Coincidence
Counting Units (CCUs)
I am
leaving this page up for archival reasons, but note that the technology
described here is obsolete, and I do not support it any more.
DE2 CCU
We have implemented a coincidence counting unit (CCU) on the Altera DE2 development and education board. The CCU takes inputs from up to four detectors, and has eight 32-bit counters that are used to count four singles counts and four arbitrary 2-, 3-, or 4-fold coincidences (coincidences are determined by switch settings on the DE2 board). The CCU has a coincidence-time resolution of less than 8 ns. Data is streamed from the CCU to a host computer over an RS232 serial interface.
The FPGA CCU is shown below.
To implement this CCU for yourself, you buy the Altera DE2, and get the design files and instructions for downloading them onto the DE2 from us. We’ll also give you the information you need to build the adapter box and use the CCU. All the info for implementing this circuit is located here. LabView code to run the CCU is here.
This CCU was largely programmed by Jesse Lord when he was at Whitman College.
The FPGA
CCU.
DE2-115 CCU
Prof. Hartmut Haeffner and others at Berkeley have taken our DE2 program and adapted it for the DE2-115. They have also improved the program, in that it is no longer necessary to redo the fitting after recompilation. You can download the files here.
NOTE: The pin connections between the FPGA and the breakout box are DIFFERENT for the DE2 and the DE2-115, so you’ll need to wire the box differently. The pin connections for the DE2-115 can be found here.
Disclaimer: This is not my code. If you have questions about it, you’ll need to contact Berkeley.
Red Dog CD48 CCU
Eric Ayars of Cal State Univ. Chico had developed the CD48 coincidence counter. It works well, but has a longer coincidence window than the DE2. This means that measured g(2)(0) values are a bit higher, and you need to subtract accidental coincidences from Bell and Hardy measurements to get a significant number of violations.
Our most recent LabView vi’s support both the DE2 and the CD48.
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webpage updated 7/11/2022