IL NUOVO CIMENTO VOL. 11 C, N. 4 Luglio-Agosto 1988 A Calorimeter Coupled with a Magnetic Spectrometer for the Detection of Primary Cosmic Antiprotons. G. BASINI, A. MORSELLI, M. 0CCHIGROSSI, M. ZIccI and P. SPILLANTINI Laboratori Nazionali INFN - Frascati (Roma) F. BONGIORNO Laboratori Nazionali INFN - Frascati (Roma) Dipartiment~ di Metodi e Modelli matematici dell'Universita ,~La Sapienza,~ - Roma P. PICOZZA Dipartimento di Fisica dell'Universita di Tot Vergata - Roma Laboratori Nazionali INFN - Frascati (Roma) A. CODINO and M. MENICHELLI INFN and Dipartimento di Fisica dell'Universit~ - Perugia S. BARTALUCCI CERN - Geneve Laboratori Nazionali INFN - Frascati (Roma) (ricevuto 1'1 Settembre 1988) Summary. -- A tracking calorimeter made of 3200 brass streamer tubes together with 3200 pick-up strips has been built to complement a magnetic spectrometer in order to detect cosmic antiprotons in space. The characteristics of such a calorimeter, the results of a preliminary test of a prototype as well as the properties of the whole apparatus are presented. The apparatus, designed to operate on a balloon at an altitude of about 40 kin, can be considered as a second generation detector, capable in principle to solve the problem of the presence of low energy (~< 1 GeV/c) antiprotons in the cosmic rays which is still open because of the disagreement between the existent experimental data. PACS 94.40 - Cosmic rays. PACS 29.40 - Radiation detectors. 23 - Il Nuovo Cimento C. 339