Gamma-ray Large Area Space Telescope Understanding SVAC CalMip Variables Monica Pepe Stefano Germani...

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

Understanding Understanding SVAC CalMip VariablesSVAC CalMip Variables

Monica PepeStefano Germani

INFN Perugia

Instrument Analysis MeetingDecember 16, 2005

SVAC Instrument Analysis Meeting, December 16, 2005

Stefano Germani & Monica Pepe 2

OutlookOutlook

• Aim of the work:– First look to the new CalMip variables in the

SVAC ntuple• Consistency check (Monica)• Direction and Correlation with tracks (Stefano)

• Data:– Surface Muons 1M Montecarlo

• SVAC Ntuple/nfs/farm/g/glast/u11/InstrumentAnalysis/MC/EngineeringModel-v5r0703p3/LAT_Surface_Muons/surface_muons_1M_svac.root



CalMipNumCalMipNum

All Events TkrNumTracks=1 Events

CalMipNum CalMipNum

Why zero Mips?

Why more than one Mip?

CalMipNum Event Fraction

0 42.9 %

1 52.4 %

2 4.6 %

3 0.03 %

4 8E-6



Why 1 Track and 0 Mip (Why 1 Track and 0 Mip (II) ?) ?

Tkr1NumHits Tkr1NumHits

1 Track and 0 Mip 1 Track and 1 Mip

The Track may not reach the CAL

as seen in next slides



Why 1 Track and 0 Mip (Why 1 Track and 0 Mip (IIII) ?) ?

Tkr1EndPos 0 Mip

Tkr1EndPos 1 Mip

Tkr1EndPos

No Mip found if track ends on LAT edge



Why 1 Track and 0 Mip (Why 1 Track and 0 Mip (IIIIII) ?) ?

Tkr1 Extrapolation to Cal: 0 Mip

Tkr1 Extrapolation to Cal: 1 Mip

Tkr1 Extrapolation at CAL entry

No Mip found if track extrapolation do not enter in CAL



Why 1 Track and >1 Mip ?Why 1 Track and >1 Mip ?

Mip Finder algorithm can find several Mip Track segments due to CAL segmentation and position resolution (Thanks Fred!)

CalMip2Pos(X) vs CalMip1Pos(X)

CalMip2Pos(Z) vs CalMip1Pos(Z)

CalMip2Pos(Y) vs CalMip1Pos(Y)

The two Mip segments belong to the same TRUE Mip (separated along Z: if Mip1 is at High Z Mip2 is at Low Z)

mm

mm

mm

mm

mm

mm



MIP EnergyMIP Energy

CalMip1Ecor

MeV

MeV

CalMip1Erm CalMip1Erm vs Mip Track Length

mm

MeV

CalMip1Ecor

is the mean vertical-equivalent energy averaging path length corrected energy on layer basis

CalMip1Erm

is the total energy in a cylinder of

1 Moliere radius (35 mm in CsI)



ConclusionsConclusions

• CalMip Ntuple – variables seems to be correctly filled

• Mip Finder – behaves as expected when the muon track

reaches the CAL

– Multiple Mips associated to the same track are actually segments of the same MIP

• Would it be necessary to improve the algorithm in order to take into account these topologies?

Gamma-ray Large Area Space Telescope Understanding SVAC CalMip Variables Monica Pepe Stefano Germani...

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