1. Gamma-ray Large Area Space Telescope
Associating
CalMip and Track Variables
Stefano Germani
Monica Pepe
INFN Perugia
Instrument Analysis Meeting
December 16, 2005

2. All plots refer to following cuts
Outlook
The second part of the study concerns Mip reconstructed directions
consistency check
correlation with the Mip segment length
comparison to the Track directions
All plots refer to following cuts
TkrNumTracks = 1
CalMipNum > 0

3. CalMip Position On Axis events have more homogeneous
TkrNumTracks=1
CalMipNum > 0
On Axis Events
VtxZDir< (25.8 deg)
All 1 Track Events
CalMip1Pos(Y)
CalMip1Pos(Y)
CalMip1Pos(X)
CalMip1Pos(X)
On Axis events have more homogeneous
CalMip1Pos distribution

4. Mip direction and segment length
CalMip1Dir(Z)
TkrNumTracks=1
CalMipNum > 0
Try to understand the
meaning of second peak
in the next slides
CalMip1ArcLen
Cal thickness ~160 mm
(8×1Layer = 8×20 mm)
CAL thickness
At least 3 layers mm

5. CalMip1Dir(Z) vs CalMip1ArcLen (I)
TkrNumTracks=1
CalMipNum > 0
Mip Finder requires:
XtalEnergy > 8 MeV
NLayers >= 3
CalMip1Dir(Z)
CalMip1ArcLen (mm)
The plot structure
reflects the number of CAL
layers crossed by the MIP
(see next slide)

6. CalMip1Dir(Z) vs CalMip1ArcLen (II)
TkrNumTracks=1
CalMipNum > 0
Energy deposition > 8 MeV
in 8 Layers
MIP
Mip Finder requires:
XtalEnergy > 8 MeV
NLayers >= 3 mm
MIP
Energy deposition > 8 MeV
in only 6 Layers mm

7. Investigating long Mip segments
Energy deposition > 8 MeV
in Layers 07
TkrNumTracks=1
CalMipNum > 0
All Events
CalMip1Dir(z)
-.88 <CalMip1Dir/z) <- .78
28° °
CalMip1Dir(z) > -.78
Selected
Region
CalMip1ArcLen (mm)
All Events
CalMip1ArcLen (mm) 0°
28°
39°
We understand correlation between Mip direction and arc length but
Why so many “green” MIPs?
CalMip1Dir(z)

8. Look at MIP segment direction
TkrNumTracks=1
CalMipNum > 0
CalMip1Dir(X)
CalMip1Dir(Y) vs CalMip1Dir(X)
CalMip1Dir(Y)
On Axis Tracks
CalMip1Dir(Z)
second peak
Fred please
cross check!

9. Correlating CAL and Track
CAL: CalMip1Dir(X,Y,Z)
Track: Vtx(X,Y,Z)Dir
TkrNumTracks=1
CalMipNum > 0
X Dir
Z Dir
CAL
CAL
Track
Y Dir
Track
CAL
MIP finder well correlated
to reconstructed track
but……….
Track

10. CalMip1Dir vs Tkr1EndDir
VtxZDir
Tkr1EndDir(2)
CAL: CalMip1Dir(X,Y,Z)
Track: Tkr1EndDir(X,Y,Z)
X Dir
CAL
Track
Z Dir
CAL
Beware of different orientation
for initial (Vtx) and final (Tkr)
Track direction
Track

11. Conclusions
Mip direction is well correlated to Track direction as expected
We have still to understand better the peaks in the Mip Direction distributions (X,Y,Z)
maybe they reflect the Cal Layer geometry ?

12. Summary of CalMip SVAC variables
We are waiting
for real data!!
Analyzed
CalMipNum
CalMipnPos(3) n=1,2
CalMipnDir(3)
CalMipnChi2
CalMipnArcLen
CalMipnEcor
CalMipnErm
Not yet checked
CalMipnD2edge
CalMipnEcorRms
Thanks Frederic for useful explanations !!