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 presented by Piero Spillantini, Univ. And INFN, Firenze, Italy Considerations of a “EUSO sub-team” from INAF – Firenze, Italy INFN – Firenze, Italy INOA – Firenze, Italy and University – 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/ telescope are: Field of View± 30° around Nadir Lens Diameter 2.5 m Entrance Pupil Diameter  2.0 m F/#< 1.25 Operating wavelengths nm Angular resolution (for event direction of arrival)~ 1° Pixel diameter (and spot size)~ 5 mm Pixel size on ground~ 0.8  0.8 km 2 Number of pixel~ 2.5  10 5 Track time sampling (Gate Time Unit)833 ns (programmable) Operational Lifetime3 years ?

new instrument for Astrophysics, Cosmology, Particle Physics A new actor on the scene of CR from space? neutrino

eletrons, photons (pair production) nuclei (photod.) neutrons (decay) (1 pc = 3.3 ly = m) protons (photopr.) neutrinos (CMB inter.) dimension of the Universe what particles? from where? Mpc

Is it possible to increase the number of detected neutrino events? -Decrease the energy threshold (5 x eV  eV) by improving the sensor efficiency (0.20  0.50) by improving the light collection (pupil  2m  5m) ( what implies reflective systems and modularity ) -Increase the target volume -by increasing the FOV (60°  140.8°) ( limited to 130º by attenuation by air and by distance ) ……. (light attenuation 0.5 for FOV 90°) ………………. x 1.5 x 8 (x 90) (x 20) x 3

° 60°65° 70° HORIZON distance from Nadir (Km) 1/2 FoV Area of the calotta (10 6 Km 2 ) Area of the calotta Area seen by EUSO Attenuation factor (respect to Nadir) attenuation due to geometry attenuation due to atmosphere * TOTAL attenuation * Considered from the sea level (EUSO) ° Florescence light attenuation as a function of the FoV (EUSO) (EUSO=1.7x10 6 km 2 ) (EUSO x 3)

EUSO min Max p +    + (1232)   N  e EU O

Protons coming from distances >20-50 Mpc interact with the CMB (GKZ effect) producing pions, and finally neutrinos. Protons with E>10 20 eV interact several times before degrading under the GKZ cut-off producing many e and  neutrinos. The energy of produced neutrinos is more than eV Cosmogenic neutrino component

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 (10 3 km 2 ) Pixel on ground (km * km) 0.8 x x 1.6  pixel on detector (cm) “ “ with corrector1.2 Area/pixel (  n. of pixels) 270k238k Pupil diameter (m) Photo detection efficiency 20%50%50%50%50% E threshold (EeV) Proton events/year, GKZ + uniform source distrib k900k1800k with E p >100 EeV) Neutrino events per year (  min) Neutrino events per year (  Max) EUSO like Multi-mirror

deployment d single mirror field of view total field of view trigger data handling telemetry sensors

26 th ICRC Durban systems FOV 30º or 3 systems FOV 50º

Design of a mirror optics, based on the Schmidt camera principle, with FOV up to 50° correcting plate and/or filter light shieldmirror focal plane INOA

Aspherical mirror + Schmidt corrector Spherical mirror + Schmidt corrector optimized at marginal field angles Spherical mirror + Schmidt corrector Spherical mirror with ± 15° FOV Spherical mirror with ± 25° FOV Resolution of 5 m EDP reflecting system INOA

Areal density of the mirrors for space

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 Active thin mirror concept Ideal form Strutture is deformed and deforms the membrane Attuators compensate the deformation

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... Conclusions INOA