The XR-100SDD is a thermoelectrically cooled solid-state silicon drift detector (SDD) and preamplifier.  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 XR-100SDD 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 XR-100SDD has a 0.5 mil Be window for good efficiency above 2 keV. For lower energies, the optional C-Series windows provide good efficiency down to the C line.   For count rates >500 kcps, the XR-100FastSDD is recommended.

In the XR-100SDD, the detector is mounted on an extender (several different lengths are available), with the preamplifier in the attached metal box. It requires a separate signal processor and power supplies; Amptek’s PX5 is recommended and is ideally suited for most laboratory uses. The same SDD detectors are available in the smaller X-123SDD package or 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
  • Hight Count Rate – 500,000 CPS
  • 25 mm2 x 500 µm Silicon Drift Detector (SDD)
  • 2-Stage Thermoelectric Cooler
  • Temperature Monitor
  • Thin Beryllium or C-Series window
  • Multilayer Collimator
  • Hermetic Package (TO-8)
  • Wide Detection Range
  • Easy to Operate


  • 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).

The XR-100SDD is an enhanced version of Amptek’s thermoelectrically cooled X-ray detectors. It uses a silicon drift detector (SDD), a silicon photodiode with a special electrode configuration giving very low capacitance, resulting in low electronic noise at high frequencies. This provides the improved energy resolution and count rate. The SDD uses special “drift” electrodes to guide the charge into its anode, hence the name “drift detector”.

As with Amptek’s other XR-100 detectors, the photodiode is mounted on a two stage thermoelectric cooler, keeping the detector and its input JFET at approximately -55 °C, reducing electronic noise without cryogenic liquid nitrogen. This cooling permits high performance in a compact, convenient package, and has been a core enabler of the portable XRF analyzer.

The hermetic TO-8 package of the detector has a light tight, vacuum tight, thin Be window to enable soft X-ray detection. There is vacuum inside the enclosure for optimum cooling. The XR-100SDD detector includes an internal multilayer collimator to minimize background and spectral artifacts. It has a reset-style preamplifier.

In the XR-100SDD, the preamplifier is enclosed in a metal box, 3.0 x 1.75 x 1.125 in (76.2 x 44.45 x 28.58 mm), with the detector on an extender (available lengths range from 3/8” to 9” or 9.53 to 228.6 mm). The XR-100SDD with a 5” or 9” extender is suitable for vacuum measurements, using the optional CP75 vacuum flange. Alternate preamplifiers are available, recommended for OEMs or where space is limited.



Detector Type Silicon Drift Detector (SDD)
Detector Size 25 mm2
Silicon Thickness 500 µm
Collimator Multilayer
Energy Resolution @ 5.9 keV (55Fe) 125 – 140 eV FWHM at 11.2 µs peaking time
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)
C Series: C1 or C2
Collimator Internal MultiLayer Collimator (ML).
Charge Sensitive Preamplifier Amptek custom reset preamplifier.
Gain Stability <20 ppm/°C (typical)
XR-100SDD Case Size 3.00 x 1.75 x 1.13 in (7.6 x 4.4 x 2.9 cm)
XR-100SDD Weight 4.4 ounces (125 g)
Total Power <2 Watt
Warranty Period 1 Year
Typical Device Lifetime 5 to 10 years, depending on use
Operation conditions 0 °C to +50 °C
Storage and Shipping Long term storage: 10+ years in dry environment
Typical Storage and Shipping: -20 °C to +50 °C, 10 to 90% humidity noncondensing
tuv 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 -100 to -200 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: When the XR-100SDD is provided without an Amptek DPP, it includes its own closed loop temperature controller.  When shipped with an Amptek DPP, temperature control is done by the DPP. (Delta_Tmax=85°C)


Preamplifier Sensitivity 0.8 mV/keV typical
Preamplifier Polarity Positive signal output (1 kohm maximum load)
Preamplifier Feedback Reset
Temperature Monitor Sensitivity PX5: direct reading in Kelvin through software.


