Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS)
雑誌名
第5回宇宙科学シンポジウム
雑誌名(英)
Proceedings of the 5th Space Science Symposium
ページ
281 - 284
発行年
2005-09
抄録（英）
EUSO is a space mission devoted to the study of Extreme Energy Cosmic Rays (EECR). The focal surface of EUSO is conceived as a mosaic of single photon sensitive sensors to realize the single photo-electron counting capability. Multianode photomultipliers (MAPMT) with bi-alkali photocathode deposited on the UV-glass entrance window are taken as primary choice for EUSO (Extreme Universe Space Observatory) focal surface detector. The present baseline is R8900-03-M36, a modified version of the R7600 series, in which photons are weakly focused along an electric field placed between photocathode and first dynode. Another solution to increase the sensitive area is a flat-panel MAPMT. The advantages of this solution are low weight and large sensitive area ratio (approximately 90 percent) without electron focusing feature. Recently Hamamatsu has developed the R8400-M256 series with UV window. A different approach is aiming to increase Detection Efficiency (D.E.) using high Quantum Efficiency (Q.E.) MAPMTs with GaAsP photocathode that have Q.E. approximately 40 percent in the visible region. In order to take advantage of this technique fluorescence light emitted in the near ultraviolet region (330-400 nm) has to be shifted in the visible one by means of wavelength shifters. RIKEN recently has produced a new type of wavelength shifter film using POPOP as a shifter and epoxy as substrate coupled with a dichroic mirror. The main characteristics of R8900-03 and R8400-M256 MAPMTs are here presented together with the principle of using a dichroic mirror together with the mentioned wavelength shifter.
EUSO mission: Development of photomultiplier tubes
