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Jupiter's moon Europa contains a subsurface ocean whose presence is inferred from magnetic field measurements, the interpretation of which depends on knowledge of Europa's local plasma environment. A recent Juno spacecraft flyby returned new observations of plasma electrons with unprecedented resolution. Specifically, powerful magnetic field‐aligned electron beams were discovered near Europa. These beams, with energies from ∼30 to ∼300 eV, locally enhance electron‐impact‐excited emissions and ionization in Europa's atmosphere by more than a factor three over the local space environment, and are associated with large jumps of the magnetic fields. The beams therefore play an essential role in shaping Europa's plasma and magnetic field environment and thus need to be accounted for electromagnetic sounding of Europa's ocean and plume detection by future missions such as JUICE and Europa Clipper. Plain Language Summary: A recent Juno spacecraft close flyby of Jupiter's moon Europa revealed the presence of powerful electrons beams. Based on previous observations and modeling of electron beams at the moon Io, such beams were not expected to be observed so close to Europa. Overall, the proximity of the beams to Europa indicates that the acceleration of these electrons takes place much closer to Europa than anticipated and that these beams, therefore, stem from a new and previously unknown acceleration mechanism. The beams are predicted to have an outsized influence on the ionization of the constituents of Europa's tenuous atmosphere and are accompanied with large magnetic field perturbations. Hence, these electron beams are an important ionization source that modify the moon's ionosphere, the electric current systems, and the magnetic field environment. In particular, the presence of electron beams will affect plasma conditions that are used to infer the extent of a subsurface ocean via the magnetic induction signal. These beams significantly impact the space plasma environment around Europa which needs to be accounted for by future missions such as ESA's (European Space Agency) JUICE (Jupiter Icy Moons Explorer) and NASA's (National Aeronautics and Space Administration) Europa Clipper mission. Key Points: Powerful electron beams that significantly shape Europa's space environment are discovered during a Juno flybyThe beams enhance electron‐impact‐excited emissions in Europa's atmosphere and are associated with large jumps of the magnetic fieldsThe beams' proximity to Europa and their pitch angle distribution constrain the source acceleration to be near or within the plasma disk [ABSTRACT FROM AUTHOR]

Thanks to their exceptional spatial, spectral and temporal resolution, highly-coherent free-electron beams have emerged as powerful probes for material excitations, enabling their characterization even in the quantum regime. Here, we investigate strong light–matter coupling through monochromatic and modulated electron wavepackets. In particular, we consider an archetypal target, comprising a nanophotonic cavity next to a single two-level emitter. We propose a model Hamiltonian describing the coherent interaction between the passing electron beam and the hybrid photonic–excitonic target, which is constructed using macroscopic quantum electrodynamics and fully parameterized in terms of the electromagnetic dyadic Green's function. Using this framework, we first describe electron-energy-loss and cathodoluminescence spectroscopies, and photon-induced near-field electron emission microscopy. Finally, we show the power of modulated electrons beams as quantum tools for the manipulation of polaritonic targets presenting a complex energy landscape of excitations. [ABSTRACT FROM AUTHOR]

The Hard X-Ray collimation system was installed at the T-15MD tokamak (major radius of R = 1.48 m, minor radius of a = 0.67 m, elongation of k = 1.7–1.9, triangularity of δ = 0.3–0.4, toroidal magnetic field of BT = 2 T, plasma current of up to Ip = 2 MA, and discharge duration of up to 30 s) to provide the possibility of measuring the spatial and temporal evolution of runaway electron beams. The diagnostic is based on LaBr3(Ce) scintillation detectors, witch provides energy spectrum measurements for energies form 0.3 to 10 MeV. Monte Carlo simulation of the shielding efficiency in the GEANT4 environment showed that the collimator provides 2° field of view (FOV). Horizontal and vertical FOV movement along the plasma cross-section is arranged by a rotating base and screw support elements. An algorithm for processing the signals from the scintillation detectors with a graphical user interface and data visualization is used for reconstruction of the spectra. The results of testing the detector in a laboratory setup and in preliminary experiments carried out with the T-15MD tokamak in which runaway electrons beams were generated are presented. [ABSTRACT FROM AUTHOR]

