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The Second International Workshop on Ultra-high-energy cosmic rays and their sources INR, Moscow, April 14-16, 2005 from Extreme Universe Space Observatory to Extreme Universe neutrino Observatory Considerations of a “EUSO sub-team” from INAF – Firenze, Italy INFN – Firenze, Italy INOA – Firenze, Italy and University – Firenze, Italy presented by Piero Spillantini, Univ. And INFN, Firenze, Italy The EUSO optics design consisting of two 2.5 m diameter plastic Fresnel lenses which focus light on a curved focal surface. Pupil ? Basic EUSO Instrument Observational characteristics for the EECR/n telescope are: Field of View Lens Diameter Entrance Pupil Diameter F/# Operating wavelengths Angular resolution (for event direction of arrival) Pixel diameter (and spot size) Pixel size on ground Number of pixel Track time sampling (Gate Time Unit) Operational Lifetime ± 30° around Nadir 2.5 m 2.0 m < 1.25 300-400 nm ~ 1° ~ 5 mm ~ 0.8 ´ 0.8 km2 ~ 2.5 ´ 105 833 ns (programmable) 3 years A new actor on the scene of CR from space? neutrino new instrument for Astrophysics, Cosmology, Particle Physics what particles? from where? dimension of the Universe 10-9 1 10-6 10 100 10-3 1000 10000 Mpc (1 pc = 3.3 ly = 3.1 1016 m) nuclei (photod.) neutrons (decay) protons (photopr.) eletrons, photons (pair production) neutrinos (CMB inter.) Is it possible to increase the number of detected neutrino events? -Decrease the energy threshold (5 x 1019eV 1018eV) x 1.5 by improving the sensor efficiency (0.20 0.50) by improving the light collection (pupil 2m 5m) x 8 (what implies reflective systems and modularity) -Increase the target volume (x 90) -by increasing the FOV (60° 140.8°) (limited to 130º by attenuation by air and by distance) …….(x 20) (light attenuation 0.5 for FOV 90°) ………………. x 3 100 Area of the calotta (106 Km2 ) 15 Florescence light attenuation as a function of the FoV 90 80 (EUSO) Attenuation factor (respect to Nadir) 70 attenuation due to geometry 10 10 60 attenuation due to atmosphere * 50 TOTAL attenuation 40 5 0.5 Area of the calotta Area seen by EUSO 30 20 (EUSO x 3) 10 (EUSO=1.7x106km2) (EUSO) 0 500 30°45° 1000 60° 65° *Considered from the sea level 1500 2000 70° distance from Nadir (Km) 1/2 FoV HORIZON p + g D+(1232) pN enn n EUSO EUnO Max min Cosmogenic neutrino component Protons coming from distances >20-50 Mpc interact with the CMB (GKZ effect) producing pions, and finally neutrinos. Protons with E>1020eV interact several times before degrading under the GKZ cut-off producing many ne and n neutrinos. The energy of produced neutrinos is more than 1018eV This is the “less unprobable” neutrino component expected at the extreme energies. It is not “model dependent” (i.e. it only depends from the proton source distribution) No other neutrino sources will be considered, even if potentially much more abundant (such “Top-Down” processes and models connected with GRB’s) H (km) Total FoV (o) Radius on ground (km) Area on ground (103km2) Pixel on ground (km * km) pixel on detector (cm) “ “ with corrector Area/pixel (n. of pixels) Pupil diameter (m) Photo detection efficiency E threshold (EeV) Proton events/year, GKZ + uniform source distrib. with Ep >100 EeV) Neutrino events per year ( min) Neutrino events per year ( Max) EUSO like Multi-mirror 400 60 235 173 0.8 x 0.8 0.6 400 90 413 536 1.6 x 1.6 2.0 1.2 238k 270k 2.0 20% 50 2.0 50% 20 5.0 50% 5.5 7.5 50% 3.2 10.0 50% 2.3 1200 100 0.6 12 8000 100 1.5 18 300k 310 18 108 900k 310 30 120 1800k 310 42 138 trigger data handling telemetry deployment d sensors total field of view 26th ICRC Durban 1997 7 systems FOV 30º or 3 systems FOV 50º INOA Design of a mirror optics, based on the Schmidt camera principle, with FOV up to 50° mirror correcting plate and/or filter focal plane light shield Resolution of 5 m EDP reflecting system INOA 40000 8 36000 7 32000 Spherical mirror with ± 25° FOV 28000 24000 gres (km ) 5 20000 4 16000 Spherical mirror with ± 15° FOV 3 Spherical mirror + Schmidt corrector 12000 2 8000 Spherical mirror + Schmidt corrector optimized at marginal field angles 1 4000 Aspherical mirror + Schmidt corrector 0 0,0 5,0 10,0 15,0 FOV (deg) 20,0 0 25,0 spot radius size (m icron) 6 Areal density of the mirrors for space Technologies Hubble primary Current Developing Membrane mirror Reflective coating Kg/m2 Kg @ 3 m 250 1767 10 71 5 35 1.0E-02 7.E-02 1.0E-04 7.E-04 Active thin mirror concept Ideal form Strutture is deformed and deforms the membrane Attuators compensate the deformation The optical surface is coupled to a structure of light rigid supports by a matrix of actuators, adjusted on the measurements of the wave front Conclusions INOA A mirror system is a consistent solution for post-EUSO The construction is possible with existing technologies The system can be scaled up, to get: higher signal lower threshold energy higher orbit increased observed area Some further optimization is possible Many items still to be investigated: tolerances thermal behavior supporting mechanics detectors costs... ......................................................................................