Single-shot electron radiography using a laser-plasma accelerator

Contact and projection electron radiography of static targets was demonstrated using a laser-plasma accelerator driven by a kilojoule, picosecond-class laser as a source of relativistic electrons with an average energy of 20 MeV. Objects with areal densities as high as 7.7 g/cm² were probed in materials ranging from plastic to tungsten, and radiographs with resolution as good as 90 μm were produced. The effects of electric fields produced by the laser ablation of the radiography objects were observed and are well described by an analytic expression relating imaging magnification change to electric-field strength.

Calibration of spectra in presence of non-stationary background using unsupervised physics-informed deep learning

Calibration is a key part of the development of a diagnostic. Standard approaches require the setting up of dedicated experiments under controlled conditions in order to find the calibration function that allows one to evaluate the desired information from the raw measurements. Sometimes, such controlled experiments are not possible to perform, and alternative approaches are required. Most of them aim at extracting information by looking at the theoretical expectations, requiring a lot of dedicated work and usually involving that the outputs are extremely dependent on some external factors, such as the scientist experience. This work presents a possible methodology to calibrate data or, more generally, to extract the information from the raw measurements by using a new unsupervised physics-informed deep learning methodology. The algorithm allows to automatically process the data and evaluate the searched information without the need for a supervised training by looking at the theoretical expectations. The method is examined in synthetic cases with increasing difficulties to test its potentialities, and it has been found that such an approach can also be used in very complex behaviours, where human-drive results may have huge uncertainties. Moreover, also an experimental test has been performed to validate its capabilities, but also highlight the limits of this method, which, of course, requires particular attention and a good knowledge of the analysed phenomena. The results are extremely interesting, and this methodology is believed to be applied to several cases where classic calibration and supervised approaches are not accessible.

Influence of a transient spark plasma discharge on producing high molecular masses of chemical products from L-cysteine

Cold atmospheric pressure plasmas are considered a forthcoming method in many research areas. Plasma modification of biomolecules has received much attention in addition to plasma-treated biomaterials. Hence, in this work, we operated a transient spark plasma (TSP) discharge to study its effect on the L-cysteine chemical structure. the TSP was configured in a pin-to-ring electrode arrangement and flowed by Ar gas. We also investigated the effect of two chemicals; dimethyl sulfoxide (DMSO) and hydrogen peroxide (H₂O₂) by the bubbling method to show how they can change the creation of new chemical bioproducts. Ultraviolet-Visible absorption spectroscopy, Fourier transform infrared spectroscopy and Liquid chromatography-mass spectroscopy were used to investigate any changes in chemical bonds of cysteine structure and to depict the generation of new biomolecules. Based on the displayed results plasma-generated reactive species had a great role in the chemical structure of the cysteine. Entering DMSO and H₂O₂ into the plasma caused the creation of new products and the heaviest biomolecule was produced by the simultaneous addition of DMSO and H₂O₂. The results also predicted that some chemical products and amino acids with a higher value molecular masse produced from the polymerization process of cysteine solution. The strong oxidation process is responsible for the heavy chemical compounds.

Effects of microplastics and surfactants on surface roughness of water waves

We study the flow physics underlying the recently developed remote sensing capability of detecting oceanic microplastics, which is based on the measurable surface roughness reduction induced by the presence of microplastics on the ocean surface. In particular, we are interested in whether this roughness reduction is caused by the microplastics as floating particles, or by surfactants which follow similar transport paths as microplastics. For this purpose, we experimentally test the effects of floating particles and surfactants on surface roughness, quantified by the mean square slope (MSS), with waves generated by a mechanical wave maker or by wind. For microplastics, we find that their effect on MSS critically depends on the surface area fraction of coverage. The damping by particles is observed only for fractions above O (5-10%), much higher than the realistic ocean condition. For surfactants, their damping effects on both mechanically generated waves and wind waves are quantified, which are shown to be much more significant than that by microplastics. Several new mechanisms/relations for roughness damping by surfactants are also identified. The implications of these experimental results to remote sensing are discussed.

