Mission design of LiteBIRD
T. Matsumura, Y. Akiba, J. Borrill, Y. Chinone, M. Dobbs, H. Fuke, A. Ghribi, M. Hasegawa, K. Hattori, M. Hattori, M. Hazumi, W. Holzapfel, Y. Inoue, K. Ishidoshiro, H. Ishino, H. Ishitsuka, K. Karatsu, N. Katayama, I. Kawano, A. Kibayashi, Y. Kibe, K. Kimura, N. Kimura, K. Koga, M. Kozu, E. Komatsu, A. Lee, H. Matsuhara, S. Mima, K. Mitsuda, K. Mizukami, H. Morii, T. Morishima, S. Murayama, M. Nagai, R. Nagata, S. Nakamura, M. Naruse, K. Natsume, T. Nishibori, H. Nishino, A. Noda, T. Noguchi, H. Ogawa, S. Oguri, I. Ohta, C. Otani, P. Richards, S. Sakai, N. Sato, Y. Sato, Y. Sekimoto, A. Shimizu, K. Shinozaki, H. Sugita, T. Suzuki, A. Suzuki, O. Tajima, S. Takada, S. Takakura, Y. Takei, T. Tomaru, Y. Uzawa, T. Wada, H. Watanabe, N. Yamasaki, M. Yoshida, T. Yoshida, K. Yotsumoto
TL;DR
LiteBIRD targets precise measurement of CMB B-mode polarization to constrain r to δr<0.001. The study presents a TES-based multichroic focal plane with six frequency bands from 60 to 280 GHz and a crossed Dragone optical system designed to achieve ~2 μK·arcmin sensitivity, supported by a detailed noise model for photon, phonon, and readout contributions. It analyzes the impact of 4 K optics and cryogenic bath temperatures on performance, and discusses systematics, detector readout architecture (SQUID/DFmux), and cosmic-ray considerations. The design is in the early phases with ongoing assessments of optics, thermal design, focal-plane integration, and mission infrastructure, targeting a launch around 2020.
Abstract
LiteBIRD is a next-generation satellite mission to measure the polarization of the cosmic microwave background (CMB) radiation. On large angular scales the B-mode polarization of the CMB carries the imprint of primordial gravitational waves, and its precise measurement would provide a powerful probe of the epoch of inflation. The goal of LiteBIRD is to achieve a measurement of the characterizing tensor to scalar ratio $r$ to an uncertainty of $δr=0.001$. In order to achieve this goal we will employ a kilo-pixel superconducting detector array on a cryogenically cooled sub-Kelvin focal plane with an optical system at a temperature of 4~K. We are currently considering two detector array options; transition edge sensor (TES) bolometers and microwave kinetic inductance detectors (MKID). In this paper we give an overview of LiteBIRD and describe a TES-based polarimeter designed to achieve the target sensitivity of 2~$μ$K$\cdot$arcmin over the frequency range 50 to 320~GHz.