Acquiring and processing longitudinal beam profiles in the CERN injector complex is essential for maintaining high beam quality for both the Large Hadron Collider and fixed-target experiments. This paper describes a new and common framework across the injector chain to continuously monitor longitudinal profiles, based on digitizers connected to wall current monitors. A new software class has been developed using the Front-End Software Architecture framework to improve real-time monitoring of longitudinal beam quality along the whole beam production cycle. The new implementation supports efficient data acquisition with highly flexible configuration options, including per-profile and per-cycle settings management. This acquisition class reduces data transfer time from the hardware and enables simultaneous beam monitoring and optimization for multiple users across the CERN accelerator complex. Beyond the raw data acquisition layer, real-time processing analyses have been developed on the Unified Controls Acquisition and Processing platform to perform bunch length, bunch-by-bunch intensity, and bunch spacing measurements, and tomographic reconstruction of the longitudinal phase space to provide key longitudinal parameters such as momentum spread and emittance. This new monitoring framework paves the way for preparing and executing the filling of the LHC in an automated manner and for optimizing fixed-target cycles for physics users.

In proton therapy, the energy degradation process that occurs after the cyclotron accelerator is essential to deliver the appropriate beam energy to the patient. However, degradation of energy increases the beam divergence, leading to particle losses and activation of the surrounding material. To mitigate this divergence, a collimator is placed downstream of the degrader, but it further increases beam losses. To enhance transmission and reduce activation, a magnetic lens can be positioned after the degrader—or even replace it entirely. In this work, we demonstrate the equivalence between two deterministic methods for modeling the emittance evolution of a proton beam in a lithium-like magnetic lens, accounting for both multiple Coulomb scattering within the material and the influence of the magnetic field on charged particle trajectories. Comparisons with numerical simulations performed using the BDSIM software identify the deterministic method and scattering power that best reproduce the simulated results. Using this validated deterministic approach, we investigate improved solutions for minimizing the emittance of the primary beam. These include degraders composed of various materials, stand-alone magnetic lenses, and combined configurations. We show that a typical medical degrader can be optimized by employing a fully beryllium-based design. Further enhancement is achieved by adding a low-field (0.4 T) beryllium lens downstream of the beryllium degrader. For research applications, optimal performance is obtained with a 10 T lithium lens placed upstream of a beryllium degrader or with a lithium lens featuring a variable length at 10 T.

This work provides a new tool based on the complementarity between X-ray Photoelectron Spectroscopy (XPS) and Reflection Electron Energy Loss Spectroscopy (REELS). More precisely, this study is focused on the in situ precise determination of indium and gallium composition of self-assembled InxGa1-x nanodroplets on GaAs(111)A substrate during the first stage of III-V quantum dots growth by droplet epitaxy. An XPS intensity model based on In4d and Ga3d core levels enables the estimation of the gallium/indium ratio within the droplets under the assumption of a homogeneous droplet. On the other hand, we develop a brand new decomposition methodology of loss probabilities curves obtained from REELS spectra for droplets deposited on a substrate. The energy of InxGa1-x bulk plasmon experimentally obtained and semi-empirically modelled allows to calculate from REELS the indium-gallium composition in the droplet. Comparison between these values obtained by both XPS and REELS provides information about In/Ga mixing to grow binary InxGa1-x nanodroplets. Their good agreement shows promising results for the growth of InxGa1-xN quantum dots by droplet epitaxy for a very large range of composition.

Radiation worker dose assessment by personal dosemeters is limited by the fact that the single-point measurements may not be representative for the whole body and by practical challenges, such as workers wearing incorrectly the dosemeters or occasionally even forgetting them. Furthermore, in neutron workplaces dosemeters can significantly over- or underestimate the dose. Computational neutron dosimetry presents an alternative monitoring method. This study aims to investigate the feasibility of using computational neutron dosimetry in a real neutron workplace, namely at the Budapest Research Reactor. The Raylab DIAMON neutron spectrometer and the Berthold LB6411 ambient neutron monitor were used for rapid neutron field characterisation. By combining the measured dose rate map with a camera-based motion tracking system, it was possible to calculate the neutron dose accumulated by a worker. This study demonstrated that worker movement can be accurately tracked, provided there are no obstacles between the camera and the worker. Additionally, the dose rate mapping can be easily done and the computational neutron dosimetry can effectively estimate worker dose in real neutron workplace fields, as long the radiation field remains stable or its intensity can be scaled using the reactor power or a reference ambient dosemeter as reference. This approach has the potential to complement or even to replace the physical dosemeters, providing improved accuracy in complex neutron fields. Combining directional and spectral data from the DIAMON could also enable calculations in terms of H p (10) or effective dose.

