Star-fst-l mailing list

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

hi Xu,

So if we use just a single timbin then I think we should seriously consider running 3 tb instead of 4 tb. One consideration is that the APV chips always read 3*N timebins, so the fixed deadtime can be much lower for 3 timebins than for 4. In 4 timebin modes the APV sends data for 6 and we ignore the last 2.

On a separate note, I think it might be worth checking the performance difference between selecting for each hit the max timebin -- I think this is what you are doing?? -- versus using a fixed timebin always which you have selected as being the right one for that APV group to get the maximum of the pulse. There's probably a difference, e.g. in effect of pileup hits at the least. But anyway, you certainly don't want to select max over a wide range that is only going to bring in more pileup and noise, so to study which way is better you don't need many timebins stored.

     Gerard

---

From: Xu Sun <sunxuhit AT gmail.com>
Sent: Sunday, December 19, 2021 1:53 PM
To: Visser, Gerard <gvisser AT indiana.edu>
Cc: Tonko Ljubicic <tonko AT bnl.gov>; Aschenauer Elke-Caroline <elke AT bnl.gov>; Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST deadtime and raw events in the data stream

 

Hi Gerard,

> What do you think about 4 timebins?

I believe the reason to use 9 time bin is to tune the latency, and that has been done.

So we should be fine to switch to 4 timebins.

> Is there a fit to the peak of the pulse, or a sum over an interval, or we just use a single timebin, or what?

We use the time bin with the maximum ADC for the hit reconstruction.

Best,

Xu

On Sun, Dec 19, 2021 at 1:32 PM Visser, Gerard <gvisser AT indiana.edu> wrote:

hi Xu,

    What do you think about 4 timebins? Are you guys planning to study different ways of using the 9 timebin data, e.g. comparing tracking resolution somehow using / not using data from more than the middle 4 timebins? By the way, how do we use the data now in the baseline plan? Is there a fit to the peak of the pulse, or a sum over an interval, or we just use a single timebin, or what?

   If there's no real study planned with the extra 5 timebins pre/post of the middle 4, then we should change to 4 tb and change latency of course to get those middle 4. Or maybe even go to 3 tb?

    Gerard

---

From: Xu Sun <sunxuhit AT gmail.com>
Sent: Sunday, December 19, 2021 1:26 PM
To: Tonko Ljubicic <tonko AT bnl.gov>
Cc: Visser, Gerard <gvisser AT indiana.edu>; Aschenauer Elke-Caroline <elke AT bnl.gov>; Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] FST deadtime and raw events in the data stream

 

Hi Tonko,

As discussed in today's meeting, I am done with the ADC timing adjustment and we should be good to set the ratio to 1:100.

Best,

Xu

On Sun, Dec 19, 2021 at 4:14 AM Tonko Ljubicic <tonko AT bnl.gov> wrote:

Hello,

I had a few private emails with Xu so we left it at 1:5 for yesterday
but right now we are again dominated by FSTs data volume
(deadtime 35% at 1300 Hz) so I will cut it down to 1:20
and then to 1:100 e.g. tomorrow.

IMHO, we should set the steps still needed before we switch to
4 timebin readout.

           -- Tonko



On Fri, Dec 17, 2021 at 9:12 PM Xu Sun <sunxuhit AT gmail.com> wrote:
>
> Hi Tonko, All,
>
> We should have enough non-zs data, switching back to 1 to 100 should be fine for us.
>
> Best,
>
> Xu
>
> On Fri, Dec 17, 2021 at 9:29 AM Visser, Gerard <gvisser AT indiana.edu> wrote:
>>
>> I see no reason to have so much non-ZS. If a test run needs more e.g. to check the ADC timing, it can be changed for one run and then put back. But this even is probably not necessary.
>>
>>       Gerard
>>
>> ________________________________
>> From: Star-fst-l <star-fst-l-bounces AT lists.bnl.gov> on behalf of Aschenauer Elke-Caroline <elke AT bnl.gov>
>> Sent: Friday, December 17, 2021 9:25 AM
>> To: Tonko Ljubicic <tonko AT bnl.gov>
>> Cc: Star-fst L <star-fst-l AT lists.bnl.gov>
>> Subject: Re: [Star-fst-l] FST deadtime and raw events in the data stream
>>
>> As we are planning to get up in lumi, we need to change this, so the FST group should think what they need and why
>>
>> Cheers elke
>>
>> On Dec 17, 2021, at 09:15, Tonko Ljubicic <tonko AT bnl.gov> wrote:
>>
>> Hello,
>>
>> from the runs last night you can notice that FST
>> runs at 1.2 kHz with ~40% deadtime.
>>
>> This is currently all due to the large number of non-zero-suppressed,
>> raw, events, currently 1 in 5.
>>
>> If we plan to at least approximate the TPC (and we plan more
>> eventually) right now I propose we drop this enhanced
>> raw data percentage to 1 in 20 or even to the usual 1 in ~100.
>> I can't imagine why you would need so many of them but
>> it's not my call.
>>
>> Let me know what you think,
>>
>>       -- Tonko
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