Surrounding effects and sensitivity of the CODALEMA experiment Thibault Garçon SUBATECH 04/12/2018 ARENA 2010 - Thibault Garçon

The CODALEMA experiments The cabled arrays Autonomous stations 04/12/2018 ARENA 2010 - Thibault Garçon

Screening and surrounding effects W S The CODALEMA antennas or any future large autonomous array may have to face various vicinities. What is their impact on the radiodetection? 04/12/2018 ARENA 2010 - Thibault Garçon

Screening and surrounding effects North Screening and surrounding effects West East Selected events: cosmic ray events in coincidence between particle detectors and at least three antennas West East North acceptance effect North No noticeable screening effect. Even a specially unfavourable vicinity seems to have no impact on the detection of cosmic rays. West East 04/12/2018 ARENA 2010 - Thibault Garçon

Distance to the shower axis (m) A sensitive detector Despite various environments, CODALEMA obtains high quality results 500 NS axis EW axis 500 Signals of 7 antenas (V) -300 0 300 NS axis (m) E (µV) E (µV) -300 0 300 EW axis (m) -300 0 300 Coordinate on the axis (m) time (2.5µs) 500 E (µV) 500 Distance to the shower axis (m) Accurate LDF (well fitted by an exponential function) and arrival direction reconstruction 04/12/2018 ARENA 2010 - Thibault Garçon

Distance to the shower axis (m) Distance to the shower axis (m) A sensitive detector Unusual LDF can reveal a breakdown of one antenna 200 200 NS axis EW axis -300 0 300 NS axis (m) E (µV) E (µV) EW axis (m) -300 0 300 EW axis (m) -300 0 300 Coordinate on the axis (m) E (µV) E (µV) Distance to the shower axis (m) Distance to the shower axis (m) 04/12/2018 ARENA 2010 - Thibault Garçon

ARENA 2010 - Thibault Garçon Autonomous detection Autonomous station Goal : 100% autonomous system (trigger, power supply and acquisition), robust, compact, cheap Prototype station at Nancay : antenna, ADC, trigger , GPS, PC and control boards 04/12/2018 ARENA 2010 - Thibault Garçon

ARENA 2010 - Thibault Garçon Autonomous detection ADC PC Trigger Power GPS Control 2 challenges: no self-induced triggering, no noise generation for other instruments of the Observatory (large and sensitive radio-telescopes) 04/12/2018 ARENA 2010 - Thibault Garçon

Electromagnetic compatibility (EMC) Tests of noise produced by the autonomous station : anechoic chamber, radioheliograph array and radiotelescope measurements -50 • No noise radiated between 10 MHz and 4 GHz • No self-induced triggering  Green light for installation @ Nançay Power (dBm/MHz) Max Hold On / Off Mean RMS On / Off -90 50 Frequency (MHz) 500 04/12/2018 ARENA 2010 - Thibault Garçon

Sensitivity of the autonomous detection Radio Frequency Identification by the stations:  evaluation of the quality of the autonomous detection  mapping of noise sources  determination of the optimal trigger threshold -200 500 NS axis (m) -200 500 EW axis (m) Very close noise sources North East West Distant transmitters, planes Thunderstorms 04/12/2018 ARENA 2010 - Thibault Garçon

Sensitivity of the autonomous detection Events observed in coincidence with the cabled array confirm the feasibility of autonomous radio-detection: ~10 coincidences in few weeks, one 2-fold coincidence few days after installation of the 3 antennas array. Cabled array Autonomous stations 3500 1500 NS axis EW axis -300 0 300 NS axis (m) E (µV) E (µV) -300 0 300 EW axis (m) -300 0 300 Coordinate on the axis (m) EW,NS 3500 E (µV) 500 Distance to the shower axis (m) 04/12/2018 ARENA 2010 - Thibault Garçon

Sensitivity of the autonomous detection Galactic background is the ultimate boundary for radio-detection: autonomous stations detect galactic background variations due to the Galaxy drift Galactic variation Transmitters Thermal noise? EW,NS Temperature of the galactic sky in galactic coordinates Temperature of the galactic sky seen by the antenna in galactic coordinates PSD (dBm/Hz) Spectra obtained in Argentina with a CODALEMA station, during 24 hours. Frequency (MHz) Atmospheric effect on AM 04/12/2018 ARENA 2010 - Thibault Garçon

Towards accurate physics? Thanks to large sensitivity and precise knowledge of the antenna response, it becomes possible to reconstruct the cosmic ray frequency spectrum over a very wide band Illustration with a powerful event (above 1018 eV) on CODALEMA Huegue, Scholten Toy model of cosmic ray spectra Factor 100 D. Charrier, in this conference inclined, 1018 eV or more, Nancay B-Field, 150 m a.s.l. 120 MHz 200 m or more Antenna response (includes lobe antenna, impedance, LNA) Simulated spectra as seen by the antenna 04/12/2018 ARENA 2010 - Thibault Garçon

Conclusion and outlook Screening effects (trees, other antennas) do not affect event detection statistics Antenna response is very well understood: simulations allows to understand and correct specific interference effects CODALEMA autonomous station is silent (no self-induced triggering, no outward noise) Sensitivity of the galactic background (ultimate noise) is reached. Large background variation observed during galactic transit. Well-known instrument: an accurate physics becomes possible, over a wide bandwidth (100 MHz) Ready for installation of large autonomous station arrays 04/12/2018 ARENA 2010 - Thibault Garçon

ARENA 2010 - Thibault Garçon 04/12/2018 ARENA 2010 - Thibault Garçon