Presentation on theme: "NSLS-II Stability Workshop – User Requirements Working Group – Day 1 Stability Requirements for soft x-ray coherent microscopy/imaging -- C. Jacobsen :"— Presentation transcript:
NSLS-II Stability Workshop – User Requirements Working Group – Day 1 Stability Requirements for soft x-ray coherent microscopy/imaging -- C. Jacobsen : STXM: vertical 0.01% intensity stability on zone plate (I0 is mitigating measure), freq. range: 0.01 Hz – 100 kHz ; full field imaging: OK Stability Requirements for 0.1meV hard (9.1keV) x-ray IXS -- Y. Shvyd’ko : vertical angular stability <= 0.25 rad (high res’n PBPMs and feedback are mitigating measure) Stability Requirements for SAXS -- L. Yang : OK Stability Requirements for powder diffraction -- P. Siddons: OK Stability Requirements for high energy (SCW) -- Z. Zhong: OK Stability Requirements for infrared -- L. Carr : vertical position stability <= 1 m in a bend ; freq. range: few hours – 10 kHz Stability Requirements for macromolecular crystallography – V. Stojanoff, L. Berman : vert. angular stability <= 1 rad
VUV, soft x-ray, and hard x-ray beamline requirements on beam stability (position and angle) Source size and angular divergence curves (photon beams) for NSLS-II IDs diverge from the diffraction-limited values above ~1 keV photon energy. The beamlines which provide the most stringent requirements on beam stability are those that accept only the diffraction-limited portion of the photon beams. Above ~1 keV, overfilling of a diffraction-limited beamline acceptance (both space and angle) provides a degree of tolerance to beam motion. Below ~1 keV, the beam is diffraction-limited and there is less fractional tolerance to beam motion. Absolute stability req’mts will be determined at highest photon energy, where diffraction-limited photon phase space is smallest. Propose stability req’mts: spatial = 10% of U19 (in 5m ID straight) photon beam size at high energy (50 keV), angular = 10% of photon beam divergence at high energy (50 keV): – vertical position: 10% of 3 micron = 0.3 micron – vertical angle: 10% of 7 microradian = 0.7 microradian – horizontal position: 10% of 40 micron = 4.0 micron – horizontal angle: 10% of 15 microradian = 1.5 microradian The corresponding fractions of the electron beam size in the 5m ID straight sections are: –vertical position: 0.3 micron / 3 micron = 10% – vertical angle: 0.7 microradian / 3 microradian = 24% – horizontal position: 4.0 micron / 40 micron = 10% – horizontal angle: 1.5 microradian / 15 microradian = 10% If any of these requirements are not very challenging to meet, consider a “stretch” goal which is 3 times tighter, i.e. –vertical position stretch goal: 0.1 micron / 3 micron = 3% of vertical electron beam size – vertical angle: 0.2 microradian / 3 microradian = 7% of vertical electron beam divergence – horizontal position: 1.3 micron / 40 micron = 3% of horizontal electron beam size – horizontal angle: 0.5 microradian / 15 microradian = 3% of horizontal electron beam divergence Time dependence: the measurement dwell times for beamlines spanning the photon energy shown on the next two slides (10eV – 100 keV) range from 1 ms to ~seconds. The scan times vary from a few ms to ~hours.