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Infrared Experimental Facilities for NSLS II

Infrared Experimental Facilities for NSLS II. Larry Carr for the NSLS II Team: esp. D. Arena, A. Blednyk, J. Hill, C. Homes, S. Hulbert, E. Johnson, L. Miller, S. Pjerov NSLS - Brookhaven Nat’l Lab. Infrared Outline. Science & Technique Requirements for IR Beamlines (brief)

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Infrared Experimental Facilities for NSLS II

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  1. Infrared Experimental Facilities for NSLS II Larry Carr for the NSLS II Team: esp. D. Arena, A. Blednyk, J. Hill, C. Homes, S. Hulbert, E. Johnson, L. Miller, S. Pjerov NSLS - Brookhaven Nat’l Lab

  2. Infrared Outline • Science & Technique Requirements for IR Beamlines (brief) • Getting the Required Performance from NSLS II • Special Optics • Beamline layout / schematic : endstation instrumentation • Environment (noise: vibration, EMI, etc.) • Short bunches and timing

  3. Science and IR Source Requirements • Biological , Chemical, Environmental, Materials, Space … • 4000 cm-1 (l=2.5 mm) to < 400 cm-1 (l=25 mm) • mid and far-IR microprobe • mid-IR chemical imaging (raster scanning -> area imaging) • Imaging needs an extended source to optimally illuminate. • Materials (especially under extreme conditions) • Mostly “single point” spectroscopy • high pressures and temperatures • laser pump-probe • cryospectroscopy • high magnetic fields, spin resonance • 4000 cm-1 down to ~ 2 cm-1 (l=5 mm)

  4. Clino-enstatite Absorbance Forsterite (Fo100) L2005*A4 Wavelength (mm) Mid and Far Infrared Microspectroscopy & Imaging Imaging(anticipate growth of this technique) Microprobe(anticipate continued demand) Fluid inclusions @ l=3mm | Miller et al

  5. Multiferroics A. Sirenko et al Science Requirements: THz / mm waves & Magnetism Antiferromagnetic Resonance in LaMnO3 D. Talbayev & L. Mihaly, Stony Brook PRL 93 (July ‘04), PRB 69 (‘04) H=12T

  6. high Intensity low lg ~ chamber dimension Edge Radiation: viable alternative? • Edge radiation emitted at transitions entering/exiting dipole magnets. • Intrinsically bright, emission into 1/g. • Radial polarization (complication). • Issues: • two-edge interference, cancellation on-axis (U13 results in agreement). • chamber cutoff due to narrow emission. Source radial size is lg. For E = 3 GeV, source size at l = 1mm is 6 meters (!) • insufficient data to confirm cutoff effect. • Not an extended source: Problems illuminating entire FPA detector. G.P. Williams et al, to be submitted

  7. 2.6 meters M2 Plane M1 Toroid Note: includes 0° edge source Infrared Extraction Schematic: NSLS II Dipole Bend Power load on 1st mirror = 1.2 kW(low critical energy of NSLS II bends helps) Power density ~ 390 W/cm2 (narrow 1/g stripe)-> lower than 570 W/cm2 of NSLS U4IR, may not need slot or protective mask Note: does not consider edge radiation component NSLS II bend radius r= 25 meters qrms= (3l/4pr)1/3 Requirements for full angle (2xqrms) l = 6 mm->8 mrad l = 100 mm->20 mrad l = 2 mm->54 mrad • Enables large horizontal collection of ~ 50 mrad • Standard dipole chamber -> 16 mrad vertical (suitable for mid-IR, can divide horizontal) • Large gap magnet dipole chamber -> 32 mrad vertical (needed for far-IR)

  8. NSLS II Infrared Extraction: Toroidal First Mirror • Initial optical analysis: • = 6 mm (1600 cm-1) R&D: mirror mat’l, finite element analysis surface figure, tolerances. range of adjustment, sensitivity to errors Toroidal mirror Source points along electron orbit

  9. Mid-IR for Chemical and Biological mProbe and Imaging NSLS II outperforms existing VUV/IR for brightness over most of mid-IR due to lower emittance. Essentially same mid-IR performance for Standard and Large Gap dipoles. NSLS II VUV/IR

  10. Magnetospectroscopy & Millimeter Spectral Range • Magnetic resonance1 T -> 1 cm-1for typical spin. • Standard NSLS-II dipole and chamber yields less than 2% of the flux from the VUV Ring at 3 cm-1. • NSLS II Large Gap provides 37% of VUV ring (@ 3 cm-1). Could be made better than VUV by increasing vertical dimension another 50%.

