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Proposed mechanisms for the production of calcium in the first stars (population III stars)—primordial stars that formed out of the matter of the Big Bang—are at odds with observations 1 . Advanced nuclear burning and supernovae were thought to be the dominant source of the calcium production seen in all stars 2 . Here we suggest a qualitatively different path to calcium production through breakout from the ‘warm’ carbon–nitrogen–oxygen (CNO) cycle through a direct experimental measurement of the 19 F( p ,  γ ) 20 Ne breakout reaction down to a very low energy point of 186 kiloelectronvolts, reporting a key resonance at 225 kiloelectronvolts. In the domain of astrophysical interest 2 , at around 0.1 gigakelvin, this thermonuclear 19 F( p ,  γ ) 20 Ne rate is up to a factor of 7.4 larger than the previous recommended rate 3 . Our stellar models show a stronger breakout during stellar hydrogen burning than previously thought 1 , 4 , 5 , and may reveal the nature of calcium production in population III stars imprinted on the oldest known ultra-iron-poor star, SMSS0313-6708 6 . Our experimental result was obtained in the China JinPing Underground Laboratory 7 , which offers an environment with an extremely low cosmic-ray-induced background 8 . Our rate showcases the effect that faint population III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, which are key mission targets of the James Webb Space Telescope 9 . Observation of a new resonance in the 19-fluorine to 20-neon thermonuclear reaction at the China JinPing Underground Laboratory (over 2 km below ground) may provide clues to observed discrepancies in calcium production in the evolution of the first stars.

The line ratios in X-ray emission resulting from charge exchange between highly charged ions (HCIs) and neutral atoms are not only crucial for accurately modeling astrophysical X-ray emissions but also offer a unique perspective on the charge exchange processes happening during collisions. The K X-ray spectra following charge exchange between Mg11+ and He are presented for a collision velocity of 1489 km/s (11.5 keV/amu). The spectra were measured by two Silicon Drift Detectors capable of resolving the Mg10+ Kα, Kβ, Kγ, and Kδ+ lines. The line intensity ratios of Kβ, Kγ, and Kδ+ relative to the Kα line, as well as the hardness ratio, were obtained. The experimental results were compared with the theoretical results from a cascade model that utilizes the state cross-sections produced by multichannel Landau–Zener (MCLZ) calculation. It was discovered that the K X-ray spectrum features can be reproduced well by MCLZ theory when the contributions of both single electron capture (SEC) and autoionizing double capture (ADC) processes are included. This finding implies that the ADC feeding mechanism is significant and should be taken into account for the X-ray emission during charge exchange between highly charged ions and multielectron atoms.

In the high-energy mode of Booster Ring (BRing) of the High Intensity heavy-ion Accelerator Facility (HIAF), the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing. The thermal deposition and irradiation damage caused by high beam intensity and high energy deposition limit the lifetime of the foil. To ensure the stable operation of HIAF, a long-lifetime stripper foil with excellent irradiation and high-temperature resistance is required. This report aims to reveal the irradiation damage evolution of several kinds of carbon foils and its impact on their physical properties. Irradiation experiments were performed at HIRFL-SFC using Xe beams with the energy loss close to that of U beams in HIAF. There were three kinds of foils from four producer irradiated in the experiments, including Multilayer graphene (MLG) produced by KANEKA Co. and the Institute of Coal Chemistry (SXICC), diamond-like carbon (DLC) foil by the Institiute of Modern Physics (IMP) and Graphene Oxide (GO) foil by TIMESNANO Co. Various characterization methods were used to study the changes in surface morphologies, microstructures, and physical properties of the foils. The results indicated that MLG has a tendency for amorphization, DLC has a tendency for graphitization, and the oxygen-containing functional groups on the GO surface are damaged. These structural changes are expected to significantly impact the mechanical properties of the foils.

A hybrid single cavity (HSC) linac, combined with radio frequency quadrupole and drift tube structure in a single interdigital-H cavity, operates with high rf power as a prototype injector for cancer therapy synchrotron. The HSC adopts a direct plasma injection scheme (DPIS) with a laser ion source. The input beam current of the HSC is designed to be 20 mA C6+ ions. According to simulations, the HSC can accelerate a 6-mA C6+ beam which meets the requirement of the particle number for cancer therapy (108∼9ions/pulse ). The HSC injector with DPIS makes the existing multiturn injection system and stripping system unnecessary; what is more, it can also bring down the size of the beam pipe in existing synchrotron magnets, which can reduce the whole cost of the synchrotron. Details of the field measurements of the HSC linac and results of the high power test are reported in this paper.

Underground Nuclear Astrophysics Experiment in China (JUNA) has been commissioned by taking the advantage of the ultra-low background in Jinping underground lab. High current mA level 400 KV accelerator with an ECR source and BGO detectors were commissioned. JUNA studies directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. In the first quarter of 2021, JUNA performed the direct measurements of 25 Mg(p, γ ) 26 Al, 19 F(p, α ) 16 O, 13 C( α ,n) 16 O and 12 C( α , γ ) 16 O near the Gamow window. The experimental results reflect the potential of JUNA with higher statistics, precision and sensitivity of the data. The preliminary results of JUNA experiment and future plan are given.

