Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download X-Ray Prototype Optics Specification
Document related concepts
no text concepts found
Transcript
X-Ray Optics and Detectors John Arthur April 29, 2004 X-ray optics and detectors John Arthur [email protected] From the LCLS Project Requirements document: The Project scope includes facilities for production and transport of a bright, high-current electron beam an undulator system in which the electron beam will generate the x-ray beam facilities for transport, diagnostics and optical manipulation of the x-ray beam endstations and related facilities for x-ray experiments conventional facilities for the accelerator systems and x-ray experiments a central lab office building to house support staff and researchers This talk will present a discussion of the prototype x-ray optics and prototype x-ray detectors that will be built for LCLS, and their basic requirements April 29, 2004 X-ray optics and detectors John Arthur [email protected] Functions of the x-ray optics Confinement (masks, slits, local apertures) Intensity attenuation (gas attenuator, solid attenuator) Focusing (K-B mirror, zone plate) Spectral filter (mirror low-pass filter, monochromator) Beam direction (flipper mirrors) Temporal filter (pulse split/delay) April 29, 2004 X-ray optics and detectors John Arthur [email protected] High peak power (fluence) poses a challenge for x-ray optics FEE NEH FEH LLNL Expected LCLS fluence compared with melt fluence for various materials April 29, 2004 X-ray optics and detectors John Arthur [email protected] Some proposed solutions to the peak power problem Low-z materials (Be, B4C, C) Grazing incidence Grazing-incidence slits Gas attenuator Distance from source Graded-density absorber April 29, 2004 X-ray optics and detectors John Arthur [email protected] Basic specifications for slits and attenuators Slit aperture range 2 x 4s beam size @ 800 eV Slit precision 1 µm Attenuator range up to 104 at any energy 800-8000 eV Attenuator precision 1% of attenuation, steps 3/10/100/103/104 April 29, 2004 X-ray optics and detectors John Arthur [email protected] X-ray focusing Produce high flux density K-B focusing mirrors Useful energy range 800 - 24000 eV Focus size < 1 µm Efficiency >10% April 29, 2004 X-ray optics and detectors John Arthur [email protected] X-ray mirrors for LCLS Energy low-pass filter Beam redirection Double-mirror low-pass filter Low-pass mirror critical energy variable 1200 eV -9000 eV Mirror mechanical stability beam jitter < 10% of beam size April 29, 2004 X-ray optics and detectors John Arthur [email protected] X-ray monochromators Energy bandpass filter Energy range 800 eV -24000 eV Bandpass < 2 x10-4 Rapid scan range 10% April 29, 2004 X-ray optics and detectors John Arthur [email protected] X-ray pulse split and delay Provides precise time delay between pulses Energy 8000, 24000 eV Delay range 0-200 ps Pulse split/delay using thin Si crystals April 29, 2004 X-ray optics and detectors John Arthur [email protected] X-ray detectors for LCLS LCLS presents unique challenges for detectors, requiring significant R&D Signal comes in large pulses (many photons) Pulses come at 120Hz April 29, 2004 X-ray optics and detectors John Arthur [email protected] Several types of x-ray detector will be built Beam imaging detector Beam intensity monitor Streak camera 2-d scattered-x-ray detector April 29, 2004 X-ray optics and detectors John Arthur [email protected] LCLS 2-d x-ray detector Many LCLS experiments will produce diffuse scattering patterns 2-d detector needs Moderate-wide angular range Moderate dynamic range (103) Low spatial resolution (1k x 1k or less) 120 Hz frame rate April 29, 2004 X-ray optics and detectors John Arthur [email protected] LCLS 2-d x-ray detector Detector technologies CCD Diode pixel array Relatively mature technology Needs R&D to reach 120 Hz Tremendous potential 120 Hz no problem Not commercial Needs lots of R&D April 29, 2004 X-ray optics and detectors John Arthur [email protected] LCLS 2-d x-ray detector LCLS detector R&D plan Begin with 1-year R&D contract ($100-200k) Investigate pixel array detector Consider investigating another technology simultaneously After 1 year, decide whether and how to continue Goal: experiment-ready detector by 9-30-08 Backup: CCD detector running at 10 Hz April 29, 2004 X-ray optics and detectors John Arthur [email protected]
