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px5 digital pulse processor, mca, and power supply

Enhanced Laboratory Digital Pulse Processor, MCA, and Power Supply


  • Single unit compatible with all current Amptek SDD, Si-PIN, and CdTe detectors
  • Includes
    • Digital pulse shaping amplifier
    • Integrated multichannel analyzer
    • Power supplies
  • Supports detectors from other manufacturers, and both reset and feedback preamplifiers of either polarity
  • Trapezoidal, and new Cusp shaping with wide range of peaking times to optimize performance
  • High count rate capability with excellent baseline stability, throughput, and pile-up rejection
  • Up to 8k output MCA channels
  • Oscilloscope mode - DAC output for pulse monitoring and adjustment
  • 8 single channel analyzer outputs


  • Interfaces: RS-232, USB, Ethernet
  • Oscilloscope mode - DAC output for pulse monitoring and adjustment
  • Onboard µcontroller with 8051-compatible core
  • Many configurable auxiliary inputs & outputs available


  • Free Display and Acquisition Software
  • Free Software Developer's Kit (SDK)


  • High voltage bias adjustable ±100 V to ±1.5 kV
  • Thermoelectric cooler supply with feedback (2-stage cooler)
  • Operates from +5V DC supply (AC power adapter included)


  • Low Power: 3 W typical
  • Small Size: 6.5 x 5.5 x 1.5 inches (165 x 135 x 40 mm)
  • Light Weight: 1.6 lbs/750 g

px5 digital pulse processor and power supply front view

px5 digital pulse processor and power supply back view


  • X-ray and gamma ray detectors
  • Nuclear Instrumentation
  • Portable, battery operated systems
  • OEM & Special Applications
  • Process Control
  • Research and Teaching


The Amptek PX5 interfaces between (1) an X-ray and gamma-ray detector with its preamplifier and (2) a computer running data acquisition and control software. Designed principally to support Amptek s XR100 series of SDD, Si-PIN, and CdTe detectors, it can be used with many other radiation detectors and preamplifiers, including HPGe detectors and scintillators. It is compatible with both reset and feedback preamplifiers of either polarity. The PX5 includes (1) a high performance digital pulse processor (replacing a conventional shaping amplifier), (2) a multichannel analyzer, and (3) both low and high voltage power supplies (±HV).

The PX5 offers several advantages over traditional systems, including improved performance (very high resolution, reduced ballistic deficit, higher throughput, and enhanced stability), many more configuration options to optimize the system, and many communications and output options. The PX5 is based on Amptek’s latest generation of digital pulse processing technology, also used in the DP5 family of products.

The signal input to the PX5 is the preamplifier output. The PX5 digitizes the preamplifier output, applies real-time digital processing to the signal, detects the peak amplitude (digitally), and bins this value in its histogramming memory, generating an energy spectrum. The spectrum is then transmitted over the PX5’s USB, Ethernet, or RS232 interface to the user’s computer.

The PX5 is compatible with both 32 and 64 bit operating systems, including Windows 7.


The PX5 complete pulse processing system and power supply

  1. Digitizes the preamp signal
  2. Implements trapezoidlifieral shaping
  3. Creates a multichannel analyzer (MCA) type output spectrum
  4. Provides all necessary power for Amptek XR100 detectors.
dp4 trapezoidal response
output spectrum
Figure 1.

px5 digital pulse processor, mca, and power supply block diagram
Figure 2. Block diagram of a typical system using the PX5 and an Amptek XR100SDD detector. Several different detector and preamp configurations are available from Amptek, Inc., with different pinouts and voltages.