Perspectives on fundamental cosmology from Low Earth Orbit and the Moon

The next generation of space-based experiments will go hunting for answers to cosmology's key open questions which revolve around inflation, dark matter and dark energy. Low earth orbit and lunar missions within the European Space Agency's Human and Robotic Exploration programme can push our knowledge forward in all of these three fields. A radio interferometer on the Moon, a cold atom interferometer in low earth orbit and a gravitational wave interferometer on the Moon are highlighted as the most fruitful missions to plan and execute in the mid-term.

A new class of transformable kirigami metamaterials for reconfigurable electromagnetic systems

The rapid development of radio frequency (RF) components requires smart multifunctional materials that can adapt their physical shapes and properties according to the environment. While most current reconfigurable systems provide limited flexibility with high manufacturing cost, this research proposes to harness the transformable properties of kirigami-inspired multistable mechanical metasurfaces that can repeatedly deform and lock into different configurations to realize a novel class of low-cost reconfigurable electromagnetic structures with a broad design space. The metasurfaces are formed by designing kinematic-based unit cells with metallised coating that can provide adjustable resonant electromagnetic (EM) properties while rotating with respect to each other. Tailoring the cut length and geometry parameters of the patterns, we demonstrate programming of the topologies and shapes of different configurations. The influence of critical parameters on the structural multistability is illustrated by means of both a simplified energy model and finite element simulations. As examples of the reconfigurable electromagnetic devices that can be realized, we report the development of a tuneable half-wave dipole and two frequency selective surface (FSS) designs featuring isotropic and anisotropic responses. While the kirigami dipole can be tuned by mechanically stretching its arms, the FSSs exhibit distinct transmittance and reflectance spectra in each of the kirigami patterns stable states. The functionality of these kirigami devices is validated both by full-wave EM simulations and experiments. The proposed transformable structures can be mechanically actuated to tune the EM response in frequency or induce anisotropies for wave propagation.

Electrodeposition and analysis of thick bismuth films

Due to its unique physical and chemical properties, bismuth is an attractive candidate for a wide range of applications such as battery anodes, radiation shielding, and semiconductors, to name a few. This work presents the electrodeposition of mechanically stable and homogenous bismuth films at micron-scale thicknesses. A simple one-step electrodeposition process using either a pulse/reverse or direct current source yielded thick, homogenous, and mechanically stable bismuth films. Morphology, electrochemical behavior, adhesion, and mechanical stability of bismuth coatings plated with varying parameters were characterized via optical profilometry, cyclic voltammetry, electron microscopy, and tribology. Scratch testing on thick electroplated coatings (> 100 µm) revealed similar wear resistance properties between the pulse/reverse plated and direct current electroplated films. This study presents a versatile bismuth electroplating process with the possibility to replace lead in radiation shields with an inexpensive, non-toxic metal, or to make industrially relevant electrocatalytic devices.

A new thermography using inelastic scattering analysis of wavelength-resolved neutron transmission imaging

Thermography using energy-dependent neutron transmission imaging can non-invasively and non-destructively visualize a real-space distribution of interior temperatures of a material in a container. Previously, resonance absorption broadening analysis and Bragg-edge shift analysis using energy-resolved neutron transmission have been developed, however some issues remain, e.g., imaging efficiency, substance limitation and temperature sensitivity. For this reason, we propose a new neutron thermography using the temperature dependence of inelastic scattering of cold neutrons. This method has some advantages, for example, the imaging efficiency is high because cold neutrons are measured with moderate wavelength resolution, and light elements can be analysed in principle. We investigated the feasibility of this new neutron thermography at pulsed neutron time-of-flight imaging instruments at ISIS in the United Kingdom and HUNS in Japan. A Rietveld-type transmission spectrum analysis program (RITS) was employed to refine temperature and atomic displacement parameters from the inelastic scattering cross-section analysis. Finally, we demonstrated interior thermography of an α-Fe sample of 10 mm thickness inside a vacuum chamber by using a neutron time-of-flight imaging detector at the compact accelerator-driven pulsed neutron source HUNS.

