We demonstrate that secondary ions sputtered from a macrocapillary's inner surface by the primary beam induce premature saturation of the guiding field, hindering fast ion guiding. By suppressing secondary ion sputtering with grooved surfaces, we achieve a guiding-field potential difference exceeding 1 kV, 2 orders of magnitude larger than previously achieved in stable ion guiding. This enables stable guiding of a 20-keV/q O^{5+} beam at offset angles up to 15°, with transmitted ions retaining their initial energy and charge state. A self-consistent field model accurately reproduces these results, revealing that guiding performance relies on managing secondary ions and the channel's voltage tolerance, while remaining robust against beam fluctuations. This Letter paves the way for ionic fibers that, much like optical fibers for light, passively and adaptively control ion transport.

We present an angular-resolved Doppler spectroscopy study of nonradiative electron capture in relativistic collisions of bare Xe54+ ions with Kr and Xe gas targets at the HIRFL-CSR storage ring. The energy spectra and angular distributions of X-rays emitted from fast-moving down-charged projectiles were measured at five observation angles of 35°, 60°, 90°, 120°, and 145° and three collision energies of 95, 146, and 197 MeV/u by employing the effect of Doppler shift. The transition intensities of Xe53+ ions with small energy differences were precisely determined. In symmetric Xe54+ \to Xe collisions, the transition intensities of Xe53+ and Xe52+ ions were identified when X-rays emitted by projectiles overlapped with K X-rays arising from target ionization. The anisotropy parameters of the K{α_1}(+M2) transition were derived from the angular emission patterns of the corresponding spectral lines. The relative populations of the L, M, and N-shell excited levels of Xe53+ and Xe52+ were further deduced from the intensity ratios of I(Ly-β)/I(Ly-α), I(Ly-γ)/I(Ly-α), and I(Kα)/I(Ly-α). The energy dependence of the population of excited projectile levels was obtained for both targets. Furthermore, the experimental results were compared with theoretical calculations of nonradiative single- and double-electron capture based on the relativistic eikonal approximation and the independent-electron approximation. These findings provide valuable insights into the magnetic-sublevel population and n-resolved state-selective population of excited states produced in relativistic collisions of highly charged heavy ions with multi-electron atoms.

We present experimental study of nonradiative double electron capture processes in collisions of 95 and 146 MeV/u bare xenon ions with krypton and xenon gaseous atoms at the HIRFL-CSR storage ring. Angular distributions of the characteristic Kα radiation of the down-charged projectile ions Xe52+* are measured, which are closely related to the magnetic sublevel population of the excited 1s2l_j states of Xe52+*. It was found that the Kα1 radiation shows pronounced anisotropic and is sensitive to the collision energies and the target atoms, whereas the Kα2 radiation gives rise to isotropic. Moreover, obviously difference in the anisotropy parameters of Lyman-α1 of Xe53+* ions and Kα transitions of Xe52+* ions separately following nonradiative single and double electron capture into the L-shell levels of projectiles is obtained and discussed.

This work presents the development and performance evaluation of a multi-channel constant-fraction discriminator (CFD) designed for delay-line position-sensitive microchannel plate detectors in atom probe tomography systems. The proposed architecture incorporates a zero-crossing level adjustment circuit to mitigate timing errors caused by signal variations. Additionally, a dedicated zero-crossing level monitor enables real-time evaluation of walk compensation effectiveness, ensuring optimal timing accuracy. This architecture achieves a time walk of +/- 57 ps across the full dynamic range (100-2000 mV). Quantitative analysis identifies an optimal input range of 500-1400 mV, which minimized overall temporal uncertainties, resulting in a total timing error of 20 ps (root-sum-square, RSS) accounting for both time walk and jitter. Experimental validation demonstrates that the discriminator sustains sub-20 ps timing resolution across a range of detection event amplitudes. These results meet the critical requirements of high-precision time-of-flight mass spectrometry and ion projection imaging applications.

