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Joint operation of the LSS and CODALEMA to explore high energy cosmic ray physics

Joint operation of the LSS and CODALEMA to explore high energy cosmic ray physics

Arnaud Belletoile
LOFAR Transients Key Project Meeting, Meudon, December 2011

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transientskp

June 23, 2012
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  1. 16/12/2011 Arnaud Bellétoile High energy cosmic rays with CODALEMA and

    LSS? Arnaud Bellétoile 1 Friday, December 16, 2011
  2. 16/12/2011 Arnaud Bellétoile High energy cosmic ray physics • The

    cosmic ray spectrum ✓ Measured via the extensive air showers ‣ Flux too low for direct measurement ✓ Described by a power law ✓ Several remarkable features ‣ Knee, 2nd knee, ankle and the cut-off • Interpretations are subject to debate ✓ Particle physics reasons ‣ New kind of interaction at high energy ? ✓ Astrophysical reasons ‣ Limit of galactic accelerators ? ‣ Transition from galactic to extra galactic CR ? ‣ Interaction with the CMB ? • At extremely high energy ✓ What is the source of the most energetic CR ? 2 Grigorov JACEE MGU TienShan Tibet07 Akeno CASA/MIA Hegra Flys Eye Agasa HiRes1 HiRes2 Auger SD Auger hybrid Kascade E [eV] E2.7F(E) [GeV1.7 m−2 s−1 sr−1] Ankle Knee 2nd Knee 104 105 103 1014 1015 1013 1016 1017 1018 1019 1020 • CODALEMA objectives ✓ Explore the 1017-1018eV energy range ‣ Gal./extra gal. transition? Composition? ✓ Develop a tool for ultra high energy cosmic rays ‣ Radio emission Nakamura et al., 2010 Friday, December 16, 2011
  3. 16/12/2011 Arnaud Bellétoile Radio signal from air showers • Two

    mechanisms in the shower ✓ Negative charge excess ✓ Geomagnetic deflection of charges • Electric field emitted ✓ Depends on the observer position ✓ Depends on the longitudinal profile ‣ Primary energy and nature • Several theoretical descriptions ✓ MGMR, SELFAS, REAS3, boosted Coulomb ... ✓ Different approaches ‣ Macroscopic / microscopic description... ‣ Refractive index ‣ Relative contributions ✓ Convergence of several models • Very promising tool for HECR ✓ High duty cycle ✓ Low cost of the detector ✓ Sensitivity to shower parameters 3 Scholten et al., 2007 Friday, December 16, 2011
  4. 16/12/2011 Arnaud Bellétoile The original CODALEMA setup • Dipole Antennas

    array ✓ 24 Active Dipoles ✓ EW polarization • Particle detectors array ✓ 13 plastic scintillators ✓ Act as a reference : ‣ Trigger ‣ EAS parameters - (θ,φ), core position, primary energy • Signal acquisition ✓ On trigger from part. detector ✓ Digitized as a function of time ✓ ADC : 12 bits, 1 GHz, 2560 ns 4 • Some numbers ✓ Operating since 2006 ✓ Effective area of 0.25 km2 ✓ Particle detector energy thres. around 1016eV ✓ Energy resolution ~ 30% at 1017eV Friday, December 16, 2011
  5. 16/12/2011 Arnaud Bellétoile Signal processing • Each array treated separately

    • Antenna array ✓ Data analysis on temporal waveform ✓ Search for transient signals ‣ Performed on each individual antenna ‣ Numerical filtering in the ad hoc band ‣ Voltage threshold - Adjusted on galactic noise ✓ On transient detection ‣ Peak amplitude ‣ Arrival time ✓ If more than 3 antenna touched ‣ Arrival direction reconstructed - planar wavefront • Particle detectors array ✓ Estimate particle densities ✓ Adjust NKG lateral distribution ✓ Energy estimated for internal events ‣ CIC method 5 0 500 1000 1500 2000 2500 ï150 ï100 ï50 0 50 100 150 voltage (mV) bin number 0 20 40 60 80 100 120 −130 −120 −110 −100 −90 PSD (dBm/Hz) Frequency (MHz) a3 − EW polarisation Friday, December 16, 2011
  6. 16/12/2011 Arnaud Bellétoile EAS radio detection validation • Comparison of

    the 2 arrays ✓ Arrival direction ✓ Arrival time • Validation ✓ Time difference < 100 ns ✓ Angular difference < 20o • Radio relative efficiency ✓ Detection threshold ~ 5x1016 eV ✓ 100% > 5x1017 eV 6 16.5 17 17.5 18 18.5 10ï1 100 101 102 103 Log Energy (eV) Entries Scintillator array Antenna array Friday, December 16, 2011
  7. 16/12/2011 Arnaud Bellétoile Geomagnetic contribution • Arrival directions of radio

    detected cosmic rays ✓ North/South asymmetry ✓ Lack of event in the geomagnetic vector direction • Coverage map reproduced ✓ Emission proportional to F=qVxB ✓ projection along the EW axis • Trigger effect • Clear signature of geomagnetic emission ✓ First order contribution 7 U (SouthïNorth axis) V (EastïWest axis) ï0.8 ï0.6 ï0.4 ï0.2 0 0.2 0.4 0.6 ï0.8 ï0.6 ï0.4 ï0.2 0 0.2 0.4 0.6 0.8 Friday, December 16, 2011
  8. 16.5 17 17.5 18 18.5 1.6 1.8 2 2.2 2.4