A fully fiber-integrated ion trap for portable quantum technologies

Trapped ions are a promising platform for the deployment of quantum technologies. However, traditional ion trap experiments tend to be bulky and environment-sensitive due to the use of free-space optics. Here we present a single-ion trap with integrated optical fibers directly embedded within the trap structure, to deliver laser light as well as to collect the ion's fluorescence. This eliminates the need for optical windows. We characterise the system's performance and measure the ion's fluorescence with signal-to-background ratios on the order of 50, which allows us to perform internal state readout measurements with a fidelity over 99% in 600 [Formula: see text]s. We test the system's resilience to thermal variations in the range between 22 and 53 [Formula: see text]C, and the system's vibration resilience at 34 Hz and 300 Hz and find no effect on its performance. The combination of compactness and robustness of our fiber-coupled trap makes it well suited for applications in, as well as outside, research laboratory environments, and in particular for highly compact portable quantum technologies, such as portable optical atomic clocks. While our system is designed for trapping ⁴⁰Ca⁺ ions the fundamental design principles can be applied to other ion species.

Monochromatic computed tomography using laboratory-scale setup

In this article, we demonstrate the viability of highly monochromatic full-field X-ray absorption near edge structure based tomography using a laboratory-scale Johann-type X-ray absorption spectrometer utilising a conventional X-ray tube source. In this proof-of-concept, by using a phantom embedded with elemental Se, Na[Formula: see text]SeO[Formula: see text], and Na[Formula: see text]SeO[Formula: see text], we show that the three-dimensional distributions of Se in different oxidation states can be mapped and distinguished from the phantom matrix and each other with absorption edge contrast tomography. The presented method allows for volumetric analyses of chemical speciation in mm-scale samples using low-brilliance X-ray sources, and represents a new analytic tool for materials engineering and research in many fields including biology and chemistry.

A home-made pipette droplet microfluidics rapid prototyping and training kit for digital PCR, microorganism/cell encapsulation and controlled microgel synthesis

Droplet microfluidics offers a platform from which new digital molecular assay, disease screening, wound healing and material synthesis technologies have been proposed. However, the current commercial droplet generation, assembly and imaging technologies are too expensive and rigid to permit rapid and broad-range tuning of droplet features/cargoes. This rapid prototyping bottleneck has limited further expansion of its application. Herein, an inexpensive home-made pipette droplet microfluidics kit is introduced. This kit includes elliptical pipette tips that can be fabricated with a simple DIY (Do-It-Yourself) tool, a unique tape-based or 3D printed shallow-center imaging chip that allows rapid monolayer droplet assembly/immobilization and imaging with a smart-phone camera or miniature microscope. The droplets are generated by manual or automatic pipetting without expensive and lab-bound microfluidic pumps. The droplet size and fluid viscosity/surface tension can be varied significantly because of our particular droplet generation, assembly and imaging designs. The versatility of this rapid prototyping kit is demonstrated with three representative applications that can benefit from a droplet microfluidic platform: (1) Droplets as microreactors for PCR reaction with reverse transcription to detect and quantify target RNAs. (2) Droplets as microcompartments for spirulina culturing and the optical color/turbidity changes in droplets with spirulina confirm successful photosynthetic culturing. (3) Droplets as templates/molds for controlled synthesis of gold-capped polyacrylamide/gold composite Janus microgels. The easily fabricated and user-friendly portable kit is hence ideally suited for design, training and educational labs.

Thermometry of stored molecular ion beams

The radiative cooling of a stored, initially rotationally hot OH[Formula: see text] ion beam is probed by photodetachment using an electrostatic ion beam trap combined with an in-trap velocity map imaging spectrometer, providing direct measurement of the time-dependent rotational population. The rotational temperatures are estimated from photodetached electron spectra as a function of time using a Boltzmann distribution model and further verified by a rate law model using known Einstein coefficients. We demonstrate that during the entire cooling time, the rotational population can be well described by a Boltzmann distribution.

