分类： 物理学 >> 核物理学 提交时间： 2025-05-20
Li, Dr. ouyi
Meng, Dr. Weijia
Fang, Dr. Wenxiang
Zhong, Dr. Bin
ma, Prof. tianyu 马天予
yu, Prof. ganglin
摘要： For controlled nuclear fusion, it is of significance to develop a comprehensive simulation environment for Inertial Confinement Fusion(ICF) . This environment must accurately calculate the energy loss of charged particles in high-temperature, high-density plasma, and simulate the physical parameters of fusion reactions and products. This study presents a novel implementation of a modified Li-Petrasso (MLP) energy loss theory within the GEANT4 framework, to address the critical challenge of simulating charged particle transport in high-temperature, high-density plasma for ICF research. The modified theory integrates binary collision terms, collective plasma effects, and quantum degeneracy corrections, enabling accurate calculations of stopping power, mean collision path, and energy transfer dynamics for particles such as recoil alpha particles, deuterons, and tritons under extreme plasma conditions. This work provides a detailed introduction to how to embed and calculate this process within GEANT4 and verifies the correctness of the embedded model. Full simulation of the fusion process is also conducted. The results demonstrate that the improved GEANT4 can effectively handle the energy loss of charged particles in such environments, calculate important fusion parameters like neutron energy spectrum and energy transfer ratios, and observe the production of ultra-high-energy neutrons. Comparisons with experimental fusion data show significant improvements in consistency, validating the improved GEANT4's validity and accuracy. This work has, for the first time, achieved full simulation of charged particle energy loss and secondary neutron spectrum of ICF using GEANT4, providing valuable insights into ICF characteristics and aiding in the development of more accurate fusion simulations.
分类： 物理学 >> 核物理学 提交时间： 2024-06-03
摘要： The medium temperature $T$ dependence of jet transport coefficient $ hat q$ is studied via nuclear modification factor $R_{AA}(p_{ rm T})$ and elliptical flow parameter $v_2(p_{ rm T})$ for large transverse momentum $p_{ rm T}$ hadrons in high-energy nucleus-nucleus collisions. Within a next-to-leading order perturbative QCD parton model for hard scatterings with modified fragmentation functions due to jet quenching controlled by $ hat q$, we check the suppression as well as the azimuthal anisotropy for large $p_{ rm T}$ hadrons, and extract $ hat q$ by global fits to $R_{AA}(p_{ rm T})$ and $v_2(p_{ rm T})$ data in $A+A$ collisions at RHIC and the LHC, respectively. Numerical results from the best fits show that $ hat q/T^3$ goes down with the local medium temperature $T$ in the parton jet trajectory. Compared with the case of a constant $ hat{q}/T^3$, the going-down $T$ dependence of $ hat{q}/T^3$ makes a hard parton jet to lose more energy near $T_c$ and therefore strengthens the azimuthal anisotropy for large $p_{ rm T}$ hadrons. As a result, $v_2(p_{ rm T})$ for large $p_{ rm T}$ hadrons is enhanced by about 10 % to fit data better at RHIC/LHC. Considering the first-order phase transition from QGP to the hadron phase and additional energy loss in the hadron phase, $v_2(p_{ rm T})$ is again enhanced by 5-10 % at RHIC/LHC.
分类： 核科学技术 >> 放射性计量学 提交时间： 2024-04-26
摘要： The aim of this study is to evaluate the uncertainty of 2πα and 2πβ surface emission rates using the windowless multiwire proportional counter method. This study used the Monte Carlo method (MCM) to validate the conventional Guide to the Expression of Uncertainty in Measurement (GUM) method. A dead-time measurement model for the two-source method was established based on the characteristics of a single-channel measurement system, and the voltage threshold correction factor measurement function was indirectly obtained by fitting the threshold correction curve. The uncertainty in the surface emission rate was calculated using the GUM method and the law of propagation of uncertainty. The MCM provided clear definitions for each input quantity and its uncertainty distribution, and the simulation training was realized with a complete and complex mathematical model. The results of the surface emission rate uncertainty evaluation for four radioactive plane sources using both methods showed an uncertainty consistency En < 0.070 for the comparison of each source, and the uncertainty results of the GUM were all lower than those of the MCM. However, the MCM has a more objective evaluation process and can serve as a validation tool for GUM results.
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