This work provides a new tool based on the complementarity between X-ray Photoelectron Spectroscopy (XPS) and Reflection Electron Energy Loss Spectroscopy (REELS). More precisely, this study is focused on the in situ precise determination of indium and gallium composition of self-assembled InxGa1-x nanodroplets on GaAs(1 1 1) A substrate during the first stage of III-V quantum dots growth by droplet epitaxy. An XPS intensity model based on In4d and Ga3d core levels enables the estimation of the gallium/indium ratio within the droplets under the assumption of a homogeneous droplet. On the other hand, we develop a brand new decomposition methodology of loss probabilities curves obtained from REELS spectra for droplets deposited on a substrate. The energy of InxGa1-x bulk plasmon experimentally obtained and semi-empirically modelled allows to calculate from REELS the indium-gallium composition in the droplet. Comparison between these values obtained by both XPS and REELS provides information about In/Ga mixing to grow binary InxGa1-x nanodroplets. Their good agreement shows promising results for the growth of InxGa1-xN quantum dots by droplet epitaxy for a very large range of composition.

Personal neutron dosimeters often experience significant overestimation or underestimation when used in neutron fields that differ from those in which they were calibrated. This discrepancy highlights the highly field-dependent nature of these dosimeters and the necessity for precise neutron field characterisation to ensure accurate calibration and reliable dosimetry. In this study, we conducted a comprehensive neutron field characterisation at the newly constructed neutron room of the Secondary Standard Dosimetry Laboratory (SSDL) of SCK CEN, Belgium, using 252 Cf and 241 Am-Be sources. The DIAMON neutron spectrometer and Bonner Sphere Spectrometer (BSS) were employed, alongside Monte Carlo simulations. The primary objectives were to evaluate the performance of the DIAMON spectrometer against the BSS, which serve as the gold standard, and to validate the simulation model of the neutron room. The shadow cone method was utilised to separate direct and scattered neutron components. Monte Carlo simulations using the PHITS code, which mimicked the actual neutron room geometry, materials, and sources, were conducted to develop the neutron room model which is validated by the measurements. Analysis of neutron ambient dose equivalent rates from both sources, in terms of direct neutron under controlled scatter conditions (in this case, below 3 m), revealed that DIAMON measurements agreed with LNK reference values within a 16% margin. The deviations of BSS measurements and PHITS simulations from the LNK reference values were kept within 19% and 10%, respectively. These findings demonstrate the reliability of the DIAMON spectrometer and the robustness of the PHITS simulation model.

Vertical fixed-field accelerators (vFFAs) feature a magnetic field that increases exponentially in the vertical direction, resulting in vertically stacked nonplanar orbits. Their magnetic field is highly nonlinear, and their solenoid and quadrupolar components induce strongly coupled optics. The detailed study of their beam dynamics must account for the transverse motion linear and nonlinear coupling. Specifically, the study of linear beam dynamics requires adequate coupling parametrizations, and the study of nonlinear beam dynamics, including the characterization of the dynamic aperture (DA), must be performed in the full 4D phase space. The zgoubi ray-tracing code is ideally suited to study the vFFA transverse dynamics, as it can perform step-by-step particle tracking in vFFA complex geometry and magnetic fields. This paper provides an in-depth study of the vFFA prototype ring designed under the ISIS-II proton driver prototype project to accelerate proton beams from 3 to 12 MeV. The magnets of this vFFA ring exhibit slow magnetic field falloffs, resulting in a significant influence of the neighboring cells on the optical lattice parameters. The determination of stable orbits and tunes requires superimposing 3D magnetic field maps in zgoubi to account for the neighboring cell residual fields. The study of nonlinear beam dynamics revealed the appearance of fourth-order stability islands. A complete characterization of the DA in the 4D phase space was conducted to give a measure of the stability domain and characterize the performance and limitations of this lattice. This study paves the way for further validation studies with experimental data and field maps.

