title: Characterization of the room temperature payload prototype for the cryogenic interferometric gravitational wave detector KAGRA.
abstract: KAGRA is a cryogenic interferometric gravitational wave detector currently under construction in the Kamioka mine in Japan. Besides the cryogenic test masses, KAGRA will also rely on room temperature optics which will hang at the bottom of vibration isolation chains. The payload of each chain comprises an optic, a system to align it, and an active feedback system to damp the resonant motion of the suspension itself. This article describes the performance of a payload prototype that was assembled and tested in vacuum at the TAMA300 site at the NAOJ in Mitaka, Tokyo. We describe the mechanical components of the payload prototype and their functionality. A description of the active components of the feedback system and their capabilities is also given. The performance of the active system is illustrated by measuring the quality factors of some of the resonances of the suspension. Finally, the alignment capabilities offered by the payload are reported.
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Fabián Erasmo
authors.initials: FE
authors.lastname: Peña Arellano
authors.affiliation: Institute for Cosmic Ray Research, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8582, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Sekiguchi
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujii
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Takahashi
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Mark
authors.initials: M
authors.lastname: Barton
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Naoatsu
authors.initials: N
authors.lastname: Hirata
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Shoda
authors.affiliation: National Institute for Subatomic Physics, Nikhef Science Park 105, 1098 XG Amsterdam, The Netherlands.
authors.forename: Joris
authors.initials: J
authors.lastname: van Heijningen
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Flaminio
authors.affiliation: Waves Group, University of Sannio at Benevento, Benevento I-82100, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: DeSalvo
authors.affiliation: SOKENDAI, The Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa 240-0193, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Okutumi
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Tomotada
authors.initials: T
authors.lastname: Akutsu
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Aso
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Hideharu
authors.initials: H
authors.lastname: Ishizaki
authors.affiliation: National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka-shi, Tokyo 181-8588, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ohishi
authors.affiliation: Institute for Cosmic Ray Research, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8582, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Institute for Cosmic Ray Research, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8582, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Uchiyama
authors.affiliation: Institute for Cosmic Ray Research, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8582, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Miyakawa
authors.affiliation: Institute for Cosmic Ray Research, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8582, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kamiizumi
authors.affiliation: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Akiteru
authors.initials: A
authors.lastname: Takamori
authors.affiliation: Istituto Nazionale di Fisica Nucleare, INFN, P.le A. Moro 2, I-00185 Rome, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Majorana
authors.affiliation: National Institute for Subatomic Physics, Nikhef Science Park 105, 1098 XG Amsterdam, The Netherlands.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Agatsuma
authors.affiliation: National Institute for Subatomic Physics, Nikhef Science Park 105, 1098 XG Amsterdam, The Netherlands.
authors.forename: Eric
authors.initials: E
authors.lastname: Hennes
authors.affiliation: National Institute for Subatomic Physics, Nikhef Science Park 105, 1098 XG Amsterdam, The Netherlands.
authors.forename: Jo
authors.initials: J
authors.lastname: van den Brand
authors.affiliation: National Institute for Subatomic Physics, Nikhef Science Park 105, 1098 XG Amsterdam, The Netherlands.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bertolini