1 CC update – momentum resolution Software news: –Converted code to read Sue’s ntuples....
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Transcript of 1 CC update – momentum resolution Software news: –Converted code to read Sue’s ntuples....
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CC update – momentum resolution
• Software news:– Converted code to read Sue’s ntuples. Allows
use of Chris’s analysis framework (including event display)
– Using ntuple files generated by Chris (Feb ’04)
• This talk:– Compare PID results using new ntuples to that
presented at previous phone meeting– Look at SR muon momentum resolution
D. A. Petyt April 2004
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Reco. efficiency – new ntuple
Reconstructed event must contain at least 1 track
CC
NC
0<y<0.25 0.25<y<0.5 0.5<y<0.75 0.75<y<1.0
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Reco. effic. – old ntuple
Track finding efficiency much higher for NC in old file. Why?
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Recoselection effic - new
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Recoselection effic - old
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PID performance
• These curves combine both reconstruction and selection efficiencies, although the effect of the trigger is not accounted for
• NEW file seems somewhat better at higher E
NEW OLD
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SR muon momentum resolutionContained events - range
TruthReconstructed
Truth (10% smearing)
Resolution function shows small (2%) negative bias and long +/- tails. Momentum resolution ~7%.
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Track hits
Tracking failure in v-z view
reco
truth
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Select clean tracks: low y events only
Apply cuts: mc_y<0.2; trk_plane_n>20; trk_end radius>40cm
TruthReconstructed
Tails are reduced (high-side tail eliminated) and resolution improved, but bias is still present
10Demux failure in v-z view (low-side tail)
11Tracking stops prematurely (-ve bias)
12Tracking stops prematurely (-ve bias)
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Contained events – q/p
TruthQ/P
Range
Right-side plot: q/p momentum resolution. High-side tail (muon momentum overestimated) is more prominent
14q/p thrown off by multiple scattering?
15Disappearing muon?
16Disappearing muon – x,y,z projections
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Range/momentum comparison
Momentum from range biased low wrt. momentum from curvature
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Resolution – range vs q/p
Multiple scattering?
In general, range measurement preferred over q/p for contained tracks.
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Partially-contained events
TruthReconstructed
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All events
TruthReconstructed
Use range measurement for contained tracks, q/p for partially-contained.
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Summary & conclusions
• Looked at SR muon momentum resolution for clean CEV/PCE tracks:– Obtained resolutions of ~6% for contained tracks, ~12% for
partially-contained– Range measurement is biased low (~2%). I think this is probably
due to the track finder stopping prematurely at the end of tracks (either because of excessive scattering or high p.h. hits)
– Low-side tail evident for CEV/PCE – demux and tracking errors contribute to this.
– Would be useful if someone could look at some of the rogue events in detail and see where/how the reconstruction is failing
• Observed large differences in reconstruction efficiencies (especially for NC) between two reconstruction passes of the same MC file– My hunch is that this is caused by different JobModule
configurations – needs looking into.