Pixel Offline Status

1
Pixel Offline Status
Jianchun Wang Syracuse University 10/28/04, Pixel
testbeam meeting
2
To Do List Of Last Month

• Finish alignment and ntuple generating.
• Skim all data files with hit trigger.
• Include real ADC-charge conversion once Lorenzo
  finishes the calibration. Currently the
  conversion uses a set of value I chose long time
  ago. And we have only charge weight, no eta
  correction.
• Put more realistic expected resolution. Currently
  we use our knowledge from last test beam.
• We need chi2 value without DUT hits for track
  selection. If you choose very loose chi2 for now
  it is not a big issue.
• Update offline instruction.

3
Tracking without DUT

• We need tracking quality of the telescope without
  DUT. In this way we can select very good track
  without worrying bias the results.
• Extra parameter to indicate DUT dut_plane(7)1
  .
• Parameters for user event trigger max_miss_plan
  es, max_miss_teles.
• In NTUPLE the parameters are chisq_t, cl_t,
  ndof_t.
• Suggested track quality selection cl_t gt 0.01

4
Issue of 1-column Hits

• In Kalman filter we treat pixel hits as two strip
  hits (strip_equivalent) one Y, and one X.
• For X planes an 1-column Y strip_equivalent hit
  is not taken into fit, whereas 2-column hit is
  included. The resolutions are 100 mm and 10mm
  respectively. Same to X hits of Y planes.
• This causes some problems if you want to estimate
  tracking resolution naively. The Kalman filter
  provides a projected error of the hit.
• The 1-column strip_equivalent hit does not help
  tracking resolution. It makes calculation of chi2
  not reasonable because the distribution is not a
  Gaussian function.
• We will continue skipping those hits.

5
FPIX1 Calibration
Plane 5, a relatively good plane.

• Hits with multiple-pixel can have charge
  weighting in determining the position.
• FPIX1 planes are not as good as FPIX2. We need to
  include inefficiency in MC simulation of tracking
  resolution.
• Absolute calibration is needed.

Parameters cleared, recalculated, copied.
6
Multiple Tracks in One Event

• Track generation in MC is tuned to real data,
  run 1981.
• Beam fully covers all detector planes.
• Number of tracks ?0.8 for full coverage.
• Beam direction spread sx0.130mrad,
  sy0.152mrad.

7
Multiple Scattering
Effects of multiple scattering A track starting
at plane 3, the spread at plane 11 (Dz90cm) is
sxsy22.7 mm. The tracking error on DUT planes
changes from 3.3 mm to 3.9 mm.
8
Comparison of ADC Value
Plane 3
Plane 7
Percentage
Absolute calibration is needed.
9
Comparison of Number of Pixels
Plane 3
Plane 7
Percentage
10
Comparison of Resolution
More studies are coming.
11
Comparison of Resolution
There is still about 2mm difference.
Real Data
MC total
MC tracking
12
Summary

• Recent activities of offline code are mainly
  focused on tuning MC simulation.
• The number of hit pixels and X resolution is
  still different from real measurement.
• I will continue this work.
• The eta correction and realistic resolution are
  yet to be included.