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Shirley LiPh.D. Advisor: John Beacom
The Ohio State University
�� Calculation of isotope yields with FLUKA
1402.4687� Isotopes are made in muon-induced showers
1503.04823� Reconstruction showers in water-Cherenkov detector
1508.05389� More to come!
Our Papers on Super-K
�� 50 kton water Cherenkov detector� Depth 2700 m.w.e., with muon rate 2 Hz� Solar neutrino 5.5 – 20 MeV; DSNB 16 – 30 MeV� Radioactivity below 6 MeV; spallation dominates 6 –
18 MeV� In the final solar data sample:
solar neutrino event rate ≈ spallation background rate
Basics about Super-K
�� Lots of previous works on neutron production� Available packages: FLUKA, GEANT4 � Simulation & measurement in oil
0907.0066 by KamLAND1304.7381 by Borexino
� Accuracy: hard to quantify, about a factor of 2
Isotope Yield Calculation
�� Only 4% isotopes are made by muons
Isotopes are made by secondary particles
Secondary particle spectra Parent particle spectra
�
Secondary particles are made in showers
A 10 GeV showerin water
Heitler’smodel
AveragedShower profile
�Isotopes are made in showers
Hadronic and electromagneticShowers:Make plenty electrons, which emitCherenkov light.
Low energy neutron showers:No charged particles, no light
�A new way to tag backgrounds!
�
How to identify showers in water-Cherenkov detector?
�Simulation vs. Measurement
�The Key: electron deflection
Muon &forward electron
Deflected electron
�
Solution: choose the most deflected electrons
Focus on the comparison between SK method and Improvement 1+2+3
�� FLUKA gives reasonable isotope yield for O.� Almost every isotope with A <= 16 is produced� Isotopes are made in muon-induced showers, and
this should be the case for other materials� Electron deflection leads to smeared shower profiles
in water Cherenkov detectors, and scintillator detectors
Conclusion