Influence of hydrodynamic expansion on specific power deposition by a heavy ion beam in matter

In this paper, we show with the help of two-dimensional numerical simulatio ns that the specific power deposition by a heavy ion beam in matter may sig nificantly decrease due to hydrodynamic expansion of the target during irra diation. It has also been shown that in order to maximize the specific ener gy deposition, one is required to determine an optimum set of beam and targ et parameters including ion energy, beam radius, and pulse length. Three di fferent values for the beam radius, namely, 0.5, 1.0, and 1.5 mm are consid ered, respectively. The target is a solid lead cylinder, which is irradiate d by a uranium beam that consists of 10(12) ions with a particle energy of 400 MeV/u. Such beam parameters will be available at the future heavy ion s ynchrotron, SIS-200 (with a magnetic rigidity of 200 Tm) at the Gesellschaf t fur Schwerionenforschung (GSI), Darmstadt. It is also assumed that the be am is incident on one face of the cylinder and the cylinder length is less than the range of the projectile ions. The ions therefore penetrate the tar get, deposit a fraction of their energy in the target material along their trajectory, and escape through the opposite face of the cylinder with a sub stantially reduced energy. The Bragg peak therefore lies outside the target and the energy deposition is approximately uniform along the target length . This beam-target configuration generates an extended volume of high-energ y-density matter, without any sharp gradients. (C) 2001 American Institute of Physics.