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| Stefan Ritt wrote: |
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| Martin Petriska wrote: |
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I have two BaF2 detectors with PMT connected to Ch1 and Ch2. At this time Im using external triger module to start DRS4. My evalution board is version 3 so I have no possibility to trigger on two or more pulses occurence on different channels. But I have this idea, trigger with analog trigger on channel 1 (start detector) will start measurement on all channels. After that using FPGA inside EVM to look if some value in Ch2 is bigger as treshold value for example 0,5V and if yes then send data by USB to PC, if signal in Ch2 is lower then restart measurement and wait on triger in Ch1. This way I want to eliminate false data transfer throw USB. Is this possible to implement it into DRS4 evaluation board firmware ?
Thanks.
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It is muuuuch easier to upgrade to a V4 board!
Modification of firmware is not so easy. You have to learn and understand VHDL. Then, you have to add additional registers for this thresholds, which requires modification of the C library as well. The data inside the evaluation boards is not yet calibrated (this is only done on the C library), so you have an uncertainty of 30-40mV in this data.
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Ok, except this, I would have a question regarding to the new trigering posibility in V4 board. At this time, I am using Ztec ZT4612 which has some pattern triger posibility. Output from this card is used as an external trigger. Regarding this I have found a problem. Pulses from PMT have about 5-8 ns width. But I need to measure time diferences between pulses in range from 0-50ns. Problem is, that coincidence between pulses is working only on short pulse area (5-8ns) when they are overlapped. Additionaly the result histogram of time diferences is proportional to the pulse shapes. I solve this problem enabling 20MHz LPF filter in ZT4612, so the pulses are wider and overlaped on larger area. But, how it is with the V4 board? Will it trigger if I have for example one 5ns pulse on begiinning of CH1 and second pulse for example 50 ns later on Ch2 with the same probability when pulses are in the same time position?
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