infrared experimental facilities for nsls ii larry carr for the nsls ii team: esp. d. arena, a....

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

BROOKHAVEN SCIENCE ASSOCIATES

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

• Biological , Chemical, Environmental, Materials, Space …– 4000 cm-1 (=2.5 m) to < 400 cm-1 (=25 m)

• 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 (=5 mm)


0 10 20 30 40 50 60 700

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X-Position [m]

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Fluid inclusions @ =3m | Miller et al

Mid and Far Infrared Microspectroscopy & Imaging

Forsterite (Fo100)

Clino-enstatite

Wavelength (m)

Ab

sorb

ance

20 30 40 50

L2005*A4

Microprobe (anticipate continued demand)Imaging (anticipate growth of this technique)


Science Requirements: THz / mm waves & Magnetism

H=12T

Antiferromagnetic Resonance in LaMnO3

D. Talbayev & L. Mihaly, Stony Brook

PRL 93 (July ‘04), PRB 69 (‘04)

Multiferroics A. Sirenko et al


Edge Radiation: viable alternative?

• Edge radiation emitted at transitions entering/exiting dipole magnets.

• Intrinsically bright, emission into 1/.• Radial polarization (complication).• Issues:

– two-edge interference, cancellation on-axis (U13 results in agreement).

– chamber cutoff due to narrow emission. Source radial size is .

For E = 3 GeV, source size at = 1mm is 6 meters (!)

– insufficient data to confirm cutoff effect.

• Not an extended source: Problems illuminating entire FPA detector.

chamber dimension

G.P. Williams et al, to be submitted

Inte

nsity

low

high


Infrared Extraction Schematic: NSLS II Dipole Bend

NSLS II bend radius 25 meters

rms= (34)1/3 Requirements for full angle (2xrms)

6 m 8 mrad100 m 20 mrad2 mm 54 mrad

Power load on 1st mirror = 1.2 kW(low critical energy of NSLS II bends helps)

Power density ~ 390 W/cm2 (narrow 1/ stripe) lower than 570 W/cm2 of NSLS U4IR, may not need slot or protective maskNote: does not consider edge radiation component

M1 Toroid

M2Plan

e

Note: includes 0° edge source 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)

2.6 meters


NSLS II Infrared Extraction: Toroidal First Mirror

Initial optical analysis: 6 m (1600 cm-1)

Source points along electron orbitToroidal mirror

R&D:mirror mat’l, finite element analysissurface figure, tolerances.range of adjustment, sensitivity to errors


Mid-IR for Chemical and Biological Probe 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

• Magnetic resonance1 T 1 cm-1 for 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

e Hutch services to includedry N2 gas and N2

Imaging Microscope w/FPAor

Cryostat / Magnet / Hi-Pressure cell

Dipole Bend

ExtractionOptics

Diamond Window

Matching & StabilizationOptics

Spectrometer &

Endstation(s)

Hutch Enclosure

1

2

3

IR Beamlines consist of 3 “sub-systems”1. Extraction (new components for NSLS II)2. Optical Matching and Transport (mostly new for NSLS II)3. End-station Instruments (e.g., spectrometers, cryostats, scopes)

– mostly from NSLS VUV/IR with assumption that they are being maintained at “state-of-the-art”.


Infrared Beamline Schematic (divided extraction)

e

Dipole Bend

ExtractionOptics

Diamond Window

Matching & StabilizationOptics

Hutch Enclosure(s)

Hutch services to includedry N2 gas and N2

2 or 3 probe endstationsindependently operating

20x20mrad to 12x12mrad(standard gap 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).


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)

• 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:1) Magnetospectroscopy / Spin Resonance2) Extreme pressures (diamond anvil cells, laser heating, cryo).3) 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

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

• Infrared has been one of the key users of the storage ring bunch structure for time-resolved studies.

• Issues:– Bunch lengths (BL for NSLS II will be 10s of picoseconds)– Pulse Rep. Frequencies & Synchronization to mode-locked lasers

• 500 MHz RF, harmonic number = 1300 • 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• 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.

infrared experimental facilities for nsls ii larry carr for the nsls ii team: esp. d. arena, a....

Documents

midir performance

extended source

source size

wcm2 of nsls u4ir

source points

nsls iilarry carrfor

ir beamlines brief

source radial size