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In essence, I am working with an old (1960s) Geiger-Muller tube and a set of counting electronics, including an amplifier. Unfortunately, I don't have access to them for the next month or so, due to maintenance in the lab. I was curious to know the effect of the gain of my amplifier on the dead time of my system. I've always used a 30 times amplification and 0.6 kV bias, bang in the middle of my plateau, which typically gives me a dead time of around 400 microseconds. I was recently asked whether the gain on my amp could have an affect on the dead time of the system. Intuitively, I'd assume that the higher gain, leading to a higher voltage spike in my counter would lead to a larger recovery period as well, but I'm bloody eager to know now, and I can't test it for myself for ages. So could anyone tell me if using a lower gain would really reduce my dead time noticeably? TL;DR, Does amplifier gain have an effect on the dead time of my Geiger Counter?

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  • $\begingroup$ "the higher gain, leading to a higher voltage spike in my counter would lead to a larger recovery period " Does the size of the output signal from the amplifier affect the size of the signal in the tube itself? Why or why not? Are there sources of dead time after the amplifier? If so do they depend on the size of the pulse from the amp? $\endgroup$ – dmckee --- ex-moderator kitten Dec 9 '16 at 18:48
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No, the amplifier gain does not determine the dead time of a Geiger counter. This is because a Geiger tube discharges the HV supply to which it is attached, before the ionization in the tube is quenched. The HV supply must remain low for a period in order for the tube to reset (the fill gas ions neutralized).

In fact, an amplifier is unnecessary to run a Geiger counter: you can just connect the HV through a speaker, and listen to the click sound.

It is the gas fill in the Geiger tube (specifically, the quench gas) that determines the delay before HV can once again be applied, and to this must be added the time for the HV supply to once again be reestablished at a suitable voltage for an avalanche cascade at the next ionizing event.

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