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SDD Silicon Drift Detector

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.

The SDD is a thermoelectrically cooled solid-state silicon drift detector.  It is recommended for applications requiring the best energy resolution, very high count rates, and lowest X-ray energies.  Its performance, small size, and low cost make it the ideal detector for many laboratory and OEM X-ray spectroscopy applications, including EDS and XRF.

The SDD can provide a resolution of 125 eV FWHM at the Mn Kα line (electronic noise of 4.5 electrons rms), a peak to background of 20,000:1, an output count rate over 500 kcps, and can detect X-rays down to the Be Kα line (110 eV).  It has a 25 mm2 active area and is 500 μm thick.

The standard SDD has a 0.5 mil Be window for good efficiency above 2 keV. For lower energies, the Patented C-Series windows  is available with our FAST SDD® provide good efficiency down to the B line.   For count rates >200 kcps, the FAST SDD® is recommended.

The SDD is normally mounted on an extender (several different lengths are available), with the preamplifier in the attached metal housing.  It requires a separate signal processor and power supplies. Amptek’s XR100 PX5 configuration option is ideally suited for most laboratory uses. The same SDD detectors are available in the smaller X-123SDD package, and also with smaller preamplifiers for OEMs and custom systems.

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  • 125 eV FWHM Resolution @ 5.9 keV
  • High Peak-to-Background Ratio – 20,000:1
  • 25 mm2 – collimated to 17 mm2
  • 500 µm Thick
  • 2-Stage Thermoelectric Cooler
  • Cooling ΔT>85 K
  • Temperature Monitor
  • Thin Beryllium 0.3 or 0.5 mil
  • Multilayer Collimator
  • Hermetic Package (TO-8)
  • Wide Detection Range
  • Easy to Operate
  • Radiation Hard


  • X-Ray Fluorescence
    • RoHS/WEEE
    • Precious metals
    • Alloy analysis
    • Light elements
  • EDS
  • Teaching and Research
  • Process Control
  • Mössbauer Spectrometers
  • PIXE
  • Wavelength dispersive XRF

Figure 1. 55Fe spectrum taken with the Amptek silicon drift detector (SDD).

  • 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 270 mm - collimated to 50 mm2
    Silicon Thickness 500 µm
    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
    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-100SDD includes its own 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
  • Configurations +

    The 25 mm2 FAST SDD is available with the standard Amptek options and OEM configurations.

    • XR100FASTSDD with PX5
    • X-123FASTSDD
    • OEM Configurations
    • Vacuum Applications
    The XR-100FAST SDD with the PX5 The FAST SDD with its preamplifier is available in several OEM configurations The X-123FAST SDD configuration includes the detector, preamplifier, digital processor and power supplies all in one box 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 +

    Mechanical Dimensions of Amptek Si-PIN and SDD detectors

    TO-8 STP File

  • Documentation +