2. September 16-19, 2008 Hamburg 2008 Olaf Scholten For the NuMoon collaboration KVI, Groningen

3. September 16-19, 2008 Hamburg 2008 Physics of Cosmic rays Spectrum is power law Flux ~ E -3 Non thermal spectrum! There must be sources! Where? What? End point? This talk: Measurement at highest E ( Area Moon = 2 10 7 km 2 ) F(E) [ m 2 sr s GeV ] -1 E [eV ] 10 -28 10 4 10 9 10 21 ← 32 orders of magnitude  ← 12 orders of magnitude  ← 1 [m -2 s -1 ] 1 [km -2 y -1 ] UHECR E -2.7 

4. September 16-19, 2008 Hamburg 2008 Cosmic ray or neutrino 100MHz Radio waves Detection: LOFAR Principle of the measurement 10 7 km 2

5. September 16-19, 2008 Hamburg 2008 Askaryan effect: Coherent Cherenkov emission Leading cloud of electrons, v  c Typical size of order 10cm Coherent Čerenkov for ν  2-5 GHz cos θ c =1/n, θ c =56 o for ∞ shower length Length of shower, L  few m Important for angular spreading ~10 cm ~2 m Cosmic ray or neutrino shower Wave front nano second pulses

6. September 16-19, 2008 Hamburg 2008 Use Westerbork radio observatory NuMoon Experiment @ WSRT 4 frequencies

7. September 16-19, 2008 Hamburg 2008 Trigger: pulse in all four frequency bands + dedispersion 18 TB raw data per 6 hr slot TimeFrequency Excise RFI Trigger

8. September 16-19, 2008 Hamburg 2008 Trigger Power Spectrum Gaussian noise Effect successive steps in analysis

9. September 16-19, 2008 Hamburg 2008 Prelimenary Results Analysis of 20 h data Data taking is continuing NuMoon collaboration: O.S., Stijn Buitink, Heino Falcke, Ben Stappers, Kalpana Singh, Richard Strom

10. September 16-19, 2008 Hamburg 2008 Future: LOFAR SKA, 1 year, LFB: 100-300 MHz MFB: 300-500 MHz From: O.S., SKA Design Study report LOFAR Core 1 month E-LOFAR, 1 year

11. September 16-19, 2008 Hamburg 2008 Conclusions Detection of Ultra-High Enegy cosmic rays & neutrinos Physics: What are the sources? Challenge: implement real-time trigger in CEP LOFAR as observer of short (n-sec) intermittent pulses.