1. Variable to distinguish up-going one muon from two muons
Motivation
Toy Monte Carlo
Variables
Results
Conclusion

2. Physics Dimuon signature =>Charm in charged current interaction
Possible to measure charm cross section at high energies
Quantitative studies done by:
Rezo Shanidze (Valencia meeting) and
Karl Lyons (Strasbourg meeting)
Summery:
There exist around 7 events
in one year Line1-5 data and
with a proposed method they could identify around 1 dimuon event
(not sure if charm was included)

3. Toy Monte Carlo Mupage file with multiplicity=1
up-going muons (change muon direction)
Km3, TriggerEfficiency (BG 60 kHz)
ScanFit (Single track assumption)

4. Variables 1. Emitted Cherenkov light per unit track length
Check two Variables:
1. Emitted Cherenkov light per unit track length
(Should be effective for nearby tracks)
2. Quality of single track fit
(Should be effective for distant tracks)

5. Cherenkov light per unit track length
Measure amount of emitted Cherenkov light per unit track length =: Ped
Ped proportinal to number of minimal ionizing muons
Project photons under Cherenkov assumption into the muon track with a weight Q*d*exp(d/lambda) (emitted intensity of Cherenkov light)
Q=measured charge, d=distance (photon emission to PMT)
lambda=absorption length (60m)

6. Claire Picq presented variable: SRF
N=Number of hits with time residual [-5ns, 5ns ]
M=Number of hits with time residual [-30ns,150ns]
SRF=N/M (Small Residual Fraction)

7. Ped results Take only photons with time residual [-50ns, 200ns]
Eliminate photons with path distances larger 200m
Better discrimination with photon weights=1 than with charge correction. Why???
Where are the two distinguished delta function?
Ped results T
Take only photons with time residual [-50ns, 200ns]
Eliminate photons with path distances larger 200m
Better discrimination with photon weights=1 than with charge correction. Why???
Where are the two distinguished delta function?

8. SRF results
Discrimination between the single and double muons sample is better for SRF than for Ped.

9. SRF versus Ped
The two variables should be independent Quality of the fit (SRF) versus averaged emitted charge per track length (Ped)
Single muon events
Two muon events
Weak discrimination between the different samples

10. Conclusion
Soon enough statistics to make analysis of up- going dimuon events interesting
Challenging task requires variables with stronger discrimination
Presented variables use information along track check also perpendicular to track plan information (e.g. Marco Bazzotti multi muon pattern recognition algorithm)
Are multi muons in GENHEN generated also from charm? Do we have a MC with charm?