2. P.W. Gorham et al.. TEST BEAM A SLAC Time relative to beam entry Antenna V/V rms Time relative to beam entry Antenna V/V rms close to shower maximumshower nearly dissipated 6 GHz bandwith oscilloscope

3. TEST BEAM A SLAC insensitive to cherenkov and transition radiation sensitive to cherenkov and transition radiation 7 ns decay constant, compatible with plasma cooling classical bremsstrahlung theory assuming coherence P.W. Gorham et al..

4. Limitations of SLAC measurements It has been proved only the existence of a microwave emission the absolute yield is not known precisely --> this affect the uncertainty on the threshold in energy of an air shower detector With the AMY experiment we would like to overcome this limitations confirming and measuring precisely the absolute microwave yield and its frequency spectrum in the range between 1 and 25 GHz the spectrum in frequency has not been measured --> it may give important informations on the underlying process --> if there are bright lines the signal/noise of a telescope can be improved --> if not, satellite televisions band are preferable to keep low the costs THE AMY OBJECTIVE

5. The DAFNE Beam Test Facility Energy range25-750 MeV Max. repetion rate50 Hz Pulse duration1 - 10 ns Particles/bunchUp to 10 10 e-/e+ In comparison to SLAC the BTF beam provides a larger shower equivalent energy

6. ANECHOIC FARADAY CHAMBER copper 2 antennas RF adsorber SATIMO AEP 12 attenuation 1GHz: 30 dB > 6 GHz: 50 dB 2 m 4 m beam axis 30 cm choice of dimensions far field approximation (-> height and width) entrance and exit walls outside the antenna field of view (-> length)

7. 2 antennas 2 m 4 m beam axis spectrum analyzer -> frequency spectrum and absolute yield power detector & FADC (*) ->time evolution of the signal (*) flexibility of a VME system (beam monitoring) ANECHOIC FARADAY CHAMBER

8. EXPECTED FLUX DENSITY depends on the degree of coherence  = 1÷2 at the maximum energy deposit within the chamber assuming an alumina target  beam-antenna distance observed track lenght alumina target

9. THE ANTENNA Rohde & Schwarz HL050 Log-periodic 0.85-26.5 GHz from 1 to 25 GHz Half-power beam width 65 0 -> 55 0 Cross-polarization factor 40 -> 35 dB 27.4 cm

10. SPECTRUM MEASUREMENT amplifier ANTENNA Spectrum analyzer Rohde & Schwarz FSV30 9 KHz - 30 GHz 40 MHz bandwidth G ampl ≈ 25 dB

11. SPECTRUM MEASUREMENT amplifier ANTENNA Spectrum analyzer Expected signal at the maximum energy deposit bandwidth amplifier antenna effective area well above the expected instrumental noise (< -80 dBm) quadratic scaling linear scaling

12. TIME MEASUREMENT amplifier ANTENNA power detector FADC 500 MS/s 4 channels 12 bit resolution AD8317/8318 up to 10 GHz response time < 10 ns (no signal  -10 dBm)

13. TIME MEASUREMENT amplifier ANTENNA power detector FADC difficult to go above 10 GHz minimum signals > -60 dBm Constraints from power detector Measuring the exponential decay with a 30-40 dB dynamic range  high amplification gain 1)perform an initial measurement around a fixed frequency (commercial feeds in satellite bands) 2)once the spectrum has been measured, study the time signal evolution in the bands we will find interesting (above 10 GHz we may use frequency down converters) C band

14. Cherenkov electric field - 1 e -

15. Cherenkov: no target - quadratic scaling density flux at the end of the camera after the adsorption (50 dB) density flux at the antenna cross-polarized (40 dB) MBR density flux at the antenna maximum shower development

16. For a realistic calculation: time separation between electrons coherence only if  t << 1/f (0.04 ns < 1/f < 1 ns) 1 ns < bunch duration < 10 ns only particles within the chamber contribute to the signal modelling RF absorption

17. Dealing with 10 10 particles Expected cherenkov signal in the spectrum analyzer in case of a copolarized antenna > -10 dBm An import goal of the test beam will be to measure the cherenkov radiation and to make a comparison with theoretical calculations

18. The experiment has been fully funded by INFN (~ 120 k€) and some of the instrumentation will be bought already during this year. Agilent (?) Agilent (?)