1 / 7

Olin Student Projects 2007

Olin Student Projects 2007. Keith Gendreau NASA/GSFC 301-286-6188. USB X-ray Flux Meter. X-ray Detector With Simple Preamp. ~10 mV. BNC. Will have MANY uses at GSFC X-ray source stability monitor at 600m beamline Calibrator of new X-ray Diffractometer/Fluorescence Instrument

Download Presentation

Olin Student Projects 2007

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Olin Student Projects 2007 Keith Gendreau NASA/GSFC 301-286-6188

  2. USB X-ray Flux Meter X-ray Detector With Simple Preamp ~10 mV BNC • Will have MANY uses at GSFC • X-ray source stability monitor at 600m beamline • Calibrator of new X-ray Diffractometer/Fluorescence Instrument • Design and build a USB connected pulse counter that can be connected to a fast X-ray detector for purposes of monitoring X-ray flux. • Project would involve circuit design • FPGA developer boards with USB interface? • Other USB developer boards • Pulse Processor • Simple comparotr trigger? • Multiple Pulseheight Triggers (eg build up spectrum AND countrate) • Pulse Profile Fitting? • Input from “Generic” X-ray Detector • APD (Simple to implement anywhere) • Proportional Counter • Software design • USB Driver • Pulseheight Analysis ~10 nsec USB Controls Amplifier USB Controls Trigger Circuit FPGA? Comparator? USB Time, cnts/sec Or Time, pulseheight Computer

  3. Material Identification using a simultaneous X-ray diffractometer/Fluorescence instrument. • GSFC has developed a new type of X-ray Diffractometer (XRD) using instruments and techniques developed for X-ray astrophysics • XRD measures the spacing between atomic planes in materials using X-rays as rulers • Data sets are very rich • Q: what is the minimum number of photons needed to ID a material with this instrument? • This will take longer to explain, but is VERY cool

  4. Material analysis with X-rays: fluorescence (XRF) and diffraction (XRD) • XRF — Elemental abundances through spectroscopy • XRD — Bragg's law describes how atomic plane spacings may be measured: Detector X-rays in 2 d Traditional monochromatic XRD methods must vary sample-detector geometry, or randomize crystal orientations by powderizing the sample: destructive!

  5. Multidimensional XRD CCDs provide energy (wavelength) and position information for individual photons. Using continuum radiation literally opens up a new dimension. The richness of the resulting data is surprising… Computer interface with event processing CCD control and readout electronics  Diffracted and fluoresced X-rays Four-dimensional event list: time, x, y, energy for each detected X-ray X-ray source x y CCD Apply geometry 2 Collimated X-ray beam  z time, , ,  for each event Sample at (xo,yo,zo) Apply Bragg’s law, n = 2d sin() An X-ray source producing Bremsstrahlung continuum X-rays (0.1-10 keV) sends a collimated beam toward a sample. The X-rays either diffract from atomic planes in the sample or excite characteristic line emission. A photon-counting, energy-resolving CCD captures some of the resulting X-rays, producing an event list that can be transformed into both fluorescence (elemental composition) and diffraction (mineral atomic-plane spacing) information on an event-by-event basis. time, d-spacing,orientation, energy for each event.

  6. The $15 X-ray CCD Camera • Go to K-mart or someplace and buy a cheap webcam. • Carefully remove housing • Using a razor and knife, carefully remove the glass cover of the CMOS detector • Put in a dark box with a radioactive X-ray source • See X-rays • Q: can we hack the software of these camera to process the frames to extract X-ray events?

More Related