Stopping cross-section curves with 1.7% uncertainty are obtained for He stopping in Au and Ni at the Bragg peak (∼1.5MeV). This is achieved by developing a novel Bayesian approach to analyze the stopping in the two target elements at once. First, the most probable stopping curves are distilled by fitting the available data in the IAEA database for the individual elements. Second, the ratio of the stopping in the two target elements is acquired with Rutherford backscattering spectrometry (RBS). Finally, this ratio is used to refine the literature curves and to simultaneously reduce the uncertainties in both targets.
Chondrites preserve records of early solar system processes, but their heterogeneous lithologies and terrestrial alteration can obscure primary signatures. In this study, micro-PIXE mapping is applied to a carbonaceous chondrite with CM-like characteristics, utilizing a magnetic deflector system to enable detection of light elements including C, N, O, F, and Na, extending the analytical reach of conventional PIXE to elements critical for volatile chemistry and parent-body interpretation. Regions of interest (∼35 µm) were selected from Na, S, O, and P elemental maps, with concentrations normalized to Na to evaluate relative enrichment patterns. Distinct compositional domains were successfully resolved, including Fe-S-rich regions with elevated Fe/Na and S/Na ratios, Mg-Al-Si-rich silicate-dominated areas, Ca-P-bearing regions consistent with phosphate phases, and carbonaceous domains enriched in C, N, and O. Fluorine enrichments are consistent with halogen-bearing phases, and consistently low Cl/Na ratios suggest localized volatile mobility. Complementary 2 MeV analysis extended the elemental range from Al through Rb, detecting siderophile and trace elements including Co (928 ± 89 ppm), Ni (3,879 ± 24 ppm), Zn (204 ± 7 ppm), and Rb (189 ± 30 ppm), with Fe/Ni ratios of 5.84 and 7.63 from spot analysis consistent with kamacite-like compositions reported for carbonaceous chondrites. The pronounced microscale heterogeneity contrasts with the homogeneous elemental distribution reported for Ryugu samples returned by Hayabusa2, consistent with a more advanced stage of secondary processing. These findings demonstrate the significant potential of dual-energy micro-PIXE for characterizing microscale elemental heterogeneity in meteoritic material, with complementary mineralogical techniques needed for definitive phase identification.
A high-throughput ion beam focusing system consisting of two Louisiana magnetic doublets (LMD) was developed for use in an ion microprobe beamline of a 3MV single-ended Pelletron accelerator. The original system consisted of a single LMD with a demagnification of 50 × 14 at an 18 cm working distance. An additional LMD was installed in a separated quadruplet configuration, spaced 0.864 m apart, to optimize the focusing system. This provided an orthomorphic demagnification of 96 × 96 at an 18 cm working distance, increased the beam current by a factor of 6 and had a minimum beam spot size of 487 × 516 nm2. This manuscript describes theoretical simulations and experimental results demonstrating the high demagnification and current density of the new system for single doublet, separated triplet and separated quadruplet configurations. Focusing and imaging capabilities were tested on 2000 mesh grids, archaeological, biological and electronic device samples.
X-ray fluorescence (XRF) spectrometry is widely used in quantitative analysis because it is fast, reliable, and non-destructive. However, challenges such as matrix effects, spectral overlap, background interference, and the need for suitable standards can make quantitative XRF analysis difficult, motivating the use of machine learning models that learn composition spectrum relationships from representative datasets. Normalized characteristic peak areas extracted from XRF spectra were used as input to predict the elemental compositions of stainless steel samples. Artificial neural network (ANN), random forest (RF), and support vector regression (SVR) algorithms were trained with datasets generated from Monte Carlo simulations. All trained models were validated using experimental XRF spectra. All models demonstrated compatibility with experimental results, with the ANN emerging as the most effective model, particularly for trace elements. These results demonstrate the feasibility of using simulation-generated datasets to train machine learning models and reduce reliance on extensive experimental data.
