The Second International Workshop on Ultra-high-energy cosmic rays and their sourcesINR, Moscow, April 14-16, 2005

from Extreme Universe Space Observatory

toExtreme Universe neutrino Observatory

presented by Piero Spillantini, Univ. And INFN, Firenze, Italy

Considerations of a “EUSO sub-team” fromINAF – Firenze, ItalyINFN – Firenze, ItalyINOA – 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 NadirLens Diameter 2.5 mEntrance Pupil Diameter 2.0 mF/# < 1.25Operating wavelengths 300-400 nmAngular resolution (for event direction of arrival) ~ 1°Pixel diameter (and spot size) ~ 5 mmPixel size on ground ~ 0.8 0.8 km2

Number of pixel ~ 2.5 105

Track time sampling (Gate Time Unit) 833 ns (programmable)Operational Lifetime 3 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 = 3.1 1016 m)

protons(photopr.) neutrinos

(CMB inter.)

dimensionof the

Universe

what particles? from where?

1 10 100 1000 10000 Mpc

10-310-610-9

Is it possible to increase the number of detected neutrino events?

-Decrease the energy threshold (5 x 1019eV 1018eV)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

01000 1500 2000

30° 60° 65° 70°

HORIZON

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distance from Nadir (Km)1/2 FoV

Area of the calotta (106 Km2 )

Area of the calotta Area seen by EUSO

Atte

nuat

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fact

or (

resp

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o N

adir)

attenuation due to geometry

attenuation due to atmosphere * TOTAL

attenuation

*Considered from the sea level

(EUSO)

500

45°

Florescence light attenuationas a function of the FoV

(EUSO)

(EUSO=1.7x106km2)

(EUSO x 3)

EUSO

minMax

p + +(1232) N

e

EUO

Protons coming from distances >20-50 Mpc interactwith the CMB (GKZ effect) producing pions,

and finally neutrinos.

Protons with E>1020eV interact several times beforedegrading under the GKZ cut-off

producing many e and neutrinos.

The energy of produced neutrinos is more than 1018eV

Cosmogenic neutrino component

This is the “less unprobable” neutrino componentexpected 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) 400 400

Total FoV (o) 60 90

Radius on ground (km) 235 413

Area on ground (103km2) 173 536

Pixel on ground (km * km) 0.8 x 0.8 1.6 x 1.6 pixel on detector (cm) 0.6 2.0

“ “ with corrector 1.2

Area/pixel (n. of pixels) 270k 238k

Pupil diameter (m) 2.0 2.0 5.0 7.5 10.0

Photo detection efficiency 20% 50% 50% 50% 50%

E threshold (EeV) 50 20 5.5 3.2 2.3

Proton events/year,

GKZ + uniform source distrib. 1200 8000 300k 900k 1800k

with Ep >100 EeV) 100 100 310 310 310

Neutrino events per year ( min) 0.6 1.5 18 30 42

Neutrino events per year ( Max) 12 18 108 120 138

EUSO like Multi-mirror

deploymentd

single mirrorfield of view

total field of view

triggerdata handlingtelemetry

sensors

26th ICRC Durban 1997

7 systems FOV 30ºor

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 shield

mirror

focal plane

INOA

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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 systemINOA

Areal density of the mirrors for space

Technologies Kg/m2 Kg @ 3 mHubble primary 250 1767Current 10 71Developing 5 35Membrane mirror 1.0E-02 7.E-02Reflective coating 1.0E-04 7.E-04

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 compensatethe 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 energyhigher orbit increased observed area

Some further optimization is possible Many items still to be investigated:

tolerances thermal behaviorsupporting mechanicsdetectorscosts...

Conclusions INOA

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