  11. Infrared Beamline Schematic IR Beamlines consist of 3 “sub-systems” • Extraction (new components for NSLS II) • Optical Matching and Transport (mostly new for NSLS II) • End-station Instruments (e.g., spectrometers, cryostats, mscopes) • mostly from NSLS VUV/IR with assumption that they are being maintained at “state-of-the-art”. Hutch Enclosure 3 2 Spectrometer & Endstation(s) Matching & StabilizationOptics 1 e Hutch services to include dry N2 gas and lN2 Diamond Window Dipole Bend Imaging Microscope w/FPA or Cryostat / Magnet / Hi-Pressure cell ExtractionOptics

  12. Infrared Beamline Schematic (divided extraction) Mid IR microprobe endstations can work with 16mrad by 16mrad extraction, so 50mrad of horizontal can be divided into 2 or 3 independently operation beamlines (similar to U10A/B and U2A/B infrared beamlines at NSLS VUV/IR ring). Hutch Enclosure(s) Matching & StabilizationOptics e Hutch services to include dry N2 gas and lN2 Diamond Window Dipole Bend 2 or 3 mprobe endstations independently operating 20x20mrad to 12x12mrad(standard gap extraction) ExtractionOptics

  13. NSLS II Infrared Capacity • Accelerator design includes 5 (=10/2) large (vertical) gap dipole magnets and chambers, and 5 standard dipole chambers, for IR. All ports will extract both dipole bend and edge radiation. • Issues: • detailed dipole chamber design and beam impedance calculations. • optics for a) extraction and b) matching to instruments and endstations. • Standard dipole chambers for mid-IR (five total). • 50 mrad horizontal. • 12 to 20 mrad vertical extraction (16 mrad average). • Up to 3 independent microprobe endstations or 1 FPA imaging endstation. • Plan to develop mid-IR beamlines on 3 extractions: • 2 or 3 Microprobe endstations sharing one port (horizontal split). • 2 FPA Imaging spectrometers each on its own port (two ports) • leaves 2 more ports available for growth. • Located in proximity to other Biological / Imaging beamlines (x-ray).

  14. NSLS II Infrared Capacity (cont’d) • Large gap dipole chambers for far-IR (five total). • 50 mrad horizontal • 24 to 40 mrad vertical (32 mrad average). • Single endstation per extraction. • Plan to develop 3 far-IR beamlines and endstations on 3 extractions: • Magnetospectroscopy / Spin Resonance • Extreme pressures (diamond anvil cells, laser heating, cryo). • Time-resolved (pump-probe with laser, cryo). Proximity to slicing? • Capacity for 2 additional (future) beamlines • Even larger vertical extraction opportunity?

  15. Illuminating an Imaging FPA Detector with mid-IR Dipole Bend Radiation R&D activity: • Dipole bend synchrotron radiation is an extended source when horizontal collection exceeds natural opening angle for emission. • NSLS II ports will extract 50 mrad horizontal. Natural angle (diffraction) at 1600 cm-1 is 8 mrad. • 6 : 1 aspect ratio. • Develop anamorphic optical system to “re-shape” beam footprint to match FPA. • Might be a simple spherical mirror used off-axis (1 meter f.l. at 5 degrees incidence, defocus slightly).

  16. RF Buckets, Bunches and Timing • Infrared has been one of the key users of the storage ring bunch structure for time-resolved studies. • Issues: • Bunch lengths (sBL for NSLS II will be 10s of picoseconds) • Pulse Rep. Frequencies & Synchronization to mode-locked lasers • 500 MHz RF, harmonic number = 1300 (=2*2*5*5*13) • Ti:Sapp prefers 76 to 82 MHz, more options with fiber lasers • note: 500MHz/13 -> PRF= 38.4 MHz = 76MHz/2 • 2 ns between pulses typically too short (need 10 ns minimum) • filling 100 symmetric buckets yields 26 ns • Jitter (bunches relative to RF, to each other) below 5% of bunch RMS • Compatibility with overall operations • constraints on current, lifetime, orbit/lattice (iterations with accelerator group) • Other options for consideration: • laser slicing and location relative to undulator/modulator. • crab cavities: not useful for IR?

  17. Summary • Infrared extraction design idea developed: challenging optical design, but appears feasible • higher mid-IR brightness than existing NSLS VUV/IR • extended dipole source for Imaging / FPA detector based instruments • competitive very far-IR performance • Capacity for growth, plus synergy with overall SR community: • 5 ports each for mid and far IR, plan to develop 3 each during early phases of NSLS II Ops. • Noise: need to minimize mechanical and electrical noise. • low frequency noise from pumps, motors, AC line. • RF sideband noise: intrinsically smaller with 500 MHz SC RF? • beam stabilization to remove residual motion. • goal: 10 to 100 times smaller than existing NSLS. • Top-off injection: compatible with high spectral resolution measurements? • Location: (attention paid to lab support facilities and slicing option) • Hutches: are quite necessary, but typically not for personnel protection. • control atmospheric (humidity) and acoustic environment. • laser safety, magnet fields. • good for optical alignment.

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