The eight-channel digital pulse processor DDC-8 was originally intended to serve as a real-time trigger for the PHOBOS experiment located in Brookhaven National Laboratory. Besides this initial application, the device is targeted at flexible general-purpose real-time digital pulse processing. The board features eight analog input channels, as well as a large number of logic inputs and outputs. The sixteen NIM inputs as well as seventeen TTL I/Os are connected to the on-board FPGA in order to process coincidence signals in real-time. The TTL lines can also serve as the high-speed, bidirectional interface to the VME digital processor XLM-80. The USB interface provides control of the device and medium-speed data readout, while the RS-232 interface allows remote operation. The digital signal processing is performed by the FPGA. The on-board microcontroller performs the monitoring and communication chores. The photograph shows the proctology board. The mechanical standard of the board is NIM. The board can also be mounted in a CAMAC enclosure, or any other enclosure from which it will receive +/-6V power.

The board:


Main parameters:

FPGA Xilinx XC2S300E
Analog to Digital Converter 10bit@40MHz
Number of channels 8
Buffer length per channel 1024 samples

Sample digitized pulse:

Gigitized Pulse
Left: A fast test pulse from the NIM pulser, which is a good approximation of a pulse from a fast phototube. The pulse lasts for only half of the DDC-8 sampling period. Right : the waveform captured with DDC-8.

Real application:

Online Muon Capture and Decay Experiment

Megan Alexander, Daniel Miner,
Wojtek Skulski, Frank Wolfs

On-line Muon experiment is here
Presentation available here
Screenshot of the on-line Muon experiment
Sample screenshot of the on-line muon experiment

Implementing in FPGA stopping Muon detection for the Online Muon Experiment 

DDC-8 firmware enhancement by Eryk Druszkiewicz as a summer Research Experience for Undergraduates (REU)

The goal was to add the ability to distinguish stopping from passing muons on-the-fly using the FPGA on DDC-8. This then gave the ability to control the ratio of passing to stopping muons captured. As one can see in the screenshot above the uncontrolled ratio is about ~200. Since the new firmware we were able to effectively decrease the ratio. For example in the experiment summarized in the figure below, the ratio was set to 4.
Sample screenshot of the on-line Muon experiment
Sample screenshot of the on-line Muon Experiment with on-the-fly muon detection

Energy spectra collection with the NaI(Tl) detector

Using a DDC-8 board an energy threshold of as low as 5 keV was achieved with the DDC-8 board during a measurement that extended into an MeV range.
Na22 Spectrum
Sample 22 Na spectrum obtained with DDC-8

Co60 Spectrum
Sample Co60 spectrum obtained with DDC-8

Cs137 Spectrum
Sample Cs spectrum obtained with DDC-8