Hi,
I am trying to work out if it is possible to count random negative analog pulses from a photon multiplier tube (PMT) with any of the NI multifunction DAQ or counter/timer boards?
Firstly, the properties of the PMT output are as follows (single photon response):
- 1.5 ns FWHM
- -50 mV to -400 mV (random due to the amplification process in the PMT)
- Up to 5 million counts per second (higher rates cause the detector to overload) arriving at random times.
All I would like to do is to do simple event counting or buffered event counting.
All the counters seem to only be able to count digital TTL pulses. In that case I have some external signal conditioning electronics in mind which will convert the pulses to positive 5V CMOS logic pulses (which according to this website is suitable for the counter inputs). It also contains a dicriminator circuit to ignore pulses below a threshold. With this signal, I am planning to send to a NI USB multifunction DAQ BNC counter input for event/buffered event counting.
However, in the hope to keep the cost of my system down, I was hoping there might be a way to set an analog trigger to create a TTL pulse from one of NI boards, therefore altogether side-stepping the need for external signal conditioning??
Any help would be gratefully received.
Kind regards
Sean