sPHENIX tracking discussion

["Frawley, Anthony" <afrawley AT fsu.edu>]

Hello Xin,

Yes, this was also mentioned in the meeting. Why the DCA resolution at low pT is much poorer for the ladders than it is for the cylinders is still an open question. There is no obvious reason why it should be. The fact that it is essentially the same for single pions as it is for pions embedded in Hijing events should a) make it easier to study and b) shows that it is not an occupancy effect.

The cluster resolution plots show that the clusters in the MAPS are being reconstructed where they should be. That still leaves the possibility that they are not being properly associated with the tracks for lower pT tracks, or not being given to the tracker correctly, or have the wrong uncertainty, or ....... This can be studied by looking at residuals between the tracks and cluster positions. I will try to look at those.

We agreed at the meeting that we do need to study fake track rates systematically, and that is an easy plot to add.

We should also be careful about what we expect to be able to deliver in the real detector. The simulation presently has zero position calibration uncertainty. What do we think we can actually deliver?

Best regards

Tony

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From: Xin Dong <xdong AT lbl.gov>
Sent: Friday, May 26, 2017 1:29 PM
To: Frawley, Anthony
Cc: sphenix-tracking-l AT lists.bnl.gov
Subject: Re: [Sphenix-tracking-l] Cluster resolution for Hijing embedded tracks

 

Dear Tony and All,

Thank you very much for the great achievements. Sorry for not being able to call in today's meeting.

I am a bit concerned about the DCA resolution. The plots on slide 4 shows at 1 GeV it is only 90 microns, this is significantly worse than the previous tracking (which is about 30 microns) outcome (at 5 GeV/c, now is 25 microns vs. ~ 10 microns before). 

>From the next email on the cluster parameters, they seem to be reasonable at least on the MAPS side. And it seems also the fake rate is small (my interpretation on your statement on "the tracker has already rejected clusters it does not like."). With these, I would expect the the dca resolution for the reconstructed tracks with MAPS hits should be close to what was achieved with previous tracker. 

(I showed in the Santa Fe workfest, slide 14 in

https://indico.bnl.gov/getFile.py/access?contribId=7&sessionId=0&resId=0&materialId=slides&confId=2641)

I believe Christof also showed another calculation from LiC with similar numbers, slide 16 in

https://indico.bnl.gov/conferenceDisplay.py?confId=2950)

sPHENIX tracking meeting (17 March 2017) indico.bnl.gov To join the Meeting: https://bluejeans.com/822435626 To join via Browser: https://bluejeans.com/822435626/browser To join with Lync: https://bluejeans.com/822435626/lync To join via Cisco Jabber Video: https://bluejeans.com/822435626/jabber To join via Room System: Video Conferencing System: bjn.vc -or- 199.48.152.152 Meeting ID: 822435626 To join via Phone: 1) Dial: +1 408 740 7256 +1 888 240 2560(US Toll Free) +1 408 317 9253(Alternate Number) (see all numbers - http://bluejeans.com

Haiwang sent out a few plots showing the dca resolution for 5 GeV/c tracks is around 10 microns a couple of days ago. So I wonder whether this sample include also Haiwang's additional patch? It would be great to find out the best DCA performance from the current tracker which is essential for open HF program.

Thanks and Best Regards

/xin

On Fri, May 26, 2017 at 9:53 AM, Frawley, Anthony <afrawley AT fsu.edu> wrote:

Hi All,

Following up on Christof's request at the tracking meeting this morning, I extracted the cluster resolutions for clusters matched to tracks embedded in Hijing events. Here are the RMS numbers for reconstructed cluster position minus truth cluster position:

Clusters matched to Hijing embedded pion tracks:

r-phi resolution:    MAPS = 4.5 microns   INTT = 28.3 microns    TPC = 128 microns

Z resolution:          MAPS = 4.7 microns    INTT = 4745 microns   TPC = 151 microns

Clusters matched to standalone 100 pion event tracks:

r-phi resolution:    MAPS = 4.5 microns   INTT = 27.4 microns    TPC = 126 microns

Z resolution:          MAPS = 4.8 microns    INTT = 4800 microns   TPC = 159 microns

Note that it is important that these are clusters matched to tracks. That means that the tracker has already rejected clusters it does not like.

Bottom line: Not much change for clusters associated with Hijing embedded tracks.

Cheers

Tony

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