  The nuclear track detector CR39 was calibrated with different ions of
different energies. Due to the low detection threshold (Z/beta~6e) and the good
charge resolution (sigma_Z ~ 0.2e for 6e < Z/beta <83e with 2 measurements),
the detector was used for different purposes: (i) fragmentation of high and
medium energy ions; (ii) search for magnetic monopoles, nuclearites,
strangelets and Q-balls in the cosmic radiation.