Ion beam analysis can determine the lithium quantity and distribution in lithium-ion batteries non-destructively. When a He ion beam is used for time-of-flight elastic recoil detection analysis (TOF-ERDA), high depth resolution can be achieved because of the low energy loss (energy straggling) of He ions. In addition, quantitative lithium analysis is possible from the surface to deeper regions of the sample.The He-Li scattering cross sections deviate from the Rutherford values in the several-MeV energy region. Although several studies have reported He-Li scattering cross sections, data at forward scattering angles remain limited. In this study, we measured the differential cross sections for the 4He-7Li reaction by detecting 7Li recoils at a scattering angle of 40.0° using a 1.5–5.0 MeV He beam, and for the 4He-6Li reaction by detecting 6Li recoils at a scattering angle of 36.9° using a 2.3–5.0 MeV He beam.
This work presents the measurement of the stopping power for 12C ions in 4He gas in the energy range between 1 and 40 MeV. The indirect experimental technique used here is based on the measurement of the residual energy of a 12C ion beam of fixed energy, crossing a fixed length inside the gas at different pressures. A curve of the gas thickness (mg/cm2) is constructed as a function of the residual beam energy and subsequently differentiated to obtain the stopping power. The experimental results have been compared with the stopping power calculated by two of the most widely used codes SRIM and MSTAR.
The three-layer structure RFQ linac features a simple structure and fabrication method while providing excellent electrical performance. The main components of the four-vane RFQ cavity (four vane electrodes and the cavity body) are divided into three parts, and machined with high precision from blocks of oxygen-free copper. Since no thermal processes such as brazing or welding are required, the machining accuracy of the vane electrodes is preserved. It has therefore been adopted for heavy-ion therapy injectors and proton accelerators for compact neutron sources. As an advanced development, a tuner-less frequency adjustment technique has been realized. Furthermore, the development of the energy-tunable cavity addresses the inherent limitation of RFQs in beam energy variability.
Electron beam accelerators are widely used for cable irradiation. Nevertheless, conventional ’8′-shaped winding layouts and insufficient cable rotation lead to uneven circumferential dose distribution, and electron beam energy outside the target region is largely wasted. This work proposes a Permanent Magnet Array Bending System (PMABS) to simultaneously improve irradiation uniformity and recycle wasted beam energy. The PMABS comprises an assistive magnet and a dipole magnet. Both magnets adopt an array of permanent magnets combined with specially profiled iron parts to produce the desired magnetic fields. Beam dynamics simulations show that the beam spot radius remains uniform along the horizontal x-axis. Although slight variations exist along the vertical y-axis, they are all within acceptable ranges. The PMABS can effectively reclaim wasted beam energy and improve cable irradiation uniformity, which provides a feasible technical solution for industrial electron beam irradiation of cables.
Lanthanide-doped Ca3(Nb/Ga)5O12-type disordered single crystals are promising media for high-power lasers with ultrashort pulse durations. In this work, planar optical waveguides in lithium-modified Yb:Ca3(Nb/Ga)5O12 single crystals have been fabricated by O or F room temperature irradiations using 20 MeV of energy and a fluence of 1 × 1015 at/cm2. The produced waveguides show 7 dark modes in the O case and 6 dark modes in the F one, monitored at λ = 632.8 nm. Light confinement is induced by a ≈3–4% drop of the refractive index at ≈4–4.5 µm of depth, which is primarily associated to electronic damage for both irradiations. The irradiation induces some crystal colouration that is largely eliminated by air annealing in the 150–600 °C temperature range. This post-irradiation annealing reduces the waveguide propagation losses at λ = 632.8 nm of F-irradiated samples down to 1.8 dB/cm while maintaining the spectrally broad nature of the Yb3+ fluorescence.