We present a Faraday Cup Array (FCA) beam profile monitor designed for rapid monitoring of high-intensity direct current ion beams. The monitor consists of 2112 small Faraday cups (FCs) arranged uniformly in a grid pattern over an area of 89.2 × 89.2 mm2. These FCs are arranged in rows and columns, forming 64 independent channels, which are evenly split into 32 x-channels and 32 y-channels, with each channel comprising 33 FCs. Each channel is connected to an independent channel of a 64-channel picoammeter, allowing all channels to conduct current measurements simultaneously and independently. The monitor is capable of directly detecting the projections of beam current distribution in both horizontal and vertical directions with a spatial resolution of 2.75 mm within 1 s. We tested it using He2+ beams with energies of 120 and 200 keV, corresponding to beam powers of 15 and 27.5 W, respectively. The temperature increases on its front and back sides were monitored during the test. We also studied the thermal conduction and temperature rise through simulations when it was exposed to ion beams.

We probe the production of single and double K-shell vacancies in xenon atoms during symmetric collisions with Xe54+ ions at 95, 146, and 197 MeV/u at the heavy-ion storage ring equipped with an internal gas-jet target. For each collision energy, the xenon K alpha x-ray spectra are measured at five observation angles, ranging from 35 degrees to 145 degrees with respect to the projectile beam. To resolve the measured Xe target K alpha x-ray spectra into four Gaussian peaks, including the hypersatellites and satellites of the K alpha 2,1 lines, we develop a data-analysis method that reduces the fitting parameters from 12 to 6. The determined intensities of the hypersatellites and satellites, which shows no significant radiation anisotropy, are subsequently used to calculate the cross-section ratio R21 for double-to-single K-shell vacancy production in the Xe target atoms. The obtained R21 values decrease from 0.286 f 0.036 to 0.176 f 0.021 as the collision energy increases. We compare these experimental results to relativistic time-dependent two-center calculations and find reasonable agreement between the theoretical predictions and the experimental data.

The saturated internal kink mode with m/n = 1/1 has been observed in the H-mode discharge of the experimental advanced superconducting tokamak, characterized by high βP and weak magnetic shear in the core. This observation was made using a combination of soft x-ray imaging and electron cyclotron emission diagnostics. It was noted that the repetitive bursting of m/n = 1/1 internal mode (large amplitude, short bursting duration) transitions into a long-lasting continuous one (small amplitude, constant frequency), when βp> 2.2 in H-mode, a much shorter bursting duration, transitioning into a long-lasting continuous one, with smaller amplitude and a constant frequency. Conversely, for typical βp< 1.5 in L/I discharge, the frequency of m/n = 1/1 mode decreases with time, associated with local poloidal electron diamagnetism drift velocity. The benign m/n = 1/1 mode in high βp has an amplitude much smaller than one in L-mode for high βP stabilization effect. By adjusting the power deposition of electron cyclotron resonance heating, it is found that the saturation level of m/n = 1/1 mode is independent of the local electron temperature gradient in H-mode discharge. It underscores that the flat current and, hence, weak magnetic shear are crucial factors influencing the saturation level of the m/n = 1/1 mode for both the off-axis electron cyclotron current driving current-dominant and off-axis bootstrap current-dominant cases. Furthermore, the outward movement with growth of the m/n = 1/1 mode in the process of L-H mode transition and the characteristic time of this process are close to the current diffusion time.

