the second international workshop on ultra-high-energy cosmic rays and their sources inr, moscow,...
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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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10
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0.5
10
distance from Nadir (Km)1/2 FoV
Area of the calotta (106 Km2 )
Area of the calotta Area seen by EUSO
Atte
nuat
ion
fact
or (
resp
ect t
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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