Current distribution monitoring enables quench and damage detection in superconducting fusion magnets

Fusion magnets made from high temperature superconducting ReBCO CORC^® cables are typically protected with quench detection systems that use voltage or temperature measurements to trigger current extraction processes. Although small coils with low inductances have been demonstrated, magnet protection remains a challenge and magnets are typically operated with little knowledge of the intrinsic performance parameters. We propose a protection framework based on current distribution monitoring in fusion cables with limited inter-cable current sharing. By employing inverse Biot-Savart techniques to distributed Hall probe arrays around CORC^® Cable-In-Conduit-Conductor (CICC) terminations, individual cable currents are recreated and used to extract the parameters of a predictive model. These parameters are shown to be of value for detecting conductor damage and defining safe magnet operating limits. The trained model is then used to predict cable current distributions in real-time, and departures between predictions and inverse Biot-Savart recreated current distributions are used to generate quench triggers. The methodology shows promise for quality control, operational planning and real-time quench detection in bundled CORC^® cables for compact fusion reactors.

Development and experimental verification of C-arm camera shooting locator

This study aimed to develop a self-made C-arm camera shooting locator and verify its accuracy and advantages. A total of 60 physicians and nurses from the Surgical System of Sanmen People's Hospital, Zhejiang Province, China, were randomly selected as filming operators. The C-arm machine with a self-made locator and a C-arm machine without a locator were used to measure the center of the circular plate. The iron nails were used to shoot. The distance between the iron nail and the center point of the circular display area on display was defined as the shooting deviation. When it was less than 3 cm, the shooting was stopped. The number of shots, total shooting time, and first-shot deviation in the C-arm camera shooting groups with and without the locator were statistically analyzed, and the advantages and disadvantages of the two were compared. The average number of shots, average total shooting time, and average first-shot deviation of the C-arm camera using the locator were significantly better than those in the group without the locator, and the differences were statistically significant. When the shooting distance (X) was equal to 30 cm and the shooting angle (Y) was equal to 0°, the average number of shots, average total shooting time, and average first-shot deviation were optimal. The C-arm camera shooting locator can improve the shooting accuracy of the C-arm camera and effectively reduce the number of shots and total shooting time. Hence, it can be applied in clinical and surgical practice.

Electron energy loss spectroscopy database synthesis and automation of core-loss edge recognition by deep-learning neural networks

The ionization edges encoded in the electron energy loss spectroscopy (EELS) spectra enable advanced material analysis including composition analyses and elemental quantifications. The development of the parallel EELS instrument and fast, sensitive detectors have greatly improved the acquisition speed of EELS spectra. However, the traditional way of core-loss edge recognition is experience based and human labor dependent, which limits the processing speed. So far, the low signal-noise ratio and the low jump ratio of the core-loss edges on the raw EELS spectra have been challenging for the automation of edge recognition. In this work, a convolutional-bidirectional long short-term memory neural network (CNN-BiLSTM) is proposed to automate the detection and elemental identification of core-loss edges from raw spectra. An EELS spectral database is synthesized by using our forward model to assist in the training and validation of the neural network. To make the synthesized spectra resemble the real spectra, we collected a large library of experimentally acquired EELS core edges. In synthesize the training library, the edges are modeled by fitting the multi-Gaussian model to the real edges from experiments, and the noise and instrumental imperfectness are simulated and added. The well-trained CNN-BiLSTM network is tested against both the simulated spectra and real spectra collected from experiments. The high accuracy of the network, 94.9%, proves that, without complicated preprocessing of the raw spectra, the proposed CNN-BiLSTM network achieves the automation of core-loss edge recognition for EELS spectra with high accuracy.