Objective Xe-129(q+) ( q=17, 20, 23, 25, 27) highly charged ions with a kinetic energy of 1360 keV are incident on the surface of metal Al and Ti solid targets respectively. The near- infrared spectral lines ( 800 - 1700 nm) of excited Xe atoms and low ionized Xe ions, and the spectral lines of excited target atoms and excited by ionization are measured during the interaction between the highly charged ions and the surface to achieve surface electron neutralization. The experimental results show that during the process of high charged ion incident on the metal surface, the potential energy carried by the ion instantly (in the femtosecond range) deposits on the target surface, ionizing and exciting the target atoms. Due to the strong Coulomb potential energy, the target atoms can form a highly ionized state and complex electronic configuration to de-excite the emission spectrum. As the charge state of the incident ion increases, the measured spectral line intensity rises, and the increasing trend is generally consistent with the growing trend of the potential energy of the incident ion, which indicates that the classical over-the- barrier model is valid in the near Bohr velocity energy region. We also hope that our experimental data can provide basic support for related research and provide new methods for spectral measurement. Methods The experiment is performed at the Heavy Ion Research Facility in Lanzhou (HIRFL) and the experimental platform is shown in Fig. 1. Gaseous Xe-129 atoms repeatedly collide with electrons in an 18 GHz microwave field in the ECR, gradually peeling off to form highly charged Xe-129(q+) ions. They are introduced at the required voltage for the experiment, and the required projectile ions are selected by analytical magnets based on the charge-to-mass ratio. The beam spot is controlled to be less than 5 mm using a beam splitter, quadrupole lens, and aperture, and the beam intensity is recorded via a Faraday tube. The beam enters a metal ultra-high vacuum chamber with magnetic shielding (vacuum degree maintained at 10- 8 Pa). The chemical purity of sample Al or Ti is 99.99%, and the surface has been purified with a target area of 15 mmx15 mm and thickness of 0.1 mm. The infrared optical window and monochromator incident slit are perpendicular to the beam direction and form a 45 degrees angle with the target surface. The experiment employs an infrared spectrometer SP-2357 produced by ARC (Action Reserve Corporation) in the United States, with a grating density of 600 g/ mm and a flashing wavelength of 1.6 mu m. The InGaA-C detector is selected with an effective range of 800-1700 nm and an integration time of 3000 ms. To improve the signal-to- noise ratio and measurement accuracy, we adopt a phase-locked amplifier (SR830) and a chopper ( SR540). Additionally, we have to operate in the darkroom or the dark cover screening to eliminate or reduce the background of spectral measurement. Results and Discussions The near-infrared spectral lines ( 800 - 1700 nm) emitted from the interaction between high charge state Xe-129(q+) (q= 17.27) and metal solid targets are measured (Table 1). These spectral lines can be adopted in the research on the damage of space-charged particles to aerospace devices, high-precision optical clocks, and in the infrared background radiation of the universe in laboratory astrophysics. Xe ion emission near-infrared is an important basis for manipulating Hall thrusters, with space stations performing attitude calibration and other actions in space. Under the action of highly charged ions, it is possible to ionize and excite transitions between complex configurations of target atoms, and electric dipole forbidden transitions (magnetic dipole and electric quadrupole transitions). Additionally, we measure spectral lines of 842.42 nm and 1525.03 nm for helium like (Al XII) Al ions (i. e. Al11+) radiation, and 1251.08 nm for lithium like (Al XI) Al ( Al10+) ions, which belong to electric dipole transition radiation. The 989.01 nm spectral line for Ti XVIII (i. e. Ti17+) de-excitation radiation belongs to magnetic dipole transition radiation. To our knowledge, these spectral lines are predicted by theoretical predictions from 1987 and 2013, and there have been no reports of experimental data so far. The classical over-the-barrier model for the interaction between highly charged ions and metal solid targets in the Bohr velocity energy region has been validated. The trend of single particle fluorescence yield increasing with the potential energy of the incident ion is measured, which is roughly the same as the charge state trend of the incident ion rising with the potential energy ( Fig. 3). The classical over- the-barrier model suggests that the charge state of the incident ion plays an important role in the ionization excitation of the target atom and the neutralization process of the target electron captured by the incident ion. Conclusions Highly charged ions are incident on a metal solid target surface and deposit the carried energy in the nanospace of the target surface within the femtosecond time scale, which ionizes and excites the target atoms and results in the emission of spectral lines. Some of the spectral lines are transitions between complex electronic configurations, leading to strong electric dipole forbidden transitions. There have been no experimental data reports on the 842.42 nm and 1525.03 nm spectral lines emitted by helium-like Al ions, as well as the 1251.08 nm spectral lines emitted by lithium-like Al ions, and the 989.01 nm spectral lines of Ti XVIII (i. e. Ti17+) ion de- excitation radiation since the theoretical calculation results were published in 1987. The relative intensity of the spectral lines (single ion fluorescence production) we measure increases with the growing charge state of the incident ion, and the increasing trend is generally consistent with the potential energy trend of the incident ion increasing with the charge state. This indicates that the classical over-the-barrier model holds true in the energy region of the incident ion s kinetic energy near the Bohr velocity. The research methods for elastic and inelastic scattering caused by collisions between ions and gas target atoms are different. Due to many novel phenomena generated by highly charged ions incident on solid surfaces, such as the controversy over Auger and ICD processes, the energy shift caused by multiple ionization of target atoms, and the dissipation channels of total energy and gain energy of incident ions, a large quantity of work should be done. Meanwhile, we sincerely hope that our study can provide basic data and support for related research, and propose new methods for spectral measurement.