Laser wakefield acceleration (LWFA) continues to grow and awaken interest worldwide, especially as in various applications it approaches performance comparable to classical accelerators. However, numerous challenges still exist until this can be a reality. The complex non-linear nature of the process of interaction between the laser and the induced plasma remains an obstacle to the widespread LWFA use as stable and reliable particle sources. It is commonly accepted that the best wavefront is a perfect Gaussian distribution. However, experimentally, this is not correct and more complicated ones can potentially give better results. in this work, the effects of tuning the laser wavefront via the controlled introduction of aberrations are explored for an LWFA accelerator using the shock injection configuration. Our experiments show the clear unique correlation between the generated beam transverse characteristics and the different input wavefronts. The electron beams stability, acceleration and injection are also significantly different. We found that in our case, the best beams were generated with a specific complex wavefront. A greater understanding of electron generation as function of the laser input is achieved thanks to this method and hopes towards a higher level of control on the electrons beams by LWFA is foreseen. [ABSTRACT FROM AUTHOR]

Purpose: Driven by advances in accelerator technology and the potential of exploiting the FLASH effect for the treatment of deep‐seated targets (>5 cm), there is an active interest in the construction of devices to deliver very high‐energy electron (VHEE) beams for radiation therapy. The application of novel VHEE devices, however, requires an assessment of the tradeoffs between the different beam parameter choices including beam energies, beam divergences, and maximal field sizes. This study systematically examines the dosimetric beam properties of VHEE beams, determining their clinical usefulness while marking their limits of applications for different beam configurations. Methods: We performed Monte Carlo simulations of the dose distributions of electron beams for different energies (25–250 MeV), source‐to‐surface distances (SSD) (50 cm, 100 cm, parallel), and field sizes (2 cm2 × 2 cm2 to 15 cm2 × 15 cm2) in water using a research version of the RayStation treatment planning system (RaySearch Labs 9A IONPG). The beam was simulated using a monoenergetic point source and perfect collimation. Central axis percentage depth dose (PDD) and transverse dose profiles at multiple depths were evaluated and compared to those of MV photon beams. Profile characteristics including therapeutic range (TR) at 90%, proximal fall‐off (PFO) at 90%, lateral penumbra (LP) at 90%–10%, and field width (FW) at 90% were obtained. Results: Very high‐energy electrons beams with SSD 100 cm and parallel beams (infinite SSD) exhibit a linear to near‐linear increase of TR as a function of energy in the simulated energy range and reach values well beyond the typical depths of lesions encountered in clinics (<20 cm). Their TR show a marked field size dependence only for field sizes <10 cm2 × 10 cm2. For VHEE beams with SSD 50 cm, TR are largely reduced (4–8 cm). For beam energies >150 MeV with large SSD (>100 cm), for many configurations, there is no substantial difference in PDD when adding an opposed beam. This may potentially reduce the number of VHEE beams needed for treatment by a factor of two compared to a treatment using lower energies and lower SSD. In order to cover deep‐seated targets homogeneously, VHEE devices with a parallel beam must provide a maximum field size up to several centimeters larger than the tumor size. For the investigated diverging beams, there is not such a significant field width reduction with depth for larger fields as it is compensated by divergence. Penumbrae of VHEE beams are smaller than those of clinical MV photon beams for lower depths (<5 cm) but increase quickly for larger depths. There is only a relatively small dependence of penumbra on the SSD of the beam. Conclusions: The findings presented in this study assess the performance of VHEE beams and offer a first estimate of treatment indications and tradeoffs for a given design of a VHEE device. SSD >100 cm results in clinically more favorable PDD. Beam energies of 100 MeV and above are needed to cover common tumors (5–15 cm in‐depth) conformally. Higher energies provide an additional benefit specifically for small and deep‐seated lesions due to their reduced lateral penumbrae. [ABSTRACT FROM AUTHOR]