Ultra-high dose rate FLASH irradiator at the radiological research accelerator facility

The Radiological Research Accelerator Facility has modified a decommissioned Varian Clinac to deliver ultra-high dose rates: operating in 9 MeV electron mode (FLASH mode), samples can be irradiated at a Source-Surface Distance (SSD) of 20 cm at average dose rates of up to 600 Gy/s (3.3 Gy per 0.13 µs pulse, 180 pulses per second). In this mode multiple pulses are required for most irradiations. By modulating pulse repetition rate and irradiating at SSD = 171 cm, dose rates below 1 Gy/min can be achieved, allowing comparison of FLASH and conventional irradiations with the same beam. Operating in 6 MV photon mode, with the conversion target removed (SuperFLASH mode), samples are irradiated at higher dose rates (0.2-150 Gy per 5 µs pulse, 360 pulses per second) and most irradiations can be performed with a single very high dose rate pulse. In both modes we have seen the expected inverse relation between dose rate and irradiated area, with the highest dose rates obtained for beams with a FWHM of about 2 cm and ± 10% uniformity over 1 cm diameter. As an example of operation of the ultra-high dose rate FLASH irradiator, we present dose rate dependence of dicentric chromosome yields.

Nanofiber formation as a promising technology for preservation and easy storage of extracellular vesicles

Extracellular vesicles (EVs) are cell-derived, membrane-enclosed particles with the potential for a wide range of future therapeutic applications. However, EVs have almost always been administered by direct injection, likely hindering their efficacy because of rapid clearance from the injection site. The present study aimed to incorporate medium-sized extracellular vesicles (mEVs) into fast-dissolving electrospun polyvinylpyrrolidone-based nanofibers to explore the storage-dependent structure-activity relationship of the resulting nanofibrous formulations. Aqueous polyvinylpyrrolidone-based precursor solutions were selected for the electrospinning process. The presence of EVs in the electrospun samples was confirmed by transmission electron microscopy, flow cytometry, and confocal laser scanning microscope. The results indicate that the fibrous structure of the samples was preserved until the end of the 12-week storage period. Furthermore, regardless of the storage temperature (4 °C or room temperature), nanofibers and nanofiber-associated EVs were present throughout the experimental period. Incorporating EVs into a stable solid polymeric delivery base could preserve their stability; meanwhile, according to the characteristics of the polymer, their targeted and controlled release can be achieved.

A hydraulic soft microgripper for biological studies

We have developed a microscale hydraulic soft gripper and demonstrated the handling of an insect without damage. This gripper is built on Polydimethylsiloxane (PDMS) with the soft material casting technique to form three finger-like columns, which are placed on a circular membrane. The fingers have a length of 1.5 mm and a diameter of 300 µm each; the distance between the two fingers is 600 µm of center-to-center distance. A membrane as a 150 µm soft film is built on top of a cylindrical hollow space. Applying pressure to the interior space can bend the membrane. Bending the membrane causes the motion of opening/closing of the gripper, and as a result, the three fingers can grip an object or release it. The PDMS was characterized, and the experimental results were used later in Abaqus software to simulate the gripping motion. The range of deformation of the gripper was investigated by simulation and experiment. The result of the simulation agrees with the experiments. The maximum 543 µN force was measured for this microfluidic-compatible microgripper and it could lift a ball that weighs 168.4 mg and has a 0.5 mm diameter. Using this microgripper, an ant was manipulated successfully without any damage. Results showed fabricated device has great a potential as micro/bio manipulator.

Ultrafast light-induced dynamics in the microsolvated biomolecular indole chromophore with water

Interactions between proteins and their solvent environment can be studied in a bottom-up approach using hydrogen-bonded chromophore-solvent clusters. The ultrafast dynamics following UV-light-induced electronic excitation of the chromophores, potential radiation damage, and their dependence on solvation are important open questions. The microsolvation effect is challenging to study due to the inherent mix of the produced gas-phase aggregates. We use the electrostatic deflector to spatially separate different molecular species in combination with pump-probe velocity-map-imaging experiments. We demonstrate that this powerful experimental approach reveals intimate details of the UV-induced dynamics in the near-UV-absorbing prototypical biomolecular indole-water system. We determine the time-dependent appearance of the different reaction products and disentangle the occurring ultrafast processes. This approach ensures that the reactants are well-known and that detailed characteristics of the specific reaction products are accessible - paving the way for the complete chemical-reactivity experiment.