Abstract Background Developments in transarterial radioembolization led to the conception of new microspheres loaded with holmium-166 (166Ho). However, due to the complexity of the scatter components in 166Ho single photon emission computed tomography (SPECT), questions about image quality and dosimetry are emerging. The aims of this work are to investigate the scatter components and correction methods to propose a suitable solution, and to evaluate the impact on image quality and dosimetry including Monte-Carlo (MC) simulations, phantom, and patient data. Methods Dual energy window (DEW) and triple energy window (TEW) methods were investigated for scatter correction purposes and compared using Contrast Recovery Coefficients (CRC) and Contrast to Noise Ratios (CNR). First, MC simulations were carried out to assess all the scatter components in the energy windows used, also to confirm the choice of the parameter needed for the DEW method. Then, MC simulations of acquisitions of a Jaszczak phantom were conducted with conditions mimicking an ideal scatter correction. These simulated projections can be reconstructed and compared with real acquisitions corrected by both methods and then reconstructed. Finally, both methods were applied on patient data and their impact on personalized dosimetry was evaluated. Results MC simulations confirmed the use of k = 1 for the DEW method. These simulations also confirmed the complexity of scatter components in the main energy window used with a high energy gamma rays component of about half of the total counts detected, together with a negligible X rays component and a negligible presence of fluorescence. CRC and CNR analyses, realized on simulated scatter-free projections of the phantom and on scatter corrected acquisitions of the same phantom, suggested an increased efficiency of the TEW method, even at the price of higher level of noise. Finally, these methods, applied on patient data, showed significant differences in terms of non-tumoral liver absorbed dose, non-tumoral liver fraction under 50 Gy, tumor absorbed dose, and tumor fraction above 150 Gy. Conclusions This study demonstrated the impact of scatter correction on personalized dosimetry on patient data. The use of a TEW method is proposed for scatter correction in 166Ho SPECT imaging.

Particle tracking codes such as MAD-X or TRANSPORT commonly use a matrix formalism to propagate beams through magnetic elements as it simplifies the analysis of particle behavior, facilitates beam optimization and component design, and enables accurate particle accelerator simulations. However, these codes are inefficient when tracking many particles or accounting for energy degradation along the beamline. To overcome these limitations, we introduce Georges, a Python library used in the field of particle accelerators for medical applications comprising two modules: Manzoni and Fermi. Manzoni is an efficient particle tracking code that can track many particles while calculating beam losses and energy degradation using the Fermi–Eyges formalism implemented in the Fermi module. In this paper, we present the implementation details of Georges, which includes a verification conducted against other software tools such as MAD-X and BDSIM, along with a documentation on computational time.

This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material.

Next-generation proton therapy centres couple treatment and research programs, leading to higher beam currents and longer irradiation times than in clinical conditions. Large fluxes of energetic secondary particles are produced and long- and short-term radioactive nuclides are generated in the concrete shielding of the cyclotron vault. While the overall long-term activation of the centre is well known from the shielding design activation studies, the short-term activation peaks are still of importance when radiation protection studies are involved. The centre shielding design was validated using the BDSIM/FISPACT-II methodology combining particle tracking and Monte Carlo particle-matter interactions simulations using Beam Delivery Simulation (BDSIM) and the computation of the activation using FISPACT-II. We establish, as the next stage of our methodology, the simulation of the decay radiation of the activated concrete shielding and the accurate scoring of the related radiation protection quantities. A single BDSIM simulation per radioactive nuclide is performed based on the nuclide concentration obtained from the prior FISPACT-II activation computations at the start of a given cooling period. The evolution of the radiation protection quantities is obtained by scaling the results with the nuclides activity obtained at later times from fast FISPACT-II computations. We show the evolution of the ambient dose equivalent in the centre vault when considering regular concrete and Low Activation Concrete (LAC) as shielding material to demonstrate the efficiency of LAC mix in mitigating the shielding activation.

