DP5 OEM Digital Pulse Processor and MCA

Pulse Processing Performance

MCA Performance

Hardware

Communications

Auxiliary Inputs and Outputs

The primary purpose of this connector is to bring out logic signals which are not required for the primary use of the DP5: acquiring spectra and transmitting them over the serial interface. These are generally “low level” logic signals associated with each pulse processed by the DP5. They are primarily used for synchronizing the DP5 data acquisition to external hardware and for direct counter/timer outputs from the DP5. The signals are described below. The connector is a 2×8 right angle Samtec part number ASP-135096-01.

Auxiliary Connector Pin Assignments

Connections

Interface Software

Power

Physical

General and Environmental

Features

• 80 MHz ADC
• Replaces both shaping amplifier and MCA
• Supports both reset and feedback preamplifiers of either polarity
• MCS Mode
• 16 SCAs
• List Mode
• Streaming Mode
• Configurable with a charge sensitive preamplifier for use with PMTs
• For OEM or custom laboratory use
• Highly configurable

Pulse Processing & MCA

• Trapezoidal shaping
• Commandable peaking time from 0.05 to 102.4 µs
• Commandable flat top duration from 0.05 to 51.2 µs
• 4,000,000 cps periodic
• Pile-up rejection, risetime discrimination, gate
• Up to 8k output MCA channels

Communications

• 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

Software

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

Physical

• Low Power: 1300 mW typical
• Small Size: 3.5 in X 2.5 in

Applications

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

DP5 Architecture

The DP5 is a component in the complete signal processing chain of a nuclear instrumentation system. The input to the DP5 is the preamplifier output. The DP5 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 DP5’s serial interface to the user’s computer. Clearly, the DP5 must be used with other components, including a detector, preamplifier, and computer.

Analog Prefilter

The input to the DP5 is the output of a charge sensitive preamplifier. The analog prefilter circuit prepares this signal for accurate digitization. The main functions of this circuit are (1) applying appropriate gain and offset to utilize the dynamic range of the ADC, and (2) carrying out some filtering and pulse shaping functions to optimize the digitization.
NOTE: The DP5 can be ordered with a charge sensitive preamplifier on the board for use with PMTs.

ADC

The ADC digitizes the output of the analog prefilter at a 20 or 80 MHz rate (software selectable). The digitized values are sent, in real time, into the digital pulse shaper. 12 bit ADC is used.

Digital Pulse Shaper

The ADC output is processed continuously using a pipeline architecture to generate a real time shaped pulse. This carries out pulse shaping as in any other shaping amplifier. The shaped pulse is a purely digital entity. Its output can be routed to a DAC, for diagnostic purposes, but this is not necessary.

There are two parallel signal processing paths inside the DPP, the “fast” and “slow” channels, optimized to obtain different data about the incoming pulse train. The “slow” channel, which has a long shaping time constant, is optimized to obtain accurate pulse heights. The peak value for each pulse in the slow channel, a single digital quantity, is the primary output of the pulse shaper. The “fast” channel is optimized to obtain timing information: detecting pulses which overlap in the slow channel, measuring the incoming count rate, measuring pulse risetimes, etc.

The DP5 uses trapezoidal pulse shaping, which offers high energy resolution, reduces ballistic deficit, and provides excellent baseline stability at high count rates.

Pulse Selection Logic

The pulse selection logic rejects pulses for which an accurate measurement cannot be made. It includes pile-up rejection, risetime discrimination, logic for an external gating signal, etc. At high count rates, the DP5 has both better pile-up rejection and higher throughput than a traditional, analog shaping amp.

Histogramming Memory

The histogram memory operates as in a traditional MCA. When a pulse occurs with a particular peak value, a counter in a corresponding memory location is incremented. The result is a histogram, an array containing, in each cell, the number of events with the corresponding peak value. This is the energy spectrum and is the primary output of the DP5. The unit also includes several counters, counting the total number of selected pulses but also counting input pulses, rejected events, etc. Auxiliary outputs include eight different single channel analyzers, and both a DAC output and a digital output showing pulse shapes from several points in the signal processing chain.

Interface

The DP5 includes hardware and software to interface between these various functions and the user’s computer. A primary function of the interface is to transmit the spectrum to the user. The interface also controls data acquisition, by starting and stopping the processing and by clearing the histogram memory. It also controls certain aspects of the analog and digital shaping, for example setting the analog gain or the pulse shaping time.

The interface includes a microcontroller that impliments RS232, USB, and Ethernet communications.

PC5 Power and Interface Board

Amptek’s DP5 Digital Pulse Processor is a component in the complete signal processing chain of a nuclear instrumentation system. It must be used with other components, including (at a minimum) a detector and preamplifier, and computer with a serial interface and software to communicate. The DP5 itself has its own power supplied so only needs a +5 V DC input. When using the DP5 with Amptek detectors, additional power supplies are needed for the detector and preamp. Amptek provides the PC5 board that mates with the DP5 and provides power to Amptek detectors.

The PC5 provides power to Amptek XR-100 detectors from a +5 VDC source. This board is intended for those using Amptek detectors and preamps. The USB interface cannot supply enough current to operate the XR-100, so an external DC supply is required, which must be between 4.0 and 5.5 V.
Dimensions: 3.5 in x 2.5 in

Software

There are two distinct software packages that are needed for the DP5: embedded software that runs on the microcontroller on the DP5 (firmware), and acquisition and control software that runs on the attached computer.

Embedded Software

The embedded software is responsible for controlling the pulse processing, controlling the MCA, carrying out some data processing, and interfacing with the personal computer. This software is fixed and cannot be modified by the user. Firmware updates will be released by Amptek and can be uploaded in the field by the user.

Interface Software

DPPMCA Software

The DP5 can be controlled by the Amptek DPPMCA display and acquisition software. This software can be used for control and display of the DP5 and supports regions of interest (ROI), calibrations, peak searching, and so on.

DPP SDK

The DP5 comes with a complete Software Development Kit (SDK). The user can use this platform to easily develop software to control the DP5 for custom applications or to interface it to a larger system. Examples are provided in VB, VC++, etc

The A250 Connected to a DP5 Digital Pulse Processor and MCA

DP5G for use with Scintillators and Photomultiplier Tubes

The Amptek DP5G is a state-of-the-art, high performance, low power digital pulse processor designed for use in scintillation spectroscopy systems. Connected to the anode of a PMT, it includes a charge sensitive preamplifier and a digital pulse processor, which replaces both the shaping amplifier and the MCA in a traditional nuclear spectroscopy system. The DP5G offers several advantages over traditional systems, including higher performance, enhanced flexibility, small size, and low cost.