X-123SDD The silicon drift detector (SDD) is also available in the X-123SDD 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, RS-232, or Ethernet connection to your computer.X-123SDD X-Ray Detector System
Silicon Drift Detector in the X-123SDD Complete Spectrometer.
Vacuum Accessories The SDD is compatible with all Amptek vacuum accessories
OEM The SDD is compatible with all Amptek OEM configurations

XR-100SDD Connectors

Preamp Output BNC coaxial connector
Power and Signal 6-Pin LEMO connector (Part# ERA.1S.306.CLL)
Interconnect Cable XR-100SDD to PX5: 6-Pin LEMO (Part# FFA.1S.306.CLAC57) to 6-Pin LEMO (5 ft length)
XR-100SDD stand-alone: 6-Pin LEMO (Part# FFA.1S.306.CLAC57) to 9-Pin D (5 ft length)

XR-100SDD 6-Pin LEMO Connector Pin Out

Pin 1 Temperature monitor diode
Pin 2 -H.V. Detector Bias, -100 to -200 V maximum
Pin 3 -9 V Preamp power
Pin 4 +9 V Preamp power
Pin 5 Cooler power return
Pin 6 Cooler power
0 to +3.5 V @ 450 mA
Case Ground and shield


The silicon drift detector (SDD) requires negative high voltage and produces a positive preamplifier output. This is the opposite of the standard Si-PIN which requires positive high voltage and produces a negative preamplifier output.

The PX5 can produce both negative and positive high voltage. When the PX5 is ordered with an XR-100SDD, the PX5 is set for negative high voltage. Using a Si-PIN XR-100CR with a negative high voltage setting will destroy the Si-PIN XR-100CR and will not be covered under warranty. Likewise, if the PX5 was ordered with a Si-PIN XR-100CR, using a positive high voltage with an XR-100SDD will destroy the silicon drift detector (SDD) detector and not be covered under warranty.

Typical Performance

Resolution vs. Peaking Time for Amptek Silicon Drift Detector (SDD)
Figure 2. Resolution vs. Peaking Time for the silicon drift detector (SDD).

Resolution vs. Peaking Time for Si-PIN and SDD Detectors
Figure 3. Comparison of Resolution vs. Peaking Time for Si-PIN and SDD Detectors.

Resolution vs. Count Rate for Different Peaking Times with Amptek SDD and DP5
Figure 4. Resolution vs. Input Count Rate for different peaking times for the silicon drift detector (SDD) with the DP5.
The plot also shows the curve of maximum output count rate. Operating to the right of that curve results in less throughput than the maximum despite a higher input rate. See Figure 5 below.

PX5 Throughput with SDD
Figure 5. Throuhgput with the silicon drift detector (SDD). Due to the detector’s smaller capacitance, a much shorter peaking time is used in the shaping amplifier without sacrificing resolution. Typically 9.6 µs or less is used. This dramatically increases the throughput of the system.

Figure 6. 55Fe spectrum with 4 million counts in the peak channel taken with the silicon drift detector (SDD).

Resolution vs. Energy for Different Peaking Times with Amptek SDD
Figure 7. Resolution vs. Energy for Different Peaking Times taken with the silicon drift detector (SDD).

Beryllium Window Transmission and SDD Interaction Efficiency
Figure 8. The figure combines the effects of transmission through the Beryllium window (including the protective coating), and interaction in the silicon drift detector (SDD). The low energy portion of the curve is dominated by the thickness of the Beryllium window – either 0.3 mil (8 µm) or 0.5 mil (12.5 µm), while the high energy portion is dominated by the thickness of the active depth of the Silicon drift detector (SDD) – 500 µm.

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.

Performance for Different Operating Conditions

Ultimate Resolution

  • 125 eV FWHM Resolution @ 5.9 keV
  • 11.2 µs Peaking Time
  • 100,000 CPS
  • Peak to Background Ratio 20,000:1

Not fast enough? Try…

  • 155 eV FWHM Resolution @ 5.9 keV
  • 0.8 µs Peaking Time
  • 500,000 CPS

Operation for Handheld Devices

  • 150 eV FWHM Resolution @ 5.9 keV
  • 3.2 µs Peaking Time
  • 200,000 CPS
  • Detector Temperature at 250 K (-24 °C)

Application Spectra

XRF analysis of stainless steel (SS316) taken with the silicon drift detector (SDD)
Figure 9. XRF of stainless steel SS316 taken with the silicon drift detector (SDD) and the Mini-X x-ray tube.

RoHS/WEEE PVC sample taken with the silicon drift detector (SDD) and the Mini-X x-ray tube
Figure 10. RoHS/WEEE PVC sample taken with the silicon drift detector (SDD) and the Mini-X x-ray tube.

