Schottky mass spectrometry utilizing heavy-ion storage rings is a powerful technique for the precise mass and decay half-life measurements of highly charged ions. Owing to the nondestructive ion detection features of Schottky noise detectors, the number of stored ions in the ring is determined by the peak area in the measured revolution frequency spectrum. Because of their intrinsic amplitude-frequency characteristic (AFC), Schottky detector systems exhibit varying sensitivities at different frequencies. Using low-energy electron-cooled stored ions, a new method is developed to calibrate the AFC curve of the Schottky detector system of the Experimental Cooler Storage Ring (CSRe) storage ring located in Lanzhou, China. Using the amplitude-calibrated frequency spectrum, a notable refinement was observed in the precision of both the peak position and peak area. As a result, the storage lifetimes of the electron-cooled fully ionized 56\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<^>{56}$$\end{document}Fe26+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<^>{26+}$$\end{document} ions were determined with high precision at beam energies of 13.7 and 116.4 MeV/u, despite of frequency drifts during the experiment. When electron cooling was turned off, the effective vacuum condition experienced by the 116.4 MeV/u 56\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<^>{56}$$\end{document}Fe26+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<^>{26+}$$\end{document} ions was determined using amplitude-calibrated spectra, revealing a value of 2x10-10\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2\times 10<^>{-10}$$\end{document} mbar, which is consistent with vacuum gauge readings along the CSRe ring. The method reported herein will be adapted for the next-generation storage ring of the HIAF facility under construction in Huizhou, China. It can also be adapted to other storage ring facilities worldwide to improve precision and enhance lifetime measurements using many ions in the ring.

Total absorption gamma-ray spectroscopy (TAGS) is a powerful tool for measuring complex γ transitions, which has been effectively applied to the study of reactor decay heat. This paper presents the design of a new TAGS detector, the large-scale modular BGO detection array (LAMBDA), tailored for measuring β-decay intensity distributions of fission products. The modular design allows the LAMBDA detectors to be assembled in various configurations. The final version of LAMBDA consists of 102 identical 60 mm × 60 mm × 120 mm BGO crystals and exhibits a high full-energy peak efficiency exceeding 80% at 0.5∼8 MeV based on a Monte Carlo simulation. Currently, approximately half of the LAMBDA modules have been manufactured. Tests using γ-ray sources and nuclear reactions demonstrated favorable energy resolution, energy linearity, and efficiency uniformity across the modules. Forty-eight modules have been integrated into the prototype LAMBDA-I. The capability of LAMBDA-I in β-delayed γ-decay experiments was evaluated by commissioning measurements using the 152Eu source. © The Author(s), under exclusive licence to China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society 2024.

We have analyzed the systematics of b and c coefficients of the quadratic isobaric multiplet mass equation (IMME) using the newly measured masses of the upper fp-shell nuclei in the experimental cooler storage ring (CSRe) in Lanzhou. The c coefficient for the A = 70, T = 1 isospin multiplet is found to be negative, which is severely deviating from overall systematics and in conflict with theoretical expectations of the isospin symmetry. This anomaly is analyzed and attributed to the presently adopted mass of 70Br in the latest Atomic Mass Evaluation (AME2020). Under the assumption of a smooth variation of Coulomb energy differences with changing mass number A, the ground-state mass excess of 70Br is deduced to be -51934(16) keV, which is 508(22) keV more bound than the adopted value. Using this mass value, the calculated c coefficient of IMME at A = 70 fits well into the systematics, and the obtained corrected Ft value for the 0+ -> 0+ superallowed beta decay of 70Br is consistent with the world-average value.

We developed a Gamow shell model based on first principles and successfully applied it to the nuclei around driplines. Herein, we review the theoretical and technical developments of this method. Starting from the realistic nuclear forces, the model uses the Berggren basis, which contains bound, resonant, and scattering continuum states. Therefore, the Gamow shell model can handle the coupling to the continuum. In the complex-momentum plane, we used many-body perturbation theory (i.e., so-called Qˆ -box folded diagrams) to derive the Hamiltonian for the valence space. Subsequently, the shell-model calculations, which included the resonance and continuum effects, were performed. Therefore, such ab initio calculations can describe the weakly bound properties of nuclei near driplines and unbound resonance properties of nuclei beyond driplines. In this study, the symmetry breaking between oxygen isotopes and their mirror nuclei is discussed, and the important continuum effects on the excitation spectra of neutron-rich carbon isotopes are analyzed. © 2023 Science Press. All rights reserved.

