LDRD for UEM (ID: 305506, UED) - PowerPoint Presentation

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LDRD for UEM (ID: 305506, UED)Demonstration of feasibility of sub-nm, picosecond electron microscope for the life sciences

Xi YangRepresenting UEM LDRD TeamPI: Timur Shaftan/Sean McSweeney/Lewis Doom (NSLS-II), Yimei Zhu (CMPMSD), Qun Liu (Biology)

LDRD 19-016 (approved and received)

22

nd

ATF Users’ Meeting

December 3 - 5, 2019

NSLS-IID. Bergman, L. Doom, M Fulkerson, G. Ganetis, Y. Hidaka, B. Kosciuk, D. Padrazo, T. Shaftan, V. Smalyuk, C. Spataro, X. Yang, J. Rose, G. Wang, K. Wilson, L. H. Yu, etc. ATFM. Fedurin, M. Babzien, R. Malone, k. Kusche, C. Cullen, etc.

CMPMSDJ. Li, L. Wu, Y. Zhu, etc.ShanghaiTech University W. Wan

UEM LDRD participants

Goal of UEM LDRD

This LDRD is to image biological cell with 10 µm size with resolution <200nm.

This effort is to design and test a proof-of-concept system, not an operational experimental instrument.The UEM system will be integrated into the current UED system with minimal interference. Expected Results: Phase I: Determine the UEM design and the required tolerances through accelerator physics studies. Phase II: Engineering design. Phase III: Equipment installed and proof-of-principle experiments carried out on a sample target at the UED setup3

Design of compact ultrafast microscopes for single- and multi-shot imagining with MeV electrons

. Ultramicroscopy

. 194 143-153 (2018). Wan, W., Chen, F. & Zhu, Y.Design basis and foundation4

Objective

Projector 1

Projector 2

UEM LDRD is built on success of UED LDRD:

Developed electromagnetic quadrupole focusing and corrector magnets and diagnostics for 3MeV beam

Installation and commissioning

Focused electron beam at high charge on sample to tens of micrometer

Gain brightness and sharpness of diffraction pattern

Conventional UED configuration

(with solenoid only focusing),

UED with optimized quadrupoles

Yang, X., et al. A compact tunable quadrupole lens for brighter and sharper ultra-fast electron diffraction imaging. Scientific Reports 9, 5115 (2019).

Preliminary Design Review

Review committee members: D. Zakharov (BNL), M. Marko (Wadsworth), Q. Liu (BNL), M. Fedurin (BNL), E. Wang (BNL), P. Musumeci (UCLA) (Chair)

The current effort represents fundamental research and is well aligned with DOE missionThe committee commends BNL efforts in assembling a team with the right mixture of accelerator scientists and electron microscopistsThe efforts in making the system compatible with the existing UED research efforts are also to be highly praised.The committee generally agrees that the outlook to achieve the preliminary goal of 200 nm spatial resolution is positive and the goal is within reach of the current design effort, even considering the various deficiencies addressed later in this report.

Design principles of UEM beamline

6

Novel approach: compact round imaging lens based on permanent quadrupole quintupletsThe design resolution of

the lens system:

We conservatively chosen the resolution

<200

nm

for the proof-of-principle experiment

1nm resolution is achievable with 10

-5

electron beam energy spread

3-stage modular design

simple design: the same objective and projector lenses

Diagnostic system

Enables stage-by-stage commissioning.

Compatible with current UED

System requirements are determined by accelerator physics analysisMagnet tolerances - fabrication, measurement and alignment. Electron beam parameters - charge, emittance and energy spread. Apertures and diagnostic flags - position, size, material and thickness.Beam-based characterization - spatial pointing and energy jitters of the electron beam

UEM beamline layout

Gun

Solenoid

QD1

QF1

QD2

QF2

Projector lens #1

► M

2

= 108.2

f

= 62 mm

Projector lens #2

► M

3

= 2078.9

f

= 62.2 mm

APER 1

5 – 100 µm

APER 2

5 -180 µm

APER 3

100 µm

APER 4

1100 µm

Objective lens

M

1

=10.4

f

= 62 mm

SAMPLE

to

IMAGE

1

0.76 m

IMAGE 1

to

IMAGE 2

0.76 m

Gun to

SAMPLE -

1.39 m

Resolution:

dominated by

electron beam qualities

APER are apertures.

