inelastic scattering beamline update

1 BROOKHAVEN SCIENCE ASSOCIATES

Inelastic Scattering Beamline Update

Yong CaiInelastic X-ray Scattering Group

Experimental Facilities Division, NSLS-II Experimental Facilities Advisory Committee Meeting

April 23-24, 2009


Outline

• Beamline Overview• Technical Requirements• Progress Since Last EFAC• Conceptual Design• Insertion Device Optimization• Performance Issues• Budget and Schedule• Outlook (Near Term)


Beamline Overview• IXS experiments at extremely high resolution of 0.1 meV at ~10 keV A key goal of NSLS-II Bridging partially the dynamical gap between existing high and low frequency probes• Proposal from BAT: two instruments based on the new optical design

Ultrahigh (0.1 meV) resolutionHigh resolution (0.5-1 meV)

– Improved resolution tailsE ~ 9 keV

– Well matched to NSLS-II undulator performance– Count rate issues (see later)

• Scientific areasCollective dynamics in liquids, glassy and biomolecular systemsPhonons in single crystals, surfaces, thin films, high pressure systems, small

samples


Technical Requirements• Incident flux at sample > 109 photons/sec/0.1meV

State-of-the-art Instruments: ~109 photons/sec/1meV• Energy resolution: 0.1 meV and 0.5~1 meV

Sharp resolution tail offered by the new scheme• Q range / resolution:

Disordered/confined systems: 0.02 ~ 10 nm-1 / 0.01 nm-1

Soft matter: 0.1 ~ 40 nm-1 / 0.1 nm-1

Hard matter 0.1 ~ 80 nm-1 / 0.1 nm-1 or lower Parallel data collection

• Focus: Vertical focus < 5 µm For high pressure, 1 µm (V) x 3 µm (H) desirable

• Sample environments Compatible with high pressure, low-T (4K), high-T (1000K), and single crystals


Progress Since Last EFAC (May 5-7, 2008)• Major progress achieved in 0.1 meV optics R&D program

Buildup of infrastructure (dedicated R&D beamline and optics test end station at NSLS, crystal fabrication lab)

Proof of principle experiment completed Greatly improved understanding of the technical requirements and challenges of the new

optics schemes, and other possible alternatives

• Refined beamline conceptual design• More realistic insertion device plan • First BAT meeting addressing issues

and concerns raised by EFAC Near-term milestones on 0.1 meV optics R&D Response to EFAC comments Action items on beamline design First BAT meeting (Dec 5, 2008)


Response to Comments from EFAC

Comment ResponseTest of critical components on a time scale compatible with beamline design decisions, and decision about how to proceed with this beamline be delayed until optics have been tested.

Near-term R&D milestones developed, in accord with overall beamline schedule

A semi-permanent test facility be setup at NSLS R&D beamline established

Count rate estimates be made in some experimental conditions, including ideal optical throughput, energy resolution, effect of sample thickness, transmission, and environment, and desired momentum resolution

Key experiments identified. Detailed calculation and count rate estimate in progress.

Specific comments on beamline design details, including comb crystal, energy resolution switching with 2nd channel cut, CDW/CDDW scheme, area detector for parallel detection of multiple momenta, etc.

These are parts of the current design features for the beamline and spectrometer

A second end station for 50 meV as backup plan in the absence of a 0.1 meV instrument.

Incompatible with the scientific objectives of the BAT.


Action Items Recommended by BATItems Status

Realistic count rate estimates for 4 key experiments:ov-SiO2

oH2OoPhonons in cupratesoHigh pressure N2 or O2 crystals

In progress

Work with the ASD and push for the highest flux undulator possible

In progress, work group on insertion devices formed b/w ASD and XFD

Explore the possibility of using a Be CRL in the front-end to reduce beam vertical size.

In progress, issues to examine include wave front propagation, heat load and transmission (intensity loss)

Detailed design calculations for the spectrometer:oUltimate q resolution achievable oEffect of sample size on q and energy resolutionoScheme for multiple q measurements with area detector

Mostly completed


• Insertion device: an IVU22-6m at a high-β long straight section as the new baseline device• Generic front-end for long straight section with beam defining X-Y slits• Be/Diamond CRL’s in front-end to collimate beam (to ≤ 10 µrad) being evaluated • Cryogenic cooled DCM, FEA analysis being revisited for IVU22-6m• CDDW high-resolution mono + channel cut

for 1 – 0.1 meV resolution switching• KB focusing mirrors to focus beam to < 5 x 5 µm2,

divergence ≤ 0.1 mrad to ensure q resolution• ML mirror(s) to collect 5 x 5 mrad2 scattered fan

horizontal to < 0.1 mrad (q resolution)vertical to < 0.1 mrad (analyzer acceptance)or other alternative schemes

