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FAST SDD® Ultra High Performance Silicon Drift Detector


This is the true State-of-the-Art!

Amptek recently brought silicon wafer manufacturing in-house and improved the process. The result is a detector with lower noise, lower leakage current, better charge collection, and uniformity from detector to detector. This makes it the best performing silicon drift detector available and the true state-of-the-art.

The FAST SDD® represents Amptek’s highest performance silicon drift detector (SDD), capable of count rates over 1,000,000 CPS (counts per second) while maintaining excellent resolution. The FAST SDD® is also available with our Patented C-Series (Si3N4) low energy windows for soft x-ray analysis.



Unlike our conventional SDDs which use a junction gate field-effect transistor (JFET) inside the hermetically sealed TO-8 package, along with an external preamplifier, the FAST SDD uses a complementary metal-oxide-semiconductor (CMOS) preamplifier inside the TO-8 package, and replaces the JFET with a metal-oxide-semiconductor field-effect transistor (MOSFET).  This significantly reduces capacitance, providing much lower series noise and yielding improved resolution at very short peaking times.  The FAST SDD® uses the same detector but with a preamplifier giving lower noise at short peaking times. Improved (lower) resolution enables isolation/separation of fluorescent X-rays with close energy values where peaks would otherwise overlap, permitting users better identification all of the elements in their sample(s).  Short peaking times also yield significant improvements in count rates; more counts provide better statistics.


  • Different detector sizes are also available.
    • 25 mm² active area collimated to 17 mm²
    • 70 mm² active area collimated to 50 mm²   - Click for 70mm2 details
  • Resolution of 122 eV FWHM at 5.9 keV
  • Count rates > 1,000,000 CPS
  • High peak-to-background ratio – 26,000/1
  • Windows: Be (0.5 mil) 12.5 µm, Be (0.3 mil) 8 µm, or Patented C-Series (Si3N4)
  • Radiation hard
  • Detector thicknesses Preamplifier Output Rise Time
    • <35 ns for 500um thick detector
    • <60 ns for 1000um thick detector
  • TO-8 Package
  • Cooling ΔT>85 K
  • Internal Multilayer Collimator

The True State-Of-The-Art

  • Lower noise → Better resolution down to 122 eV FWHM
  • Lower leakage current → Higher temperature operation (save battery life)
  • Better charge collection → Better photopeak shape (no tailing)
  • Quality → Detectors have consistent performance allowing for easier calibrations
  • Applications

    • Ultra-fast benchtop and handheld XRF analyzers
    • Scanning/mapping of samples in an SEM as part of an EDS system
    • On-line process control
    • X-Ray Sorting Machines
    • Space and Astronomy
    • OEM
    A view of the NICER X-ray Timing Instrument on the Space Station showing 96 Amptek FAST SDDs® with C2 windows mounted on the focal plane, before light shield assembly. Credits: NASA/Keith Gendreau
    Questions about how to integrate the FAST SDD in your instrument?
    • Performance +

      Typical Performance Characteristics
      Resolution Peaking Time
      124 eV FWHM 4 µs
      126 eV FWHM 1 µs
      134 eV FWHM 0.2 µs

      Table 1. Resolution vs. Peaking Time for the FAST SDD®.

      Figure 1. Resolution vs. peaking time for the FAST SDD® and standard SDD at 210 K.

      Figure 2. Resolution vs. peaking time at different detector temperatures. Note that there is little change in resolution over temperature for the peaking times that are typically used with the FAST SDD® 

      Figure 4. Throughput for the FAST SDD®.

      Figure 5. Resolution vs. Input Counts Rate (ICR) for Various Peaking Times for FAST SDD®.

      Figure 5. Energy resolution, efficiency, and X-ray energy: This plot shows how the intrinsic efficiency (top) and energy resolution (bottom) depend on the X-ray energy.

      In the bottom plot, the black curve represents “Fano broadening”, the theoretical limit with a Si based detectors, arising from quantum fluctuations in the charge production process.  The colored curves represent the combination of Fano broadening and intrinsic electronic noise under optimum conditions (full cooling and long peaking time).  The detector selection is most important at the lowest energies because Fano broadening dominates at high enough energies.

      In the top plot, the efficiency at low energies is determined by transmission through the window and detector dead layer.  The efficiency at high energies is determined by attenuation in the active depth of the detector.  A Si detector with Be window is recommended between about 2 and 30 keV.  A Si detector with a C1 or C2 window is recommended at lower energies, while a CdTe detector is best at energies above 30 keV.

      Efficiency Package: A ZIP file of coefficients and a FAQ about efficiency. This package is provided for general information. It should not be used as a basis for critical quantitative analysis.

