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How to distinguish between STT hits in barrel part and forward tracker? [message #19183]

Mon, 11 April 2016 15:08

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

Hi everyone,

I want to get the number of Hits in the STT. Unfortunately, if I use

RhoCandidate * c;
PndPidCandidate *pidCand = (PndPidCandidate*)c->GetRecoCandidate();
pidCand->GetSttHits()

I get the number of hits in the STT and the fts.
Is there any way to distinguish between to distinguish these hits?

Cheers,
Jenny

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Re: How to distinguish between STT hits in barrel part and forward tracker? [message #19184 is a reply to message #19183]

Mon, 11 April 2016 15:13

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *to.infn.it

pidCand->GetTrackBranch() will return you different numbers for STT and FTS tracks.

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Re: How to distinguish between STT hits in barrel part and forward tracker? [message #19185 is a reply to message #19183]

Mon, 11 April 2016 15:17

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

Hi Stefano,

thanks for your quick answer. I already tried this, but if the particle is leaving hits in both parts, STT and fts, the number I get from pidCand->GetTrackBranch() is the same as for a particle which is only leaving hits in the fts.

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Re: How to distinguish between STT hits in barrel part and forward tracker? [message #19186 is a reply to message #19185]

Mon, 11 April 2016 15:23

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *to.infn.it

In theory the standard pattern recognition algorithms do not overlap tracks with both STT and FST hits, but they are always separated.
An alternative way would be to use FairLinks, but I don't have the details for such method.

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Re: How to distinguish between STT hits in barrel part and forward tracker? [message #19343 is a reply to message #19183]

Wed, 22 June 2016 17:05

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

Hi everyone,

some time ago I had the question how to distinguish between STTHits and FTS Hits. I still have this problem.

I simulated 100 piminus with boxgenerator using a theta range of [6 .. 9] degrees and a momentum range of p=[0.1 .. 0.7] GeV/c. (This momentum range corresponds to the momentum range of the pions produced in my channel pbar p → Xi(1820) anti-Xi @ 4.6 GeV/c.)
For the reconstruction, I used ideal PR with the condition of more than 3 hits in MVD, STT or GEM and ideal PID.

Nearly all events are looking like the one shown in the picture below.
index.php?t=getfile&id=8699&private=0

The blue squares denote the MVD hits, the red squares are the GEM hits and the pink squares are the FTS hits. As you can see, there are no hits in the STT.
The next pictures show the number of hits in the MVD, STT and GEM detector for the reconstructed particle (looking at the same Evt).

index.php?t=getfile&id=8704&private=0

And here you can see, that there are counted STT hits.

This means, that the selection criterion I mentioned above does not work because this pion would not be discarded.
At the moment, there is no chance for me to switch to a realistic PR.

Best regards,

Jenny

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Attachment: gem_hits.png
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Attachment: mvd_hits.png
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Attachment: stt_hits.png
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Re: How to distinguish between STT hits in barrel part and forward tracker? [message #19344 is a reply to message #19343]

Thu, 23 June 2016 02:30

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *kek-visitor.jp

As I told you during the meeting, we have two separate PndTrack TClonesArrays for MVD+STT+GEM and MVD+FTS+GEM. This means you cannot have both STT and FTS in the same track.
The function PndPidCandidate::GetSttHits() returns the number of STT hits if you have the PndSttMvdGemTrackingIdeal and the number of FTS hits if you have the PndFtsTrackerIdeal. The two track branches are separate by the function PndPidCandidate::GetTrackBranch().

This means that if you want to select tracks with at least 3 STT hits, you should use the condition GetTrackBranch()==XX && GetSttHits()>=3, where XX is the index of the central tracking TClonesArray number (if you plot the GetTrackBranch() you will have only two numbers, the central track is the first). And if you want to have at least 3 FTS hits then GetTrackBranch()==YY and GetSttHits()=3.

You can check macro/run/plot_pid.C, and see how the histograms hSttHits and hFtsHits are filled.

In any case, if you hit particles between 6 and 9 degrees you won't have any STT hit.

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