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

Abstract

In this paper, we show with the help of two-dimensional numerical simulations that the specific power deposition by a heavy ion beam in matter may significantly decrease due to hydrodynamic expansion of the target during irradiation. It has also been shown that in order to maximize the specific energy deposition, one is required to determine an optimum set of beam and target parameters including ion energy, beam radius, and pulse length. Three different values for the beam radius, namely, 0.5, 1.0, and 1.5 mm are considered, respectively. The target is a solid lead cylinder, which is irradiated by a uranium beam that consists of 1012 ions with a particle energy of 400 MeV/u. Such beam parameters will be available at the future heavy ion synchrotron, SIS-200 (with a magnetic rigidity of 200 Tm) at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt. It is also assumed that the beam 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 target, deposit a fraction of their energy in the target material along their trajectory, and escape through the opposite face of the cylinder with a substantially 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-energy–density matter, without any sharp gradients.