Production threshold impact on a GEANT4 calculation of the power deposition in a fast domain: MEGAPIE spallation target Abdesslam Lamrabet 1,2 • Abdelmajid Maghnouj 1 • Jaouad Tajmouati 1 • Mohamed Bencheikh 1 Received: 21 August 2018 / Revised: 1 October 2018 / Accepted: 3 November 2018 / Published online: 9 April 2019 Ó China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society and Springer Nature Singapore Pte Ltd. 2019 Abstract The calculation time in the Monte Carlo simu- lations consistently represents an essential issue. It is often very long, and its decrease constitutes a challenge for the simulator. Generally, an MC simulation is qualified as quality or not according to two main criteria: the calcula- tion time and the accuracy of the results. However, in most cases, the optimization of one criterion affects negatively the other. Therefore, a compromise between both of them is always required in this kind of simulation. The present work aims at studying the impact of the production threshold (or cut) of the GEANT4 toolkit on the calculation of the power deposition in the MEGAPIE spallation target. The production threshold of secondaries is a GEANT4 intrinsic parameter. It indicates the limit of energy we can reach in the production of secondary particles. This study has allowed us to make the following conclusions. First, the influence of the cut on the calculation of the deposited power depends on the volume size, its arrangement and the importance of the electromagnetic processes occurring within. Second, the accuracy of the calculations can be acceptable only below a given value of the cut energy. Third, this accuracy remains almost unchangeable from a certain value of the cut. The study has also made it possible to explore the prevalence of certain interactions in the zone of spallation in the MEGAPIE target. Keywords Production threshold Á Power deposition Á Spallation Á MEGAPIE Á GEANT4 1 Introduction The Monte Carlo (MC) codes are divided into two classes [1] according to their specific approaches in the particle tracking. Class I gathers the so-called general codes like MCNP [2] that uses the condensed history method [3–6]. Class II gathers codes that mix the con- densed method and the detailed one [7]. In the condensed method, the produced interactions and particles in a step are not all explicitly simulated. This method consists of grouping the individual interactions into global steps dur- ing which the deposited energy, displacement and direction are sampled from relevant multiple-scattering distributions. Conversely, the detailed method consists of simulating all interactions explicitly so that each step corresponds to one interaction. GEANT4 [8–10], which interests us in this study, is a class II code. In this code, the interactions are divided into two types: hard and soft. The simulation of the hard interactions is performed with the detailed method; whereas, the soft interactions are simulated with the con- densed method. The classification of the interactions in class II codes is made according to an energy called ‘‘production threshold’’ [11]. In a GEANT4 simulation, all the particles, primaries and secondaries are tracked down to zero energy. However, the so-called production threshold (cut) limits the generation of the secondary particles. This parameter also acts on the calculation accuracy and on the computing time. The cut is usually taken into account in the low-energy fields, but in this work, we have dealt with this subject in the MEGAPIE spallation target [12, 13] & Abdesslam Lamrabet abdesslam.lamrabet@usmba.ac.ma 1 Laboratory of Integration of Systems and Advanced Technologies, Faculty of Sciences Dhar El mahraz, University Sidi Mohamed Ben Abdellah, 30000 Fe `s, Morocco 2 El Hajeb, Morocco 123 NUCL SCI TECH (2019) 30:75 https://doi.org/10.1007/s41365-019-0603-5