Energetic electrons can be trapped in Earth’s magnetic field, forming the radiation belts (also known as the Van Allen Belts). These electrons, which can originate from the solar wind or a high-altitude nuclear explosion (HANE), have the potential to damage satellites in low-Earth orbit (LEO). For example, in 1962, the U.S. detonated a nuclear device at an altitude of about 400 km in the Starfish experiment. The resulting enhancement of the radiation belts disabled several satellites within a few months and energetic electrons remained in the radiation belts for up to several years. In order to address this potential vulnerability, schemes have been proposed to drain electrons from the radiation belts, with the most promising approaches based on using high-power very-low-frequency (VLF) waves to scatter the electrons into more field-aligned trajectories, forcing them to precipitate into Earth’s atmosphere. This paper will provide an overview of enhanced electron distributions in the radiation belts as well as approaches to VLF wave belt remediation including the use of either antennas or relativistic electrons beams in space to generate the VLF waves. [ABSTRACT FROM AUTHOR]

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Radiotherapy treatments become more and more accurate, using very small irradiation fields and complex dose depositions. So small dosimeters for real time and in vivo dosimetry, suitable for photons as well as for electrons beams are highly desired. In this context, a scintillating fiber dosimeter(SFD) has been developed by the Laboratoire de Physique Corpusculaire de Caen (LPC Caen), France, in collaboration with one of the French regional center for cancer treatment Centre Régional de lutte contre le cancer F. Baclesse (CRLCC F. Baclesse), Caen, France, and the ELDIM Company, Hérouville, France. This plastic dosimeter is water equivalent, and it is suitable for photons as well as for electrons beams without correction. It is a real time dosimeter, with an excellent signal to noise ratio, and a spatial resolution of about a few millimeters. The aim of this study was to reduce the size of the scintillator in order to improve the spatial resolution of this dosimeter. So, a new light collection device has been developed to reduce the length of the scintillator from 1 cm to 1 mm without loss in the signal to noise ratio. The accuracy of this improved prototype has been tested by comparison with standard ionization chambers and the difference between the two devices never exceeded one percent for photon and for electron irradiation beams. A first set of commercial SFD is under completion at ELDIM and it will be soon clinically tested in several French centers for cancer treatment. [ABSTRACT FROM AUTHOR]

We utilize a Fourier transformation-based representation of Maxwell's equations to develop physics-constrained neural networks for electrodynamics without gauge ambiguity, which we label the Fourier–Helmholtz–Maxwell neural operator method. In this approach, both of Gauss's laws and Faraday's law are built in as hard constraints, as well as the longitudinal component of Ampère–Maxwell in Fourier space, assuming the continuity equation. An encoder–decoder network acts as a solution operator for the transverse components of the Fourier transformed vector potential, A ^ ⊥ (k , t) , whose two degrees of freedom are used to predict the electromagnetic fields. This method was tested on two electron beam simulations. Among the models investigated, it was found that a U-Net architecture exhibited the best performance as it trained quicker, was more accurate and generalized better than the other architectures examined. We demonstrate that our approach is useful for solving Maxwell's equations for the electromagnetic fields generated by intense relativistic charged particle beams and that it generalizes well to unseen test data, while being orders of magnitude quicker than conventional simulations. We show that the model can be re-trained to make highly accurate predictions in as few as 20 epochs on a previously unseen data set. [ABSTRACT FROM AUTHOR]

