sPHENIX tracking discussion

["Anderson, Derek [PHYSA]" <dmawxc AT IASTATE.EDU>]

Hi Xin,

Sure, I can easily put that plot together!

> I doubt this is in micrometers. I believe this is pT integrated figure. The pointing resolution, at best with MVTX hits included, is at the level of tens of microns.

Ah, yes. You're right: the axis is 10 microns -- consistent with slides 8 - 11. (It's been a while since I made those plots, so the details escaped me: I made a mistake in scaling the dca values for those, and then mislabeled the axes.)

 -- Derek

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From: Xin Dong <xdong AT lbl.gov>
Sent: Friday, February 3, 2023 5:08 PM
To: Anderson, Derek [PHYSA] <dmawxc AT IASTATE.EDU>
Cc: sphenix-tracking-l AT lists.bnl.gov <sphenix-tracking-l AT lists.bnl.gov>; Anthony Frawley <afrawley AT fsu.edu>
Subject: Re: [Sphenix-tracking-l] Tracking software meeting Wednesday February 1 at 10 am ET

 

Hi Derek,

Thank you very much for your clarification. These are very helpful for my understanding. A couple of follow up questions

> Slide 24, what is the unit on your X-axis? mm? And are the silicon hits required in tracks for producing these figures?

The x-axis here is in micrometers, and that's correct: these were made requiring silicon hits (they were from before the iterative tracker was implemented back in December).

I doubt this is in micrometers. I believe this is pT integrated figure. The pointing resolution, at best with MVTX hits included, is at the level of tens of microns. You may also have mixed contributions from tracks without MVTX hits which typically have the pointing resolution even larger.

Sorry for asking a bit much, but if convenient for you, could you please help generate the following figures?

1) ratio of number of tracks with N_MVTX >=2  / total number of tracks vs. pT.

2) for tracks with N_MVTX >=2, could you please plot   DCA_XY and DCA_Z vs. pT  2D figures?

For reference, you may compare to the figures in the MVTX proposal Fig. 16 in the early simulations

https://www.dropbox.com/s/hr0js41pv3ej9kk/sPHENIX-MVTX-proposal-20180214.pdf?dl=0

These KPP distributions pretty much define the secondary vertex performance for HF and other physics. Thanks and Best Regards

/xin

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From: Xin Dong <xdong AT lbl.gov>
Sent: Wednesday, February 1, 2023 7:33 PM
To: Anderson, Derek [PHYSA] <dmawxc AT IASTATE.EDU>
Cc: sphenix-tracking-l AT lists.bnl.gov <sphenix-tracking-l AT lists.bnl.gov>; Anthony Frawley <afrawley AT fsu.edu>
Subject: Re: [Sphenix-tracking-l] Tracking software meeting Wednesday February 1 at 10 am ET

 

Dear Derek,

Thank you for your very comprehensive slides. I am sorry that I couldn't attend the meeting for discussion. I have a few questions about your slides and would appreciate your clarifications.

1) Slide 7, you showed nicely that most of the weird tracks lie at sector boundaries. Presumably these tracks will have less number of hits on track compared to others, yielding worse resolution. Shall we evaluate these tracking qualities (chi2, pT resolution) vs. nHits as well? If the tail in the pT distribution is just due to the worse resolution that yields due to few nHits, I would view this is not really an issue we should worry (but just feature?).  And I may have missed your study before, do you have the momentum resolution vs. pT performance plot (maybe not only mean, but also the mean value)?

2) Slide 24, what is the unit on your X-axis? mm? And are the silicon hits required in tracks for producing these figures?

3) Slide 29, Is Delta_DCA the error of DCA? I know often people plot DCA / DCA_error and defined as chi2primary (used in KFParticle).

4) Slide 31/32/33, these distributions are peaked at very small values. I think it is because you have often finite values for pT, eta, phi. Is it better to plot   pT_err / (pT_rec - pT_truth) or (pT_rec - pT_truth) / pT_err. In this way, if the tracking has a good estimation of the error, the distributions will be more like chi2 distributions too.

5) Slide 37/38, similarly, I am curious whether the silicon hits are used in tracking. Can we access the reconstructed hit information on track to tell whether it is the real MC hit coming from the associated MC track? This information can be helpful to determine the ghost hit rate, particularly on silicon MVTX detector.

6) Slide 54/55, I am wondering what is the difference compared to slide 37/38? Are these using tracking with silicon hits? I think then one would need different scales for the DCA axis to look into its distributions.

Thank you and Best Regards

/xin

On Wed, Feb 1, 2023 at 10:47 AM Anderson, Derek [PHYSA] via sPHENIX-tracking-l <sphenix-tracking-l AT lists.bnl.gov> wrote:

Hi all,

Just following up: please find my slide from today attached!

 -- Derek

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From: sPHENIX-tracking-l <sphenix-tracking-l-bounces AT lists.bnl.gov> on behalf of Anthony Frawley via sPHENIX-tracking-l <sphenix-tracking-l AT lists.bnl.gov>
Sent: Tuesday, January 31, 2023 2:25 PM
To: sphenix-tracking-l AT lists.bnl.gov <sphenix-tracking-l AT lists.bnl.gov>
Subject: [Sphenix-tracking-l] Tracking software meeting Wednesday February 1 at 10 am ET

 

Hi All,

We will have our usual tracking software meeting tomorrow, Wednesday February 1, at 10 am ET.

The zoom link is:

 https://fsu.zoom.us/j/98126117840

The indico page is:

https://indico.bnl.gov/event/18283/

Cheers

Tony

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--

==================================================
Xin Dong
Nuclear Science Division, Lawrence Berkeley National Laboratory
MS70R0319, One Cyclotron Road
Berkeley, CA 94720, USA
Tel: +1-510-486-4121
Email: XDong AT lbl.gov
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--

==================================================
Xin Dong
Nuclear Science Division, Lawrence Berkeley National Laboratory
MS70R0319, One Cyclotron Road
Berkeley, CA 94720, USA
Tel: +1-510-486-4121
Email: XDong AT lbl.gov
==================================================