We studied the nonradiative double-electron capture in collisions of 95, 146, and 197 MeV/u / u Xe54+ 54 + ions with Kr and Xe atoms by measuring the x-ray intensity ratios I (1 s 'n p-* 1s2)/I('np s 2 ) / I ( 'n p-* 1s) s ) ('n 'n = 2, 3, and 4) of the resulting Xe52+& lowast; 52 +& lowast; and Xe53+& lowast; 53 +& lowast; ions. It was found that the double-electron capture becomes more important with decreasing projectile energy, although the single-electron capture is always dominant. At the lower energies of 95 and 146 MeV/u / u the intensity ratios I (1 s 2 p-* 1s2) s 2 ) : I (1 s 3 p-* 1s2) s 2 ) : I (1 s 4 p-* 1s2) s 2 ) of Xe52+& lowast; 52 +& lowast; ions were found to be nearly identical to the ratios I (2 p-* 1s) s ) : I (3 p-* 1s) s ) : I (4 p-* 1s) s ) of Xe53+& lowast; 53 +& lowast; ions for the Kr target, which implies that the double-electron capture can be regarded as two uncorrelated one-electron capture processes, whereas this feature disappears for the heavier Xe target. It was also found that at 95 and 146 MeV/u / u the relative double-electron capture intensity for Xe54+ 54 + + Xe collisions is significantly larger than that for Xe54+ 54 + + Kr collisions. We speculate that the resonant electron transfer plays an important role in the symmetric Xe54+ 54 + + Xe collisions and the double-electron capture therein cannot be regarded as two independent one- electron capture events.

BackgroundCompton imaging technology is a new radiation hotspot location technology that does not require collimation and has a wide field of view, high efficiency, and broad application prospects. With the development of nuclear technology, Compton cameras with the above-mentioned advantages have a wide range of applications not only in the nuclear industry but also in the field of nuclear medicine, hence recently become a popular research field worldwide.PurposeThis study aims to develop a double-layer separated Compton camera for far-field imaging of specific radiation scenes in nuclear facilities.MethodsFirst of all, two pixel-type cadmium zinc telluride (CZT) detectors and an application-specific integrated circuit (ASIC)-based readout electronics system were adopted for the development of a double-layer separated Compton camera. A list-mode maximum likelihood expectation maximization (LM-MLEM) image reconstruction algorithm was implemented in the host computer software. Then, 137Cs point source was used for experimental test of imaging performance of the system, and the parameters affecting the imaging performance, such as the detector layer spacing and area of the absorption layer, were optimized. Finally, far-field three-dimensional imaging of the radiation source was performed by moving the measuring position of the detector.ResultsThe test results show that the energy resolution of the CZT detectors is approximately 3% (FWHM@662 keV), which can determine the location of the point source at a distance of 5 m, and the angular resolution for θ and φ directions of the optimized system is approximately 10°.ConclusionsDouble-layer separated Compton camera of this study has advantages of adjustable structure, low detector cost, relatively simple readout electronics, and wide imaging field of view. The angular resolution of this double-layer separated Compton camera can be improved by proper adjustment of the imaging influence parameters (such as layer spacing and the area of the absorption layer).

This paper first introduced the load sensing hydraulic system and elaborated on its load feedback, pressure cut-off, and constant power control principles. Moreover, based on the response hysteresis of the load sensing hydraulic system in the actual commissioning of the project, this paper proposed the possible influence of the sensor on the response of the hydraulic system through troubleshooting analysis. Third, experiments were conducted to obtain the system dynamic response curves given different sensor positions and to prove the hypothesis. Meanwhile, the influence mechanism and improvement measures were analyzed. Finally, the optimal installation positions of the sensor based on different operating conditions were discussed.