Cr2+ solid solution in UO2 evidenced by advanced spectroscopy

Advanced Cr-doped UO₂ fuels are essential for driving safe and efficient generation of nuclear energy. Although widely deployed, little is known about their fundamental chemistry, which is a critical gap for development of new fuel materials and radioactive waste management strategies. Utilising an original approach, we directly evidence the chemistry of Cr⁽³⁺⁾₂O₃-doped U⁽⁴⁺⁾O₂. Advanced high-flux, high-spectral purity X-ray absorption spectroscopy (XAS), corroborated by diffraction, Raman spectroscopy and high energy resolved fluorescence detection-XAS, is used to establish that Cr²⁺ directly substitutes for U⁴⁺, accompanied by U⁵⁺ and oxygen vacancy charge compensation. Extension of the analysis to heat-treated simulant nuclear fuel reveals a mixed Cr^2+/3+ oxidation state, with Cr in more than one physical form, explaining the substantial discrepancies that exist in the literature. Successful demonstration of this analytical advance, and the scientific underpinning it provides, opens opportunities for an expansion in the range of dopants utilised in advanced UO₂ fuels.

Results of the performance test for quality assessment of personal radiation dosimetry services including the influence of the dosimeter readout frequency

This study was to determine the significance of factors considered for the measurement accuracy of personal dosimeter in dosimetry services such as dosimetry service, irradiation category, years of use and readout frequency. The investigation included management information questionnaire, on-site visit and blind test. The blind test with random selected personal badge was used in inter-comparison of eight dosimetry services, and the test results followed ANSI/HPS N13.11 criteria. This study also analyzed the measurement deviations if they felt in the criteria of ICRP 75 or not. One-way ANOVA tests were used to analyze the significant difference of the measurement deviations in different dosimetry services, irradiation categories, and years of use. Simple linear-regression test was performed for the significance of the prediction model between measurement deviations and readout frequencies. All visited dosimetry services followed the proper statue of basic management and passed the performance check of the tolerance level. The average deviations corresponding to category I, category II deep dose, and category II shallow dose were 6.08%, 9.49%, and 10.41% respectively. There had significant differences of measurement deviation in different dosimetry services (p < 0.0001) and irradiation categories (p = 0.016) but no significant difference in years of use (p = 0.498). There was no significance in the linear-regression model between measurement deviation and badge readout frequencies. Based on the regular calibration of the personal dosimeter, the deviation of the measured value is mainly affected by different dosimetry services and irradiation categories; and there shows no significant influence by years of use and readout frequency.

Observation of Rayleigh-Lamb waves generated by the 2022 Hunga-Tonga volcanic eruption with the POLA detectors at Ny-Ålesund

The eruption of the Hunga-Tonga volcano in the South Pacific Ocean on January 15, 2022, at about 4:15 UTC, generated a violent explosion, which created atmospheric pressure disturbances in the form of Rayleigh-Lamb waves detected all over the globe. Here we discuss the observation of the Hunga-Tonga shock-wave performed at the Ny-Ålesund Research Station on the Spitsbergen island, by the detectors of the PolarquEEEst experiment and their ancillary sensors. Online pressure data as well as the results of dedicated offline analysis are presented and discussed in details. Results include wave arrival times, wave amplitude measurements and wave velocity calculation. We observed five passages of the shock wave with a significance larger than 3 [Formula: see text] and an amplitude up to 1 hPa. The average propagation velocity resulted to be (308 ± 0.6) m/s. Possible effects of the atmospheric pressure variation associated with the shock-wave multiple passages on the cosmic-ray rate at ground level are also investigated. We did not find any significant evidence of this effect.

