CC analysis progress This talk: –A first attempt at calculating CC energy sensitivity using the...
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Transcript of CC analysis progress This talk: –A first attempt at calculating CC energy sensitivity using the...
CC analysis progress
• This talk:– A first attempt at calculating CC energy sensitivity
using the Far Mock data MC files with full reconstruction.
– Quite a few changes from Five year plan plots:• “Real” events used rather than fast MC with histogrammed
flux and y distributiuons• Reconstructed track and shower energies used rather than
Gaussian-distribution resolution functions• Nuclear effects accounted for including intranuclear re-
scattering• Neugen 3 used with flatter y-distribution
– This analysis is not optimised yet – should be able to improve energy resolution and event selection efficiencies
D.A. Petyt June 2004
Event ID – PDFs (top row – CC, bottom row – NC)
Require that all events contain at least 1 reconstructed track
Event length (planes) Track p.h./event p.h track p.h./plane (siglin ADC)
CC efficiencies – Reco and PID chain
Should be better in R1.8
First 5 efficiency plots are sequential, last plot is cumulative
Energy reconstruction
• Ereco=EEhad
• Use track fitter to provide muon momentum: range for contained tracks, 1/(q/p) for exiting tracks (min 3m track length)
• How to estimate Ehad?– Test some ideas on NC
events:• Ehad = Shower ph*scale
factor?• Ehad = Event ph * scale
factor
– Using event ph works better: ph/GeV distribution has 15% higher mean and narrower width
True NC events
Number of reco tracks and showers
Fraction of event p.h. in reco shower(s)
Shower p.h./Ehad (siglin ADC units)
Event p.h./Ehad (siglin ADC units)
Showers in CC events• Attempt to use same algorithm
to estimate shower energies in CC events
• Must account for pulse height contribution of muon track in shower region.
• Can’t use SR trk.ph.siglin, as this includes shower ph for strips in which tracks and showers overlap
• Estimate track pulse height as trk.ndigit*295, where scaling factor is determined from long muons
• Subtract estimated track p.h. from event ph to yield shower energy
• Scaling factor obtained: 10500 siglin ADC/GeV
True CC events
Numerator: shw p.h.
Denominator: event ph – estimated track ph.
Shower p.h./Ehad (siglin ADC units)
Estimated shower p.h./Ehad (siglin ADC units)
Resolution functions
Asymmetric tails caused by shower fluctuations
Small negative bias. Tails mostly due to q/p errors
All (reco-true)/true
Comparison of true and reconstructed E spectra
True CC events True NC events
Identified CC-like events: PID >-0.3
TrueReconstructed
Energy spectra and spectrum ratios
Unoscillated
NC
Oscillated
Identified CC-like events: m2=0.002, sin22=1, scaled to 16e20 p.o.t
No NC subtraction in ratio plot
Unoscillated
NC
Oscillated
Identified CC-like events: m2=0.002, sin22=1, scaled to 16e20 p.o.t
Energy spectra and spectrum ratios
NC contribution subtracted with 20% error
What happened to the low energy rise?
I can think of 4 likely reasons:• Energy smearing due to nuclear/mass/pion absorption
effects in NEUGEN. Already saw some evidence of this when I compared toy MC event generator with NEUGEN last June
• Additional smearing caused by non-Gaussian tails in resolution functions. Andy Culling’s Ehad method should help here
• Toy MC used a binned FarDet energy spectrum with linear interpolation between bins. Will tend to over-estimate event rate in lowest energy (0-1 GeV) bin
• Track finding efficiency is lower, especially at low E
What happened to the low energy rise?
Track finding efficiency, old and new
• Track finding efficiency is much higher in the old ntuple. I suspect that this is because the reconstruction was configured with cosmic parameters which contain much looser cuts on what constitutues a “track” plane. Tracks are also found in most NC events, but these can be suppressed with the PID cut.
• “NEW” efficiency is set to improve with R1.8 (low p tuning by Niki, bug fixes by Jim)
Old (NEUGEN2) MC file, tracker run with cosmic mu parameters?
Mock Data MC files, tracker run with R1.7
What next?
• Re-do analysis with R1.8, which will contain a number of reco improvements. How much does this help?
• Look into incorporating Andy Culling’s Ehad prescription to improve shower energy resolution
• Look at events that do not have a reconstructed track. Are there usable CC events in this sample? How can we extract them?