Docstoc

transparencies _ppt_ - rencontres de blois

Document Sample
transparencies _ppt_ - rencontres de blois Powered By Docstoc
					The NuMoon experiment:
first results

                                   Stijn Buitink
                     for the NuMoon collaboration
               Radboud University Nijmegen
       20th Rencontres de Blois, 2008 May 19
The Cosmic Ray Spectrum
                                                104

                                                                                    ← 1 [m-2 s-1]




                                                       ← 32 orders of magnitude 
What is the origin?




                      F(E) [ m2 sr s GeV ] -1
Acceleration sites?                                                                           E-2.7
Top down models?



Search for sources
                                                                                    1 [km-2 y-1]      
 highest energies
                                                          ← 12 orders of magnitude 
                                 10-28
                                                      109                                                 1021
                                                                                         E [eV ]
Propagation of cosmic rays




                             Cronin 2004
GZK Cutoff   The GZK
             Distance




  The GZK
   Energy
Search for UHE CRs and neutrino’s
  Flux above 1020 eV:
  1 /km2/sr/century




Pierre Auger Observatory   IceCube ~1 km3
3000 km2
  Principle of the measurement
                        Cosmic ray


Detection:
Westerbork
antennas                               107 km2


                                     100MHz
                                     Radio waves
Askaryan effect:
Coherent Cherenkov emission
                                   ~2 m
        Cosmic ray
                                                       ~10 cm

                          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
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
Small scale roughness
`scatters’ radiation


Large scale roughness
disfavours CR detection




                          James & Protheroe 2008
Spreading around Čerenkov-cone

                     Lunar regolith: n ≈ 1.8
       GHz     GHz




                        Scholten et al. 2006
Reflection

Spreading is diminishing internal reflection




                                  100 MHz
                                  3 GHz
   Position on Moon
                                                                     Calculations for
                                                                       Ecr=4 1021 eV
Partial Detection probability




                                                                     Detection treshold: 500 Jy
                                                                     for 20 MHz bandwidth

                                                                      With decreasing ν :
                                                                       - increasing area
                                                                       - increasing probability



                                                                       ∫ over surface Moon
                                Normalized distance from center           D  ν-3

                                                                  Scholten et al. 2006
                                          Detection off the
Goldstone Lunar UHE
Neutrino Search (GLUE)                         Moon
P. Gorham et al., PRL 93, 041101 (2004)




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




Two antennas at JPL’s Goldstone, Calif. Tracking Station @ 2.2
GHz
James & Protheroe, 2008
       NuMoon Experiment @ WSRT
Use 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
      NuMoon Experiment @ WSRT
Use Westerbork radio observatory




                                   4 frequencies
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 =
                                                + dedispersion



Trigger: 4σ pulse in all four frequency bands
Trigger Power Spectrum
Effect successive
steps in analysis




            Gaussian noise
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




                              Small dishes for higher
                              frequency range


                              SKA to be build in
 Planar Aperture Arrays for   Australia or South Africa
 lower frequency range
                              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                  Log-periodic antennas
    lightning observation
   Viewed Greenland ice
    (1997-99)
       1.9 MILLION km3
       38 days




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




Angular spread
                                                             D. Saltzberg et al
Z0 ~ Δc~λ/L=1/Lν                                             PRL 86 (2001) 2802




                            1 Jy = 10-26 W/m2/Hz

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:3/30/2013
language:Unknown
pages:32