Abstract
The KArlsruhe TRItium Neutrino experiment, with a proposed sensitivity of 0.20 eV (90% CL), aims to start taking neutrino mass data in 2010. The focal-plane detector and associated hardware are currently under construction. Like much of the experiment, this apparatus must conform to extremely high vacuum standards and high magnetic fields. The detector, a segmented Si PIN-diode array, will be calibrated with an electron gun and radioactive gamma sources. The detector backgrounds, which must be limited to 1 mHz, are reduced with a passive shield and a scintillator veto. The electronics, cooling, and data-acquisition system are currently being tested with prototype silicon detectors. Commissioning of the detector system in stand-alone mode will start at the University of Washington later this year, in parallel with Main Spectrometer tests in Karlsruhe. Design and status of each of the detector system components will be covered.