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[Gerard Visser <gvisser AT indiana.edu>]

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