Variable to distinguish up-going one muon from two muons Motivation Toy Monte Carlo Variables Results Conclusion
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)
Toy Monte Carlo Mupage file with multiplicity=1 up-going muons (change muon direction) Km3, TriggerEfficiency (BG 60 kHz) ScanFit (Single track assumption)
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)
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)
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)
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?
SRF results Discrimination between the single and double muons sample is better for SRF than for Ped.
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
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?