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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


Infrared outline l.jpg
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

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


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)

H=12T


Edge radiation viable alternative l.jpg

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


Infrared extraction schematic nsls ii dipole bend l.jpg

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)


Nsls ii infrared extraction toroidal first mirror l.jpg
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


Mid ir for chemical and biological m probe and imaging l.jpg
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


Magnetospectroscopy millimeter spectral range l.jpg
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%.


Infrared beamline schematic l.jpg
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


Infrared beamline schematic divided extraction l.jpg
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


Nsls ii infrared capacity l.jpg
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).


Nsls ii infrared capacity cont d l.jpg
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?


Illuminating an imaging fpa detector with mid ir dipole bend radiation l.jpg
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).


Rf buckets bunches and timing l.jpg
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?


Summary l.jpg
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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