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["Visser, Gerard" <gvisser AT indiana.edu>]

Ok, sure. But can't we also make plots offline from existing data, imposing a higher threshold? In my ignorance this sounds like an incredibly simple bit of analysis work...

I understand statistics will be small. But if the threshold is high enough to wipe out the noise we may still see evidence of a peak, if consistently so in several runs I guess that would be convincing enough.

     Gerard

---

From: Zhenyu Ye <yezhenyu2003 AT gmail.com>
Sent: Sunday, November 21, 2021 11:48 PM
To: Visser, Gerard <gvisser AT indiana.edu>
Cc: Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST timing relative to trigger

 

From the numbers that I was told, only a few cosmic particle going through FST are expected per run (~30 min). I asked Xu to change the Latency setting to the Run14 IST setting with 9 time bins, which he did last night, and also to contact Tonko to increase the ZS thresholds. Let’s see if we can see cosmic signals. 

Zhenyu

On Nov 21, 2021, at 10:39 PM, Visser, Gerard <gvisser AT indiana.edu> wrote:

Ok, yeah that makes some sense this could be a result of the timebin dependence of noise (which is still a strange/non-understood thing I think).

I hope someone can analyze offline and make max TB plot with a high cut on signal size so we don't have noise hits. It seems the only way to confirm the timing. (And since the rate is certainly low, if we don't​ see the peak in present data should we increase the number of timebins? We never ran more than 9 but I think there isn't a problem to do so, at low rates. 15, 18 perhaps?

     Gerard

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From: Zhenyu Ye <yezhenyu2003 AT gmail.com>
Sent: Sunday, November 21, 2021 11:31 PM
To: Visser, Gerard <gvisser AT indiana.edu>
Cc: Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST timing relative to trigger

 

It might have something to do with the time-bin dependence of noise, and how this is taken 

into account in making the online plots. To make the non-ZS online plots, it only reads in 

pedestal mean/RMS of one time bin, and apply to all time bins. This won’t explain the ZS plots

On Nov 21, 2021, at 10:22 PM, Visser, Gerard <gvisser AT indiana.edu> wrote:

Then we should look at a plot of max TB for hits with a much higher threshold of being a hit. Can such a plot be made easily from the data already taken?

Even as it is though with the plots, the distributions do not look consistent with uniform distribution over timebins that we should expect -- right?? -- for noise. How would you interpret that? (e.g. I look at 22325098 to be specific)

     Gerard

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From: Ye, Zhenyu
Sent: Sunday, November 21, 2021 11:12 PM
To: Visser, Gerard
Cc: flemming videbaek; Tonko Ljubicic; Star-fst L
Subject: Re: [Star-fst-l] FST timing relative to trigger

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
cell     :  631-681-1596

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