Rapid proton capture nucleosynthesis stalls at waiting-point nuclides, including Ge-64. Precision mass measurements in the vicinity of this nuclide influence state-of-the-art calculations of X-ray bursts from accreting neutron stars.X-ray bursts are among the brightest stellar objects frequently observed in the sky by space-based telescopes. A type-I X-ray burst is understood as a violent thermonuclear explosion on the surface of a neutron star, accreting matter from a companion star in a binary system. The bursts are powered by a nuclear reaction sequence known as the rapid proton capture process (rp process), which involves hundreds of exotic neutron-deficient nuclides. At so-called waiting-point nuclides, the process stalls until a slower beta(+) decay enables a bypass. One of the handful of rp process waiting-point nuclides is Ge-64, which plays a decisive role in matter flow and therefore the produced X-ray flux. Here we report precision measurements of the masses of Ge-63, As-64,As-65 and Se-66,Se-67-the relevant nuclear masses around the waiting-point Ge-64-and use them as inputs for X-ray burst model calculations. We obtain the X-ray burst light curve to constrain the neutron-star compactness, and suggest that the distance to the X-ray burster GS 1826-24 needs to be increased by about 6.5% to match astronomical observations. The nucleosynthesis results affect the thermal structure of accreting neutron stars, which will subsequently modify the calculations of associated observables.

A novel isochronous mass spectrometry, termed as Bp-defined IMS, has been established at the experimental cooler-storage ring CSRe in Lanzhou. Its potential has been studied through high precision mass measurements of 58Ni projectile fragments. Two time-of-flight detectors were installed in one of the straight sections of CSRe, thus enabling simultaneous measurements of the velocity and the revolution time of each stored short-lived ion. This allows for calculating the magnetic rigidity Bp and the orbit length C of each ion. The accurate Bp(C) function has been constructed, which is a universal calibration curve used to deduce the masses of the stored nuclides. The sensitivity to single stored ions, fast measurement time, and background-free characteristics of the method are ideally suited to address nuclides with very short lifetimes and smallest production yields. In the limiting case of just a single particle, the achieved mass resolving power allows one to determine its mass-over-charge ratio m/q with a remarkable precision of merely similar to 5 keV. Masses of Tz = -3/2 fp-shell nuclides are re-determined with high accuracy, and the validity of the isospin multiplet mass equation is tested up to the heaviest isospin quartet with A = 55. The new masses are also used to investigate the mirror symmetry of empirical residual proton-neutron interactions.

Using a novel method of isochronous mass spectrometry, the masses of 62Ge, 64As, 66Se, and 70Kr are measured for the first time, and the masses of 58Zn, 61Ga, 63Ge,65As, 67Se, 71Kr, and 75Sr are redetermined with improved accuracy. The new masses allow us to derive residual proton-neutron interactions (5Vpn) in the N = Z nuclei, which are found to decrease (increase) with increasing mass A for even-even (odd-odd) nuclei beyond Z = 28. This bifurcation of 5Vpn cannot be reproduced by the available mass models, nor is it consistent with expectations of a pseudo-SU(4) symmetry restoration in the fp shell. We performed ab initio calculations with a chiral three-nucleon force (3NF) included, which indicate the enhancement of the T =1 pn pairing over the T = 0 pn pairing in this mass region, leading to the opposite evolving trends of 5Vpn in even-even and odd-odd nuclei.

从第一性原理(ab initio)出发研究原子核已经成为当今理论核物理领域的前沿方向,它不仅能够提供高精度的计算结果与可靠的理论预言,而且能够在有效场论的基础上建立起与底层基本理论(量子色动力学-QCD)联系的桥梁.近年来,随着手征核力

核素图是原子核科学与技术领域基本的工具之一。基于原子核基本性质实验数据评估（The NUBASE2020 evaluation of nuclear physics properties）的公开数据制作了核素图,用颜色和文字展示了目前已知的基态原子核性质,包括同位素丰度、放射性衰变类型、半衰期、质量误差等实验信息。本工作评述了核素图数据可视化的最新进展,简述了核素版图的拓展历史和德国卡尔斯鲁厄核素图的发行历史,介绍了新版核素图的设计细节和未来展望,推荐了免费以及开源的核素图绘制程序。同时,还设计了印刷版核素图,计划随AME和NUBASE新版本发行同步更新,使它们成为展示NUBASE数据库简明信息的常规媒介。