Counting electromagnetic showers from muons in the sea

1
Counting electromagnetic showers from muons in
the sea

• S.Mangano

2
Sky-trigger for underwater detector

• Neutrinos from Gamma-Ray Bursts
• Mieke Bouwhuis

3
Run after trigger for a static telescope

• Neutrinos from Dark Matter (Galactic Center)
• Gordon Lim

4
What is this presentation about

• Electromagnetic showers
• from muons
• Physics well known, but
• 500 m long tracks
• Energy above 1 TeV
• Calorimeter-, Vertex-Detector
• No neutrinos

5
Motivation

• Extract more information
• many muons have showers
• additional variables (shower multiplicity)
• Not explored yet
• numbers of showers per track length
• gt energy estimator
• Distinguish event topologies
• tau-decay
• Eleonora Presani

6
Identify showers in three steps

• 1. Track selection
• Algorithm developed by Ronald Bruijn
• muon candidates
• 2. 1-dimensional pre-selction
• Select hits with associated shower(s)
• shower candidates
• 3. Final selection
• 3-dimensional fit of pre-selected hits
• shower candidates with 3D position

7
Identification Method

• Muon emits
• continuously Cherenkov photon
• and sometimes discrete electromagnetic showers
• After a transformation Peak signalize shower
  position

8
Reduction to one dimensional problem by
projection on the muon direction
9
Z-Display for one MC event
All reconstructed emission points of the photons
on muon trajectory
From the algorithm selected hits
Generated shower positions on the muon axes

• Atmospheric muon event including background

10
Algorithm to find shower

• Take muon direction
• Calculate Z-position
• Search shower candidates
• Eliminate background
• Fit 3-dimensional position
• Muons with shower multiplicity

11
Downgoing muon
Detected photon

Result of muon reconstruction
Used in fit
Flat distribution of photons on muon trajectory
12
Downgoing muon with shower
Result of the 3D shower reconstruction
PeakShower position on muon trajectory
13
Downgoing muon with two showers
14
Select muon candidates Data-MC comparison

• Multiple atmospheric
• muon event generator
• Reconstruct zenith and
• azimuth angle of muons
• Muon rate 1 Hz
• Select long muon tracks
• for the shower algorithm

15
Number of showers per muon

• 5 (0.5) of muons have
• one (two) rec. showers
• MC shows
• Position reconstruction 10m
• Shower Efficiency 5
• Shower Purity 70

16
Conclusion

• Antares Neutrino-, Calorimeter- and
  Vertex-Detector
• Analysis Idea
• project the hit information to muon-axis
• search significant peaks
• make 3-dimensional fit
• gt identification of muons with showers
• Antares sees electromagnetic showers from muons
  
• Shower multiplicity fairly well reproduced by MC