分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： An experimental method was used to evaluate the primary isotope yields of semi-central collisions in the reaction system 64Zn+112Sn at 40A MeV. The characteristic nature of the hot nuclear matter at the time of the isotope formation was studied. The multiplicities of light particles (LPs) associated with intermediate mass fragments (IMFs) were determined experimentally by using a kinematical focusing technique. The primary isotope distributions, reconstructed by a Monte Carlo method, were compared with those of the AMD-Gemini simulations. ac/T=0.11 and asym/T=3.34 were extracted from the reconstructed primary fragments yield. These are consistent with those of the primary fragments of the AMD simulation.
分类： 物理学 >> 核物理学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The symmetry energy at the time of the production of intermediate mass fragments (IMFs) is studied using experimentally observed IMF multiplicities combined with quantum statistical model calculations (QSM of Hahn and Stcker). The ratios of difference in chemical potentials between neutrons and protons relative to the temperature, (np)/T, and the double ratio temperature, T, were extracted experimentally in the reactions of 64,70Zn, 64Ni+58,64Ni, 112,124Sn, 197Au, 232Th at 40A MeV. The extracted (np)/T scales linearly with NN, where NN is the asymmetry parameter, (NZ)/A, of the emitting source and (np)/T=(11.11.4)NN0.21 was derived. The experimentally extracted (np)/T and the double ratio temperatures are compared with those from the QSM calculations. The temperatures, T, and densities, , extracted from the (np)/T values agreed with those from the double ratio thermometer which used the yield ratios of d, t, h and particles. However the two analyses of the differential chemical potential analysis and the initial temperature analysis end up almost identical relation between T and . T=5.250.75 MeV is evaluated from the (np)/T analysis, but no density determination was possible. From the extracted T value, the symmetry energy coefficient Esym=14.63.5 MeV is determined for the emitting source of T=5.250.75 MeV.
分类： 物理学 >> 核物理学 提交时间： 2023-09-07
摘要： The thermodynamic properties of charged particles, such as the energy density, pressure, entropy density, particle density, and squared speed of sound at the kinetic freeze-out in the $ mathrm{Au+Au}$ collisions from the relativistic heavy ion collider (RHIC) beam energy scan program ($ sqrt{s_ text{NN}}$=7.7--200 GeV) and in the $ mathrm{Cu+Cu}$ collisions at $ sqrt{s_ text{NN}}$=62.4, 200 GeV are studied using the thermodynamically consistent Tsallis distribution. The energy density, pressure, and particle density decrease monotonically with the collision energy for the same collision centrality; These properties also decrease monotonically from the central to peripheral collisions at the same collision energy. While the scaled energy density $ varepsilon/T^4$ and scaled entropy density $s/T^3$ demonstrate the opposite trend with the collision energy for the same collision centrality. There is a correlation between $ varepsilon/T^4$ and $s/T^3$ at the same centrality. In addition, the squared speed of sound was calculated to determine that all the collision energies share nearly the same value at different collision centralities.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-07-28
Ma, Long
Xie, Dehao
Wang, Yanxi
Wang, Shuo
Han, Jifeng
Lin, Weiping
Liu, Jianli
Liu, Xingquan
Liu, Yuguo
Luo, Xiaobing
Luo, Yuan
Qu, Guofeng
Qu, Yufan
Ren, Peipei
Wada, Roy
Zang, Linge
Zhu, Jingjun
摘要： Stripping unit plays an important role in the neutral particle analyzer (NPA). An updated gas stripping unit was constructed for the newly designed E//B NPA. The pressures at the gas inlet ($P_0$) and the vacuum chamber ($P_3$) were measured with the working gas of H$_2$, and the pressure distribution inside the gas stripping room was calculated using Ansys Fluent with the measured $P_0$ and $P_3$ as the boundary conditions. The stripping efficiency of the stripping unit is then simulated using Geant4 Monte Carlo code for H and D particles. The pressure $P_0$ = 40 Pa, which is four times less than that in previous design and corresponds to a thickness of 1.27$\times 10^{17}$ atoms/cm$^2$, is obtained as the optimum working pressure for the updated stripping unit.A 50 kV electron cyclotron resonance (ECR) ion source platform has been designed and constructed for the E//B NPA calibration, and its performance was measured. Utilizing the ECR ion source platform, the efficiency of the stripping unit was measured in an inverse experiment with proton beams. The current ratio of the measurements with and without H$_2$ gas are compared with those of Geant4 simulation. Good agreements of the overall trend between the experiment and the simulation are found. The large deviation at the incident energy below 20 keV could be the scattering effect of low energy protons, where the accuracy breaks down in the single scattering physics involved in the Geant4 simulations. {After the scattering corrections observed in the reverse experiments, more accurate stripping efficiencies for H and D atoms in the energy range of 20-200 keV are obtained and the global efficiency reaches the maximum values of 95.0\% for H atoms and 78.9\% for D atoms at 200 keV.
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