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Charge Mapping in SCT_Digitisation

Charge Mapping in SCT_Digitisation. SCT Digitisation Task Force Meeting. 24 th August 2010. Richard Batley. (Cambridge). First look at charge maps provided by Taka :. -- compare different grid spacings. -- compare with pulse map. -- use toy line charges and “real” GEANT events.

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Charge Mapping in SCT_Digitisation

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  1. Charge Mapping in SCT_Digitisation SCT Digitisation Task Force Meeting 24th August 2010 Richard Batley (Cambridge) First look at charge maps provided by Taka : -- compare different grid spacings -- compare with pulse map -- use toy line charges and “real” GEANT events (Charge maps would be more straightforwardto implement in SCT_Digiand would maintain factorisation of induced charge and electronics models)

  2. Induced Charge Model (ICM) maps Maps available (so far) from Taka : 1) Pulse map -- 5mm grid, Dt = 1ns [5] : strips -2, -1, 0, +1, +2 [17] : 0, 5, 10, ..., 80 µm Pulse[5][17][57][50] [57] : 2.5, 7.5, ..., 282.5 µm [50] : 0, 1, 2, ..., 49 ns map electronics response vs time for point charges  (including crosstalk as in current SCT_Digitisation) 2) Charge maps -- 7.5, 5.0, 2.5, 1.0mm grids, Dt = 0.5ns Charge[5][11][38][50], ... , Charge[5][81][285][50] map induced charge vs time for point charges  Use linear interpolation between nearest grid points

  3. Geometry : Strip -1 Strip 0 Strip +1 All maps for Vbias = 150 V, Vdep = 65 V, T = 0oC

  4. Induced charge profiles for point charges (examples) : strip -2 strip -1 strip 0 strip +1 strip +2 (x,y) = (5,20) (x,y) = (40,250) Map = piecewise linear interpolation with Dt = 0.5 ns (too coarse ?)

  5. Corresponding pulseheight profiles : strip -2 strip -1 strip 0 strip +1 strip +2 (x,y) = (5,20) (x,y) = (40,250) solid curves : from charge map + electronics model dashed curves : directly from pulse map

  6. Response to toy tracks Uniform 1-MIP line charges : (1-MIP = 108 eh / mm) Strip -1 Strip 0 Strip +1 Step length along each toy track = 0.1mm

  7. Response to uniform line charges (examples) : strip -2 strip -1 strip 0 strip +1 strip +2 f = 0, x = 0 f = 0, x = 40 blue : 1mm charge map red : current SCT_Digitisation model

  8. Corresponding pulseheight profiles : strip -2 strip -1 strip 0 strip +1 strip +2 f = 0, x = 0 f = 0, x = 40 blue : 1mm charge map (dashed = 5mmpulse map) red : current SCT_Digitisation model

  9. Cluster size versus angle 7.5mm 5.0mm 2.5mm 1.0mm something strange about the 7.5mm charge map 5.0mm grid probably too coarse -- 2.5mm looks like a reasonable compromise ? But : what is the real answer (from the induced charge model) ?

  10. Charge map (5.0mm) Comparison with current SCT_Digitisation model : Pulse map (5.0mm) SCT_Digi

  11. Cluster position bias Average , integrated over local x of track : 7.5mm 5.0mm 2.5mm 1.0mm ( Apply Lorentz correction : )

  12. Implementation in SCT_Digitisation Hacked SCT_Digitisation-00-11-41-01 in 15.6.8 to install the 5mm charge map as an option Processed 100 ZZ4l events using both the charge map and standard digitisations (charge map digitisation runs very slowly) standard charge map

  13. Reconstructed tracks : standard charge map

  14. Summary Looked at Taka’s charge maps for toy line charges ... gives results consistent with pulse map  suggests using a 2.5mm grid size ?  how does map comparewith full ICM ?  ... and for “real” GEANT events using hacked version of SCT_Digitisation ... (easier to implement than pulse maps, though CPU time may be an issue) it works !  next: study GEANT single muons  (need to get single particle generator working again)

  15. BACKUP SLIDES

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