Performance of the CREAM-III Calorimeter

Cosmic Ray Energetics And Mass (CREAM) is a balloon-borne experiment to directly measure the elemental spectra of protons to iron nuclei with energies up to ~ 10¹⁵ eV. Energies of these cosmic-ray particles are measured by an ionization calorimeter comprised of 20 layers of 1 radiation length thick tungsten plates and 20 layers of 0.5 mm diameter scintillating fibers. Each tungsten plate is 500 times 500 times 3.5 mm³ and the fibers are grouped into fifty 1 cm wide ribbons. After construction, the CREAM-III calorimeter was tested at CERN, the European high energy physics lab, in the H2 beam line of the SPS. Following the CERN test, the calorimeter was integrated into the CREAM-III instrument, and flown successfully in the 3rd flight of the project, during the 2007/8 Antarctic campaign. We present the performance of the CREAM-III calorimeter in lab and beam tests.