In this study, we examine particle energization and injections that show energetic electron enhancements at both MMS in the magnetotail and Van Allen Probes in the inner magnetosphere. Observing injections along with a corresponding flow burst allows us to better understand injections overall. Searching for suitable events, we found that only a small number of events at MMS had corresponding injections that penetrated far enough into the inner magnetosphere to observe with Van Allen Probes. With the four suitable events we did find, we compared the energy spectra at the two spacecraft and mapped the boundary of where the injection entered the inner magnetosphere. We found that, among these injections in the inner magnetosphere, the electron flux did not increase above ~400 keV, similar to previous results, but the corresponding signatures in the tail observed increased fluxes at 600 keV or higher. There does not appear to be a comparable flux increase at Van Allen Probes and MMS for a given event. None of our injections included ion enhancements at Van Allen Probes, but one included an ion injection at geosynchronous orbit in the GOES spacecraft. All of our injections were dispersed at Van Allen Probes, and we were therefore able to map an estimate of the injection boundary. All of the injections occurred in the premidnight sector. Although we found some events where particle energizations in the tail are accompanied by inner magnetospheric injections, we do not find a statistical link between the two. [ABSTRACT FROM AUTHOR]

We have monitored the cathodoluminescence (CL) emitted upon injection of free electrons into a hybrid structure consisting of a thin magnetic Fe layer deposited on a p-GaAs substrate, in which InGaAs quantum wells are embedded. Electrons transmitted through the unbiased metal/ semiconductor junction recombine radiatively in the quantum wells. Because of the electron spinfiltering across the Fe/GaAs structure, the CL intensity, collected from the backside, is found to depend on the relative orientation between the injected electronic spin polarization and the Fe layer magnetization. The spin asymmetry of the CL intensity in such junction provides a compact optical method for measuring spin polarization of free electrons beams or of hot electrons in solid-state devices. [ABSTRACT FROM AUTHOR]

• The ITER-grade tungsten limiters tested in the T-10 tokamak. • Strong destruction of the limiters under the combination of the high heat and particle fluxes observed. • Intensive cracking of the tungsten tiles observed at the heat loads from 1 MW/m2 up to 30 MW/m2. • In the areas of highest heat loads, tungsten plates were melted and close to full destruction. • The nonambipolar flow due to the arcs and sparks can explain the observed overheating and melting of the tungsten surface. The tungsten limiters were tested in the T-10 tokamak during the 2015–2017 experimental campaign. The limiters were made from the ITER-grade WMP "POLEMA" tungsten. Inspection of the tungsten limiters after experimental campaign has revealed their strong destruction due to the combination of the high heat and particle fluxes from the edge plasma toward the limiters surface. The influence of the edge tokamak plasma on tungsten limiters leads to significant cracking of the tungsten. Heat load up to 2 MW m−2 leads to micro-cracks at the grain boundaries. Heat loads exceeding 5 MW m−2 lead to macro-cracks formation. In the areas of highest heat loads, tungsten plates are melted and close to full destruction. In these zones, intensive sparking and arcing were observed. Arc craters have been scattered across the surface, and along the cracks. It is supposed that the nonambipolar flow due to the arcs and sparks can explain the observed overheating and melting of the tungsten surface. Disruptions and runaway electrons beams have driven extreme heat loads of more than 1 GW/m2 causing strong melting of the tungsten on the outer board of the ring limiter. [ABSTRACT FROM AUTHOR]