We calculated a local inverse inelastic mean free path (local‐IIMFP) for electrons crossing a medium–medium interface, considering various incident electron energies, crossing angles and combinations of materials. We used an extension of a classical dielectric model developed by Li and co‐workers for an electron crossing a surface (interface vacuum‐medium). Moreover, the integration over the distance of the local‐IIMFP allows to obtain the interface excitation parameter (or IEP) characterizing the change in excitation probability for an electron crossing an interface once caused by the presence of the interface in comparison with an electron for which only volume excitations are considered. We perform these calculations for angles between 0° and 80°, for electron energies between 500 and 2500 eV and for various pairs of materials, as Al/In for its academic interest or Au/Si and SiO 2 /Si for their technological importance. Small but not negligible variations of the local‐IIMFP and the IEP were observed for metal–metal or metal–semiconductor interfaces, while quite significant variations are obtained when one of the materials is a insulator.

The coupling of transverse motion is a natural occurrence in particle accelerators, either in the form of a residual coupling arising from imperfections or originating by design from strong systematic coupling fields. While the first can be treated perturbatively, the latter requires a robust approach adapted to strongly coupled optics, and a parametrization of the linear optics must be performed to explore beam dynamics in such peculiar lattices. This work highlights the key physical interpretations of the main parametrization formalisms to describe linear coupled optics, along with explicit links and comparisons of these parametrizations. Concepts rarely illustrated in other works, such as forced mode flips and local coupling, are explored in detail, clarifying some anomalies that can arise in lattice functions. The analytical methods have been implemented in a reference Python package and connected with ray-tracing and integration codes to explore examples of strongly coupled lattices, which are discussed in detail to highlight the key physical interpretations of the parametrizations and characteristics of the lattices.

Vertical Fixed Field Accelerators (vFFAs) feature complex and highly non-linear magnetic fields, which require simulation codes allowing step-wise particle tracking. Methods to model the 3D magnetic field of scaling vFFAs have been developed in the ray-tracing code Zgoubi. The field modeling and particle tracking methods include the field non-linearities, the fringe fields, and the field superposition of neighboring magnets. The procedure implements the vFFA analytical field expressions, allowing design studies and parameter optimizations using the Zgoubi built-in fit method. The vFFA procedure has been applied to a ten-fold symmetry ring with a triplet focusing structure designed to accelerate protons from 3 MeV to 12 MeV and studied under the ISIS-II proton driver prototype project. Results from particle tracking in externally generated 3D semi-analytical field maps and the developed vFFA analytical model are shown to be in excellent agreement.

The treatment protocols of cancerous ocular diseases with proton therapy are well established, and dedicated eye-treatment systems can produce the clinical beam properties that meet the peculiar features required by eye-treatment modalities. However, for general-purpose multiroom systems comprising eye-treatment beamlines and nozzles, the design and commissioning procedures must be optimized to achieve the performances of fully dedicated systems in terms of depth-dose distal falloff, lateral penumbra, and dose rate. This paper presents a realistic start-to-end beam transport and particle-matter interactions model of the ion beam applications Proteus (R) Plus (P+) single-scattering eye-treatment room with Beam Delivery SIMulation (BDSIM) using Geant4. The model is used to establish optimization patterns in terms of beam optics to achieve a smaller depth-dose distal falloff than the design baseline while maintaining a nominal dose rate and lateral flatness of the dose deposition profile. An alternative design is proposed to increase the dose rate further by up to a factor 3, allowing for delivering a complete hypofractionated treatment session under 60 s. It uses a beam-stopping device to complement the existing scattering features of the nozzle. An in-depth study of the system is performed using BDSIM and the numerical simulations are discussed in detail.

We present the user‐friendly and freely available software package QUEELS (QUantitative analysis of Electron Energy Losses at Surfaces) that allows to calculate effective inelastic scattering cross sections within the dielectric response description, for swift electrons travelling nearby surfaces in several environments. We briefly describe the underlying theoretical models and illustrate its use to evaluate the distribution of energy losses taking place in electron spectroscopies like transmission electron energy loss spectroscopy (TEELS), X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS), which are widely used for material analysis. This includes the intrinsic excitations due to the core hole in XPS and AES.

