soft x-ray undulator beamline would be equipped with at least 3 gratings, interchangeable under computer control
12 3D schematic of soft x-ray undulator layout Cylindrical Collimating MirrorEPUElliptical cylinderKB refocusing mirrorsExit SlitExperimentalStationPlane MirrorPlane GratingBeam Chopper
14 To ensure complete overlap, defocus and/or Spot sizes on sample, dual (canted) undulator beamsNear, e.g. LCP, beamFar, e.g. RCP, beamh=200eV: h=2.2m, v=1.1mh=1000eV: h=2.4m, v=1.1mh=200eV: h=2.6m, v=1.1mh=1000eV: h=2.0m, v=1.1mTo ensure complete overlap, defocus and/ortrim with baffles
15 Comparisons of selected soft x-ray beamlines in the US
16 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 designExample soft x-ray scientific programs well matched to this beamline design: XRMS, RIXS, imaging, coherent scatteringActual 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, …).