• 10 m arm and Area detector

Current Conceptual Design

CRL30m

Single mirror possibilities


Possible Combination of End Stations

1.0 meV Arm-CDDW Analyzers (1.0 meV)

- 0.1nm-1 q resolution- 0.1~80nm-1 q range (~120°)

- ½ wave phase plate to rotate polarization near 90°

(mature scope)

0.1 meV Arm-CDDW Analyzers (0.1 meV)

- 0.01 nm-1 q resolution- 0.1~40 nm-1 q range

FOEKB + PP

HRM

(CDDW + CC)DCM

Beamline to occupy a high-β long straight section

Combine two end stations in one hutch


Insertion Device Optimization• Flux at sample > 109 photons/s/0.1meV Flux at source > 1015 photons/sec/0.1%bw

(assuming 10% overall beamline optics efficiency) • Optimization to maximize flux at 9.1 keV: magnet period vs length vs minimum gap

Fundamental Photon Energy vs GapFundamental Photon Energy vs Gapfor Different IVU Periodsfor Different IVU Periods

IXS requirement @ 5th Harmonic

IVU Lengths ~Satisfying “Stay Clear” IVU Lengths ~Satisfying “Stay Clear” Constraint Constraint in High-Beta Straight Sectionin High-Beta Straight Section

Calculations by O. Chubar

IVU parameters by T. Tanabe

βy0 value suggested by J. Bengstsson βy0 = 3.4 m


Key Points on Insertion Device• The baseline IVU20-3m cannot be used on a high-β straight due to “stay-clear” constraint• The high-β straight offers lower heat load on optics and smaller beam cross section

throughout the beamline • An IVU22-6m device based on current “warm” NEOMAX magnet NdFeB with Br = 1.12T

provides the best possible performance with the current lattice design. Maximum spectral flux = 1.6x1015 photons/sec/0.1%bw @ 9.1 keV, aperture 100 μrad (H) x 50 μrad (V)

• Important accelerator-related issues (e.g., tune shift compensation) need to be addressed• Further optimization possible with cold devices and/or extended long straights

9.1keV @ 5th Harmonic

Maximal Spectral Flux Maximal Spectral Flux through 100 through 100 μμrad (H) rad (H)

x 50 x 50 μμrad (V) Aperturerad (V) Aperture

E-Beam Current: 0.5 AHigh-β Straight Section

By O. Chubar


Horizontal Horizontal Cuts (y=0)Cuts (y=0)

Partially-Coherent Wavefront Propagation Simulationsfor IXS: Beam Collimation by 1D CRL

1D CRL (Be, parab., Fy~15 m @ 9.1 keV, rmin~250 μm, dy = 1 mm, 2 lenses)U22-6m

20 m 10 m 20 m 60 m (from CRL)

Spectral Flux through 100 Spectral Flux through 100 μμrad (H) x 50 rad (H) x 50 μμrad (V) Ap.rad (V) Ap.

Vertical Vertical Cuts (x=0)Cuts (x=0) Intensity Distributions at Different Longitudinal PositionsIntensity Distributions at Different Longitudinal Positions

at Photon Energy near at Photon Energy near H5 Peak (9.114 keV)H5 Peak (9.114 keV)

Harm. 5Harm. 5

#1 #2 #3 #4 #5

#1: Before CRL#1: Before CRL F ≈ 1.5x10F ≈ 1.5x1015 15 Ph/s/0.1%bwPh/s/0.1%bw

#2: Just After CRL#2: Just After CRL F ≈ 1.37x10F ≈ 1.37x1015 15 Ph/s/0.1%bwPh/s/0.1%bw

#3: At 10 m After CRL#3: At 10 m After CRL

#4: At 20 m After CRL#4: At 20 m After CRL

#5: At 60 m After CRL#5: At 60 m After CRL (vertical waist) (vertical waist)

By O. Tchoubar


Estimated U22 Total Emitted and Absorbed (by CRL) Power Density Distributions

CRL Transmission at 9.1 keV

Total Emitted (integrated over all Photon Energies)

Absorbed Power Densityvs Vertical Position at x = 0

Integral Absorbed Power Density inside CRL

P ~ 10 kW

CRL

Work in progress …

By O. Chubar


Shadow Ray Tracing (in progress…)

Model , LN2 cooled DCM(εx = 0.55nm-rad)

Spot size , μm(No distortion)

Flux, ph/sec (No distortion)

Spot size, μm(W/ distortion)

Flux, ph/s/eV (W/ distortion)

Hi-β, U19-3m, 5th harmonic, 22W 7.1 x 1.9 2.81 x 1013 7.0 x 3.4 2.79 x 1013

• Initial tracing by Oxford-Danfysik:

• New tracing, to be performed, to include:o Insertion device IVU22-6mo Be CRL + filter, or collimating mirroro FEA analysis of Be CRL and DCMo Tracing thru CDDW optics

