1. for the Detection of UHE Cosmic Rays and Neutrinos
Optimal Radio Window
for the Detection of UHE
Cosmic Rays and Neutrinos
Olaf Scholten
KVI, Groningen
For the NuMoon collaboration
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2. Principle of the measurement
Cosmic ray
Detection:
Westerbork antennas
107 km2
100MHz Radio waves
Proefje door Tjalling Nijboer en Martin Stokroos:
Statische electriciteit van wrijfstok is hoorbaar via radio ontvanger op de middengolf.
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3. Radio emission Mechanisms
In air: Geo-synchotron radiation
Coherent emission in Atmosphere
LOPES
In matter: Askaryan effect
Coherent Čerenkov emission in
ice, salt, rock, ….
FORTE, RICE, SALSA, GLUE,
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4. Askaryan effect: Coherent Cherenkov emission
~10 cm
~2 m
Cosmic ray
shower
Wave front
Leading cloud of electrons, v  c
Typical size of order 10cm
Coherent Čerenkov for ν  2-5 GHz
cos θc =1/n , θc=56o for ∞ shower length
Length of shower, L  few m
Important for angular spreading
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5. Importance of angular spread
Vacuum
Cosmic particle
interaction
3 GHz θc
High frequency:
- Internal reflection
Δθc≈λ/ℓ
= (at 2.2 GHz)
100 MHz
Vacuum
Cosmic particle
interaction θc
Lower frequencies:
Considerable emission
Larger angular acceptance
Δθc = (at 0.1 GHz)
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6. Spreading around Cherenkov-cone
Old :
n=1.8
New :
GHz
MC calculations
Sine profile
L=1.7 m , E=1020
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7. Influence of frequency
Case:
with surface
Calculations for
Ecr= eV
Influence of frequency
Simulations for Moon
Minimal signal = 3000Jy
0.1 GHz
85% of area
2.2 GHz
0.8% of area
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Intensity v.s. cos θ, φ

8. Cosmic rays, Position on Moon
Calculations for
Ecr= eV
With decreasing ν :
- increasing area
- increasing probability
∫ over surface Moon
D  ν-3
Partial Detection probability
Normalized distance from center
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9. Detection Limits, Cosmic rays
Minimum Flux for detecting
1 count/100h
Detection threshold = 500Jy
Decreasing ν :
Increasing threshold
like ν-1
Increase sensitivity
like ν-3
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10. Neutrino Showers above 1020 eV
Hadronic Shower (20%)
Relatively short
EM Shower (80%) e
Long EM shower
EM= 36 cm/sqrt(E/1015 eV)
Shower length ~ 60 m (E/1019 eV)1/3
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
seminar

11. Detection Limits, Neutrinos
Present results compared with that of GLUE experiment
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12. NuMoon Experiment @ WRST
Use Westerbork radio observatory
Advantages:
MHz band
25 m diameter dishes
5 degree field of view
12-14 coincident receivers
500 hour observation time
40 M samples/sec (PuMa2)
Polarization information
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13. NuMoon Experiment @ WRST
Use Westerbork radio observatory
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14. NuMoon Experiment @ LOFAR
Total collecting area 0.5 km2
Cover whole moon,
Sensitivity 25 times better than WSRT.
Bands:
30-80 MHz (600 Jy)
MHz (20 Jy)
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15. Cosmic Rays Sensitive to flux beyond GKZ limit ν=140 MHz
Detection threshold taken at Fdet= 25 Fnoise
Δν=20 MHz , 4 bands
ν=140 MHz
WSRT: Fdet = 15,000 Jy
WSRT: Fdet = 500 Jy
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16. Neutrinos WSRT, 500 hours 2 counts LOFAR, 30 days 40 counts
Theoretical predictions:
Waxman-Bahcall limit
GZK induced flux
Phys.Rev.D64(04)93010
Topological defects
AstroPhys. J. 479(97)547
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17. Status experiment Tests data are being analyzed
Observation time granted at WSRT
- 100h per half year, total 500h
- starting July 14
Part of LOFAR Key Science Program
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18. Observations raw data After Removing RFI time amplitude
Frequency spectrum
After Removing RFI
20 kHz, low resolution
1.5 kHz, high resolution
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19. Conclusions NuMoon Future: NuMoon @ WRST: NuMoon @ LOFAR
MHz band
Large field of view
Polarization information
Future:
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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20. LORD efficiency for neutrinos
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21. Angular spread
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22. Additional Radio-absorbtion length= λ/ν[GHz]: default: λ=9 m
Stopping power,
default: X0 = 22.1 g/cm2
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23. sensitivity to top-soil
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24. Angular spread emitted power Δθc≈λ/ℓ
Particle hits Moon (radius=1700 km; area = 6π 106 km2):
protons interacts at surface
neutrinos inside
Transmission through Moon material λr= 9[m] /  [GHz] = 4m (at 2.2 GHz)
Transmissivity across Moon surface – vacuum boundary eV eV
Angular spread emitted power Δθc≈λ/ℓ
Hadronic component:
Δθc= 2.5 (3/) =
750 (at 0.1 GHz)
100 MHz
Vacuum
Cosmic particle
interaction θc
Case:
with surface
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