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

2. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 2 Outlook 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

3. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 3 CalMipNum All EventsTkrNumTracks=1 Events CalMipNum Why zero Mips? Why more than one Mip? CalMipNumEvent Fraction 042.9 % 152.4 % 2 4.6 % 30.03 % 48E-6

4. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 4 Why 1 Track and 0 Mip (I) ? Tkr1NumHits 1 Track and 0 Mip 1 Track and 1 Mip The Track may not reach the CAL as seen in next slides

5. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 5 Why 1 Track and 0 Mip (II) ? Tkr1EndPos 0 Mip Tkr1EndPos 1 Mip Tkr1EndPos No Mip found if track ends on LAT edge

6. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 6 Why 1 Track and 0 Mip (III) ? 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

7. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 7 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

8. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 8 MIP Energy CalMip1Ecor 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)

9. SVACInstrument Analysis Meeting, December 16, 2005 Stefano Germani & Monica Pepe 9 Conclusions 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?