CDDW optics in Shadow


Count Rate Estimates (9.1 vs 21.7 keV)

H. Sinn, J. Phys. Cond. Mat. 13, 7525 (2001)

2 2 2 22

2 20

( )2

e Babs

i

r c q k TI Z lI eE M

22

2

( ) 2( )i

qE

2

0

( ) absI lI

• Given the same q resolution, I/I0 is proportional to analyzer solid angle and sample absorption length:

Sample labs (µm)(9.1 keV)

labs (µm)(21.7keV)

Thickness (µm)

Solid Angle mrad2

Int. @ ΔE(Ph/S @ meV)

Count Rate(cnts/sec)

v-SiO2 190.2 2454.7 ~400 ~30 4x109 @ 1.6 ~0.2 @21.7 keV

H2O 1468 17165 ~700 ~30 4x109 @ 1.6 ~1.0 @21.7 keV

La2CuO4 7.13 75.3 ~140 ~30 2.7x1010 @ 3.3 ~0.5 @ 17.8 keV

Solid O2 - - ~30 ~30 1.0x1010 @ 3.3 ~1.5 @ 17.8 keV

(Data courtesy of M. Krisch)State-of-the-art experiments operate with count rate @ ~ 1cnts/sec


• Sample volume (thickness) not optimized for higher energies by up to a factor of 25!o Not always possible to go with the absorption length (e.g., biological samples)o High-pressure samples limited by pressure vessels

• Angular acceptance of backscattering analyzers is resolution limited

Estimate for NSLS-II spectrometer operating at 9.1keV compared to ESRF ID28

Count Rate Estimates (continued)

Sample labs Ratio Gain

Solid AngleGain

Intensity Gain @ 1meV

Count Rate(cnts/sec)

v-SiO2 ~ 6 ~0.85 ~4 ~4

H2O ~ 24.5 ~0.85 ~4 ~83

La2CuO4 ~ 0.5 ~0.85 ~1.2 ~0.25

Solid O2 ~10? ~0.85 ~3.3 ~42

Here we assume:•Experiments at 9.1keV can be carried out with sample thickness of one absorption length•New optical scheme delivers flux of 1x1010 ph/sec at 1meV resolution•New analyzer scheme is as efficient as state-of-the-art backscattering analyzers

Estimated CR = Mea. CR x labs Gain x SA Gain x Int. Gain


WBS Dictionary: All activities related to design, construction, and commissioning (without beam) of an insertion device beamline for inelastic x-ray scattering.

Cost Baseline ($ x 1000)

WBS Description

Burdened $

Total Burdened

& Escalated

FTEs Labor Non-Labor (Mtrl, Trvl, Act)

1.04.05.01 Undulator Beamline 1Inelastic X-ray Scattering (IXS) 18.88 3,126 7,122 10,4351.04.05.01.01 Enclosures 0.41 67 1,070 1,137

1.04.05.01.02 Beam Transport 0.11 18 659 677

1.04.05.01.03 Utilities 1.04 123 208 331

1.04.05.01.04 White Beam Components 0.06 9 234 243

1.04.05.01.05 High Heatload Optics 0.44 76 618 694

1.04.05.01.06 Beam Conditioning Optics 0.50 85 1,812 1,897

1.04.05.01.07 Personnel Safety System 0.81 103 76 179

1.04.05.01.08 Equipment Protection System 0.40 53 30 83

1.04.05.01.09 Endstation 1 4.17 661 1,813 2,474

1.04.05.01.10 Endstation 2 0.0 0 0 0

1.04.05.01.11 Beamline Controls 0.68 120 540 660

1.04.05.01.12 Beamline Control Station 0.0 0 34 34

1.04.05.01.13 Beamline Management 10.26 1,900 28 2,028

Includes three enclosuresMajor components Include:

• Slits: $180K

• Beam Monitors: $169K

• Fluor. Screens: $106K

• KB mirrors (1set): $652K

• VFM/VCM (1set): $301K

Includes the 0.1meV HRM and the spectrometer

Cost estimate currently under revision!


Schedule Summary

• Now~2011: Actively pursue 0.1meV resolution R&D and design beamline based on 1meV prototype

• 2011~2013: Construct beamline based on 1meV resolution but ensure compatibility with 0.1meV resolution, continue R&D to achieve 0.1meV

• 2014~2015: Commission 1meV instrument, develop 0.1meV instrument with NSLS-II source

• 2016~: realize 0.1meV goal. (no major impact on basic beamline design)


Outlook for the Next 6 Months

• Continue to work with ASD to re-baseline insertion device (IVU22-6m)• Complete FEA heat load analysis on DCM and Be CRL’s• Complete Shadow ray tracing including CDDW mono plus channel cut• Complete efficiency analysis of analyzer system• Carry out more realistic count rate estimates• Revise cost estimates• Finalize conceptual design

inelastic scattering beamline update

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