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OverviewThe 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. | |
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The PX5 complete pulse processing system and power supply
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  Figure 1. |
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| Gain Settings | Combination of coarse and fine gain yields overall gain continuously adjustable from x0.75 to x516. |
| Coarse Gain | 16 log spaced coarse gain settings from x0.75 to x413. |
| Fine Gain | Adjustable between 0.75 and 1.25, 13 bit resolution. |
| Full Scale | 1000 mV input pulse @ x1 gain. |
| Gain Stability | <30 ppm/°C (typical). |
| ADC Clock Rate | 20 or 80 MHz, 12 bit ADC. |
| Pulse Shape | Trapezoidal 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 Times | Software selectable peaking times between 0.05 and 102 µs, corresponding to semi-Gaussian shaping times of 0.04 to 42.5 µs. |
| Flat Top Times | Software selectable values for each peaking time (depends on the peaking time), >0.05 µs. |
| Max Count Rate | With a peaking time of 0.2 µs, 4 MHz periodic signal can be acquired. |
| Dead Time per Pulse | 1.05x peaking time. No conversion time. |
| Fast Channel Peaking Times | 20 MHz: 200, 400, 1600 ns 80 MHz: 50, 100, 400 ns |
| Fast Channel Pulse Pair Resolving Time | 1.2 x Fast Channel Peaking Time (minimum of 60 nsec) |
| Pile-Up Rejection | Pulses separated by more than the fast channel resolving time and less than 1.05x peaking time are rejected. |
| Baseline Restoration | Asymmetric - 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. |
| Gate | The 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). |
| Number of channels | Commandable to 256, 512, 1k, 2k, 4k, or 8k channels. |
| Bytes per channel | 3 bytes (24 bits), 16.7 M counts. |
| Preset Acquisition Time | 10 ms to 466 days. |
| Data Transfer Time | USB: 1k channels in 4.8 ms; Ethernet 1k channels in 35 ms |
| Conversion Time | None |
| Presets | Time, total counts, counts in an ROI, counts in a channel. |
| MCS Timebase | 10 ms/channel to 300 s/channel. |
| External MCA Controls | Gate Input - Pulses accepted only when gated on by external logic. Input can be active high or active low. |
| Counters | Slow channel events accepted by MCA. Incoming counts (fast channel counts above threshold), event rejected by selection logic, and external event counter. |
| Microprocessor | Silicon Labs 8051F340 8051-compatible core. |
| External Memory | 512 kb low-power SRAM |
| Firmware | Signal processing is programmed via firmware, can be upgraded in the field. |
| RS-232 | Standard serial interface, 115 or 56 Kbaud. |
| USB | Standard 2.0 full speed (12 Mbps). |
| Ethernet | Standard 10base-T. |
| Analog Input (BNC) | The analog input accepts positive or negative going pulses from a charge sensitive preamplifier. |
| Power | +5 VDC. Mates with a center positive 5.5 mm x 2.1 mm power plug. |
| USB | Standard USB mini-b jack. |
| Ethernet | Standard 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. |
| 1 | Temperature |
| 2 | Bias (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 |
| 5 | Cooler - (grounded) |
| 6 | Cooler + (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 Transient | 2 A for <100 ns |
| 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 Analyzers | 8 SCAs, independent software selectable LLDs and ULDs, LVCMOS (3.3 V) level (TTL compatible). |
| Digital Outputs | 2 independent outputs, software selectable between 8 settings including INCOMING_COUNT, PILEUP, MCS_TIMEBASE, etc. LVCMOS (3.3V) levels (TTL compatible). |
| Digital Inputs | 2 independent inputs, software selectable for MCA_GATE, EXTERNAL_COUNTER. |
| DAC Output | Used in oscilloscope mode to view the shaped pulse and other diagnostic signals. Range: 0 to 1 V. |
| Digital Oscilloscope | Displays oscilloscope traces on the computer. Software selectable to show shaped output, ADC input, etc., to assist in debugging or optimizing configurations. |
| 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 |
| Compliance | RoHS Compliant |
 | TUV Certification Certificate #: CU 72112987 01 Tested to: UL 61010-1: 2004 R10.08 CAN/CSA-C22.2 61010-1-04+GI1 (R2009) |
| Size | 6.5” x 5.5” x 1.5” / 165 x 135 x 40 mm |
| Weight | 1.6 lbs / 750 g |
| DPPMCA | The 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. |
| SDK | The 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 Software | The 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. |
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Figure 4. PX5 throughput for various peaking times. Taken with an Amptek XR-100SDD x-ray detector.
Figure 5. PX5 waveforms, showing from the preamp output to the shaped pulse etc.
Figure 6. PX5 cusp waveform.
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.
Figure 7. PX5 High Voltage jumper set to positive for Si-PIN or CdTe.
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.
Figure 9. Complete XRF system.
PX5 Specifications in PDF
Digital Pulse Processor FAQ
PX4 FAQ
Glossary
Revised December 29, 2011