CaCl2 solution (800 ppm Ca, 1200 ppm Cl) taken with silicon drift detector (SDD) and the Mini-X x-ray tube
Figure 11. CaCl2 solution (800 ppm Ca, 1200 ppm Cl) taken with silicon drift detector (SDD) and the Mini-X x-ray tube.

Sulphur in crude oil (1100 ppm) with some KCl taken with silicon drift detector (SDD) and the Mini-X x-ray tube
Figure 12. Sulphur in crude oil (1100 ppm) with some KCl taken with silicon drift detector (SDD) and the Mini-X x-ray tube.

Automotive Catalyst taken with silicon drift detector (SDD) and the Mini-X x-ray tube
Figure 13. Automotive Catalyst taken with silicon drift detector (SDD) and the Mini-X x-ray tube.

Platinum (Pt) ring XRF analysis taken with silicon drift detector (SDD) and the Mini-X x-ray tube
Figure 14. Platinum (Pt) ring XRF taken with silicon drift detector (SDD) and the Mini-X x-ray tube.

Signal Processor/Power Supply Modules

PX5 Digital Pulse Processor, MCA and Power Supply

Power to the XR-100SDD is provided by the PX5 Digital Pulse Processor and Power Supply. The PX5 is DC powered by an AC adaptor and provides a variable Digital Pulse Processing Amplifier (0.200 µs to 100 µs peaking time), the MCA function, and all power supplies for the detector.

The XR-100SDD/PX5 systems ensures stable operation in less than one minute from power turn-on.

Block Diagram with PX5 and XR-100SDD Silicon Drift Detector
Block diagram of a typical system using the PX5 and an Amptek XR-100SDD detector. Several different detector and preamp configurations are available from Amptek, Inc., with different pinouts and voltages.

DP5/PC5 OEM Digital Pulse Processor, MCA, and Power Supply

XR-100SDD with the DP5 and PC5 is an option that requires some assembly and possibly a custom enclosure depending on the application on the part of the customer.

Standard XR-100SDD connected to the DP5/PC5
Figure 15. Standard XR-100 box connected to the DP5 and PC5.

Window Options and Thicknesses

Amptek SDDs are available with either beryllium windows, or our C Series windows.  The Be options are Paralyne coated (to prevent gas diffusion), and are supplied in two thicknesses, 0.3 mil or 0.5 mil (8 or 12 μm). The C-Series windows are designed for low Z element detection down to Carbon (C).

Options and Accessories

X-123SDD X-Ray Detector System
Figure 16a. The X-123 configuration, which includes
the detector, preamplifier, digital processor, and power
supplies all in one box.
PA-230 Housing
Figure 16b. The detector/preamplifier is available in OEM configurations to fit the requirements of any system. Pictured is the detector with the PA-230 preamplifier and housing. See the OEM page for details.

XR-100 SDD and Si-PIN detectors with various length extensions
Figure 17. XR-100SDD Detector Extender Options.

Use of Collimators

All of Amptek’s Si detectors contain internal multilayer collimators to improve spectral quality. X-rays interacting near the edges of the active volume of the detector may produce small pulses due to partial charge collection. These pulses result in artifacts in the spectrum which, for some applications, obscure the signal of interest. The internal collimator restricts X-rays to the active volume, where clean signals are produced. Depending on the type of detector, collimators can improve peak to background (P/B), eliminate edge effects, eliminate false peaks.

collimated vs not collimated detector
Figure 18. This plot shows a comparison between a collimated detector and a detector without a collimator.

Multilayer Collimator (ML)

A multilayer collimator is made by progressively using lower Z materials. Each layer acts as an absorber to the fluorescence peaks of the previous layer. The final layer will be of the lowest Z material whose fluorescence peaks are of low enough energy to be outside the anticipated X-ray detection range.

Amptek has developed a state-of-the-art internal Multilayer Collimator (ML). The base metal is 100 µm of tungsten (W), the first layer is 35 µm of chromium (Cr), the second layer is 15 µm of titanium (Ti), and the last layer is 75 µm of aluminum (Al).

Additional Information

1.5 Inch Extender (standard)

XR100CR Mechanical Dimensions
Figure 19. All dimensions in inches ±0.005.

No Extender

XR100CR with no extention.
Figure 20. All dimensions in inches ±0.005.

General AXR (T0-8) Mechanical Dimensions

General AXR (T0-8) Mechanical Dimensions
Figure 21. All dimensions in inches ±0.005.

Typical Detector Geometry

Typical Detector Geometry
Figure 22. Typical Detector Geometry.

Mechanical Dimensions Table