STAR task force for evaluating tracking efficiency uncertainty

["Van Buren, Gene" <gene AT bnl.gov>]

Hi, Rongrong

> On Oct 20, 2022, at 1:56 PM, Ma, Rongrong <marr AT bnl.gov> wrote:
> 
> Hello Gene
> 
> Thanks for following up on this, and providing the additional information. 
> 
> My momentum resolution is the relative resolution, and therefore the "a" 
> value is equivalent to p1. 
> 
> I am a bit surprised to see that the momentum resolution from MC with HFT 
> has a p1 value of 0.008. Are those primary tracks with HFT hits?

No, that plot was labeled "Global". Here is the plot for primaries, which of 
course is much better:
https://www.star.bnl.gov/~jwebb/2016/BaseQA_April_13/evals1/pidPtiRPr_zy_1.png


> In single particle embeddings, we have constantly seen p1 values of ~ 
> 0.0035 over the years, which we know is way too good compared to data. 

Odd, as the S&C Team's QA did not show it to be that good. Jason Webb may 
have more such plots from over the years: the code to generate them was 
originally Yuri's for track-by-track comparisons, and I think Jason modified 
it for QA of Monte Carlo by setting one set of tracks to be the true 
simulation quantities.

> 
> Do we have a back-of-envelope estimate of what the TPC momentum resolution 
> at 1 GeV/c should be? 

Yes, the colored lines on the first two plots of this page I sent earlier 
were generated via a model created by Jim Thomas:
https://drupal.star.bnl.gov/STAR/subsys/tpc/perf/tpc-pt-and-dca-resolution
The first plot assumes "nearly all" 45 padrows have hits, while the second 
plot has hits on every other padrow (i.e. half the hits). Reality is expected 
to fall somewhere between the two cases. 

The blue lines on the plots are for full field global tracks, and the 
coefficient is 0.009 in the first case, and 0.013 in the second case, as 
written on the web page. The relative momentum resolution at pT = 1 GeV/c 
appears to be about 0.013 in the first case and about 0.017 in the second 
case, from looking at the plots.

> 
> I think we can start with Run11 and Run14 cosmic ray data, and decide later 
> on whether we need to produce Run19 cosmic ray. 

DataCarousel requests for Runs 11 and 14 are already submitted. Run 11 will 
appear on DD and accessible via FileCatalog queries. The Run 14 data was not 
catalogued (special production) and I am restoring them to a few locations on 
NFS. I'll let you know when they're complete.