APER1 cuts dark current.

APER2 controls aperture angle 0.1-3

mrad

.

IMAGE 2

to

DETECTOR

1.28 m

C2

C1

C3

C4

C5

C6

C7

Trim Q

Trim Q

Trim Q

Skew Q

SAMPLE

IMAGE 1

IMAGE 2

Condenser lens

Skew Q

DETECTOR

Beamline lattice design is complete

Quadrupoles are in production

Design of the apertures is complete

Beam flags will be reused, one more flag for the sample has been designed

Longitudinal Field Profile of the UEM lens

8

Corrector

Quintuplet PM Quadrupoles

Condenser Quadrupole

Raspberry Pi Based Motion Control

Engineering implementation

Modular magnet assemblies

Objective, Projector 1 and Projector 2 are all the same

Re-use as many other parts from UED LDRD

Condenser and corrector magnets and power supplies

Vacuum components

Diagnostics: Flags, cameras, filter wheels

Controls: electronics, switches, software

Remote positioning

sample, permanent magnets, apertures and flags

Engineering design

fast transition between UED and UEM modes

Studies on UED to assess feasibility of UEM

Beam-based measurements:

Shot-to-shot energy jitter is ~2·10-3.Spatial pointing jitters are ~10 µrad. Energy spread ~4·10-3 at 2 pC9Charge (pC)dE/E

0.05

0.0001

5

0.0100

References

Yang, X., et al. A novel nondestructive diagnostic method for mega-electron-volt ultrafast electron diffraction. Scientific Reports 9, 17223 (2019).

Electron beam parameters:

Charge at the detector

Np

·

n

·

e

=

0.4pC Np is the number of pixels of the detector (500*500)n

is the estimated number of electrons per pixel (n

= 10)Charge at the gun needs to be several times higher (1-5pC) due to electron-sample interaction ~10%. Beam size at the sample is ~10µm.

Risk assessment

10

Shot-to-shot energy jitter (~2·10-3)The energy jitter will limit the UEM performance in the low-charge accumulation mode.Energy spread (~10-2 for 4-5pC)Single-shot resolution of the UEM system will be limited by the energy spread at the required charge.Sample material

how the biological sample scatters the electrons?

Schedule is unknown

How to mitigate risks?

Apply NSLS-II LLRF system with better stability

RF amplifier with better stability 10

-4

Optimize laser parameters to improve electron beam quality

Plans

Optimize system parameters at the nominal design energy. (2 weeks)

Electron beam parameters (charge, bunch length, emittance and energy spread) as functions of machine parameters (laser size on cathode, laser intensity, gun phase and solenoid current).Set up online optimization (2 weeks)Imaging experiments with calibrated samplesGolden and TaS2 single crystal samples. (1 week)Measure and optimize the resolution and magnification of sharp aperture edges.Understand effects of bunch charge, length, emittance and energy spread. (2 weeks)Imaging biological objects (~10um). (2 weeks).11

Experiment Time Request

12

CapabilitySetup HoursRunning HoursUED Facility160360

CY2020 Time Request

Special Equipment Requirements and Hazards

User Sample and SetupGolden and TaS2 single crystal samples. Candidate biological samples: Fatty acid synthase (Cryo-EM structure) http://www.rcsb.org/structure/6TA1

2) T4 baseplate-tail tube complex (the largest structure in PDB) (Cryo-EM structure) http://www.rcsb.org/structure/5IV53) Eukaryotic ribosome (Crystal structure)http://www.rcsb.org/structure/4V88Special Equipment:UEM assemblyPump Laser Requirements: NoHazards & special installation requirements:Large installation (UEM assembly): YCryogens: YIntroducing new magnetic elements: YIntroducing new materials into the beam path: YAny other foreseeable beam line modifications: N13

Conclusion

UEM physics design with <200nm resolution is completeBeam physics studies provide risks assessmentMitigation plans are under discussionFunded SBIR projects related to BNL UEMDesign of a new superconducting gun Objective lens with high-gradient permanent magnet to reach sub-nm resolution