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About Reconstruction [message #14936] Tue, 09 July 2013 10:27 Go to next message
Jifeng Hu is currently offline  Jifeng Hu
Messages: 31
Registered: October 2012
continuous participant
From: *physik.uni-giessen.de
Dear all,
I wonder to know (1) whether the existed implementation of EMC reconstruction associate charged tracks with showers? (2)
after a full reconstruction for all sub-detectros, whether PndTrack is the only interface to access all tracks, both charged and neutral ones? (3) under time-based simulation, how to organize these tasks together to reconstruct tracks using time information?


BTW, at present, within time-based framework, only implementation for photons has been done.
Re: About Reconstruction [message #14937 is a reply to message #14936] Tue, 09 July 2013 10:36 Go to previous messageGo to next message
StefanoSpataro is currently offline  StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino
first-grade participant

From: *to.infn.it
(1) the association is done inside the PndPidCorrelator
(2) the starting object is the PndPidCandidate, for both charged and neutral particles.
Re: About Reconstruction [message #14965 is a reply to message #14937] Wed, 17 July 2013 10:58 Go to previous messageGo to next message
Jifeng Hu is currently offline  Jifeng Hu
Messages: 31
Registered: October 2012
continuous participant
From: *wlan.uni-giessen.de
I read the pid packages in last week.

Considering a fully
time-based reconstruction for EMC, the time-stamp will be used.
To identify a shower belongs to which event, we need compare the shower's time (T_shower) to the event time (T_evt), suppose the event time is determined by the fastest TOF detector for events containing charged track, or determined by EMC for neutral decays.
Usually, T_shower = T_evt + T_flying + T_signal, this means from the event time T_evt, one track spent T_flying time and hit EMC, then spent T_signal time and produced a shower.
And now I hope to get a calibrated event time by calibrating T_shower, so the flying path is needed. this work has been done for photons. The flying path is easily taken as a straight line by connecting the hitting position with the collision vertex.

However, a little hard for charged tracks, becasue

<1> After associating charged tracks with showers, how to access the flying path between origin and EMC hitting position? Since the helix parameters only offer the path inside tracking detector without any extrapolation?

<2> with different charged particles hypothesis, calibration results should be different.

what are your opinions? many thanks.
Re: About Reconstruction [message #14967 is a reply to message #14965] Wed, 17 July 2013 17:36 Go to previous message
StefanoSpataro is currently offline  StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino
first-grade participant

From: *to.infn.it
Hi,
about track length from the interaction point to the EMC, you could take a look into the method I wrote for the tof in PndPidCorrelator::GetTofInfo. You can see there that you have a tofLength which is the sum of the two extrapolated parts, from ip to last point of the track, from last point of the track to tof. Geane has a function which calculates the path length, then it is very easy.
If you don0t want to use geane, from the helix, in theory you could do the following: from the pt you can calculate the circle radius, and you have to add quadratically the "z" component. In this sense you have a lath length valid ONLY where the field is constant, i.e. it will not work in the endcap regions.

In theory the radius depends on the momentun and not on the particle type, then I believe one parametrization is enough. The only different thing is the energy loss for different particle, but I believe it will not change so much the path length.
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