Olaf Scholten

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Radio detection of UHE Neutrinos off the Moon
Olaf Scholten KVI, Groningen For the NuMoon
collaboration
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Principle of the measurement
Cosmic ray
Detection Westerbork antennas
107 km2
100MHz Radio waves
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Radio emission Mechanisms

• In air Geo-synchotron radiation
• Coherent emission in Atmosphere
• LOPES
• In matter Askaryan effect
• Coherent Cerenkov emission in
• ice, salt, rock, .
• FORTE, RICE, SALSA, GLUE,

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Askaryan effect Coherent Cherenkov emission

• Leading cloud of electrons, v ? c
• Typical size of order 10cm
• Coherent Cerenkov for ? ? 2-5 GHz
• cos ?c 1/n , ?c56o for 8 shower
  length
• Length of shower, L ? few m
• Important for angular spreading

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Importance of angular spread
High frequency - Internal reflection
??c?/l 3.50 (at 2.2 GHz)

• Lower frequencies
• Considerable emission
• Larger angular acceptance

??c 750 (at 0.1 GHz)
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Spreading around Cherenkov-cone
Old
n1.8
New
GHz
MC calculations
Sine profile L1.7 m , E1020
O.S. etal., Astropart.Phys. 2006
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Influence of frequency
Case Shower _at_ 2.50 with surface
Calculations for Ecr4 1021 eV
Simulations for Moon Minimal signal 3000Jy
0.1 GHz 85 of area
2.2 GHz 0.8 of area
Intensity v.s. cos ?, f
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Cosmic rays, Position on Moon
Calculations for Ecr4 1021 eV

• With decreasing ?
• - increasing area
• - increasing probability
• ? over surface Moon
• D ? ?-3

Partial Detection probability
Normalized distance from center
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Detection Limits, Cosmic rays
Minimum Flux for detecting 1 count/100h Detection
threshold 500Jy

• Decreasing ?
• Increasing threshold
• like ?-1
• Increase sensitivity
• like ?-3

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Neutrino Showers above 1020 eV
Landau Pomeranchuck Migdal effect J.
Alvarez-Muniz, E. Zas, P.L. B434 (98)396,
Phys.Rev.D62(2000)63001
Shorter showers give larger angular spread
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Detection Limits, Neutrinos
Present results compared with that of GLUE
experiment (_at_2.2GHz)
Waxman-Bahcall
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NuMoon Experiment _at_ WSRT
Use Westerbork radio observatory

• Advantages
• 117-175 MHz band
• 12--25 m diameter dishes
• 5 degree field of view
• 40 M samples/sec (PuMa2)
• Polarization information

Measurements have started !!
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NuMoon Experiment _at_ WSRT
Use Westerbork radio observatory
Simultaneously 2 strips on the Moon _at_ 4
frequency bands
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NuMoon Experiment _at_ LOFAR

• Total collecting area 0.5 km2
• Cover whole moon,
• Sensitivity 25 times better than WSRT.
• Bands
• 30-80 MHz (600 Jy)
• 115-240 MHz (20 Jy)

Start 2008
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Cosmic Rays
Sensitive to flux beyond GKZ limit
Detection threshold taken at Fdet 25
Fnoise ??20 MHz , 4 bands ?140 MHz WSRT Fdet
15,000 Jy LOFAR Fdet 500 Jy
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Neutrinos
WSRT, 500 hours 2 counts
LOFAR, 30 days 40 counts
Theoretical predictions Waxman-Bahcall
limit GZK induced flux Phys.Rev.D64(04)93010 Top
ological defects AstroPhys. J. 479(97)547
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Status experiment
Observation time granted at WSRT - 100h per half
year, total 500h - 60 h Observation already
Data are being analyzed, Part of LOFAR Key
Science Program 2008 ?
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Observations
raw data
time amplitude
Frequency spectrum
After Removing RFI
20 kHz, low resolution
1.5 kHz, high resolution
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Future SKA,LORD
1 year observation, LFB 100-300 MHz MFB 300-500
MHz
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Conclusions

• NuMoon _at_ WSRT
• 117-175 MHz band
• Large field of view
• Polarization information

Future NuMoon _at_ LOFAR
Within 100 hours competitive
Sensitivity to cosmic rays and
neutrinos
NuMoon
NuMoon collaboration KVI Jose Bacelar, Ad van
den Berg, O.S. Astron Robert Braun, Ger de
Bruyn, Heino Falcke, Ben Stappers,
Richard Strom (also UvA,RUG,RU)
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SKA-Hadrons
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LORD efficiency for neutrinos
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Angular spread
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Additional
Radio-absorbtion length ?/?GHz default ?9 m
Stopping power, default X0 22.1 g/cm2
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sensitivity to top-soil
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• Particle hits Moon (radius1700 km area 6p 106
  km2)
• protons interacts at surface
• neutrinos inside
• Transmission through Moon material ?r 9m / ?
  GHz 4m (at 2.2 GHz)
• Transmissivity across Moon surface vacuum
  boundary

60 km _at_ 1021 eV 6 km _at_ 1024 eV
Angular spread emitted power ??c?/l Hadronic
component ??c 2.5 (3/?) 750 (at 0.1 GHz)
Case Shower _at_ 2.50 with surface