High-power electrons beams generated in a single injection magnetron gun with secondary-emission cathodes and in a set of such guns are studied. Hollow electron beams of current 50-100 A, electron energy 30-100 kV, and peak power 1-5 MW are obtained. The beams can be used as electron sources in accelerators and ordinary and multibeam high-power microwave devices. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess the accuracy of a modified electron beam calibration based on the IAEA TRS‐398 and AAPM‐TG‐51 in multicenter radiotherapy. Methods: This study was performed using the Elekta and Varian Linear Accelerator electron beams with energies of 4–22 MeV under reference conditions using cylindrical (PTW 30013, IBA FC65‐G, and IBA FC65‐P) and parallel‐plate (PTW 34045, PTW 34001, and IBA PPC‐40) chambers. The modified calibration used a cylindrical chamber and an updated k′Q$k{^{\prime}}_Q$ based on Monte Carlo calculations, whereas TRS‐398 and TG‐51 used cylindrical and parallel‐plate chambers for reference dosimetry. The dose ratio of the modified calibration procedure, TRS‐398 and TG‐51 were obtained by comparing the dose at the maximum depth of the modified calibration to TRS‐398 and TG‐51. Results: The study found that all cylindrical chambers' beam quality conversion factors determined with the modified calibration (k′Q)$({{{k^{\prime}}}_Q})$ to the TRS‐398 and TG‐51 vary from 0.994 to 1.003 and 1.000 to 1.010, respectively. The dose ratio of modified/TRS‐398cyl and modified/TRS‐398parallel‐plate, the variation ranges were 0.980–1.014 and 0.981–1.019, while for the counterpart modified/TG‐51cyl was found varying between 0.991 and 1.017 and the ratio of modified/TG‐51parallel‐plate varied in the range of 0.981–1.019. Conclusion: This multi‐institutional study analyzed a modified calibration procedure utilizing new data for electron beam calibrations at multiple institutions and evaluated existing calibration protocols. Based on observed variations, the current calibration protocols should be updated with detailed metrics on the stability of linac components. [ABSTRACT FROM AUTHOR]

Understanding and quantifying the electronic inelastic interactions of swift ions and electrons in metals is fundamental for many applications of charged particle beams. A common theoretical approach is moreover desirable for the case of both types of projectiles, as large numbers of secondary electrons arise as the result of ion interaction with metals. The electronic cross section, stopping power and energy-loss straggling resulting from the interaction of swift protons, alpha particles and electrons when moving through the metals aluminum, iron, copper, molybdenum, platinum and gold, are calculated theoretically for a wide energy range of the projectiles. The model is based on the dielectric formalism, which realistically accounts for the excitation spectrum of each metal through the Mermin Energy-Loss Function-Generalized Oscillator Strength (MELF-GOS) methodology. The impact of the complexity of the excitation spectrum of each metal (encompassing interband transitions and collective excitations), as well as the different sources of (sometimes conflicting) optical data is analysed in detail. Specific interactions are considered for each projectile, such as electron capture/loss and electron cloud polarisation for ions, and indistinguishability, exchange and low-energy corrections for electrons. An estimate of possible contributions of surface excitations to the interaction probabilities of low energy electrons is given. Comparison of our results with a large collection of available experimental data shows good agreement. As a practical and useful outcome of the work, we provide analytical expressions fitting all our calculated quantities, which can be applied for simulation or comparison purposes. [ABSTRACT FROM AUTHOR]

We present a new model designed to simulate the process of energetic particle precipitation, a vital coupling mechanism from Earth's magnetosphere to its atmosphere. The atmospheric response, namely excess ionization in the upper and middle atmosphere, together with bremsstrahlung X‐ray production, is calculated with kinetic particle simulations using the Geant4 Monte Carlo framework. Mono‐energy and mono‐pitch angle electron beams are simulated and combined using a Green's function approach to represent realistic electron spectra and pitch angle distributions. Results from this model include more accurate ionization profiles than previous analytical models, deeper photon penetration into the atmosphere than previous Monte Carlo model predictions, and predictions of backscatter fractions of loss cone electrons up to 40%. The model results are verified by comparison with previous precipitation modeling results, and validated using balloon X‐ray measurements from the Balloon Array for RBSP Relativistic Electron Losses mission and backscattered electron energy and pitch angle measurements from the Electron Loss and Fields Investigation with a Spatio‐Temporal Ambiguity‐Resolving CubeSat mission. The model results and solution techniques are developed into a Python package for public use. Plain Language Summary: The upper atmosphere and near‐Earth space interact with each other through the transport of charged particle (e.g., electrons) from space into the atmosphere in a process called energetic particle precipitation. This process disturbs the atmosphere and causes X‐rays to be generated, among other direct and indirect effects to the atmosphere, including ozone destruction. This work describes a physics‐based model that simulates this process across realistic input values for energy and electron velocity direction. Results of this work include an estimate of the number of excess ion‐electron pairs generated in the atmosphere from precipitation, how many electrons are lost to the atmosphere versus those that rebound and return to space, and the energy and amount of X‐rays generated by precipitation. The model outputs are checked using balloon‐based measurements of X‐rays in the middle atmosphere and by a low Earth orbiting satellite that spins to measure electrons heading toward and away from Earth. Key Points: A Geant4‐based model has been developed to simulate radiation belt energetic particle precipitation (EPP)Mono‐energy and mono‐pitch angle beams are simulated to be combined using inversion methods to represent EPP quantities of interestModel results and inversion methods are validated using remote and in‐situ measurements that compare favorably to modeled observations [ABSTRACT FROM AUTHOR]