Autonomous digitizer calibration of a Monte Carlo detector model through evolutionary simulation

Simulating the response of a radiation detector is a modelling challenge due to the stochastic nature of radiation, often complex geometries, and multi-stage signal processing. While sophisticated tools for Monte Carlo simulation have been developed for radiation transport, emulating signal processing and data loss must be accomplished using a simplified model of the electronics called the digitizer. Due to a large number of free parameters, calibrating a digitizer quickly becomes an optimisation problem. To address this, we propose a novel technique by which evolutionary algorithms calibrate a digitizer autonomously. We demonstrate this by calibrating six free parameters in a digitizer model for the ADAC Forte. The accuracy of solutions is quantified via a cost function measuring the absolute percent difference between simulated and experimental coincidence count rates across a robust characterisation data set, including three detector configurations and a range of source activities. Ultimately, this calibration produces a count rate response with 5.8% mean difference to the experiment, improving from 18.3% difference when manually calibrated. Using evolutionary algorithms for model calibration is a notable advancement because this method is novel, autonomous, fault-tolerant, and achieved through a direct comparison of simulation to reality. The software used in this work has been made freely available through a GitHub repository.

Sharp dose profiles for high precision proton therapy using strongly focused proton beams

The main objective of radiotherapy is to exploit the curative potential of ionizing radiation while inflicting minimal radiation-induced damage to healthy tissue and sensitive organs. Proton beam therapy has been developed to irradiate the tumor with higher precision and dose conformity compared to conventional X-ray irradiation. The dose conformity of this treatment modality may be further improved if narrower proton beams are used. Still, this is limited by multiple Coulomb scattering of protons through tissue. The primary aim of this work was to develop techniques to produce narrow proton beams and investigate the resulting dose profiles. We introduced and assessed three different proton beam shaping techniques: (1) metal collimators (100/150 MeV), (2) focusing of conventional- (100/150 MeV), and (3) focusing of high-energy (350 MeV, shoot-through) proton beams. Focusing was governed by the initial value of the Twiss parameter [Formula: see text] ([Formula: see text]), and can be implemented with magnetic particle accelerator optics. The dose distributions in water were calculated by Monte Carlo simulations using Geant4, and evaluated by target to surface dose ratio (TSDR) in addition to the transverse beam size ([Formula: see text]) at the target. The target was defined as the location of the Bragg peak or the focal point. The different techniques showed greatly differing dose profiles, where focusing gave pronouncedly higher relative target dose and efficient use of primary protons. Metal collimators with radii [Formula: see text] gave low TSDRs ([Formula: see text]) and large [Formula: see text]([Formula: see text]). In contrast, a focused beam of conventional ([Formula: see text]) energy produced a very high TSDR ([Formula: see text]) with similar [Formula: see text] as a collimated beam. High-energy focused beams were able to produce TSDRs [Formula: see text] and [Formula: see text] around 1.5 mm. From this study, it appears very attractive to implement magnetically focused proton beams in radiotherapy of small lesions or tumors in close vicinity to healthy organs at risk. This can also lead to a paradigm change in spatially fractionated radiotherapy. Magnetic focusing would facilitate FLASH irradiation due to low losses of primary protons.

Direct observation of positron capture process at the positron source of the superKEKB B-factory

A direct simultaneous detection of electron (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^-$$\end{document}e-) and positron (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+) bunches was successfully performed using wideband beam monitors and a detection system at the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ capture section of the SuperKEKB B-factory. The time intervals between the secondary-generated \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^-$$\end{document}e- and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ bunches were measured to investigate their dynamical capture process. The results show that the time intervals were measured in the range of 20–280 ps on average, and the line-order switch of the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^-$$\end{document}e- and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ bunches and their dynamical phase-slip process in the axial direction were clearly observed as a function of the capture phase of accelerating structures. In this report, the dynamical capture and phase-slip process for the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^-$$\end{document}e- and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ bunches under the two-bunch acceleration scheme is described in detail. This study opens up a new window for direct observation of the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^-$$\end{document}e- and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ capture process at any present and future \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e^+$$\end{document}e+ sources.