CALET measurements with cosmic nuclei and performance of the charge detectors

CALET is an all-calorimetric electron telescope in preparation for a launch to the International Space Station (ISS), where it will be installed on the Exposure Facility of the Japanese Experiment Module (JEM-EF). With observations over a period of five years, CALET will be able to unveil the presence of possible nearby sources of high energy electrons and search for signatures of dark matter. The instrument includes a two-layered Charge Detector (CHD) module of scintillator paddles designed to identify - via a measurement of their electric charge - individual nuclear species from proton to iron and to detect trans-iron elements. Complementary charge information is provided by the Imaging Calorimeter (IMC). CALET will be able to perform precision measurements of individual element spectra and of the energy dependence of secondary/primary abundance ratios. The extension of the present measurements of boron/carbon to the energy region above 1 TeV/amu will provide an important input to theoretical models of particle propagation in the galaxy. In this paper, we will review the main physics goals of CALET measurements with nuclei, the expected performance of the charge detectors and the results of a prototype test with a fragmentation beam of relativistic ions that took place at the SPS of CERN in January 2013.