    • Specifications +

      Detector Type Silicon Drift Detector (SDD) with CMOS preamplifier
      Detector Size 25 mm2 - collimated to 17 mm2
      Also available 70mm2 - collimated to 50 mm2
      Silicon Thickness 500 µm  or 1000um available
      Collimator Internal MultiLayer Collimator (ML)
      Energy Resolution @ 5.9 keV (55Fe) 122 - 129 eV FWHM at 4 µs peaking time (guaranteed)
      Peak to Background 20,000:1 (ratio of counts from 5.9 keV to 1 keV) (typical)
      Detector Window Options Beryllium (Be): 0.5 mil (12.5 µm) or 0.3 mil (8 µm)

      Patented C Series (Si3N4) Low energy windows
      Charge Sensitive Preamplifier CMOS
      Gain Stability <20 ppm/°C (typical)
      (see Configurations)
      Detector module: TO-8 package (0.640 in. high including pins, 0.600 in. diameter)
      XR100 box: 3.00 x 1.75 x 1.13 in (7.6 x 4.4 x 2.9 cm) excluding extender
      X-123 box: 2.7 x 3.9 x 1 in (7 x 10 x 2.5 cm ) excluding extender
      OEM configurations vary
      (see Configurations)
      Detector module: 0.14 oz (4.1 g)
      XR100 box: 4.4 ounces (125 g)
      X-123 box: 6.3 oz (180 g)
      OEM configurations vary
      Total Power <2 Watt
      Warranty Period 1 Year
      Typical Device Lifetime 5 to 10 years, depending on use
      Operation conditions -35°C to +80°C
      Storage and Shipping Long term storage: 10+ years in dry environment
      Typical Storage and Shipping: -40°C to +85°C, 10 to 90% humidity non condensing
      TUV Certification
      Certificate #: CU 72072412 02
      Tested to: UL 61010-1: 2004 R7 .05
      CAN/CSA-C22.2 61010-1: 2004
      Preamp Power XR100 configuration: ±8 V @ 15 mA with no more than 50 mV peak-to-peak noise
      X123 or OEM configuration (PA210/230 or X-123): ±5 V
      Detector Power -100 to -180 V @ 25 µA very stable <0.1% variation
      Cooler Power Current = 450 mA maximum, voltage = 3.5 V maximum with <100 mV peak-to-peak noise
      Note: the XR-100 can include its own internal temperature controller
      Preamplifier Sensitivity 3.6 mV/keV typical (may vary for different detectors)
      Preamplifier Polarity Positive signal output (1 kohm maximum load)
      Preamplifier Feedback Reset
      Temperature Monitor Sensitivity Varies with configuration
      When used with PX5, DP5, or X-123: direct reading in Kelvin through software.
      Preamplifier Output Rise Time <35 ns for 25mm2, <60 ns for 70mm2
    • Configurations +

      The FAST SDD is available with the standard Amptek options and OEM configurations.

      • XR100FASTSDD with PX5
      • X-123FASTSDD
      • OEM Configurations
      • Vacuum Applications
      The XR-100 FAST SDD® with the PX5 The X-123FAST SDD configuration includes the detector, preamplifier, digital processor and power supplies all in one box
      The FAST SDD with its preamplifier is available in several OEM configurations
      The FAST SDD is compatible with all Amptek vacuum accessories
    • Options, Accessories & Additional Info +

    • Applications +

      Example Spectra

      Figure 6. Stainless Steel 316 Spectrum taken in 1 second with the FAST SDD®.

      Stainless Steel 316 Quantitative Analysis with FAST SDD®

      The below table displays the quantitative analysis of the data in figure 4. This spectrum was taken in 1 second with the FAST SDD®.

      Element Certified Concentration Fast SDD® Result in 1 second
      V 0.05 0.16 ± 0.28
      Cr 18.45 18.32 ± 0.80
      Mn 1.63 0.40 ± 0.55
      Fe 64.51 65.89 ± 1.64
      Co 0.10 0.00 ± 0.40
      Ni 12.18 12.56 ± 0.47
      Cu 0.17 0.19 ± 0.02
      Mo 2.38 2.34 ± 0.08

      Figure 7. Solder spectrum taken in 1 second (1 µs peaking time) with the FAST SDD®.

      Figure 8. Multielement standard taken with the FAST SDD® at different count rates up to 1 Mcps.

      Space Exploration Application

      NICER attached to the ISS

      The Neutron star Interior Composition Explorer (NICER) is an International Space Station (ISS) payload devoted to the study of neutron stars through soft X-ray timing.  The heart of the instrument is an aligned collection of 56 Amptek silicon drift detectors (SDD) with C Series Windows and X-ray “concentrator” optics (XRC) pairs. Each XRC collects X-rays over a large geometric area from a roughly 30 arcmin2 region of the sky and focuses them onto a small SDD. The Amptek FAST SDD® detects individual photons, recording their energies with good (few percent) spectral resolution and their detection times to an unprecedented 100 nanoseconds RMS relative to Universal Time. Together, this assemblage provides a high signal-to-noise-ratio photon-counting capability within the 0.2-12 keV X-ray band, perfectly matched to the typical spectra of neutron stars as well as a broad collection of other astrophysical sources.

      For an overview of the NICER mission, please see this presentation.

    • Detector Geometry +

    • Documentation +