An introduction and the status of R&D activities for a high-resolution, "cold" beam position monitor (BPM) and the related read-out electronics are discussed. Two different BPM detector concepts, to be attached to the SC quadrupole and located inside the ILC cryomodule, are currently under investigation: A resonant dipole-mode cavity-style BPM pickup, developed at Fermilab, and a re-entrant resonant coaxial waveguide BPM, designed by CEA-Saclay. While the 1.5 GHz dipole-mode cavity BPM is still in the R&D phase, the re-entrant BPM has already passed first beam tests, including its read-out system. Furthermore, the LAPP group is developing radiation tolerant digital read-out systems, which are tested at the CLIC test facility (CTF).
@article{arxiv.0902.3017,
title = {Status of the ILC Main Linac BPM R&D},
author = {M. Wendt and T. Lefevre and C. Simon and S. Vilalte},
journal= {arXiv preprint arXiv:0902.3017},
year = {2009}
}