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[Xu Sun <sunxuhit AT gmail.com>]

Hi Gerard,

Sorry for the late reply. Please find the FST & IST noise study in the attached file.

I see a similar behaviour for IST with a much smaller magnitude.

Best,

Xu

On Tue, Aug 4, 2020 at 1:12 PM Gerard Visser <gvisser AT indiana.edu> wrote:

Hi Xu, Zhenyu,
        Do we see the timebin-dependece of noise as you show here

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

in the IST data too?
        Thanks,

                Gerard


p.s. And, if possible to answer, there is also the question whether this was
seen in the IST installed in STAR/HFT? I don't remember hearing about it before.


On 8/4/2020 12:39 PM, Zhenyu Ye wrote:
> 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
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