Inclined showers detected by LOPES neutrino detection

1
Inclined showers detected by LOPES-neutrino
detection-

• Jelena Petrovic
• Radboud University Nijmegen
• The Netherlands
• Lopes collaboration

2
Cosmic ray air showers

• Heavy nuclei, protons ? strong hadronic component
  large number of muons
• Gamma photons ? strong electromagnetic component
  lower number of muons
• Neutrinos ? inclined showers

3
Inclined showers
B
p,Fe,?
zenith
r
l
Zenith angle
?
l2

geomagnetic angle

• l2 gt l gt r larger zenith angle ? longer path
• Electrons are mostly absorbed, muons not

4
Why are inclined showersinteresting?

• If triggered high in the atmosphere by protons,
  nuclei, photons ?Long traveling path through the
  atmosphere ?electrons mostly absorbed
• Neutrinos can initiate showers deeper in the
  atmosphere
• Inclined shower with large number of electrons on
  the ground level initiated deep in the
  atmosphere ?neutrino!!!

5
Possible sources of neutrinos

• GRB,AGN ? shocks accelerate particles
• Protons interact with photons producing pions
• Neutrinos are produced in charged pions decays

6
Selection of inclined events

• LOPES data for 2004 500 000 events (triggers
  from KASCADE ? reconstruction of shower
  properties)
• Z gt 50º ? 2017 events, about 1 in 30 detected
• Muon number gt 105 ? 51 event ? 40 detected in
  radio
• Problem KASCADE is not optimized for large
  zenith angles and shower properties might not be
  accurately reconstructed for zgt60º no accurate
  reconstruction

7
Example 1 event March 2004

• Zenith angle 54º , geomagnetic angle 70º
• Muons 1.5x106 , electrons 1.5x106

8
Example 1 event March 2004

• Zenith angle 54º , geomagnetic angle 70º
• Muons 1.5x106 , electrons 1.5x106

9
Radio detection efficiency increases with the
geomagnetic angle (north)
Nµgt105
10
Preferred direction for radio detection
north-south (antenna sensitivity)
11
Radio detection efficiency increases with the
muon number
12
Radio detection is not clearly correlated with
the electron number (absorption)
13
Radio pulse height and geomagnetic
anglecorrelation
Petrovic et al. LOPES collab., 2005, in prep.
14
Bright events selection

• Falcke et al. LOPES collab., Nature, 2005

15
Example 2 event from January 2004

• Zenith angle 77º, geomagnetic angle 96º

16
Example 3 event from July 2004

• Zenith angle 75º, geomagnetic angle 88º

17
Conclusions

• highly inclined cosmic ray air showers can be
  detected in the radio domain by LOPES (current
  max z80º)
• Large geomagnetic angle (north)
• Large muon number
• north-nouth direction (antenna sensitivity)
• signature for neutrino events
• primary interaction is deep in the atmosphere
• large number of electrons reaches the ground
• LOFAR will be able to determine distance to the
  primary interaction ?neutrino detection!

18
(No Transcript)