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 resolution is the same as the standard SDD (125 eV FWHM at the Mn Ka line), and the typical peak-to-background ratio of 20,000:1 is the same, but at a much higher count rate.  The FAST SDD® is also available with our C-Series 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.

PA-230 Housing
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


For a given measurement:

  • Get better precision on your samples for the same measurement time, or
  • Shorten your measurement times for equivalent precision

Our Highest Performance Silicon Drift Detector

The FAST SDD® is available in all three standard Amptek packages, permitting you to select the version best-suited to your requirements

  • X-123FAST SDD – a complete system including detector/preamplifier, digital pulse processor (DPP) and power supplies
  • XR-100FAST SDD – detector/preamplifier for use with either Amptek DP5/PC5 or PX5 DPP/power supplies or your own
  • AXR FAST SDD – configured especially for OEMs, it uses a special version of either our PA-210 or PA-230 preamplifier optimized for use with the FAST SDD®
  • View our video of the FAST SDD® running at > 1 million counts per second (CPS)


  • 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



Performance Characteristics

Resolution Peaking Time
125 eV FWHM 4 µs
130 eV FWHM 1 µs
140 eV FWHM 0.2 µs
160 eV FWHM 0.05 µs

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

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

Energy resolution and count rate

Figure 2. Energy Resolution and Count Rate:  This plot shows how the energy resolution at 5.9 keV is related to the output count rate for Amptek’s X-ray detectors, as a function of the pulse shaping time and the equivalent peaking time in a digital processor.  These are typical values at full cooling (220K). For example, at a Tpeak of 9.6 microseconds (equivalent to 4.0 microsecond pulse shaping time) the output count rate at 50% dead time is 18 kcps.  This is a function only of the pulse processing so is the same for all detectors.  The energy resolution for a 6 mm2 Si-PIN is just under 160 eV FWHM while for a 25 mm2 SDD it is 130 eV FWHM.

Throughput for the FAST SDD

Figure 3. Throughput for the FAST SDD®.


Figure 4. Resolution vs. Input Counts Rate (ICR) for Various Peaking Times for FAST SDD.

Energy resolution efficiency x-ray energyFigure 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 pacakge 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
Silicon Thickness500 µm, See efficiency curves
CollimatorInternal MultiLayer Collimator (ML)
Energy Resolution @ 5.9 keV (55Fe)125 - 140 eV FWHM depending on peaking time
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)

C Series Low energy windows
Charge Sensitive PreamplifierAmptek custom reset preamplifier
Gain Stability<20 ppm/°C (typical)
XR-100FastSDD Case Size3.00 x 1.75 x 1.13 in (7.6 x 4.4 x 2.9 cm)
XR-100FastSDD Weight4.4 ounces (125 g)
Total Power<2 Watt
Warranty Period1 Year
Typical Device Lifetime5 to 10 years, depending on use
Operation conditions0°C to +50°C
Storage and ShippingLong term storage: 10+ years in dry environment
Typical Storage and Shipping: -20°C to +50°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±8 to 9 V @ 15 mA with no more than 50 mV peak-to-peak noise
Detector Power-70 to -200 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 Sensitivity4 mV/keV typical (may vary for different detectors)
Preamplifier PolarityPositive signal output (1 kohm maximum load)
Preamplifier FeedbackReset
Temperature Monitor SensitivityPX5: direct reading in Kelvin through software
X-123FastSDDThe silicon drift detector (FastSDD) is also available in the X-123SDD Silicon Drift Detector System configuration. The X-123SDD configuration includes the detector, preamplifier, DP5 digital pulse processor and MCA, and the PC5 power supply. All that is needed is a +5 Volts DC input and a USB, RS232, or Ethernet connection to your computer.
X-123SDD X-Ray Detector System
X-123SDD X-Ray Detector System
Vacuum AccessoriesThe FastSDD is compatible with all Amptek vacuum accessories
OEMThe FastSDD is compatible with all Amptek OEM configurations


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. Mn spectrum taken at 1.2 Mcps (0.2 µs peaking time) with the FAST SDD®.superfast6

Figure 8. Solder spectrum taken in 1 second (1 µs peaking time) with the FAST SDD.

Typical Detector Geometry

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


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.

Fast SDD® Specifications in PDF format
Reset Preamplifier Application Note in PDF format