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Problems with new GEM Geometry [message #22477] Tue, 17 April 2018 11:22 Go to next message
Tobias Stockmanns is currently offline  Tobias Stockmanns
Messages: 489
Registered: May 2007
first-grade participant
From: *ikp.kfa-juelich.de
Dear PandaRooters and GEM experts,

in the analysis of the reaction: pbar p -> Xi Xibar pi pibar -> 3 pi 3 pibar p pbar we see a significant drop in the reconstruction efficiency depending on the GEM geometry we use. With the old geometry (gem_3Stations_Tube.root) we get 18.3% (15.2% MCTruth matched) of reconstructable events with all final state particles in the event, while with the new geometry (gem_3Stations_realistic_v2.root) this value drops to 6.4% (4.3% MCTruth matched).

It is not clear if this is a real effect of the additional material introduced by the more realistic description of the GEMs or if there is still a bug in the geometry description which causes the drop of a factor 3.

It would be great if an expert on the GEMs could have a look.

Cheers,

Tobias
Re: Problems with new GEM Geometry [message #22480 is a reply to message #22477] Tue, 17 April 2018 11:28 Go to previous messageGo to next message
StefanoSpataro is currently offline  StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino
first-grade participant

From: *pg.infn.it
Something similar happened several years ago, when the geometry of one GEM plane was shifted a bit, and the corresponding recohits were not properly updated (and the Kalman was not able to fit such wrongly placed hits).
Re: Problems with new GEM Geometry [message #22491 is a reply to message #22480] Tue, 17 April 2018 13:26 Go to previous messageGo to next message
Radoslaw Karabowicz is currently offline  Radoslaw Karabowicz
Messages: 108
Registered: June 2004
Location: GSI
continuous participant
From: *gsi.de
Hi there,

Does it happen only for this one specific channel?

I will have a look into the problem tomorrow.

yours
radek
Re: Problems with new GEM Geometry [message #22493 is a reply to message #22491] Tue, 17 April 2018 13:56 Go to previous message
Tobias Stockmanns is currently offline  Tobias Stockmanns
Messages: 489
Registered: May 2007
first-grade participant
From: *ikp.kfa-juelich.de
I cannot tell if it is only for this channel but I guess that this effect is there for all particles with long decay lengths like lambdas and cascades.
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