  The Technical Design for the COMET Phase-I experiment is presented in this
paper. COMET is an experiment at J-PARC, Japan, which will search for
neutrinoless conversion of muons into electrons in the field of an aluminium
nucleus ($\mu-e$ conversion, $\mu^- N \to e^- N$); a lepton flavor violating
process. The experimental sensitivity goal for this process in the Phase-I
experiment is $3.1\times10^{-15}$, or 90 % upper limit of branching ratio of
$7\times 10^{-15}$, which is a factor of 100 improvement over the existing
limit. The expected number of background events is 0.032. To achieve the target
sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will
be used. Two types of detectors, CyDet and StrECAL, will be used for detecting
the \mue conversion events, and for measuring the beam-related background
events in view of the Phase-II experiment, respectively. Results from
simulation on signal and background estimations are also described.
