EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 2 September 1999 GEANT4 SIMULATION OF ENERGY LOSSES OF SLOW HADRONS

The algorithm of the simulation of energy losses for hadrons with kinetic energy down to few eV is described. The details of its implementation in Geant4 are discussed. The comparison of the results of simulation with the experimental data is presented. 1 Introduction GEANT4 [1] is a toolkit for Monte Carlo particle transport simulation for a wide range of applications and it is based on the Object Oriented technology. The transparency of the physics implementation allows a rigorous procedure in validating the physics results. The flexibility of the GEANT4 design hence allows simulation of physical processes in such diverse fields as high energy physics, space and cosmic ray applications, nuclear and radiation computations, as well as heavy ion and medical applications. In high energy physics the precise hadron energy losses in matter are important for hadrons with more than a few MeV kinetic energy. In a number of other applications, on the other hand, the precise simulation of energy loss and stopping of lower-energy protons and ions in matter is one of the main requirements for the simulation tool. In medical research, especially in hadron irradiation treatment, very precise simulation of the energy loss of both the incident particles and their secondary particles in tissue is required. To maximise patient safety, accurate knowledge is required of the 3-D distribution of the radiation dose within small volumes, implying low energy production thresholds and small step lenghts in the simulation. In space instrumentation, on the other hand, reduction in component size has led to higher susceptibility to the so-called Single Event Phenomena (SEP). These phenomena are primarily due to incident protons and ions in space, and are characterised by large energy deposits in small sensitive volumes, particularly near the end of the particle track. Such phenomena usually cause memory bit-flips, and may result either in a temporary operational glitch of an instrument or the spacecraft or, in the worst case, in the loss of the entire mission. Another example of a low-energy application is the particle-induced X-ray emission (PIXE). This is an analytical method for identifying the composition of a target material by irradiating it with low-energy charged particles, usually protons or alpha particles, inducing X-ray fluorescence emission. The part of the emission emerging from the topmost layer of the target can be observed, and is characteristic of the elements present in the target material. PIXE methods have found wide applications in …