General plots

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Fast Simulator plots description


Recently a Fast Simulator was implemented and is now available in CVS.
Basically we take the hits from Geant, smear the local coordinates according to the hits resolution in r/&phi and then write them to the SsdHitCollection.

To use it, instead of the slow simulator, you have to replace in your bfc chain option "ssd" by "ssdfast".

We write 5 histograms, that can be retrieved using the ".hist.root" of your process.
From this ".hist.root" file : The hits resolution are :

General plots

dX
Distribution of the X global coordinate before and after the smearing
Eplanation of the peak at 0 : here

dY
Distribution of the Y global coordinate before and after the smearing
dZ
Distribution of the Z global coordinate before and after the smearing
HitsMap
HitsMap
Distribution of the number of hits per wafer.
In this example, 10 events were process ; assuming #hits/wafer ~ 10 and knowing the active area of a wafer, it leads us to a hit density :
&epsilon ~ 0.30 hits /cm2 Here is a plot of the density : here

Wafer Id
Wafer Id
The numbering is :
id_wafer = 7000 + (wafer*100) + (ladder),
where wafer goes from 1 to 16 and ladder from 1 to 20.



Updates

2 methods are implemented in order to remove hits from the dead and from the inactive areas for each wafer.
Figure : ssd wafer
IsOnWafer():removes hits after smearing if they don't match the requirement to belong in the active area
RemoveTriangle() : removes hits from the triangle area.

The 2 next pictures show the local (x-y) position of hits :
Figure : local position of hits before the 2 methods Figure : local position of hits after the removal of hits



The 2 next pictures show the ratio between the number of hits written in StEvent after the application of the 2 methods with the geant ssd hit table.
Without the methods, the ratio is 1.
I run the fast simulator over 100 events in this exemple.
Figure : before the 2 methods Figure : after the removal of hits


The 2 next pictures show the efficiency of tracking as a function of momentum.
Figure : before the 2 methods Figure : after the removal of hits
ssd back button Jonathan.Bouchet