Alloy 800H/Ni interfaces are relevant to structural materials for advanced high-temperature nuclear systems, where irradiation-induced defects and interfacial cavities can degrade mechanical performance. Here, molecular dynamics (MD) simulations were used to investigate displacement cascade evolution and post-irradiation tensile behavior in 800H/Ni interfaces containing interfacial nanovoids with radii of r = 1–4 nm. Displacement cascades were simulated at 1000 K using primary knock-on atom (PKA) energies of EPKA= 1, 5, and 10 keV. The simulations reveal asymmetric defect retention across the interface, with a higher surviving defect density in the 800H region than in Ni. Void evolution is strongly size dependent, i.e., r≤2nm undergoes substantial recombination-assisted shrinkage during cascade relaxation, whereas r>2nm remains stable and promotes strain localization during subsequent tensile loading. Corresponding changes in Young’s modulus (E) and ultimate tensile strength (UTS) correlate with the residual void morphology and surviving defect population following irradiation. A physics-informed machine-learning (PIML) framework trained on MD-derived descriptors predicts E and UTS and identifies void size and residual void morphology as the most influential predictive features. This integrated MD–PIML approach links irradiation-induced microstructural evolution to the mechanical response in 800H/Ni interfaces.
We report the development and validation of a Medium Energy Ion Scattering (MEIS) system at the University of Helsinki, based on a toroidal electrostatic analyzer (ESAR120) operating in the 50–500 keV energy range, bridging the analytical gap between surface-sensitive Low Energy Ion Scattering (LEIS) and Rutherford Backscattering Spectrometry (RBS). The system achieves a total energy resolution of 320 eV, a solid angle of ∼5×10−4 sr, and supports scattering angles from 60° to 165°. Performance was validated using HfO2/Al2O3 nanolaminates with layer thicknesses of 2.8–5.7 nm prepared by atomic layer deposition (ALD). Experimental spectra acquired with 120 keV He+ ions are in good agreement with PowerMEIS simulations, resolving individual layers down to 2.8 nm, with residual discrepancies at peak edges attributed to finite system energy resolution and stopping power approximations. The system fills a critical analytical gap within the ion beam analysis suite at the University of Helsinki, providing a quantitative tool for compositional depth profiling of ultrathin films with nanometer-scale depth resolution.
Radiation-induced defect formation in fluoride crystals such as magnesium fluoride (MgF2) has been extensively studied due to its importance in optical systems operating under extreme radiation environments. Under irradiation by gamma rays, electrons, neutrons, and energetic ions, these materials exhibit ionoluminescence (IL) associated with the formation of vacancies and color centers. The study of this IL produces valuable insight into the mechanisms governing radiation-induced damage. In this work, we present a novel in-situ optical monitoring system capable of continuously tracking IL emissions during irradiation with high temporal resolution, enabling direct observation of defect evolution in real time. Using this system, IL response of MgF2 under different ion irradiations spanning a range of electronic stopping powers (0.15 to 3 keV/nm) was investigated. The results reveal a strong dependence of the emission spectra on the stopping power of the incident ions, highlighting the critical role of local energy deposition in the formation and evolution of luminescent defect centers. These findings demonstrate the potential of real-time IL monitoring as a powerful operando technique for studying radiation-induced dynamic defects in fluoride materials as well as possible non-studied transition between emission bands in MgF2.
Prior AMS measurements at ASTER, beryllium oxides (BeO) samples are mixed with metal conducting powder and packed in copper target to improve ionisation efficiency.Several tests were performed at LN2C, the National Laboratory of Cosmogenic Nuclides in France, to monitor the behaviour of 9Be current - including intensity, stability and longer-lived ion beam current performance - for various Nb (or Fe)/Be ratios that can sustain measurements lasting up to one hour under routine AMS conditions.From these tests, setting an amount of 2.5 mg of niobium with variable 9Be carrier additions from 0.15 to 0.3 mg shows no variation in 9Be current during for one hour.
