Highlights of science of USR Yuhui Dong BSRF, IHEP, CAS 2012/10/29

The emitance of storage ring 1GLS 3GLS ERL/Diff. limited storage ring

Coherence of X-ray The spatial (transverse) coherent of light: 4  ·  ·  ´= where  : the size of light source;  ´ : the divergence of light source;  : the wavelength.  If the source is small enough (point source), or the divergence is small enough (parallel beam), then we obtain coherent light.

The improvement of storage rings 1GLS emitance ~100nmrad, coherent wavelength: 1256nm Coherent length (transverse) at X-ray: L t ~500nm. 3GLS (SSRF) emitance: 4nmrad, coherent wavelength: 50nm L t ~5mm 3GLS (NSLS-II) 1nmrad, 12.56nm L t ~20mm ERL 0.1nmrad, 1.256nm Diffraction limit ring (SPring-8 upgrading plan) 10pmrad, 1.256Å

Longitude (temporal) coherence Longitude coherence is related to energy resolution: L c = 2 /  1Å X-ray,  / =10 -4, L c =10 4 Å;  / =10 -7, L c =10 7 Å. Usually the longitude coherent length is enough for structure determination.

The key point: emitance Low emitance source = coherent X-ray source The only available source now: X-FEL Maybe diffraction limit storage ring or ERL?

e-gun: 1mmrad Linac: 1nmrad （  =10 6 ） Undulator: slicing, ~10pmrad 4  ·  ·  ´= 4  ·10pm=1.256Å Pictures from Dr. Zhirong Huang, LCLS

Comparison between XFEL and USR XFELUSR Pulse intensity phs/pulse phs/pulse (not totally coherent, every wave pocket ~3phs) Pulse duration~100fs~10ps Coherent flux in a pulse phs/s phs/s Average coherent flux phs/s (100Hz) phs/s (~100MHz)

The possible scientific cases of USR Nano- or Meso-Scale Science Techniques  Diffraction: diffraction of single nano-object.  Imaging (CDI): imaging of meso-scale structures (3~5nm) without lens  XPCS: dilute samples, better time-resolution

Diffraction of nano-tube 10,000 cps 1250 cps Single molecule Single atom Au dopant Calculated Diffraction Patterns Pictures courtesy Dr. Chi-Chang Kao, SLAC

CDI: Resolution vs. intensity 1mm size sample phs 3~5nm reso. 1s collecting time Required intensity: phs/s/mm 2 /mrad 2 ce phs/mm ample, 1  m spot size

Three-Dimensional Visualization of a Human Chromosome Using Coherent X-Ray Diffraction 38nm resolution structure of chromosome Coherent x-ray diffraction microscopy is an ideal form of x-ray phase-contrast imaging, since there is no contrast degradation due to lenses Disadvantage ： TEM: the sample must be thinned Confocal microscopy: the sample must be labeled with fluorescent dyes Advantage : Due to the absence of resolution limiting optics and the penetrative ability of X-rays, Coherent X-Ray Diffraction technique ultimately offers new insights into the structure of intact, three- dimensional (3D) biological specimens. PRL 102, (2009)

Coherent X-ray diffraction imaging of strain at the nanoscale Visualization of strain inside a Pb nanocrystal. CDI, resolution ~30nm Nature material,vol 8,2009

Three-dimensional imaging of strain in a single ZnO nanorod Nature material,vol 9,2010 CDI of ZnO nanorod. The strain field can be reconstructed.

CDI and XPCS Time plot Dynamic Picture courtesy Prof. John Miao and Dr. Aymeric Robert Coherence of X-ray

XPCS at USR Signal-to-noise ratio of XPCS is proportional to the square of the coherent flux. (Falus et al., JSR 2006) USR ~10 times of coherent flux Dilute samples become possible Faster dynamic studies become possible (~10ns)

The requirement for hard X-ray For basic research, brilliance up to phs/s/mm 2 /mrad 2 /0.1%BW is necessary. For industrial materials, hard X-ray (energy up to 300keV) is necessary.

BSRF (2.5GeV, 1GLS) HLS (0.8GeV, 2GLS) The SR facilities in mainland of China Hard X-ray is required. SSRF (3.5GeV, 3GLS)

The importance of hard X-ray Penetrative ability: 300keV X-ray, 10cm Al or 2cm steel, real workpiece. High resolution: atomic resolution at nm range. Real matter, Real conditions, Real time High energy storage ring is needed.

Summary For the requirement of basic research AND industrial material studies, the future SR facility in China should provide: Brilliance of phs/s/mm 2 /mrad 2 /0.1%BW Focus spot can reach to 1mm (for diffraction, CDI) or 10nm (for nano-probe) Photon energy up to 300keV More ID as possible.

Thank you for your attention