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Gamma-ray Large Area Gamma-ray Large Area Space TelescopeSpace Telescope

AssociatingAssociatingCalMip and Track CalMip and Track

VariablesVariables

Stefano GermaniMonica Pepe

INFN Perugia

Instrument Analysis MeetingDecember 16, 2005

SVAC Instrument Analysis Meeting, December 16, 2005

Stefano Germani & Monica Pepe 2

Outlook 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



CalMip PositionCalMip Position

CalMip1Pos(X)C

alM

ip1P

os(

Y)

CalMip1Pos(X)

Cal

Mip

1Po

s(Y

)

All 1 Track EventsOn Axis Events VtxZDir<-0.9 (25.8 deg)

On Axis events have more homogeneous CalMip1Pos distribution

TkrNumTracks=1CalMipNum > 0



Mip direction and segment lengthMip direction and segment length

CalMip1Dir(Z)

CalMip1ArcLen

mm

CAL thickness

Cal thickness ~160 mm(8×1Layer = 8×20 mm)

Try to understand the meaning of second peak in the next slides

At least 3 layers




CalMip1Dir(Z) vs CalMip1ArcLen (I)

CalMip1ArcLen (mm)

Cal

Mip

1Dir

(Z)

Mip Finder requires:• XtalEnergy > 8 MeV• NLayers >= 3

The plot structure reflects the number of CAL layers crossed by the MIP(see next slide)




CalMip1Dir(Z) vs CalMip1ArcLen (II)

Energy deposition > 8 MeV in 8 Layers

Energy deposition > 8 MeV in only 6 Layers

mm

mm

MIP

MIP

Mip Finder requires:• XtalEnergy > 8 MeV• NLayers >= 3




Investigating long Mip segments

Energy deposition > 8 MeV in Layers 07

All Events

SelectedRegion

CalMip1Dir(z)

CalMip1ArcLen (mm)

All Events

CalMip1Dir(z) > -.78

-.88 <CalMip1Dir/z) <- .7828° 39°C

alM

ip1

Dir

(z)

CalMip1ArcLen (mm)

We understand correlation between Mip direction and arc length but

Why so many “green” MIPs?

0°28°

39°




Look at MIP segment directionLook at MIP segment direction

CalMip1Dir(X)

CalMip1Dir(Y)

CalMip1Dir(Y) vs CalMip1Dir(X)

Fred please Fred please

cross check!cross check!

On Axis Tracks

CalMip1Dir(Z) second peak




Correlating CAL and TrackCorrelating CAL and Track

X Dir

Y Dir

Z Dir

CA

L

CA

L

CA

L

Track

Track

Track

CAL: CalMip1Dir(X,Y,Z)

Track: Vtx(X,Y,Z)Dir

MIP finder well correlated to reconstructed track

but……….




CalMip1Dir vs Tkr1EndDirCalMip1Dir vs Tkr1EndDir

X Dir

Z Dir

VtxZDir

Tkr1EndDir(2)

CAL: CalMip1Dir(X,Y,Z)

Track: Tkr1EndDir(X,Y,Z)

CA

LC

AL

Track

Track

Beware of different orientation for initial (Vtx) and final (Tkr) Track direction



ConclusionsConclusions

• 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 ?



Summary of CalMip SVAC variablesSummary of CalMip SVAC variables

• Analyzed– CalMipNum– CalMipnPos(3) n=1,2– CalMipnDir(3)– CalMipnChi2 – CalMipnArcLen– CalMipnEcor– CalMipnErm

• Not yet checked– CalMipnD2edge– CalMipnEcorRms

Thanks Frederic for useful explanations !!

We are waiting for real data!!