In hadron therapy beamlines, passive elements are used to reduce the beam energy or to shape its transverse profile and frequently complement the magnetic transport channel elements. In particular, cyclotron-based facilities feature energy degraders to tailor the energy to the treatment value. As such, the numerical modeling of hadron therapy beamlines is crucially reliant on the accuracy of the available beam–matter interaction models to simulate the beam properties at levels suitable for clinical applications. While integrated Monte Carlo codes reach these accuracy levels, ultra-fast numerical codes are essential for beam commissioning controls applications or fast iterative optimization of new designs. To that end, we propose a novel effective model to compute the beam–matter interactions in a hybrid fashion, using tabulated range tables, the semi-analytical Fermi–Eyges approximation, and fits extracted from Monte Carlo data. In this work, we detail the method and benchmark each step with Geant4 simulations. Finally, we validate its accuracy with beam-based measurements from a proton therapy facility using our Python-language implementation which is shown to provide computation time of the order of milliseconds. The results are discussed in detail.

The coupling of transverse motion is a natural occurrence in particle accelerators, either in the form of a residual coupling arising from imperfections or originating by design from strong systematic coupling fields. While the first can be treated perturbatively, the latter requires a robust approach adapted to strongly coupled optics and a parametrization of the linear optics must be performed to explore beam dynamics in such peculiar lattices. This paper reviews the main concepts commonly put forth to describe coupled optics and clarifies the proposed parametrization formalisms. The links between the generalized Twiss parameters used by the different approaches are formally proven, and their physical interpretations are highlighted. The analytical methods have been implemented in a reference Python package and connected with a ray-tracing code to explore strongly coupled lattices featuring complex 3D fields. Multiple examples are discussed in detail to highlight the key physical interpretations of the parametrizations and characteristics of the lattices.

Purpose/objective: The objective of this study was to verify the accuracy of treatment plans of stereotactic body radiation therapy (SBRT) and to verify the feasibility of the use of Monte Carlo (MC) as quality control (QC) on a daily basis. Material/methods: Using EGSnrc, a MC model of Agility T linear accelerator was created. Various measurements (Percentage depth dose (PDD), Profiles and Output factors) were done for different fields sizes from 1x1 up to 40x40 (cm(2)). An iterative model optimization was performed to achieve adequate parameters of MC simulation. 40 SBRT patient's dosimetry plans were calculated by Monaco T 3.1.1. CT images, RT-STRUCT and RT-PLAN files from Monaco T being used as input for Moderato MC code. Finally, dose volume histogram (DVH) and paired t-tests for each contour were used for dosimetry comparison of the Monaco T and MC. Results: Validation of MC model was successful, as <2% difference comparing to measurements for all field's sizes. The main energy of electron source incident on the target was 5.8 MeV, and the full width at half maximum (FWHM) of Gaussian electron source were 0.09 and 0.2 (cm) in X and Y directions, respectively. For 40 treatment plan comparisons, the minimum absolute difference of mean dose of planning treatment planning (PTV) was 0.1% while the maximum was 6.3%. The minimum absolute difference of Max dose of PTV was 0.2% while the maximum was 8.1%. Conclusion: SBRT treatment plans of Monaco agreed with MC results. It possible to use MC for treatment plans verifications as independent QC tool.

Hadron therapy centres are evolving towards reducedfootprint layouts, often featuring a single treatment room. The evaluation of beam properties, radiation protection quantities, and concrete shielding activation via numerical simulations poses new challenges that can be tackled using the numerical beam transport and Monte-Carlo code Beam Delivery Simulation (BDSIM), allowing a seamless simulation of the dynamics as a whole. Specific developments have been carried out in BDSIM to advance its efficiency toward such applications, and a detailed 4D Monte-Carlo scoring mechanism has been implemented. It produces tallies such as the spatial-energy differential fluence in arbitrary scoring meshes. The feature makes use of the generic boost::histogram library and allows an event-by-event serialisation and storage in the ROOT data format. The pyg4ometry library is extended to improve the visualisation of critical features such as the complex geometries of BDSIM models, the beam tracks, and the scored quantities. Data are converted from Geant4 and ROOT to a 3D visualisation using the VTK framework. These features are applied to a complete IBA Proteus One model.