Thanks,
-Gene

> 
> Best
> Rongrong
> 
>> On Oct 20, 2022, at 1:14 PM, Van Buren, Gene <gene AT bnl.gov> wrote:
>> 
>> Hi, all
>> 
>>> On Oct 20, 2022, at 8:38 AM, Ma, Rongrong via Star-tf-trkeff-l 
>>> <star-tf-trkeff-l AT lists.bnl.gov> wrote:
>>> 
>>> Hello Robert
>>> 
>>> Thanks a lot. The new fit looks very nice, and the p1 value is very close 
>>> to what we have seen based on Jpsi width from Run18 Isobar data.
>> 
>> So the fit is actually p0 + p1 *pT, and the finding is that p1 is 0.0075.
>> 
>> If we focus on the high pT region, then I think we can all agree that the 
>> relative resolution of pT (the absolute resolution of pT, divided by pT) 
>> is equal to the relative resolution of (1/pT), and that these rise 
>> linearly in pT. This relation can be derived from the understanding that 
>> the TPC measures points in physical space with a generally pT-independent 
>> spatial resolution, such that the absolution resolution of (1/pT) is 
>> generally constant at high pT. That constant is p1:
>> 
>> dpT / pT = d(1/pT) / (1/pT)
>> =>
>> relative resolution = p1 / (1/pT) = p1 * pT
>> 
>> Rongrong's study has me a little confused. Is his momentum resolution the 
>> relative resolution, or the absolute resolution? If it is relative 
>> resolution, then his "a" parameter is the same as p1, determining the high 
>> pT behavior of the resolution.
>> 
>> Past studies have shown (see the links I sent)  that p1 for tracks without 
>> a primary vertex in their fit get values near 0.01.  The cosmic ray study 
>> I did got something like 0.014. I managed to find one of the Monte Carlo 
>> QA plots from 2016 when the S&C team was trying to get HFT tracking 
>> working:
>> https://www.star.bnl.gov/~jwebb/2016/BaseQA_April_13/evals1/pidPtiRGl_zy_1.png
>> In that plot we can see a rise of ~0.008 between pT = 2 GeV/c to 3 GeV/c, 
>> so perhaps as good as 0.008 with the HFT.
>> 
>> Robert's result of 0.0075 manages to get close to that even without the 
>> HFT. And Rongrong's past results of 0.0054 are much better, and his 0.0035 
>> number from embedding blows that away. I don't see how we could have ever 
>> had it that good.
>> 
>> So, I'm confused about these numbers and findings. If someone understands 
>> something I've missed, please let me know.
>> 
>>> So we have a good consistency here. I really appreciate if you can help 
>>> analyze other datasets (Run11, 14, 19) as well. Hopefully, this won't 
>>> take too much of your time. 
>>> 
>>> Gene: is it possible that you can restore cosmic ray data from Run11, 
>>> Run14 and Run19? I think a quarter of the Run18 statistics used here for 
>>> each dataset is probably sufficient. 
>> 
>> Run 11, I see P11id FullField and ReverseFullField MuDsts that I will 
>> restore.
>> 
>> Run 14, I see P14ih Half, Fulll, and ReverseFullField MuDsts that I will 
>> restore.
>> 
>> Run 19, I do not think we did an official production, but I believe Yuri 
>> handled a private production for use in TPC calibration work. We can do an 
>> official production if it is desired.
>> 
>> Thanks,
>> -Gene
>> 
>>> 
>>> 
>>> Best
>>> Rongrong
>>> 
>>>> On Oct 20, 2022, at 8:21 AM, Robert Líčeník <licenik AT ujf.cas.cz> wrote:
>>>> 
>>>> Hello Rongrong,
>>>> 
>>>> since the y axis is log-scale (but the values are not), a simple linear 
>>>> function will not work, so I think you meant something like p0 + p1*10^x 
>>>> . It seems to do much better.
>>>> Here are the updated slides:
>>>> https://drupal.star.bnl.gov/STAR/event/2022/10/18/Tracking-Efficiency-Uncertainty-meeting/Cosmics-2018-update
>>>> Would it be helpful if I shared the file with the produced TTree with 
>>>> you? That way you can have a quick look by yourself and you don't have 
>>>> to wait for me in a different time zone every time.
