NSLS-II Soft X-ray Undulator Beamlines Steve Hulberta Dario Arenaa Cecilia Sánchez-Hankea Ruben Reiningerb aBrookhaven National Laboratory bScientific Answers & Solutions, Madison, WI Cylindrical Collimating Mirror EPU Elliptical cylinder KB refocusing mirrors Exit Slit Experimental Station Plane Mirror Plane Grating Beam Chopper

NSLS-II source brightness

Higher harmonic interference: use QEPU Source polarization: linear (horiz., vert. or any angle in between), circular, or elliptical

Proposed NSLS-II soft x-ray undulator beamlines High flux Soft x-ray imaging and coherent scattering High resolution Soft x-ray resonant magnetic and inelastic scattering (XRMS, RIXS) Coherent XRMS Imaging RIXS 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.

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 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, U4B 2. ALS BL 4.0.1 3. 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

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, HTc “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

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 sample beam size ~few m on pinhole resolving power ~104 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) Eisebit & Luening, Nature 432, 885-888 (2004)

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. Beamline requirements (with 2013-state-of-the-art optics) resolving power ~104 STXM: flux > 1012 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 1013 photons/s on sample, beam size ~few m on sample Magnification Acceleration, focusing and magnification Energy and angle selection Comparable endstations (incomplete list) NSLS/CFN, ALS, BESSY, ESRF, SLS, Trieste, Spring8, Pohang Light Source, Diamond, Soleil, HASYLAB, … http://xraysweb.lbl.gov/peem2/PEEM2-02.html PEEM

Soft x-ray beamline design: VLS PGM illuminated by collimated light Possible planarM1 Rapid Switching: change M2 and M4 Side View Beamline High resolution High flux Source to M1 27m 30m M1 to M2 1m M2 to M3 PGM design M2 to grating ~2m Grating to exit slit 20m 10m Exit slit to M4 1.85m M4 to M5 0.5m M5 to sample 1.0m Total 53.35m 46.35m Horizontal Focusing by M4 -- 52:1

Sample spot size and divergence Req’d figure error 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 100nrad RMS planes 0.5rad RMS Elliptical, cylinder meridional Req’d figure error

Calculated flux & resolving power Higher resolution beamline 1010’s @ 105 rp; 1012’s @ 104 rp Higher flux beamline 1012’s @ 2104 rp; 1013’s @ 5103 rp Each soft x-ray undulator beamline would be equipped with at least 3 gratings, interchangeable under computer control

3D schematic of soft x-ray undulator layout Cylindrical Collimating Mirror EPU Elliptical cylinder KB refocusing mirrors Exit Slit Experimental Station Plane Mirror Plane Grating Beam Chopper

Canted undulator optical schematic, polarization switching Side view Single beam mode M5 M2 M3 Exit slit M4 M1 Planar gratings RCP LCP RCP LCP M5 Exit slit Top view Single beam mode M3 M4 M2 Planar gratings M1 Mechanical Chopper M5 Top view Fast switching mode M3 M4 Exit slit M2 RCP LCP Planar gratings M1 RCP LCP

To ensure complete overlap, defocus and/or Spot sizes on sample, dual (canted) undulator beams Near, e.g. LCP, beam Far, e.g. RCP, beam 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 To ensure complete overlap, defocus and/or trim with baffles

Comparisons of selected soft x-ray beamlines in the US

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, …).