Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation
  Isotopic effects in the fragmentation of excited target residues following collisions of $^{12}$C on $^{112,124}$Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4$\pi$ detector. The measured yield ratios for light particles and fragments with atomic number $Z \leq$ 5 obey the exponential law of isotopic scaling. The deduced scaling parameters decrease strongly with increasing centrality to values smaller than 50% of those obtained for the peripheral event groups. Symmetry term coefficients, deduced from these data within the statistical description of isotopic scaling, are near $\gamma =$ 25 MeV for peripheral and $\gamma <$ 15 MeV for central collisions. 
The INDRA and ALADIN Collaborations: A. Le F\`evre, G. Auger, M.L.   Begemann-Blaich, N. Bellaize, R. Bittiger, F. Bocage, B...