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["Ye, Zhenyu" <yezhenyu AT uic.edu>]

Whatever we see from online plots with the current cosmic data will be dominated (>99.9%) by noise hits.

Zhenyu

On Nov 21, 2021, at 4:11 PM, Visser, Gerard <gvisser AT indiana.edu> wrote:

Thanks... Ideally, we should use IST_4tb_latency+2 for FST_9tb_latency, if trigger timing is same.

The two peaks seem pretty clear in e.g. 22325057 Jplots, and I don't have any explanations other than if the trigger latency is not constant. That is not implausible, there is history of such things in STAR. I would first check that TOF sees a clean cosmic timing before worrying about if FST does.

    Gerard

---

From: videbaek <videbaek AT bnl.gov>
Sent: Sunday, November 21, 2021 5:07 PM
To: Tonko Ljubicic <tonko AT bnl.gov>
Cc: Visser, Gerard <gvisser AT indiana.edu>; Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST timing relative to trigger

 

xu said he changed timing from uic/teststand setup to ist settings.
it is my understanding the trigger timing is the same as earlier years 
after several iterations.





On 2021-11-21 16:57, Tonko Ljubicic wrote:
> Hi Gerard,
> 
> there was an email about a dramatic change of delays from Xu so
> my guess is that the old value was completely wrong. But Xu should 
> comment.
> 
> No clue about GMT. Never bothered to look at that detector :-).
> 
> 
> 
> 
> On Sun, Nov 21, 2021 at 10:47 PM Visser, Gerard <gvisser AT indiana.edu> 
> wrote:
>> 
>> It seems like GMT is also seeing two peaks. I'm suspecting we are not 
>> triggering with a clean timing, whether that is inherent or something 
>> not quite right in the trigger setup today, I don't know.
>> 
>> TOF should show this very clearly if there is a single clean peak or 
>> two peaks. But I think this kind of timing plot is not in the TOF 
>> Jplots, or I don't understand where it is. But we could ask the TOF 
>> group to make a plot to check is the data coming in with one clean 
>> cosmic peak or possibly two peaks? (Or are you already sure, Tonko, 
>> that is is one peak?)
>> 
>>       Gerard
>> 
>> 
>> ________________________________
>> From: Star-fst-l <star-fst-l-bounces AT lists.bnl.gov> on behalf of Tonko 
>> Ljubicic <tonko AT bnl.gov>
>> Sent: Saturday, November 20, 2021 12:08 PM
>> To: Star-fst L <star-fst-l AT lists.bnl.gov>
>> Subject: [Star-fst-l] FST timing relative to trigger
>> 
>> Hello,
>> 
>> what I think we should do is make _sure_ we are
>> seeing the correct trigger crossing. Looking at the
>> timebin plots (where the x-axis is the timebin, 0 to 9)
>> I'm not sure we do. We see 2 peaks which I don't
>> understand at all.
>> 
>> First, we should make the ZS data used in the plot
>> more stringent, with a higher N-sigma cut so that
>> we think it is an actual particle and not just noise.
>> For this exercise I would even exaggerate a bit,
>> e.g. 6 sigma.
>> 
>> Secondly, we should do a quick scan of the global
>> APV latency-from-trigger (there is such a register,
>> can't remember the actual name) by moving it in
>> e.g. 100ns steps or so. Where does the current
>> setting come from, BTW? Gerard?
>> 
>> I picked up a Cosmics run with IST from 2015
>> and you can find the same plot attached. Note the
>> peak.
>> 
>>            -- Tonko
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-- 
Flemming Videbaek
senior scientist
videbaek @ bnl.gov
Brookhaven National Lab
Physics Department
Bldg 510D
Upton, NY 11973

phone: 631-344-4106
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