The NuMoon experiment: first results

Stijn Buitinkfor the NuMoon collaboration

Radboud University Nijmegen

20th Rencontres de Blois, 2008 May 19

The Cosmic Ray Spectrum

What is the origin?Acceleration sites?

Top down models?

Search for sources

highest energies

F(E

) [

m2

sr s

GeV

] -1

E [eV ]

10-28

104

109 1021

← 3

2 or

ders

of

mag

nitu

de

← 12 orders of magnitude

← 1 [m-2 s-1]

1 [km-2 y-1]

E-2.7

Propagation of cosmic rays

Cronin 2004

GZK Cutoff

The GZK The GZK EnergyEnergy

The GZK The GZK DistanceDistance

Search for UHE CRs and neutrino’s

Pierre Auger Observatory 3000 km2

IceCube ~1 km3

Flux above 1020 eV:

1 /km2/sr/century

Cosmic ray

100MHz Radio waves

Detection:

Westerbork antennas

Principle of the measurement

107 km2

Askaryan effect: Coherent Cherenkov emission

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

~10 cm

~2 mCosmic ray

shower

Wave front

Neutrino’s vs. CRs

CR convert all energy into hadronic shower Neutrino: 20% of energy into electromagnetic

shower

CR interacts close to surface Neutrino can penetrate deeply

Surface roughness

James & Protheroe 2008

Small scale roughness `scatters’ radiation

Large scale roughness disfavours CR detection

Spreading around Čerenkov-cone

Lunar regolith: n ≈ 1.8GHz

Scholten et al. 2006

GHz

Reflection

Spreading is diminishing internal reflection

3 GHz100 MHz

Position on MoonP

art

ial D

ete

ctio

n p

rob

abili

ty

Normalized distance from center

Calculations for

Ecr=4 1021 eV

Detection treshold: 500 Jy for 20 MHz bandwidth

With decreasing ν :

- increasing area

- increasing probability

∫ over surface Moon

D ν-3

Scholten et al. 2006

Goldstone Lunar UHE Neutrino Search (GLUE)P. Gorham et al., PRL 93, 041101 (2004)

Two antennas at JPL’s Goldstone, Calif. Tracking Station @ 2.2 GHz

Detection off the Moon

First experiment: 12 hrs using single Parkes 64m dish in Australia: T. Hankins et al., MNRAS 283, 1027 (1996)

James & Protheroe, 2008

NuMoon Experiment @ WSRTUse Westerbork radio observatory

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

NuMoon coll.: O.Scholten, S.Buitink, H.Falcke, B.Stappers, K.Singh, R.Strom

Use Westerbork radio observatory

4 frequencies

NuMoon Experiment @ WSRT

Processing Pipeline

18 TB raw time series data per 6 hr slot Removal of narrow-band radio interference (RFI) Dedispersion for ionosphere Peak search ~1% of data stored for offline processing

Simulated pulse dispersed in ionosphere(TEC = 10)

+ raw data =

Trigger: 4σ pulse in all four frequency bands

+ dedispersion

Trigger Power Spectrum

Gaussian noise

Effect successive steps in analysis

Prelimenary Results

Analysis of

10 h 40 min data

Future: Lofar

Lofar High Band antennas

120-240 MHz

77 stations; 2x2 km core + outlying stations

Lofar neutrino sensitivity

Lofar UHE CR sensitivity

Lunaska

Australia Telescope Compact Array Undergoing upgrade 2 GHz bandwidth; 5 antenna’s

SKA & Pathfinder (ASKAP)

100 MHz – 25 GHz

Planar Aperture Arrays for lower frequency range

Small dishes for higher frequency range

SKA to be build in Australia or South Africa

Pathfinder in Australia

Future sensitivity

LOFAR

James & Protheroe, 2008

Conclusions Radio detection of lunar showers promising

technique for detection of highest energy particles

NuMoon @ WSRT sets competitive limits on UHE neutrino flux

Future missions will provide constraints for TD models

SKA will be sensitive to expected GZK flux

FORTE satellite(Fast On-orbit Recording of Transient Events)

Main mission: synaptic lightning observation

Viewed Greenland ice (1997-99) 1.9 MILLION km3

38 days

Log-periodic antennas

N. Lehtinen et al., PRD 69, 013008 (2004)

Askaryan effect: confirmation in sand Experiment at SLAC with beams of photons

And 1010 e-/bunch: effective shower energies 0.06-1.10 1019 eV

1 Jy = 10-26 W/m2/Hz

Angular spread

Z0 ~

Δc~λ/L=1/Lν

D. Saltzberg et alPRL 86 (2001) 2802