  The N/Z dependence of projectile fragmentation at relativistic energies has
been studied in a recent experiment at the GSI laboratory with the ALADiN
forward spectrometer coupled to the LAND neutron detector. Besides a primary
beam of 124Sn, also secondary beams of 124La and 107Sn delivered by the FRS
fragment separator have been used in order to extend the range of isotopic
compositions of the produced spectator sources. With the achieved mass
resolution of \Delta A/A \approx 1.5%, lighter isotopes with atomic numbers Z
\le 10 are individually resolved. The presently ongoing analyses of the
measured isotope yields focus on isoscaling and its relation to the properties
of hot fragments at freeze-out and on the derivation of chemical freeze-out
temperatures which are found to be independent of the isotopic composition of
the studied systems. The latter result is at variance with the predictions for
limiting temperatures as obtained with finite-temperature Hartree-Fock
calculations.
