Loading...

Design and optimization of the spallation neutron source target system using 800 MeV protons produced in the synchrotron using Geant4 Monte Carlo code

Azimi Nasrabadi, Fatemeh Sadat | 2025

0 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58441 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Hosseini, Abolfazl
  7. Abstract:
  8. Among various neutron sources such as fission reactors, radioisotopic sources, photoneutron reactions, and others, the spallation neutron source has attracted significant attention due to advantages like high flux, notable neutron yield, and a broad energy spectrum. The spallation process occurs when high-energy light particles, typically protons in the order of giga-electron volts, collide with heavy targets such as lead or mercury. This interaction produces a large number of neutrons, protons, deuterons, pions, and other particles. To increase neutron production efficiency and achieve a desirable energy spectrum, a target system composed of a target, moderator, and reflector is used. In this study, using Monte Carlo simulations with the Geant4 code, an optimized structure was sought based on the geometric model of the Chinese spallation neutron source. By varying the materials used for the target, moderator, and reflector, and using an 800 MeV proton beam, the goal was to achieve maximum neutron flux and a suitable energy spectrum. Among the physics lists QGSP_BIC_HP, QGSP_BERT_HP, QGSP_INCLXX_ABLA_HP, and QGSP_INCLXX_HP, the QGSP_INCLXX_HP list was chosen for modeling the physics of the problem, as it showed the smallest deviation — only about 8.89% — from experimental neutron yield results. The optimization process began with a bare target using three different materials — mercury, lead, and lead-bismuth — and selecting the one with the highest neutron yield. Mercury was then chosen as the optimal target material and placed in the geometric layout, followed by evaluating nine reflector configurations. These configurations included three materials (graphite, heavy water, and beryllium) in the first layer and three (iron, lead, and stainless steel SS316) in the second layer. The setups were compared based on neutron flux and yield. Finally, three types of moderators — water, methane, and ammonia — were assessed using the previously optimized target and reflector materials. Results showed that using a mercury target, ammonia as the moderator, and a reflector composed of graphite (first layer) and lead (second layer) yielded the highest neutron flux and production efficiency. The neutron flux at the sample location, adjacent to the moderator, in the thermal region was calculated as 5×10⁸ n/cm².s, which is 5 to 10 times higher than the referenced data
  9. Keywords:
  10. Monte Carlo N-Particle (MCNP)Code ; GEANT4 Toolkit ; Optimization ; Spallation Neutron Source

 Digital Object List

 Bookmark

No TOC