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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 l.jpg

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

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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

Science and ir source requirements l.jpg
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)

Mid and far infrared microspectroscopy imaging l.jpg



Forsterite (Fo100)


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

Science requirements thz mm waves magnetism l.jpg

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)


Edge radiation viable alternative l.jpg




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

Infrared extraction schematic nsls ii dipole bend l.jpg

2.6 meters



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)

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NSLS II Infrared Extraction: Toroidal First Mirror

  • Initial optical analysis:

  • = 6 mm (1600 cm-1)


mirror mat’l, finite element analysis

surface figure, tolerances.

range of adjustment, sensitivity to errors

Toroidal mirror

Source points along electron orbit

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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.



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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%.

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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



Spectrometer & Endstation(s)

Matching & StabilizationOptics



Hutch services to include

dry N2 gas and lN2

Diamond Window

Dipole Bend

Imaging Microscope w/FPA


Cryostat / Magnet / Hi-Pressure cell


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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


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)


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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).

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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?

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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).

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RF Buckets, Bunches and Timing Radiation

  • 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?

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Summary Radiation

  • 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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