I want compare the performance of the pmt(H7422P-40) with a my own pmt (H10682-210). Could you highlight the major difference for me?
Spec sheets are below, and I attached sensitivity and noise specs in picture.
It seems that those items has simmilar sensitivity at 450nm wavelength (7422 is only about 1.2times better)and even H7421 has a higher dark count rate in ambient temperature...is this correct?
PS.1 7422 is analog output(current output)model and 10682 is digital output(PMT + discriminator). So I think I cannot compare this two model directly. Therfore I attatched spec sheet of 7421 that shares same GaAsP photodetector but digital output.
PS.2 I will use 7422 with additional discriminator circuit that i already have. (pulse resolution is much better than internal discriminator of 7421)
Best Regards.
http://www.hamamatsu.com/resources/pdf/etd/m-h10682e.pdf
http://www.hamamatsu.com/resources/pdf/etd/m-h7421e.pdf
Hi,
I agree with your conclusions.
There doesn't seem to be much between them in quantum efficiency.
The 10682 clearly has a better dark noise performance: 50 e- at 25C, with the potential to have even less at lower temperatures: it appears to follow a classic ~6-degrees dark-doubling temperature increment. There's no built-in cooling to help exploit this, though.
The 7421 is a curious beast: it comes with 35 degrees of TE cooling, yet its dark current curve is absolutely flat at 100 e-, from 35 C down. I wonder what causes that dark noise floor (and what the point of the TE cooling is, if it doesn't help below an ambient temperature of 35C!).
The other specs to watch are the pulse-pair resolution and output pulse width - essentially determining the time resolution of the instrument, and the ability to distinguish events under higher count rates. The 7421 is again markedly inferior to the 10682 in these metrics: 70 and 30 ns vs. 20 and 10 ns.
@Ray Butler
Thanks for your kind answer
I will postpone this purchase and find some better devices
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