Pulse Processing Performance

Gain SettingsCombination of coarse and fine gain yields overall gain continuously adjustable from x0.75 to x516.
Coarse Gain16 log spaced coarse gain settings from x0.75 to x413.
Fine GainAdjustable between 0.75 and 1.25, 13 bit resolution.
Full Scale1000 mV input pulse @ x1 gain.
Gain Stability<30 ppm/°C (typical).
ADC Clock Rate20 or 80 MHz, 12 bit ADC.
Pulse ShapeTrapezoidal or Cusp. A semi-gaussian amplifier with shaping time t has a peaking time of 2.4t and is comparable in performance with the trapezoidal shape of the same peaking time.
Peaking TimesSoftware selectable peaking times between 0.05 and 102 µs, corresponding to semi-Gaussian shaping times of 0.04 to 42.5 µs.
Flat Top TimesSoftware selectable values for each peaking time (depends on the peaking time), >0.05 µs.
Max Count RateWith a peaking time of 0.2 µs, 4 MHz periodic signal can be acquired.
Dead Time per Pulse1.05x peaking time. No conversion time.
Fast Channel Peaking Times20 MHz: 200, 400, 1600 ns
80 MHz: 50, 100, 400 ns
Fast Channel Pulse Pair Resolving Time1.2 x Fast Channel Peaking Time (minimum of 60 nsec)
Pile-Up RejectionPulses separated by more than the fast channel resolving time and less than 1.05x peaking time are rejected.
Baseline RestorationAsymmetric - 16 software selectable slew rate settings.
Rise Time Discriminator (RTD)The digital pulse processor can be programmed to select input pulses based on their rise time properties.
GateThe gate input is used with external circuitry to determine if events should be included or excluded from the spectrum. The gate can be active high or active low (or disabled).

MCA Performance

Number of channelsCommandable to 256, 512, 1k, 2k, 4k, or 8k channels.
Bytes per channel3 bytes (24 bits), 16.7 M counts.
Preset Acquisition Time10 ms to 466 days.
Data Transfer TimeUSB: 1k channels in 4.8 ms; Ethernet 1k channels in 35 ms
Conversion TimeNone
PresetsTime, total counts, counts in an ROI, counts in a channel.
MCS Timebase10 ms/channel to 300 s/channel.
External MCA ControlsGate Input - Pulses accepted only when gated on by external logic. Input can be active high or active low.
CountersSlow channel events accepted by MCA. Incoming counts (fast channel counts above threshold), event rejected by selection logic, and external event counter.


MicroprocessorSilicon Labs 8051F340 8051-compatible core.
External Memory512 kb low-power SRAM
FirmwareSignal processing is programmed via firmware, can be upgraded in the field.


RS-232Standard serial interface, 115 or 56 Kbaud.
USBStandard 2.0 full speed (12 Mbps).
EthernetStandard 10base-T.


Analog Input (BNC)The analog input accepts positive or negative going pulses from a charge sensitive preamplifier.
Power+5 VDC. Plug mates with 3.5 mm x 1.3 mm x 9.5 mm female barrel, center positive, straight connector.
USBStandard USB mini-b jack.
EthernetStandard Ethernet jack.
AUX-1 (BNC)Configured in software as (1) an analog output, to view shaped pulses or diagnostic signals, (2) a digital output, to view a discriminator output or diagnostic signals, or (3) a digital input.
AUX-2 (BNC)Configured in software as (1) a digital output, to view a discriminator output or diagnostic signals, or (2) a digital input, to gate or synchronize data acquisition.
AUX-3 (15 pin D connector female)Includes (a) the lines for a serial RS232 interface, (b) two lines which can be configured for digital inputs or outputs, (c) 8 single channel analyzer (SCA) outputs, and (d) a control line to command the power on or off remotely.

XR100 Power: 6-Pin Lemo Connector

2Bias (up to ±1500V)

WARNING: Using the wrong polarity will destroy the detector and will NOT be covered under warranty. Always check that the correct HV polarity is set before turning on the PX5.

3-8.5 or -5 VDC
4+8.5 or +5 VDC
5Cooler - (grounded)
6Cooler + (2-stage cooler)
Ground on shield


+5 V+5 VDC at 500 mA (2.5 W) typical. Current depends strongly on Tdet, ranging from 300 to 800 mA at 5 VDC.
Input Range+4 V to +5.5 V (0.4 to 0.7 A typical).
Initial Transient2 A for <100 ns

Auxiliary Inputs and Outputs

The connectors bring out logic signals which are not required for the primary use of the PX5: acquiring spectra and transmitting them over the serial interface. These are generally “low level” logic signals associated with each pulse processed by the PX5; used for synchronizing the PX5 data acquisition to external hardware and for direct counter/timer outputs from the PX5. The signals are described below.
Single Channel Analyzers8 SCAs, independent software selectable LLDs and ULDs, LVCMOS (3.3 V) level (TTL compatible).
Digital Outputs2 independent outputs, software selectable between 8 settings including INCOMING_COUNT, PILEUP, MCS_TIMEBASE, etc. LVCMOS (3.3V) levels (TTL compatible).
Digital Inputs2 independent inputs, software selectable for MCA_GATE, EXTERNAL_COUNTER.
DAC OutputUsed in oscilloscope mode to view the shaped pulse and other diagnostic signals. Range: 0 to 1 V.
Digital OscilloscopeDisplays oscilloscope traces on the computer. Software selectable to show shaped output, ADC input, etc., to assist in debugging or optimizing configurations.

