WehavestudiedthefragmentationprocessinheavyioncollisionssystematicaIlybyusingIsospin-dependentQuantumMolecularDynamics(IQMD)modelandfoundthatthemultiplicityofintermediatemassfragmentsN_(imf)canbeusedasaprobetoextracttheinformationofin-mediumnmuleon-nucleoncrosssection.Fig.1shows