End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot1 Euso-balloon Lenses A)Design: - Alex Zuccaro (now at ESTEC) - Yoshiyuki Takizawa (Takky): RIKEN B)Production: - Takky (RIKEN) - H. Ohmori (IKEGAMI & RIKEN) C)Measure of instrument focal length - Massimiliano Bonamente (Max): UAH Huntsville, Alabama D)Integration - Peter Von Ballmoos: IRAP French representative: myself, on behalf of the Jem-Euso collaboration

Euso-balloon lenses End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot2 2 Lenses JEM-EUSO (hence Euso-balloon) is a telescope made with lenses. - Why lenses instead of a mirror which is lighter? Because of ISS (and balloon) movements! - Why Fresnel: because of weight! - Tools used: Code V (and a faster ray-tracing program written by Yoshiyuki Takizawa (Takky)) and a TOSHIBA lathe UTD-3400 at IKEGAMI factory.

End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot3 Balloon lenses 3 one sided lenses square flat 1 x 1 m 2 classical 1 diffractive both made of Shinkolite L PMMA-000 Radius of curvature of FS: 509 mm (implies the flat ECs will be at 5.6° one from each other) This is the result of a compromise between the smallest FOV required to recognize a shower and the angle of the rays on the FS

Spot sizes End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot4 One MAPMT pixel is 2.88 x 2.88mm  stability of response

End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot5 Positionning Optics Tolerances (RMS spot sizes change ±10%) Important difference between normal and Fresnel lens: It is easy to predict the focal length for a normal lens It is impossible to manufacture precisely a Fresnel lens with a predicted focal length: the total focal length could be ± 10 cm! So it is necessary to measure the true focal length of the system with a large parallel beam of the good wavelength (290 – 430 nm), measuring the PSF with fine granularity detector (CCD). This equipment is ready for us at UAH (Huntsville, Alabama) No problem for the lenses, but the PDM must be on an axial manual movement

Lenses mechanics End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot6

7 Development plan Telescope SYSTEM The Optical Lenses system consists in three PMMA lenses each having a Fresnel shaped face side and the other side is flat. Riken laboratory has the responsibility of the calculation of the exact shape of the lenses for EUSO BALLOON. The PMMA material will be provided by Mitsubishi Rayon Co., LTD. The lenses are manufactured by IKEGAMI Molt Ltd in Japan. Series of Bread Board Module has already been produced and there is no particular difficulty in the machining. Thus the process of fabrication has already been validated. The FM will be directly produced by this company, under RIKEN responsibility. Each manufactured lens will be checked in acceptance test in RIKEN. The optical performances of the set of three lenses will be checked in Riken. Then the three lenses and the optical test system will be delivered to IRAP for the final acceptance Integration and Tests.

End of phase A meeting CNES (Toulouse) 2/02/2012 Ph. Gorodetzky APC - Paris Diderot8 Risk analysis 1)Management: delay in lens delivery Failure of the facility (IKEGAMI). Recovery time is estimated at 2 months and has been measured after big earthquake. Fabrication is estimated at 2 weeks / lens. Highest priority will be given. 2)Technological: a lens is damaged Material for an extra lens will be stored in RIKEN. With high priority, the damaged lens will be replaced in 4 weeks.