[Halld-pid] Hamamatsu timing resolution

[Beni Zihlmann]

Hi All,
I tried to determine the intrinsic timing resolution of the H10534 PMT.
Unfortunately I think my setup is not good enough to do that and the
result is completely dominated by the led pulser jitter. you can see
this in the attached file. The number of photons and width of the ADC
spectrum make sense as the width comes out almost exactly as the
square root of the number of photo electrons as it should be if the
correct gain was used to calculate it. However the timing resolution
does not look good and I think it is an artefact of my setup with a
pulsed LED. I see a similar behavior with a reference PMT an XP2262
which is a 12 stage tube and has higher gain. But the XP2262 gives
about the same result. The empty bin in the timing spectrum is
a binning problem that I have not fully understood yet. It seems to come
from the translation from TDC counts into time.

If somebody has an idea to better determine the intrinsic timing of the PMT
or has a more accurate LED pulser system let me know.

cheers,
Beni
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