General and Environmental

Operating Temperature -40 °C to +85 °C.
Warranty Period 1 year
Typical Device Lifetime 5 to 10 years, depending on use.
Long-term Storage 10+ years in dry environment.
Typical Storage and Shipping-40 °C to +85 °C, 10 to 90% humidity noncondensing
ComplianceRoHS Compliant
TUV CertificationTUV Certification
Certificate #: CU 72112987 01
Tested to: UL 61010-1: 2004 R10.08
CAN/CSA-C22.2 61010-1-04+GI1 (R2009)


Size6.5” x 5.5” x 1.5” / 165 x 135 x 40 mm
Weight1.6 lbs / 750 g

Interface Software

DPPMCAThe PX5 can be controlled by the Amptek DPPMCA display and acquisition software. This software completely controls and configures the PX5, and downloads and displays the data. It and supports regions of interest (ROI), calibrations, peak searching, and so on. The DPPMCA software includes a seamless interface to the XRF-FP quantitative X-ray analysis software package. Runs under Windows XP PRO SP3 or later. Click here for the software download page.
SDKThe PX5 comes with a free Software Developer's Kit (SDK). The user can use this kit to easily write custom code to control the PX5 for custom applications or to interface it to a larger system. Examples are provided in VB, VC++, etc. Click here for the software download page.
VB Demonstration SoftwareThe VB demonstration software runs on a personal computer and permits the user to set the PX5 parameters, to start and stop data acquisition, and to save data files. It is provided with source code and can be modified by the user. This software is intended as an example of how to manually control the PX5 through either the USB, RS-232, or Ethernet interface using the most basic calls without the SDK. This is primarily needed as an example when writing software for non-Windows platforms. Click here for the software download page.

Digital I/O: 15 pin D connector (female)

2RS232 - TX
3RS232 -RX
4SCA 6 Out
5SCA 5 Out
7Aux 3
8Aux 4
9SCA 8 Out
10External Power On
11SCA 7 Out
12SCA 1 Out
13SCA 2 Out
14SCA 3 Out
15SCA 4 Out

Figure 3. Photo of the I/O cable.

PX5 Throughput vs. Peaking Time

throughput, input vs. output count rate for silicon drift detector
Figure 4. PX5 throughput for various peaking times. Taken with an Amptek XR-100SDD x-ray detector.

PX5 Waveforms

px5 waveforms
Figure 5. PX5 waveforms, showing from the preamp output to the shaped pulse etc.

px5 cusp waveform
Figure 6. PX5 cusp waveform.

High Voltage Jumper

WARNING: Using the wrong polarity will destroy the detector and will NOT be covered under warranty. Always check that the correct HV polarity is set before turning on the PX5.

The PX5 can produce both negative and positive high voltage. The polarity is set by the jumper seen below. Amptek Si-PIN and CdTe detectors require positive high voltage. Using negative HV will destroy the Si-PIN and CdTe and will not be covered under warranty. Amptek silicon drift detectors (SDD) require negative high voltage. Using positive HV will destroy the SDD and will not be covered under warranty.

px5 hv jumper = positive for Si-PIN or CdTe
Figure 7. PX5 High Voltage jumper set to positive for Si-PIN or CdTe.

px5 hv jumper = negative for SDD
Figure 8. PX5 High Voltage jumper set to negative for SDD.

WARNING: Using the wrong polarity will destroy the detector and will NOT be covered under warranty. Always check that the correct HV polarity is set before turning on the PX5.

Complete XRF System

complete xrf system
Figure 9. Complete XRF system.

Complete XRF System Includes

See the Experimenter's XRF Kit.

PX5 Specifications in PDF
Digital Pulse Processor FAQ

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Revised December 29, 2011