分类: 物理学 >> 核物理学 提交时间: 2023-09-11
摘要: A trigger system has been designed and implemented for the HIRFL-CSR external target experiment (CEE), the spectrometer for studying nuclear matter properties with heavy ion collisions in the GeV energy region. The system adopts master-slave structure and serial data transmission mode using optical fiber to deal with different types of detectors and long-distance signal transmission. The trigger logic can be accessed based on command register and controlled by a remote computer. The overall field programmable gate array (FPGA) logic can be flexibly reconfigured online to match the physical requirements of the experiment. The trigger system has been tested in beam experiment. It is demonstrated that the trigger system functions correctly and meets the physical requirements of CEE.
分类: 物理学 >> 核物理学 提交时间: 2023-07-08
摘要: The HIRFL-CSR external-target experiment (CEE) under construction is expected to provide novel opportunities to the studies of the thermodynamic properties, namely the equation of state of nuclear matter (nEOS) with heavy ion collisions at a few hundreds MeV/u beam energies. Based on Geant 4 packages, the fast simulations of the detector responses to the collision events generated using transport model are conducted. The overall performance of CEE, including spatial resolution of hits, momentum resolution of tracks and particle identification ability has been investigated. Various observables proposed to probe the nEOS, such as the production of light clusters, $\rm t/^3He$ yield ratio, the radial flow, $\pi^{-}/\pi^{+}$ yield ratio and the neutral kaon yields, have been reconstructed. The feasibility of studying nEOS beyond the saturation density via the aforementioned observables to be measured with CEE has been demonstrated.
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: 2023-06-02
摘要: In this study, the rapidity distribution, collective flows, and nuclear stopping power in 197Au+197 Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics (UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.