In pursuit of a fourth-generation electron cyclotron resonance (ECR) source, a powerful Nb 3 Sn superconducting magnet system employing a sextupole-in-solenoid configuration has been recently developed at the Institute of Modern Physics (IMP) in Lanzhou, China. These superconducting magnets operate under extreme conditions, experiencing high magnetic fields, cryogenic temperatures, and mechanical stresses. Understanding their stress/strain behaviors, therefore, is of utmost importance to ensure reliable operation and optimal performance. However, the conventional single-point strain gauges commonly exhibit certain limitations that pose challenges in measuring global strain within complex and larger structures. The presence of substantial electromagnetic interference further exacerbates the difficulty in obtaining accurate strain measurements. To address these challenges, a novel approach was undertaken in this study to develop a distributed real-time strain monitoring system specifically designed for the sextupole superconducting magnets, which is based on optical frequency domain reflectometry (OFDR) combined with high spatial resolution distributed optical fiber technology. The strain profile and evolution of the magnets system have been comprehensively monitored throughout the entire operational process, including assembly, cooling down, excitation, and quenching stages. Consequently, valuable insights into the global strain characteristics of the superconducting magnets have been attained, revealing intriguing features such as asymmetrical distribution and extreme values. The development of this distributed real-time strain monitoring system represents a notable advancement in the field of superconducting magnet technology.

A 4th generation ECR (electron cyclotron resonance) ion source FECR (first 4th generation ECR ion source) is under construction at IMP (Institute of Modern Physics). Aiming to be operated with the microwave power of 20 kW at 45 GHz, a fully superconducting Nb 3 Sn magnet is to be developed to realize the optimum ECR plasma confinement. As the first superconducting ECR magnet that utilizes single-strand Nb 3 Sn (niobium three tin) wire for the winding of coils consisting of 4 sets of axial solenoids and one sextupole, it poses many challenges in the coil fabrication, cold mass assembly, magnet quench protection, and so on. With a shell-based structure and bladder-and-key technology, we have completed a 1/2-length FECR cold mass prototype. It has been fully tested when immersed in 4.2 K liquid helium. The critical issue in this work is to keep the brittle Nb 3 Sn wire safe during the complicated mechanical process and protect it against the high current high magnetic field excitation. In this paper, we will report on the details of how to design, fabricate, assemble, and test a high-performance Nb 3 Sn sextupole with the existence of sophisticated magnetic fields and stresses. The successful test of a high-current sextupole coil in a so-called mirror structure will be reported. The application of the bladder-and-key structure to the prototype and the performance will be presented. This research has also tackled the solutions to mitigate very intense flux jump that has caused severe challenges to quench detection and protection.

The line ratios in X-ray emission resulting from charge exchange between highly charged ions (HCIs) and neutral atoms are not only crucial for accurately modeling astrophysical X-ray emissions but also offer a unique perspective on the charge exchange processes happening during collisions. The K X-ray spectra following charge exchange between Mg[sup.11+] and He are presented for a collision velocity of 1489 km/s (11.5 keV/amu). The spectra were measured by two Silicon Drift Detectors capable of resolving the Mg[sup.10+] K α, K β, K γ, and K δ+ lines. The line intensity ratios of K β, K γ, and K δ+ relative to the K α line, as well as the hardness ratio, were obtained. The experimental results were compared with the theoretical results from a cascade model that utilizes the state cross-sections produced by multichannel Landau–Zener (MCLZ) calculation. It was discovered that the K X-ray spectrum features can be reproduced well by MCLZ theory when the contributions of both single electron capture (SEC) and autoionizing double capture (ADC) processes are included. This finding implies that the ADC feeding mechanism is significant and should be taken into account for the X-ray emission during charge exchange between highly charged ions and multielectron atoms.

Jinping Underground laboratory for Nuclear Astrophysics (JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of 25 Mg(p, γ ) 26 Al, 19 F(p, α ) 16 O, 13 C(α, n ) 16 O and 12 C(α, γ ) 16 O reactions. The experimental setup, which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.

The scientific installation project (HIAF)will be undertaken by the Institute of Modern Physics of the Chinese Academy of Sciences. LEAF (Low Energy intense-highly-charged Accelerator Facility) is a pre-research project for the future large-scale scientific installation about HIAF. It was received the support of the National Major Instrument Equipment R&D Fund. In the accelerator control system, motion control plays an important role. Motion control is a branch of automation. It mainly uses servos and motors to control the position or speed of the machine. The motion control system designed in this paper is mainly used to control the gas in and out, slits motion control, beam diagnostics and other equipment. It mainly studies the hardware architecture of the motion control system, the application of EPICS in the motion control system, the HMI design of the CSS and the test of the motion control system.