>>>> However, I understand that you are very busy and I am of course more 
>>>> than happy to help.
>>>> 
>>>> Cheers,
>>>> Robert
>>>> 
>>>> On Wed, Oct 19, 2022 at 8:06 PM Ma, Rongrong <marr AT bnl.gov> wrote:
>>>> Hello Robert
>>>> 
>>>> Could you try a linear function y = p0 + p1*x to do the fit? Thanks. 
>>>> 
>>>> Best
>>>> Rongrong
>>>> 
>>>>> On Oct 19, 2022, at 11:55 AM, Robert Líčeník <licenik AT ujf.cas.cz> wrote:
>>>>> 
>>>>> Hi Rongrong,
>>>>> 
>>>>> you are correct. The fit function is written on the first slide with 
>>>>> momentum resolution and the range is the full histogram for the red fit 
>>>>> and (-0.4 - 2) for the blue fit.
>>>>> 
>>>>> Cheers,
>>>>> Robert
>>>>> 
>>>>> On Wed 19. 10. 2022 at 17:40 Ma, Rongrong <marr AT bnl.gov> wrote:
>>>>> Hi Robert
>>>>> 
>>>>> Thanks for the update. However, the fit does not seem to work well. 
>>>>> What function and fit range are you using? Thanks. 
>>>>> 
>>>>> Best
>>>>> Rongrong
>>>>> 
>>>>>> On Oct 19, 2022, at 9:05 AM, Robert Líčeník <licenik AT ujf.cas.cz> wrote:
>>>>>> 
>>>>>> Hi Rongrong,
>>>>>> 
>>>>>> no problem, here are the updated slides:
>>>>>> https://drupal.star.bnl.gov/STAR/event/2022/10/18/Tracking-Efficiency-Uncertainty-meeting/Cosmics-2018-update
>>>>>> 
>>>>>> Cheers,
>>>>>> Robert
>>>>>> 
>>>>>> On Tue, Oct 18, 2022 at 11:00 PM Ma, Rongrong <marr AT bnl.gov> wrote:
>>>>>> Hello Robert
>>>>>> 
>>>>>> Thanks. If possible, could you redo the fit starting from the lowest 
>>>>>> point, i.e. log(pt) ~ -0.4, and add the slope of the fit to the 
>>>>>> figures? 
>>>>>> 
>>>>>> Best
>>>>>> Rongrong
>>>>>> 
>>>>>>> On Oct 18, 2022, at 2:38 PM, Robert Líčeník via Star-tf-trkeff-l 
>>>>>>> <star-tf-trkeff-l AT lists.bnl.gov> wrote:
>>>>>>> 
>>>>>>> Hi everyone,
>>>>>>> I uploaded my slides from today's meeting:
>>>>>>> https://drupal.star.bnl.gov/STAR/event/2022/10/18/Tracking-Efficiency-Uncertainty-meeting/Cosmics-2018-update
>>>>>>> The only difference is that I replotted the momentum resolution 
>>>>>>> figures in log-log scale, as requested. 
>>>>>>> Cheers,
>>>>>>> Robert
>>>>>>> 
>>>>>>> On Mon, Oct 17, 2022 at 12:07 PM Petr Chaloupka via Star-tf-trkeff-l 
>>>>>>> <star-tf-trkeff-l AT lists.bnl.gov> wrote:
>>>>>>> Dear All,
>>>>>>> 
>>>>>>> Please join our meeting tomorrow at 10:00 New York time.
>>>>>>> 
>>>>>>> Please upload any material for discussion to the drupal page:
>>>>>>> https://drupal.star.bnl.gov/STAR/event/2022/10/18/Tracking-Efficiency-Uncertainty-meeting
>>>>>>> 
>>>>>>> With best regards,
>>>>>>> Petr
>>>>>>> 
>>>>>>> To join the meeting:
>>>>>>> 
>>>>>>> https://bnl.zoomgov.com/j/1607035037?pwd=WDVqaEdwa0RtTEM5a1VvZ24yU2gwdz09
>>>>>>> Meeting ID: 160 703 5037
>>>>>>> Passcode: 099371
>>>>>>> 
>>>>>>> One tap mobile
>>>>>>> +16692545252,,1607035037#,,,,,,0#,,099371# US (San Jose)
>>>>>>> +16468287666,,1607035037#,,,,,,0#,,099371# US (New York)
>>>>>>> 
>>>>>>> Dial by your location
>>>>>>>        +1 669 254 5252 US (San Jose)
>>>>>>>        +1 646 828 7666 US (New York)
>>>>>>> Meeting ID: 160 703 5037
>>>>>>> Passcode: 099371
>>>>>>> Find your local number: https://bnl.zoomgov.com/u/aoARs6rfR
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> Star-tf-trkeff-l mailing list
>>>>>>> Star-tf-trkeff-l AT lists.bnl.gov
>>>>>>> https://lists.bnl.gov/mailman/listinfo/star-tf-trkeff-l
>>>>>>> _______________________________________________
>>>>>>> Star-tf-trkeff-l mailing list
>>>>>>> Star-tf-trkeff-l AT lists.bnl.gov
>>>>>>> https://lists.bnl.gov/mailman/listinfo/star-tf-trkeff-l
>>>>>> 
>>>>> 
>>>> 
>>> 
>>> _______________________________________________
>>> Star-tf-trkeff-l mailing list
>>> Star-tf-trkeff-l AT lists.bnl.gov
>>> https://lists.bnl.gov/mailman/listinfo/star-tf-trkeff-l
>> 
>