1. Detecting UHE cosmic-rays and neutrinos hitting the Moon
The νMoon project:
Detecting UHE cosmic-rays
and neutrinos hitting the Moon
νMoon Collaboration: J. Bacelar (KVI)
R.Braun (ASTRON)
G. de Bruyn (ASTRON)
H. Falcke (ASTRON)
O. Scholten (KVI)
B. Stappers (ASTRON)
R. Strom (ASTRON)

2. Neutrino detection needs large detector volumes!
Use the moon …

3. Cosmic Ray
Westerbork antennas
100 MHz Radio Waves

4. Particle hits Moon (radius=1700 km; area = 6×106 km2):
Interacts: protons within meters, V
Askaryan effect -> Coherent Cherenkov emission
Shower development -> including LPM effect
Transmission through Moon material λr= 15[m] /  [GHz] = 7m (at 2.2 GHz)
Transmissivity across Moon surface – vacuum boundary eV eV
Moon n=
Vacuum
Cosmic particle
interaction
θc ≈ 560
Vacuum
Moon n=
Spread emitted power density
in a gaussian of width Δθc≈λ/ℓ
Hadronic component:
Δθc= 2.5 (3/) = (at 2.2 GHz)
EM component
Δθc= 2.5 (3/)( / E)1/3 =
θc ≈ 560 θc
2.2 GHz

5. Particle hits Moon (radius=1700 km; area = 6×106 km2):
Interacts: protons within meters, V
Askaryan effect -> Coherent Cherenkov emission
Shower development -> including LPM effect
Transmission through Moon material λr= 15[m] /  [GHz] = 150 m (at 0.1 GHz)
Transmissivity across Moon surface – vacuum boundary eV eV
Moon n=
Vacuum
Cosmic particle
interaction
θc ≈ 560
Spread emitted power density
in a gaussian of width Δθc≈λ/ℓ
Hadronic component:
Δθc= 2.5 (3/) = (at 0.1 GHz)
EM component
Δθc= 2.5 (3/)( / E)1/3 = 0.50 θc
100 MHz

6. Where can one do this experiment at 150 MHz ?
GMRT in India (30 dishes 45m diameter)
Problem: Data acquisition, Ionosphere, Interference,separation between telescopes
WSRT Westerbork – available at present (14 dishes 25 m diameter)
Use “PUMA II” backend for pulsar observations
LOFAR – available in the future
Dedicated mode for moon experiment

7. Westerbork (WSRT) Experiment
Basic Properties:
14 x 25 m diameter dishes
12 dishes phased-up
110 hour observation time
40 M samples/sec (PuMa II)
Full Polarization information
MHz band
8 dual-pol bands of 20 MHz
3×1020 eV would give 15 σ peak (req.)
2 separate 4’ × 6° pencil beams
covering 50% of moon
Westerbork Synthesis Radio Telescope

8. Westerbork (WSRT) Experiment
4 freq. bands
4 freq. bands
Westerbork Synthesis Radio Telescope

9. Schedule Pilot experiment at WSRT, followed by campaign at LOFAR
First: Director’s time at WSRT
2005, 14th June 17:00-19:00 several different daq. Options tried (PuMa I)
2005, 8th July 07:00-09: measurements at 117 and 162 MHz (PuMa I)
2006, 20th Feb :00-06:00 measurement with PuMaII
2006: νMoon approved as Long-Term Project
First 110 hrs granted, starting July 15, 2006
A total of 510 hrs requested for subsequent years
Currently observed 24 hrs / 12 hrs of useful data

10. Spectrum before & after interference excision
Processing Pipeline
Spectrum before & after interference excision
18 TB raw data per 6 hr slot
Excision of narrow-band interference
De-Dispersion of ionosphere with GPS TEC values
Indentification of peaks
100:1 to 180 GB

11. First Data Products: Noise Distribution & Power Spectra
Simulation of data
for 15 events within
1 hour data taking
Noise is Gaussian down to 10-7
10 s of data

12. Scholten et al. (NuMoon Collab.) 2006, Astropart. Phys., in press
Expected Sensitivity
Cosmic Rays
Neutrinos
TDs
GZK ν´s
Scholten et al. (NuMoon Collab.) 2006, Astropart. Phys., in press

13. Summary
Low-Frequency radio observations are ideal to study super-GZK particles.
Westerbork experiment has just begun
Data pipeline is working
100 hrs granted, 500 hrs expected in total
Search for pulses is next …
Very interesting first limit within one year!?
LOFAR will improve limits(?) even more