Post on 22-Jun-2018
Very Large Space Optics for anVery Large Space Optics for an Investigation of the Extreme
Universe
Presented by Jim Adams for the Super EUSO Collaboration*for the Super EUSO Collaboration
*Eberhard Karls Universität Tübingen; MPI für Physik, München; Universidad de Alcalá; APC (France); Swedish Institute of Space Physics; LIP (Portugal); Università di Genova; INAF (Palermo Italy);Physics; LIP (Portugal); Università di Genova; INAF (Palermo, Italy); INFN and INOA, (Florence, Italy); Università di Roma Tor Vergata; Università di Perugia; Observatoire de Neuchâtel; Skobeltsyn Institute; UNAM, Mexico; RIKEN, Japan; Univ, of Ala., Huntsville; Vanderbilt Univ ; Sp Sci Lab UCB; UCLA; Univ of Utah; NASA
8/25/08 1
Vanderbilt Univ.; Sp. Sci. Lab., UCB; UCLA; Univ. of Utah; NASA-MSFC and NASA-GSFC
https://ntrs.nasa.gov/search.jsp?R=20090002566 2018-07-11T17:43:42+00:00Z
8/25/08 2
(cosmic rays); X (active galactic nuclei); blue shading (exposure)
Event Arrival Direction Reconstruction
8/25/08 3
Extreme Energy Cosmic Rays (EECR )(EECRs)
• Energies extending to at least 50 Joules/particleg g p• Fluxes of 1 particle/(km2∗century)
8/25/08 4http://www.astroparticlephysics.nl/cosmic_rays.jpg
Shower Time Profile
8/25/08 5
Hybrid Ground-based ArrayHybrid Ground based Array
8/25/08 6
Fluorescence Detector
8/25/08 7
8/25/08 8
Super-EUSO
•Variable orbit 1000 km
•Free Flyer•Variable orbit 1000 km
• FOV
• yr5Life ≈sr km104.2A 26inst
aper ⋅×≈
25° y5ife% 2010cycle ÷≈η
( ) yrsrkm104221A 26×≈
25
( ) yrsrkm104.22.1Aexp ×−≈
Tilted mode (?)
8/25/08 9(?) L10A 7
exp →
Super EUSO Instrument R iRequirements
• Very large wide-angle telescope with high optical th h t d 1 illi di l l tithroughput and ~1 milliradian angular resolution
• High efficiency pixelated photo-detectors with single photon sensitivity– Photomultiplier tubes with ultra-bialkali photocathodes or– Silicon photomultipliers
• Optics Design Options– Reflective optics:
• Schmidt or Maksutov optics– Convex focal surface
– Refractive optics (the JEM-EUSO concept)Refractive optics (the JEM EUSO concept)• Very large and light-weight Fresnel lenses • Diffractive lens for chromatic correction
– Antireflective coatings needed in either case
8/25/08 10
Photomultiplier Tubesp• Hamamatsu Ultra-Bialkali photocathodes
40 45% Q E f 330 400– 40-45% Q.E. from 330-400 nm– Off the shelf (Hamamatsu)
L i t t b f– Large inter-tube gaps on a convex surface• Back-illuminated Silicon Photomultipliers
– 90% Q.E. from 330-400 nm– Requires cooling– Developmental (Siemens)– Small inter-device gaps on a convex surface
8/25/08 11
g p
Optics Design ConceptsOptics Design Concepts
Maksutov optical design with an Schmidt design with an f/# of 0.7 and a
8/25/08 12
f/# of 0.66, CAO at UAH, Huntsvilleg
50° field of view, CNR- INOA, Firenze
Optics Throughput
Obscuration due to focal surfaceObscuration due to focal surface
+ Mirror reflectivity + transmission of Schmidt corrector reduce of ~ 0.9
Filt t id d f !!
8/25/08 13
Filters not considered so far!!
Refractive Opticsp
500.00 MM Diffractive/Fresnel
Focal Surface
8/25/08 14
Achromatic Fresnel- Diffractive, f/1.0 Scale: 0.05 AZ 28-Apr-04
Throughput is less than with reflective systems
Shower Imaging and ReconstructionSuper-EUSO functions like a high-speed and wide angle video camera• Frame rate: ~3 μsec/frameFrame rate: 3 μsec/frame
• Pixel Size: 4×4 mm2 on the focal surface or 1×1 km2 on Earth
R t ti i 1 1 1 k 3 l• Reconstruction in 1×1×1 km3 voxels
• Arrival direction reconstruction to <0.2°
• Energy reconstructed from fitted e gy eco st ucted o ttedintensity at shower maximum
For those events with a detected Cherenkov reflection at a knownCherenkov reflection at a known altitude:• Shower profile versus atmospheric depth will be reconstructed
8/25/08 15
depth will be reconstructed.
Optics Manufacturing R iRequirements
• Surface RoughnessSurface Roughness– 20 nm RMS on refractive elements
5 nm RMS on reflective elements– 5 nm RMS on reflective elements• Tilt errors
– <0.5 milliradian• Anti-reflective Coatings on refractive
elements– >90% transmission in the 330-400 nm band
8/25/08 16
Super EUSO Spacecraft Concepts
These folding concepts were developed to fit Super-EUSO into an existing faring.
8/25/08 17
ARES V OptionARES V Option• Launch Super p
EUSO as a rigid unit– Spherical mirror
constructed from regular hexagonalregular hexagonal zones
– Segmented corrector plate in the style of a lighthouse lens
8/25/08 18
lighthouse lens
Notional Designg
Segmented Corrector Plate Mirror constructed from
8/25/08 19
hexagonal spherical segments
Summaryy• Super EUSO is needed to find out how the
most energetic cosmic accelerators workmost energetic cosmic accelerators work and what they are accelerating?
• The Super-EUSO instrument must be aThe Super EUSO instrument must be a very large high-speed and wide-angle video camera in space.p
• We are open to suggestions for improvements in design and also concepts p g pfor manufacturing such an instrument.
8/25/08 20
The End
8/25/08 21