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[Zhenyu Ye <yezhenyu2003 AT gmail.com>]

Hi Gerard, 

> On Aug 4, 2020, at 11:19 AM, Gerard Visser <gvisser AT indiana.edu> wrote:
> 
> hi Zhenyu,
>       That timebon dependence sounds definitely odd. Are you sure? Do we 
> see that in IST too, only more mildly? I wasn't aware of this.
‘
Please take a look at Xu’s presentation in FST meeting on May 4 (FST) and 11 
(FST and IST):

https://drupal.star.bnl.gov/STAR/event/2020/05/04/star-forward-silicon-tracker-meeting/prototype-module-assembly-and-test
https://drupal.star.bnl.gov/STAR/event/2020/05/11/star-forward-silicon-tracker-meeting/prototype-module-assembly-and-test

>       The capacitance of FST is much larger than IST, I think. This may 
> certainly be relevant. For sure it is relevant to CMN.
>       Anyway, I agree we should investigate these noise issues, I do not 
> like to ignore them. However on the other hand it _may_ be an inherent 
> property of APV chips.

>       - Gerard
> 
> 
> 
> On 8/4/2020 12:12 PM, Zhenyu Ye wrote:
>> Hi Gerard,
>> From the plots that Xu sent, there is a clear pattern where the channels 
>> showing enhanced noise level after mounting the sensors, also show 
>> enhanced noise level before mounting the sensors.
>> An independent topic, we see that the CMN in FST is much higher than IST, 
>> and show a strong time-bin dependence, i.e., when we read in 9 time bins, 
>> the 1st, 5th and 9th time bins have much higher CMN than the other time 
>> bins. I don’t feel comfortable to ignore it w/o knowing the cause, as it 
>> may get worse in the real experiment.
>> Best,
>> Zhenyu
>>> On Jul 23, 2020, at 5:13 PM, Gerard Visser <gvisser AT indiana.edu> wrote:
>>> 
>>> hi Xu, Zhenyu,
>>>     Yes that would be interesting to know (especially the unconnected 
>>> case). Also, as mentioned (I think I mentioned?) it would also be good to 
>>> do the bias scan similarly but with IST. I wonder if the curiously 
>>> (maybe?) large increase in signal above full depletion voltage will be 
>>> seen there too. That's a completely separate topic but related data set 
>>> to get & plot.
>>>     Thanks,
>>> 
>>>             Gerard
>>> 
>>> 
>>> On 7/23/2020 6:04 PM, Zhenyu Ye wrote:
>>>> Hi Xu,
>>>> Can you please check the data before mounting the sensors, and the data 
>>>> with IST, to see if they have such a feature?
>>>> Thanks,
>>>> Zhenyu
>>>>> On Jul 23, 2020, at 2:53 PM, Gerard Visser <gvisser AT indiana.edu> wrote:
>>>>> 
>>>>> 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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