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[Gerard Visser <gvisser AT indiana.edu>]

hi Xu,
	Thank you, this is interesting indeed. It would seem that an anomalous-noise 
channel has roughly the same dependence on detector capacitance as a 
typical-noise channel, which indicates this noise is really sampled from the 
frontend amplifier, not just something independent added after the sampling.
	I think that rules out ADC timing issues -- which anyway you have already ruled 
out by having adjusted the ADC timing -- and it also rules out noise coupled 
from the power supplies that comes in response to the transient load of the 
readout process starting (since the samples in question are not being written at 
the time of the readout.
	Your result is definitely worth documenting in reply to the list, so I do that 
here, re-attaching your plot. (X-axis is bias voltage, Y is ped rms of the 
channel; or correct me if I'm wrong there, Xu)
        Sincerely,

                Gerard


On 7/23/2020 3:38 PM, Xu Sun wrote:
> Hi Gerard,
>
> Please find the pdf attached.
>
> Best,
>
> Xu
>
> On Thu, Jul 23, 2020 at 1:39 PM Gerard Visser <gvisser AT indiana.edu 
> <mailto:gvisser AT indiana.edu>> wrote:
>
>     Hi Xu,
>              Can you do pdf or png? eps is kind of a pain windows machine, I
>     don't know
>     quite how to view it. Of ocurse I can transfer to linux machine etc. but 
> if you
>     can easily make a pdf it will be appreciated.
>
>              - GV
>
>
>     On 7/23/2020 2:37 PM, Xu Sun wrote:
>      > Hi Gerard,
>      >
>      > Sorry for the late reply.
>      > Please find the plot in the attachment.
>      >
>      > It took longer than I expected, the most time was used to determine the
>     channel
>      > number and corresponding readout order.
>      > And I found the following feature might be useful to determine the 
> source of
>      > those high noise channels.
>      > I have summarized all the noisy channels in each APV chips (I should do
>     this in
>      > the first place), you could find the table below:
>      >
>      > APV 0: Physical Channel: 0, 32, 64, 96
>      > APV 0: Readout Order:     0,   1,   2,   3
>      > APV 1: Physical Channel: 0, 32, 64, 96
>      > APV 1: Readout Order:     0,   1,   2,   3
>      > APV 2: Physical Channel: 0, 32, 64, 96
>      > APV 2: Readout Order:     0,   1,   2,   3
>      > APV 3: Physical Channel: 0, 32, 64, 96
>      > APV 3: Readout Order:     0,   1,   2,   3
>      > APV 4: Physical Channel: 0, 32, 64, 96
>      > APV 4: Readout Order:     0,   1,   2,   3
>      > APV 5: Physical Channel: 0, 32, 64, 96
>      > APV 5: Readout Order:     0,   1,   2,   3
>      > APV 6: Physical Channel: 0, 32, 64, 96
>      > APV 6: Readout Order:     0,   1,   2,   3
>      > APV 7: Physical Channel: 0, 32, 64, 96
>      > APV 7: Readout Order:     0,   1,   2,   3
>      > APV 8: Physical Channel: 0, 32, 64, 96
>      > APV 8: Readout Order:     0,   1,   2,   3
>      >
>      > It turns out the noisy channels are always the first 4 readout 
> channels.
>      > I am not sure how this will help to determine the source, but it seems 
> to
>     me a
>      > feature independent of the sensors and might be useful.
>      >
>      > Best,
>      >
>      > Xu
>      >
>      >
>      > On Mon, Jul 20, 2020 at 8:26 PM Gerard Visser <gvisser AT indiana.edu
>     <mailto:gvisser AT indiana.edu>
>      > <mailto:gvisser AT indiana.edu <mailto:gvisser AT indiana.edu>>> wrote:
>      >
>      >     Actually if it is just as easy with and without the CMN 
> correction, I
>     guess do
>      >     both. I don't know quite what to expect to find, I hope we'll learn
>     something
>      >     from looking at these plots. Thanks...
>      >
>      >              - Gerard
>      >
>      >
>      >     On 7/20/2020 9:24 PM, Xu Sun wrote:
>      >      > Hi Gerard,
>      >      >
>      >      > Thanks for the suggestion. I will make those plots and send them
>     to you.
>      >      >
>      >      > Best,
>      >      >
>      >      > Xu
>      >      >
>      >      > On Mon, Jul 20, 2020 at 7:44 PM Gerard Visser 
> <gvisser AT indiana.edu
>     <mailto:gvisser AT indiana.edu>
>      >     <mailto:gvisser AT indiana.edu <mailto:gvisser AT indiana.edu>>> wrote:
>      >      >>
>      >      >> Hi Xu,
>      >      >>          Do you have a dataset that could be used to make a 
> plot of
>      >     noise vs. bias
>      >      >> similar to the left hand plot on your slide 10, for the two 
> cases of:
>      >      >>
>      >      >> - The channel (of a typical chip) which was the worst noise 
> i.e. this
>      >     would be
>      >      >> one of the few anomalous channels.
>      >      >>
>      >      >> - A single channel of same chip that shows the typical noise.
>      >      >>
>      >      >>          This would show clearly if these anomalously noisy 
> channels'
>      >     noise are related
>      >      >> to the frontend amplifier ( <==> related to detector 
> capacitance) or
>      >     not. For
>      >      >> instances noise due to soe crosstalk from the digital header 
> (perhaps
>      >     from ADC
>      >      >> timing wrong) should not have anything to do with detector
>     capacitance.
>      >     Noise
>      >      >> that we may speculate coming from the power glitch that happens
>     when readout
>      >      >> starts, would similarly have nothing to do with detector 
> capacitance.
>      >      >>
>      >      >>          I suppose these plots are easiest and most meaningful
>     without a
>      >     CMN correction,
>      >      >> simply the raw noise seen in pedestal on the channel as a 
> function of
>      >     detector
>      >      >> bias as in that figure on slide 10.
>      >      >>          If it is not too hard to get such plots, I'd look 
> forward to
>      >     seeing them. Thanks,
>      >      >>
>      >      >>          Gerard
>      >      >> _______________________________________________
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>      >

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