In this paper, a novel MEMS defect detection sensor based on Lorentz force is designed. The bow beam structure is proposed, 3D model is established by COMSOL Multiphysics 6.0, and a multi-objective optimization of the sensor structural parameters is carried out using the NSGA-II algorithm and MOPSO algorithm. The simulation results show that, the stability of the sensor optimized by the MOPSO algorithm is improved by 56.14 and 87.48

We measured the angular distribution of the subsequently emitted Lyman- α 1 transition of Xe 53+* ions following nonradiative electron capture in collisions of 197 MeV u −1 Xe 54+ projectiles with gaseous krypton target. The alignment of the projectile 2 p 3/2 state and the relative population of its magnetic substates were further deduced. In contrast to the available lower energy results (Yang et al 2020 Phys. Rev. A 102 042803), it is found that at 197 MeV u −1 the Lyman- α 1 radiation becomes much less anisotropic and the magnetic substates are nearly statistically populated. Moreover, the experimental findings are compared with the results of the corresponding radiative electron capture mechanism, obviously different energy dependence of the magnetic-substate population is obtained and discussed using semiclassical arguments, which help reveal the population mechanism of excited states in collisions of highly charged high- Z ions with atoms.

In this paper, K-shell X-ray spectra of nitrogen are measured by the interaction of Nq+ (q = 3, 5) ions with Al and Cu surfaces in the impact energy range of 25–100 keV. K-shell X-ray yields per incident ion and then ionization cross sections are deduced from the measured K-X-ray spectra. It is found that both the yields and cross sections increase quickly with increasing impact energy, but have no apparent dependence on the target material and the charge state of the incident ion. The experimental results reveal that the incident Nq+ (q = 3, 5) ions have been neutralized and achieved a charge-state equilibration before the K-shell electron is ionized. The experimental ionization cross sections are compared with those from the plane wave Born approximation (PWBA) and the classical binary encounter approximation (BEA) theory. The BEA calculations are better consistent with the experimental data than the PWBA. It means that the K-shell ionization of the incident Nq+ (q = 3, 5) ions is due to the direct Coulomb excitation processes that occurred below the target surface. K-shell ionization cross sections of Nq+ ions incident on an Al target. The theoretical calculations of BEA and PWBA models are also shown for comparison

Fast beam range measurements are required to maximize the time available for patient treatment,given that the beam range requires verification with respect to quality assurance to maintain accelerator commissioning standards and ensure patient safety.A novel beam range monitor based on a plastic scintillator and multi-pixel photon counter(MPPC)arrays is therefore proposed in this paper.The monitor was constructed using 128 plastic scintillator films with a thickness of 1 mm and an active area of 50×50 mm2.A customized MPPC array read the scintillation light of each film.The advantage of dividing the active detector volume into films is that it intercepts the particle beam and enables direct differential light yield measurement in each film,in addition to depth-light curve generation without the need for image analysis.A GEANT4 simulation,including scintillator quenching effects,was implemented,and the results revealed that Birks'law exhibited a slight little influence on the position of the beam range,only changing the shape and absolute normalization of the Bragg curve,which is appropriate for the calculation of the beam range using the depth-light curve.The performance of the monitor was evaluated using a heavy-ion medical machine in Wuwei City,Gansu Pro-vince,China.The beam range measurement accuracy of the monitor was 1 mm,and the maximum difference between the measured and reference ranges was less than 0.2％,thus indicating that the monitor can meet clinical carbon ion therapy requirements.

