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eta_c with event mixing for STT [message #12584]

Tue, 30 August 2011 00:35

Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...

first-grade participant

From: *play-internet.pl

Dear colleagues,

I have analaised the eta_c data produced on the GRID with event mixing, and at the moment I still do not understand the results.

But I just want to share some plots to show the current status.

So multiplicity of charged tracks:

index.php?t=getfile&id=6599&private=0

Only 8% of events have >=4 tracks which is much lower than 72% without event mixing.

Invariant mass of phi and eta_c with preselection on phi mass window:

index.php?t=getfile&id=6600&private=0

Here there is no indication of phi or eta_c peak.

And aplying MC Truth PID does not change this distribution much.

And finaly only 4 events out of 100k pass the selection cuts.

So the results still have to be understood.

Dima

Attachment: n_charged_stt.png
(Size: 10.06KB, Downloaded 961 times)
Attachment: m_nocuts_stt.png
(Size: 13.20KB, Downloaded 1023 times)

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Re: eta_c with event mixing for STT [message #12603 is a reply to message #12584]

Fri, 02 September 2011 11:37

Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...

first-grade participant

From: *fuw.edu.pl

Dear colleagues,

Here I update plots on eta_c reconstruction with STT and event mixing with runs mix301, mix311, mix321, mix331.

There is an improvement comparing to previous results but the results are still far from reasonable.

Multiplicity of charged tracks:
index.php?t=getfile&id=6615&private=0

23% of events have >=4 tracks in comparing to 8% in previous run and 72% without event mixing.

And invariant mass of phi and eta_c with preselection on phi mass window:
index.php?t=getfile&id=6616&private=0

Here phi peak appears but still no indication of eta_c peak.

Finally 36 events were reconstructed from 100 k.

Dima

Attachment: n_charged.png
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Attachment: m_nocuts.png
(Size: 13.50KB, Downloaded 829 times)

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Re: eta_c with event mixing for STT [message #12609 is a reply to message #12584]

Fri, 02 September 2011 17:26

Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...

first-grade participant

From: *fuw.edu.pl

Just for comparison here I present invariant mass distributions for eta_c and phi with the same version of STT software (august11).

index.php?t=getfile&id=6619&private=0

This run is produced with cleanup code and eta_c reconstruction efficiency is 7.8%

Dima

Attachment: m_nocuts_nomix.png
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Re: eta_c with event mixing for STT [message #12635 is a reply to message #12584]

Thu, 08 September 2011 02:48

Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...

first-grade participant

From: 140.181.10*

Hi all,

With the latest run eta_c events produced with STT with background mixing are reconstructable.

Multiplicity of reconstructed tracks is rather high:

index.php?t=getfile&id=6627&private=0

With rough pre-selection on phi mass invariant mass distributions looks like:

index.php?t=getfile&id=6628&private=0

So there is small indication of eta_c peak.

But after the final selection:

index.php?t=getfile&id=6629&private=0

eta_c is reconstructed with efficiency 3.3%

Dima

Attachment: n_charged_stt_mix.png
(Size: 10.05KB, Downloaded 838 times)
Attachment: m_nocuts_stt_mix.png
(Size: 14.37KB, Downloaded 881 times)
Attachment: m_final_vtx_stt_mix.png
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