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.

fast sdd

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.


  • 25 mm² active area collimated to 17 mm²
    Also available 70 mm² collimated to 50 mm²
  • 122 eV FWHM resolution at 5.9 keV
  • Count rates > 1,000,000 CPS
  • High peak-to-background ratio – 26,000/1
  • Preamplifier Output Rise Time <35 ns
  • Windows: Be (0.5 mil) 12.5 µm, or Patented C-Series (Si3N4)
  • Radiation hard
  • Detector thickness 500 µm
  • TO-8 Package
  • Cooling ΔT>85 K
  • 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

FAST SDD with 122 eV FWHM


  • 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


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®.

standard vs FAST SDD

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

25 mm2 FAST SDD resolution vs. peaking time and temperature

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® (<1µs).

Throughput for 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®.

Energy resolution efficiency x-ray energy

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.


Detector TypeSilicon Drift Detector (SDD) with CMOS preamplifier
Detector Size25 mm2 - collimated to 17 mm2
Also available 70 mm2 - collimated to 50 mm2
Silicon Thickness500 µm
CollimatorInternal MultiLayer Collimator (ML)
Energy Resolution @ 5.9 keV (55Fe)122 - 129 eV FWHM at 4 µs peaking time (guaranteed)
Peak to Background20,000:1 (ratio of counts from 5.9 keV to 1 keV) (typical)
Detector Window OptionsBeryllium (Be): 0.5 mil (12.5 µm) or 0.3 mil (8 µm)

Patented C Series (Si3N4) Low energy windows
Charge Sensitive PreamplifierCMOS
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 Period1 Year
Typical Device Lifetime5 to 10 years, depending on use
Operation conditions-35°C to +80°C
Storage and ShippingLong 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 PowerXR100 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 PowerCurrent = 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 Sensitivity3.6 mV/keV typical (may vary for different detectors)
Preamplifier PolarityPositive signal output (1 kohm maximum load)
Preamplifier FeedbackReset
Temperature Monitor SensitivityVaries with configuration
When used with PX5, DP5, or X-123: direct reading in Kelvin through software.
Preamplifier Output Rise Time<35 ns


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

PA-230 Housing X-123 FAST SDD Spectrometer with C2 Window, Vacuum Extender, and Feedthrough Coupling
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



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®.

fast sdd multi element standard

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.

Detector Geometry

Mechanical Dimensions of Amptek Si-PIN and SDD detectors
Mechanical Dimensions of Amptek Si-PIN and SDD detectors

TO-8 STP File


All results on this page are typical performance values at full cooling; please Contact Us to discuss guaranteed performance under different operating conditions.  Specifications subject to change without notice.