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Neutrino search using full waveform information Dmitry Chirkin, LBNL
Neutrino search using full waveform information
Dmitry Chirkin, LBNL
Reconstruction methods
Feature Extractor:• Simple single-peak feature-extraction: first peak, total charge• Multi-peak unfolding-based feature-extraction
Rime:• simple 5-parameter reconstruction• joint 6-parameter reconstruction
• Ice-layered model• bulk ice model
Basic cut variables
rllh
Cut at 8
Closest approach to COGxy
cut at 40
Zenith angle reconstructed uncertainty
cut at 20
Differences between reconstruction results
cut at 20
Differences between reconstruction results
cut at 20
Reconstructed energy cut variables
cut at 0.5
cut at 0.7
Angular resolution
no convenient parameterization of angular resolution was found
Angular resolution is defined as the value below which are 2/3 of the histogram entries
Cuts optimization
For all of the cut variables:tighter cuts improve angular resolution
Optimization:for a given fraction of data left, find the cuts which produce
the subset with the best angular resolution
Method 1: Simply go through all possible combinations and evaluate the angular resolution. For N=20 parameters and initial MC set of M events and fraction r, this will require to go through O(C(N,rM+N)) combinations
Method 2: for a given reduction of fraction of events dr estimate the improvement of the angular resolution dA (by removing M*dr events with largest cut values, which reduce the cut by dC). Then, using the “fastest decent”, use dr*(dA/dr) to find the optimum cut value for each cut variable.
Cut optimization
Starting from initial cuts or no initial cuts, the method converges to the same result at small enough fraction of events left
Correlated parameters
Although many of the cut parameters are correlated, the method works:e.g., for 2 completely same parameters, dC/dr will be the same
Cut matrixFor each Nch from 6 to 100
1ppw
NppwAn
gula
r re
solu
tion
Fraction of events left
From initial cuts
To the cuts at A=4
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Final event selection
Events left at given A
Results
• 70 events at A=4• 163 events at A=5
Comparison with previous results
52 events in June from John
38 events from John are in the sample with all reco results above 80 deg.
At most ~30 in (0; 60) deg.
12 events coincide at A=4
16 events coincide at A=5
Conclusions
• A new approach to searching for upgoing muons was presented
• Instead of applying cuts to maximize signal/background ratio directly, the cuts are used to maximize the angular resolution; the background is suppressed very well by using so-selected events with higher angular resolution.
• Full waveform information is used. It remains to be seen if an improvement is achieved.
• Some overlap in found events with John’s analysis is observed
