IL NUOVO CIMENTO Vol. 24 C, N. 4-5 Luglio-Ottobre 2001 Search for magnetic monopoles at the Chacaltaya cosmic ray laboratory( ∗ ) The SLIM Collaboration S. Cecchini( 1 )( 7 ), G. Giacomelli( 1 ), M. Giorgini( 1 ), J. McDonald( 3 ) G. Mandrioli( 1 ), S. Manzoor( 1 )( 4 ), A. Margiotta( 1 ), J. Nogales( 6 ) L. Patrizii( 1 ), J. Pinfold( 3 ), V. Popa( 1 )( 5 ), I. E. Qureshi( 4 ), M. A. Rana( 4 ) O. Saavedra( 2 ), P. Serra( 1 ), M. I. Shahzad( 4 ), M. Spurio( 1 ), R. Ticona( 6 ) V. Togo( 1 ), A. Velarde( 6 ) and A. Zanini( 2 ) ( 1 ) Dipartimento di Fisica dell’Universit` a di Bologna and INFN - 40127 Bologna, Italy ( 2 ) Dipartimenti di Fisica Sperimentale e Generale dell’Universit` a di Torino and INFN 10125 Torino, Italy ( 3 ) Centre for Subatomic Research, University of Alberta Edmonton, Alberta T6G 2N4, Canada ( 4 ) RPD - Pinstech, P.O. Nilore, Islamabad, Pakistan ( 5 ) Institute for Space Sciences - 76900 Bucharest, Romania ( 6 ) Laboratorio de Fisica Cosmica de Chacaltaya - UMSA, La Paz, Bolivia ( 7 ) Istituto TeSRE/CNR - 40129 Bologna, Italy (ricevuto il 13 Ottobre 2000; approvato il 12 Febbraio 2001) Summary. — The new large area (400 m 2 ) experiment—SLIM—to search for mag- netic monopoles and other exotic massive particles is presented. It uses of nuclear track detectors and is being deployed at the Chacaltaya cosmic ray laboratory for at least 4 years. The detection capability of the experiment is discussed. PACS 14.80.Hv – Magnetic monopoles. PACS 29.90 – Other topics in elementary-particle and nuclear physics experimental methods and instrumentation. PACS 01.30.Cc – Conference proceedings. 1. – Introduction Grand Unified Theories (GUT) of electroweak and strong interactions predict the ex- istence of superheavy magnetic monopoles (MM) with masses larger than 10 16 GeV [1]. They would have been produced at the end of the GUT epoch, at the mass scale ( ∗ ) Paper presented at the Chacaltaya Meeting on Cosmic Ray Physics, La Paz, Bolivia, July 23-27, 2000. c  Societ` a Italiana di Fisica 639