    2.6 2.8 3 3.2 3.4 3.6 log Energy (eV) log (E 0 /||vxB EW ||) (µV/m) East ï West axis (m) South ï North axis (m) ï100 ï50 0 50 100 ï100 ï50 0 50 100 • Correlation of E0 with primary energy ✓ Estimated with particle detector array • Shift of the radio core position ✓ With respect to the particle core position ✓ Interpreted as a charge excess signature 16/12/2011 Arnaud Bellétoile Electric field profile • Exponential dependence of the electric field with impact parameter ✓ E(b) = E0 x exp(-b/b0) • 4 parameters fitted ✓ Amplitude parameter E0 ✓ Field extension b0 ✓ Shower core position X0,Y0 8 Friday, December 16, 2011
  9. 16/12/2011 Arnaud Bellétoile Toward higher energy • Increase the detection

    area ✓ Standalone detector needed • The CODALEMA station ✓ Butterfly antenna ‣ Dedicated lna ‣ 2 polarisations ‣ Increase sensitivity ✓ Triggering ‣ Trigger on the radio signal ‣ External input ✓ Timing system ‣ Embedded GPS ‣ 1 ns resolution ✓ ADC ‣ 12 bits / 1 GHz / 2560 ns ✓ Embedded computer ‣ On board processing ✓ Data transfer ‣ Optical link or wifi transmission ✓ Power supply ✓ Shielded electronic box 9 Friday, December 16, 2011
  10. 16/12/2011 Arnaud Bellétoile The CODALEMA Standalone Antenna Array • Around

    the existing apparatus • Deployment status ✓ 33 standalone stations deployed last spring ✓ 27 more within a few months • Covered area ✓ Nearly 1.5 km2 10 Friday, December 16, 2011
  11. 16/12/2011 Arnaud Bellétoile Transient radio background • Several sources ✓

    Mainly of anthropic origin : ‣ power lines, voltage transformers ✓ Atmospheric : ‣ thunderstorms • Airplane trajectories ✓ Calibration tools! • Remain the main radio detection issue ✓ Reduce effective time of observation ✓ Imply large amount of data storage • Enhancing background immunity ✓ More elaborated embedded algorithms ‣ Restrictive conditions on pulse shape ‣ Periodicity mask ‣ Directional mask • Occasional solution ✓ Hybrid trigger with associated plastic scintillator ‣ Narrow time coincidence window ‣ Extremely low fortuitous rate • 11 Friday, December 16, 2011
  12. 16/12/2011 Arnaud Bellétoile Toward pure radio identification criterion • One

    month of science data taking ✓ June 2011 ✓ Time Coincidences searched • 4 EAS candidates identified ✓ Time coincidences with particle detector array ‣ Within 10 µs • Orientation of the Electric field vector ✓ Expected orientation ψth ‣ vxB vector projected on the ground ✓ Measured orientation ψmeas • Validated candidates 12 WestïEast direction cosine SouthïNorth direction cosine Predicted s values (o) ï1 ï0.5 0 0.5 1 ï1 ï0.8 ï0.6 ï0.4 ï0.2 0 0.2 0.4 0.6 0.8 1 10 20 30 40 50 60 70 80 E field EW NS ψ Friday, December 16, 2011
  13. 16/12/2011 Arnaud Bellétoile A revolutionary profile 13 Corstanje et al.,

    ICRC 2011 Friday, December 16, 2011
  14. 16/12/2011 Arnaud Bellétoile The neighborhood 14 LSS LOFAR from J.

    Girard Friday, December 16, 2011
  15. 16/12/2011 Arnaud Bellétoile Conclusion • The radio detection technique reaches

    progressively maturity ✓ Understanding of the electric field emission progresses ✓ EAS identification based on radio signals only seems feasible ‣ Toward autonomy of radio with respect to particle detectors ✓ Access to the primary composition is the next objective • The CODALEMA Standalone Antenna Array will be soon complete ✓ Dedicated to the 1017-1018 eV energy range ‣ 1.5 km2 of effective area ‣ 60 autonomous detectors ✓ A cosmic ray radio detector of 2nd generation • The LSS is very interesting for CODALEMA physics ✓ Different length scales, different energy range, complementary designs • The Nançay LOFAR station could also bring interesting informations 15 Friday, December 16, 2011