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: Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained.
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: How the initial fluctuation affects on the elliptic flow is investigated by investigating the rapidity, transverse 4-velocity, centrality dependencies of elliptic flow for Au+Au at 1 GeV/A with the help of an Isospin Quantum Molecular Dynamics (IQMD). In addition, we compare the flow calculated with respect to participant plane created by the initial geometry in coordinate space with the flow reconstructed by the experimental event-plane method, and compare the flow with the experimental data of the FOPI collaboration. It shows that there exists some discrepancy between the flows reconstructed by the above two methods.
分类: 物理学 >> 核物理学 提交时间: 2023-10-07
摘要: In the RD for upgrading the KL0and detector (KLM) in Belle II experiment using scintillator and silicon photomultiplier (SiPM), we design a compact preamplifier with high#2;speed and low-noise. The preamplifier has a good gain stability, a baseline noise level of 0.3 mV, a good time resolution that can achieve < 20 ps, and can be applied comprehensively to SiPMs. To reduce the pile-up in using a large size SiPM or an array of SiPMs, which is due to the large capacitance and high dark count rate, we adopt pole#2;zero-cancellation which reduce both the rise time and the fall time of a SiPM signal. The combinations of the preamplifier and several kinds of SiPMs show time resolutions better than 50 ps for most of the cases; when the number of detected photons is larger than 60, a time resolution of about 25 ps can be achieved