Splitting of fragmentation peaks of light ions in 56 Fe + 9 Be collisions at 0.23 GeV/nucleon

The FRAGM experiment at the ITEP-TWA heavy ion facility has a unique opportunity of measuring the momentum distributions of nuclear fragments. We present the results of 56 Fe fragmentation into light ions on 9 Be target at 0.23 GeV/nucleon. The momentum spectra of projectile like fragments were measured with a high resolution beam line spectrometer. In contrast to the carbon fragmentation, where the momentum spectra have Gaussian-like shapes, in the emission of the light fragments the shapes have a double-humped structure. This splitting is most pronounced in proton spectra. The possibility of describing this effect by asymmetric fission and multifragmentation is discussed. A comparison is made with the results of the FRS measurements at GSI. The obtained experimental data are in a reasonable agreement with the predictions of several transport codes such as BC, INCL and LAQGSM.