分类: 物理学 >> 核物理学 提交时间: 2024-05-24
摘要: The recently discovered, extremely proton-rich nuclide18Mg exhibits ground-state decay via two sequential two-proton (2p) emissions through the intermediate nucleus,16Ne. This study investigates the structure and the initial2pdecay mechanism of18Mgby examining the density and correlations of the valence protons using a three-body Gamow-coupled-channel method. The results show that the ground state of18Mgis significantly influenced by the continuum, resulting in a significants-wave component. However, based on the current frame- work, this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the18Mg-18Cpair. Additionally, the time evolution analysis of the18Mgground state suggests a simultaneous2pemission during the first step of decay. The observed nucleon–nucleon correlations align with those of the light–mass2pemitters, indicating a consistent decay behavior within this nuclear region.
分类: 物理学 >> 核物理学 提交时间: 2023-08-15
摘要: A particle detector array designed for light-charged particles, known as the CsI-bowl, was conceived for the purpose of refining exit channel selection for in-beam gamma-ray spectroscopy experiments. This device is composed of 64 CsI(Tl) detectors, organized in a structure reminiscent of a tea-bowl. High quantum efficiency photodiodes, characterized by their minimal mass, were employed to collect scintillation light. The comprehensive account of the CsI-bowl includes details on its design, construction, particle identification resolution, and its efficacy in relation to exit channel selection. In source tests, the optimal figure of merit for the identification of alpha-particles and gamma-rays using the charge comparison method was found to be 3.3 and 12.1 for CsI detectors paired with photodiodes and avalanche photodiodes, respectively. The CsI-bowl demonstrated effectiveness in identifying particles, specifically the emission of protons and alpha-particles in the 58Ni(19F, xpyn) fusionevaporation reaction, thereby enabling the selection of the desired exit channels
分类: 物理学 >> 核物理学 提交时间: 2023-06-21
摘要: The electric quadrupole moment of $^{49}$Sc was measured by collinear laser spectroscopy at CERN-ISOLDE to be $Q_{ rm s}=-0.159(8)$~$e$b, and a nearly tenfold improvement in precision was reached for the electromagnetic moments of $^{47,49}$Sc. The single-particle behavior and nucleon-nucleon correlations are investigated with the electromagnetic moments of $Z=21$ isotopes and $N=28$ isotones as valence neutrons and protons fill the distinctive $0f_{7/2}$ orbit, respectively, located between magic numbers, 20 and 28. The experimental data are interpreted with shell-model calculations using an effective interaction, and textit{ab-initio} valence-space in-medium similarity renormalization group calculations based on chiral interactions. These results highlight the sensitivity of nuclear electromagnetic moments to different types of nucleon-nucleon correlations, and establish an important benchmark for further developments of theoretical calculations.
分类: 物理学 >> 核物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2023-06-21
摘要: Collinear laser spectroscopy is known as one of the powerful tools for the study of nuclear spins, electromagnetic moments and charge radii of the exotic nuclei. Aiming at studying these nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility (BRIF) and the future High Intensity Heavy-ion Accelerator Facility (HIAF), we have firstly developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system. The overall performances of this state-of-the-art technique and device have been commissioned by using the bunched stable ion beam. High-resolution optical spectra of $^{40,42,44,48}$Ca isotopes were successfully measured for the 4$s$ $^{2}S_{1/2}$ $ rightarrow$ 4$p$ $^{2}P_{3/2}$ (D2) ionic transition and the extracted isotope shifts relative to the $^{40}$Ca show an excellent agreement with the literature values. This system is now ready to be applied at the ratioactive ion beam facility, such as BRIF, and has paved the way for further development of the higher-sensitivity collinear resonant ionization spectroscopy.
分类: 核科学技术 >> 粒子加速器 提交时间: 2021-12-31
摘要: Collinear laser spectroscopy is a powerful tool for studying the nuclear spins, electromagnetic moments, and charge radii of exotic nuclei. To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion#2;beam Facility (BRIF) and the future High Intensity Heavy-ion Accelerator Facility (HIAF), we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system. The overall performance of this state-of-the-art technique was evaluated and the system was commissioned using a bunched stable ion beam. The high-resolution optical spectra for the 4s 2S1/2 → 4p 2P3/2 (D2) ionic transition of 40,42,44,48Ca isotopes were successfully measured. The extracted isotope shifts relative to 40Ca showed excellent agreement with the literature values. This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonant ionization spectroscopy techniques.
分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: The study of the relative phase between strong and electromagnetic amplitudes is of great importance for understanding the dynamics of charmonium decays. The information of the phase can be obtained model-independently by fitting the scan data of some special decay channels, one of which is ψ′ → K+K−. To find out the optimal data taking strategy for a scan experiment in the phase study of ψ′ → K+K− decay, the minimization process is analyzed in detail from a theoretical point of view.