Transcript ppt
Gamma-ray Large Area
Space Telescope
Understanding
SVAC CalMip Variables
Monica Pepe
Stefano Germani
INFN Perugia
Instrument Analysis Meeting
December 16, 2005
SVAC
Instrument Analysis Meeting, December 16, 2005
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/EngineeringModelv5r0703p3/LAT_Surface_Muons/surface_muons_1M_svac.root
Stefano Germani & Monica Pepe
2
SVAC
Instrument Analysis Meeting, December 16, 2005
CalMipNum
All Events
TkrNumTracks=1 Events
CalMipNum
CalMipNum
CalMipNum
Event Fraction
0
42.9 %
1
52.4 %
2
4.6 %
3
0.03 %
4
8E-6
Stefano Germani & Monica Pepe
Why zero Mips?
Why more than one Mip?
3
SVAC
Instrument Analysis Meeting, December 16, 2005
Why 1 Track and 0 Mip (I) ?
1 Track and 0 Mip
Tkr1NumHits
1 Track and 1 Mip
Tkr1NumHits
The Track may not reach the CAL
as seen in next slides
Stefano Germani & Monica Pepe
4
SVAC
Instrument Analysis Meeting, December 16, 2005
Why 1 Track and 0 Mip (II) ?
Tkr1EndPos 0 Mip
Tkr1EndPos
Tkr1EndPos 1 Mip
No Mip found if track ends
on LAT edge
Stefano Germani & Monica Pepe
5
SVAC
Instrument Analysis Meeting, December 16, 2005
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
Stefano Germani & Monica Pepe
6
SVAC
Instrument Analysis Meeting, December 16, 2005
Why 1 Track and >1 Mip ?
The two Mip
segments
belong to the
same TRUE Mip
(separated along Z:
if Mip1 is at High Z
Mip2 is at Low Z)
CalMip2Pos(X) vs CalMip1Pos(X)
mm
CalMip2Pos(Z) vs CalMip1Pos(Z)
mm
mm
CalMip2Pos(Y) vs CalMip1Pos(Y)
mm
mm
mm
Stefano Germani & Monica Pepe
Mip Finder algorithm can find
several Mip Track segments
due to CAL segmentation and
position resolution (Thanks Fred!)
7
SVAC
Instrument Analysis Meeting, December 16, 2005
MIP Energy
CalMip1Ecor
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)
MeV
CalMip1Erm vs Mip Track Length
MeV
CalMip1Erm
MeV
Stefano Germani & Monica Pepe
8
mm
SVAC
Instrument Analysis Meeting, December 16, 2005
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?
Stefano Germani & Monica Pepe
9