NIM-Modules / Questions and Answers
I use fast position-dependent detectors with delay-line read out. The maximum count rate that I can reach using two 7072T TDC's in coincidence and MPA-3 is only about 350 kHz per input. Is there a solution that can handle a higher count rate?
I could verify a rate of 900,000 cps in the 1 TDC singles mode when using short NIM pulses at start- and stop input of the 7072T. In coincidence mode i could see a maximum useful rate of 370,000 per input. For higher rates the coincidence mode does not longer work correctly and a lot of counts appear in channel zero.
Yes, there is a solution for higher rates: you can use the MCS6A / MCS8A instead of the MPA-3. You can directly connect a start signal and up to five stop inputs, no TDC is needed. The maximum overall count rate is limited by the USB 2.0 Bus to 35 MByte/sec, i.e. using a 6 byte datalength a total count rate of 5.8 million events/sec. For short acquisitions up to 1 minute the count rate can be even much higher due to a large 2 GB FIFO. With MCS8A and USB 3 the count rate is even much larger, the permanent througput limit is about 240 MB/s.
The software is already well prepared for position-dependent detectors.