AMS measurements of 10Be have been the domain of conventional AMS systems with terminal voltages of 3 MV or higher. However, low energy AMS systems operating at terminal voltages of less than 300 kV offer substantial potential for 10Be analysis. We describe the Multi Isotope Low Energy AMS System (MILEA), a novel AMS system based on a 300 kV vacuum insulated HV platform for its performance of 10Be measurements. Charge exchange processes, molecular break-up reactions, as well as ion detection and identification processes are discussed. Charge state distribution measurements reveal an unexpected increase of the Be2+ charge state yield below 200 keV ion energy which is not observed for B2+ ions of the same energy. This increases overall detection efficiencies and enhances isobar suppression. The coulomb explosion at lower energies of the injected BeO− ion during the stripping process causes increase energy spread in addition to the energy loss straggling. This results in additional tailing of the ion beam during transport through subsequent dispersive beam optical elements. Nevertheless, the presence of a SiN degrader foil positioned after charge state analysis in combination with optimized gas ionization detectors offers sufficient isobar suppression capability to acieve background levels well below 5x10−15. Tests of the system under routine operation conditions using accepted AMS 10Be standards show the high reproducibility and demonstrate the excellent performance of the system.
We present Millipede, a new facility for particle radiobiology research at the 6MV Tandetron accelerator at the Helmholtz-Center Dresden-Rossendorf. The setup was developed for in vitro irradiation with multiple ion species over a broad linear energy transfer (LET) range and combines microscopy-based sample positioning, scanned field delivery, and downstream single-particle detection. Its performance was evaluated using clonogenic survival and γH2AX/53BP1 immunofluorescence staining after irradiation with 10 MeV protons, 16 MeV helium, and 35 MeV boron ions. Additional proof-of-principle foci measurements were performed with lithium and carbon ions. The biological data showed clear LET-dependent trends. Proton irradiation produced survival characteristics like the X-ray reference, while helium and boron ions had steeper survival curves and increased biological effectiveness. DNA damage foci imaging showed increasingly clustered damage patterns with increasing LET. These results demonstrate the feasibility and reproducibility of radiobiological experiments at Millipede and establish the beamline as a robust platform for future particle beam research.
This technical report documents the comparison and validation of proton-beam measurements performed at the Paul Sherrer Institute (PSI) Proton Irradiation Facility (PIF) with MRADSIM simulations for Martian regolith simulants once processed by Spark Plasma Sintering at the University of Cagliari. Thin targets of two regolith formulations (MGS-1 and JEZ-1) with thicknesses of 2mm and 3mm were irradiated under multiple degrader settings, spanning approximately 30–151MeV proton energies at the regolith surface. Experimental detector-response spectra were calibrated using regolith-free reference runs, and peak energies were extracted using Gaussian fits. The PIF geometry was imported into MRADSIM toolkit via GDML, and the regolith simulants were implemented as composite materials. Simulated detector observables were obtained in a downstream 50mm-thick LYSO scintillator detector volume, enabling direct experiment–simulation benchmarking of the peak deposited energy and the transmitted-proton fluence. In addition, several Geant4 hadronic physics lists were evaluated using a reduced chi-square (χ2/ν) analysis to select a robust baseline model for regolith transport within the validated energy range.
In recent years, the magnet section at the Paul Scherrer Institute (PSI) has considerably strengthened its expertise in the design, fabrication, and qualification of advanced magnet technologies for particle accelerators. This progress, driven by flagship initiatives such as the Swiss Light Source upgrade (SLS 2.0) and the Swiss Accelerator Research and Technology (CHART) program, has led to the establishment of key competencies in magnet design, dedicated infrastructure, and high-precision magnetic qualification. A prominent example is the SLS 2.0 upgrade, which implements a unique combination of magnet technologies: NdFeB-based permanent magnets, compact combined-function copper electromagnets, and, in a later phase, NbTi superconducting dipoles with a longitudinal field gradient. All magnets are designed, assembled, and magnetically qualified in-house to meet the stringent field-quality and alignment requirements of the new storage ring. In parallel, low-temperature (Nb-Ti, Nb3-Sn) and high-temperature (REBCO) superconducting technologies are being developed and tested in prototype magnets, including those for the PSI Positron Production experiment and for future collider projects such as FCC-ee and FCC-hh, within the framework of CHART. This paper presents an overview of PSI's recent advancements in magnet technology and discusses prospects. These developments serve both PSI's internal research programs and collaborative projects with European and international partners, paving the way for a new generation of efficient and environmentally responsible accelerator magnets.
