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Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Advanced Detection of Radio Signals from Cosmic Rays for KASCADE Grande and Auger (with Self.

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Presentation on theme: "Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Advanced Detection of Radio Signals from Cosmic Rays for KASCADE Grande and Auger (with Self."— Presentation transcript:

1 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Advanced Detection of Radio Signals from Cosmic Rays for KASCADE Grande and Auger (with Self Triggered Array of Radio-detectors (STAR)) Why Radio? Why something new? Choice of antenna Background Sensitivity Self-Trigger Future Cheap detectors, easy to deploy Duty cycle 24 hours/day Practical no attenuation Bolometric measurement –integral of EM-signal over shower evolution Also for neutrinos Potential problems: –Radio Freq. Interference (RFI) –trigger by lightning (as FD) –only practical above ~10 17 eV

2 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA a. requirements: -bandwidth: 40 MHz to 80 MHz -good polarisation detection: north-south, east-west, circular -beam width (-3dB): -60° ° (at Karlsruhe), -80°...+80° (at Auger) -high 90° and backward attenuation -reasonable precision for impedance: frequency independent -> real -simple calibration -bull-proof, wind-proof, low cost, simple assembly b. Considered antennas 1.V-dipole (LOFAR) 2.Logarithmic periodic conical helix (CODALEMA) 3.Logarithmic periodic dipole antenna (STAR) Choice of antenna for STAR

3 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA What I know about LOPES V-dipole f[MHz] [m] l/ < 1/4 Impedance 55MHz j 150 impedance matching to keep best timing information reflectivity r: Bothe 45 -> |r| > 50%, ??? precision & sensitivity ??? this antenna is optimized for LOFAR but not for STAR? h l/2 a)h = /8, b) h = /4, c) h =3 /8, d) h = /2 For straight dipole over ground, depends on of ground and f !!!

4 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Logarithmic periodic antennas Conical helix (tested also at Ka) Large Helix, 4 x 4 x 5 m 3, nice : –more complicated to build and –crosstalk between both polarisations -> no further considerations Surviving: Logarithmic periodic dipole antenna (LPDA)

5 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA identical LPDAs mounted orthogonally on a shared pole 2 polarizations Bandwidth: 35…90 MHz Gain: 5.5 dBi Impedance: 50 Ohm Coax Return loss: - 12 dB Beam width [-3dB]: 50° (E-Plane) 70° (H-Plane) Backward attenuation: 20 dB ± 90°-attenuation: 20 dB (E-Plane) 6 dB (H-Plane) Polarisation isolation: > 20 dB Size (without pole): 4 x 4 x 3 m 3 Weight (without pole): 15 kg Antenna Station on IPE building (south) Crossed logarithmic-periodic Dipole Antenna Lightning protection preamplifier

6 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Beam width [-3 dB]: 50° Backward attenuation: 20 dB 90°-attenuation: > 20 dB E-Plane directional diagram of LPDA

7 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Beam width [-3 dB]: 70° Backward attenuation: > 15 dB 90°-attenuation: 6 dB H-Plane directional diagram of LPDA

8 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Real impedance Return loss (50 ): < -12 dB 94 % of the antenna signal power accepted by receiver Return loss of LPDA

9 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA V-dipol Capacitive impedance difficult matching r > 50% -> dont match: current f-dependance Very simple to build but not for the case top on a pole (ground plane) High wind-load at 200km/h? Bad side & backward attenuation -> needs a well defined ground plane Polarisation needs good calibration from antenna to antenna Why not V-Dipol Logarithmic-Periodic Dipole Antenna Real impedance 60 simple matching very small reflectivity r < 10% (<12dB) negligible f-dependance Simple to build also on top of a pole Low wind-load at 200km/h Very good side & backward attenuation (necessary because of noise from surface detectors of Auger) -> needs not a well defined ground plane Relative calibration is mostly given by construction -> polarisation measurement easy

10 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA VME, 6HE/160mm, 8 Channels, 3.3V(160mA), 65 mW/Channel From antenna to ADC 50 ohm design Analog RF Front End

11 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Filtering and Amplification Band-pass Filter 32th order ! Pass-band Gain (41…79 MHz): + 55 dB Loss by 100m cable - 5 dB Ripple (41…79 MHz): ± 3 dB Slope: 10 dB/MHz Stop-band Short Wave Attenuation: -110 dB FM Radio Attenuation: - 90 dB VHF Attenuation - 80 dB

12 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Filtered Antenna Signal with Crossed LPDA FM radio, short wave and VHF are well rejected by the band-pass filter (32 th order) Within 40…80 MHz band an ARD TV Transmitter is located: -Raichberg, Schwäbische Alb -ARD, channel E04, 100 kW -Video carrier: 62,25 MHz -Audio carrier: 67,75 MHz -with V-Dipol (LOPES) 10 dB larger interference signal FM Radio Short Wave Airplane Amateurs Police VHF TV TV Transm. Raichberg 32th order band pass filter

13 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Radio background at Auger 20 to 30 dB better than at Karlsruhe !!!

14 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA AD-Conversion and circular buffer (test system) Self designed ADC- and Circular-Buffer- System planed until end of 2005 Standard VME DAQ-System 16 Channels, 12 Bit, 80 MSample/s Circular Buffer, 2 x 128 kSample/Channel (trigger = freeze) Data Transfer, optical VME-PCI Interface

15 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA h = 56 m human made Interference from the horizon Pulses from the horizon ( = 90°, interference sources) have a delay of: T h / c = 190 ns problem: if source of interference is inside the triangle !! Pulses with higher elevation < 80 (e.g. from air showers) reach the antennas more simultaneously: 0 < T < 190 ns 65 m Self trigger: Coincidence of three antennas Mono-Flop 190 ns Envelope A1 THR + - Mono-Flop 190 ns Envelope A2 THR + - Mono-Flop 190 ns Envelope A3 THR + - = 3

16 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Envelope RF Signal 20 mV 5 mV 200 ns Triggering with envelope signals Envelope signals are generated by the analog RF front end Advantage: –continuous RF -> shift of DC offset and -> easily rejected Threshold 20mV: –Single rate KA <.2 Hz –Coincidence rates mHz

17 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA north east south north + east + south but T > 190 ns no trigger 10 mV 200 ns Usable threshold 10 mV Radio field-strength: Sensitivity

18 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Hartmut Gemmeke, IPE, ARENA Future: Test-field for Auger North Installation of several triangle LPDA setups in Argentina (shifted to Oct. 2006, financial situation), optimize l,L between 65 to 800 m Detailed proposal at next spring Radio will give very useful comple- mentary information: Energy Self trigger is possible choice of antenna may limit the obtainable E-resolution radio is a cost-effective option for –Auger S&N –detector for space weather –But is also an excellent lightning detector (as Fluorescence Detector) … Calibration, GPS, DAQ-Container near to a power-line at Loma Amerilla l L


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