The spectra emitted by highly charged ions, which are abundant in laboratory plasma and stellar systems, cover a wide range of wavelengths from near-infrared to x-rays. Measurements on such spectral lines can provide plasma information such as the electron temperature, electron/ion density, chemical composition, and the evolution of these parameters. To simulate the x-ray emission from comets and other celestial bodies irradiated by solar wind ions in the laboratory, we established an experimental platform for x-ray measurements at Institute of Modern Physics, Chinese Academy of Sciences, and measured the x-ray emission spectra from a series of metal and silicate minerals bombarded by slow highly charged nitrogen and oxygen ions. In this paper, we describe the x-ray measurement platform in detail and report the x-ray emission caused by the interaction of 1.5–20 keV/q Oq+ (q = 3, 5, 6) and Nq+ (q = 3, 5) ions with nickel surface. It is discovered that the measured x-ray yield and production cross section increase rapidly as increasing the impact energy, but have no discernible dependence on the charge state of incident ions. The experimental results reveal that the incident ions have been neutralized and achieved charge state equilibration before the K-shell electron is ionized. When the incident energy is greater than 5 keV/q, the Binary Encounter Approximation calculations are consistent well with the experimental data, indicating that the K-shell ionization of incident ions is due to direct Coulomb excitation processes that occur below the target surface. However, the experimental ionization cross sections clearly deviate from the Binary Encounter Approximation calculations when the impact energy is less than 5 keV/q. The discrepancy at the low collision energy is discussed and explained based on a multi-electron excitation model.

We report on the K X-ray emission for 9–140 keV oxygen ions with initial charge states from 3 to 7 approaching a copper surface. The peak center of the measured X-ray spectrum slightly shifts towards higher energies with the increasing of the initial charge state of the incident ions. For the collisions of oxygen ions with no K-vacancies (q = 3–6), the X-ray yield per incident ion increases gradually with the projectile’s kinetic energy, while for the O7+ ions (with a K-vacancy) it is nearly independent of the energy. The K-shell ionization cross-sections for the oxygen ions with no K-vacancies obtained from the experiments are well consistent with the calculations of the binary encounter approximation model when the collision energy is larger than 30 keV, whereas they are several times larger than the theoretical values at collision energies of less than 30 keV.

We present an experimental study on the double K-shell ionization of argon in single collisions with the Xe54+ ion at 197 MeV/u. The X-ray spectra of multi-ionized argon are measured at the observation angles of 90° and 145° with respect to the projectile beam. The target K X-ray satellite and hypersatellite lines are analyzed with a fitting model and the cross-section ratio of double to single K-shell ionization is derived. The experimental results are compared to the relativistic time-dependent, two-center calculations, and a reasonable agreement is reached.

The study of the interaction between highly charged ions and solid surfaces not only has great significance for basic scientific research such as atomic physics, astrophysics, and high energy density physics but also has promising application prospects in biomedicine, nanotechnology, surface analysis, and microelectronics. In this paper, the intermediate Rydberg states formed during highly charged O7+ and N6+ ions incident on Al surface are studied theoretically by using the two-state vector model. Both the probability of electron capture into different Rydberg states (nA = 2 − 7) and the most probable neutralization distances are given. The calculation shows that the larger principal quantum number nA is relevant to smaller probability. Therefore, the X-rays emitted by O7+ and N6+ ions incident on the Al surface come mainly from the de-excitation of the smaller nA to the ground state. In order to confirm the calculations, we measured the X-ray emission spectra of O7+ and N6+ ions in collisions with the Al surface in the energy range of 3-20 keV/q. The experiments were performed at an ECR ion source located in Institute of modern physics. We also calculated the transition energies (np-1s) from different high Rydberg states to the ground state by using the FAC code. The center of the measured K X-ray peak is close to the calculated transition energy from the principal quantum number n=2 to n=1, it is consistent with our results obtained by the two-state vector model as well. In addition, we found the experimental K X-ray yield for O7+ ions incidence at lower energy collisions is almost the same with N6+ ions, but larger at higher energy collisions. When the ion incident kinetic energy is low, the X-ray emission is mainly owing to the decay of “above the surface”hollow atoms. Because of the small difference in the critical distances for the capture of electrons by O7+ and N6+ to form hollow atoms, the X-ray yields produced in both cases are almost the same at low energy collisions. In contrast, as increasing the incident energy, the ions have a long-range in the target, so the contribution from the decay of “above the surface” and “below the surface”hollow atoms need to be considered at the same time.