Development of the Cylindrical Detector System for an experimental search for kaonic nuclei at J-PARC

The experiment J-PARC E15 searches for the simplest kaonic nuclear bound state, $K^-pp$, by in-flight $^3$He$(K^-,n)$ reaction. To reconstruct invariant mass spectroscopy via the expected decay $K^-pp \to \Lambda p \to p\pi^-p$, the Cylindrical Detector System (CDS) has been constructed at the K1.8BR beam-line in the J-PARC 50GeV PS. The CDS consists of a solenoid magnet, Cylindrical Drift Chamber (CDC) and Cylindrical Detector Hodoscope (CDH) with the invariant-mass resolution via the $K^- pp$ decay of 19 MeV/$c^2$ ($\sigma$). In addition, we are developing a thick-GEM (TGEM) TPC as an inner tracker for the upgrade of the experiment. In this talk, an overview of the detectors and the preparation status will be presented.