Transcript mants

Shower along muon track
Salvatore Mangano (IFIC)
Muon energy loss
Below 1 TeV:
Continuous energy loss
Above 1 TeV:
Discrete energy loss
Large energy fluctuation
=> Electromagnetic showers
• Extract more information
many muons have showers
additional variables (shower multiplicity)
• Not explored yet
numbers of showers per track length
=> energy estimator
• Distinguish event topologies
charged current interaction
Identification Method
Muon emits:
continuously Cherenkov photons
and sometimes discrete electromagnetic showers
After a transformation: Peak signals shower position
1. Take muon direction
2. Calculate photon emission positions (weight=1)
Ealry times (|20 ns|) late times (20-250 ns)
Cerenkov emission  spherical emission
3. Search shower candidates
Simulation and selection
Corsika simulation with background
(Horandel, QGSJET,KM3)
1-5 line configuration
Muon selection
at least 125 m long
• Shower selection
10 hits in 10 m => hard cuts
5 hits in 20 m => soft cuts
5 hits from different floors
Photon emission along MC muon track
all reconstructed emission points
of the photons on muon trajectory
hits selected by the algorithm
positions of generated showers
along the muon direction
Muon and shower energy
Averaged muon energy:
1.2 TeV
Soft: 2.4 TeV
Hard: 3.2 TeV
Averaged shower energy:
160 GeV
200 GeV
460 GeV
Shower efficiency and purity
n_gen = MC hits in at least 5 diff. LCM and produced in detector
n_rec = shower position |x_gen – x_rec| < 25 m
Shower efficiency = n_rec/n_gen
Shower purity
= n_rec/n_rec^all
Number of showers
versus muon energy
More showers=>higher muon energy Light deposit of showers
Different primary models
Number of showers per muon
Tested for 2007 data (47 days of lifetime)
Shower energy
Muon energy with shower 3.7TeV
Position resolution
Shower Efficiency
Shower Purity
Main systematic errors:
• Water absorption length
• PMT acceptance
Analysis Idea:
project the hit information to muon-axis
search significant peaks
=> identification of muons with showers
Goal: Shower multiplicity to distinguish different MC
Back up slide
Reduction to one dimensional problem by
projection on the muon direction
Downgoing muon (5 lines)
Detected photon
Used in fit
Result of muon reconstruction
Flat distribution of photons on muon trajectory
Downgoing muon with shower
Result of the 3D shower reconstruction
Peak=Shower position on muon trajectory
Shape of number of showers
Driven by
Binomial formula!
(Works only for high purity)
entries with 2 gen. showers times
(efficiency not to detect a shower)
entries with 1 gen shower times
efficiency not to detect a shower
entries with 0 gen. shower
entries with 0 rec. shower
n0,rec  n0, gen  n1, gen (1   )  n2, gen (1   ) 2  ....
n1,rec  n1, gen  n2, gen (1   )  n3, gen (1   ) 2  ....