  The CMS Beam Conditions and Radiation Monitoring System, BRM, will support
beam tuning, protect the CMS detector from adverse beam conditions, and measure
the accumulated dose close to or inside all sub-detectors. It is composed of
different sub-systems measuring either the particle flux near the beam pipe
with time resolution between nano- and microseconds or the integrated dose over
longer time intervals. This paper presents the Fast Beam Conditions Monitor,
BCM1F, which is designed for fast flux monitoring measuring both beam halo and
collision products. BCM1F is located inside the CMS pixel detector volume close
to the beam-pipe. It uses sCVD diamond sensors and radiation hard front-end
electronics, along with an analog optical readout of the signals. The
commissioning of the system and its successful operation during the first be
ams of the LHC are described.
