Transcript Slide 1

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...
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