Magnetic reconnection (MR) is a fundamental plasma process associated with conversion of the magnetic field energy into kinetic plasma energy, which is invoked to explain many non-thermal signatures in astrophysical events. Here we demonstrate that ultrafast relativistic MR in a magnetically dominated regime can be triggered by a readily available (TW-mJ-class) laser interacting with a micro-scale plasma slab. Three-dimensional (3D) particle-in-cell (PIC) simulations show that when the electrons beams excited on both sides of the slab approach the end of the plasma, MR occurs and it gives rise to efficient energy dissipation that leads to the emission of relativistic electron jets with cut-off energy ~12 MeV. The proposed scenario allows for accessing an unprecedented regime of MR in the laboratory, and may lead to experimental studies that can provide insight into open questions such as reconnection rate and particle acceleration in relativistic MR. [ABSTRACT FROM AUTHOR]

The remarkable success of x-ray free-electron lasers and their ability to image biological macromolecules while outrunning secondary radiation damage due to photoelectrons, by using femtosecond pulses, raise the question of whether this can be done using pulsed high-energy electron beams. In this paper, we use excited state molecular dynamics simulations, with tabulated potentials, for rare gas solids to investigate the effect of radiation damage due to inelastic scattering (by plasmons, excitons, and heat) on the pair distribution function. We use electron energy loss spectra to characterize the electronic excitations responsible for radiation damage. [ABSTRACT FROM AUTHOR]

The Galileo spacecraft performed close flybys of the moon Callisto between 1996 and 2001. We reanalyzed particle data of the energetic particles detector onboard Galileo and derived pitch angle distributions in the energy range of several keV to MeV during Callisto flybys C3, C9, C10, and C30. We establish that field‐aligned beams observed during the flyby periods are more likely to originate from Callisto's magnetospheric interaction rather than by independent magnetospheric processes. These beams are prominent only during flyby C3, they come mainly from the North, and connect the moon and the ionosphere of Jupiter. For short intervals they have also been observed propagating from the South. The beams are regularly unidirectional and typically extend to 300 keV in energy, occasionally reaching above 600 keV. Energetic particle depletions in Callisto's wake during the downstream flybys are not at all obvious, even at low altitudes and in the wake center. The signature of the wake becomes more apparent when energetic particle observations are organized in pitch angle. In that case, pitch angle distribution minima at 90 deg can be discerned in some flybys, however, not always associated with a profound drop in the absolute signal intensity. They instead indicate that field‐aligned particle flux within the wake is higher. Outside the wake these minima continue in an energy‐dependent disturbed region toward Jupiter which seems to be at least partially collocated with Alfvén‐wing structures as predicted from magnetohydrodynamic simulation results or simple flyby geometry considerations. Plain Language Summary: Pitch angle distributions of energetic electrons and ions during four close Callisto encounters of the Galileo spacecraft are analyzed and clear signatures of electron beams were found only for one of the four flybys. The beam energies extend up to 300 keV at least. The origin of those beams lies in the interaction between the plasma in the Jovian magnetosphere and the exosphere of Callisto. The electron beams were observed in regions of changing density and magnetic field values where the electrons are accelerated to maintain the current flow. The acceleration itself is most probably related to Alfvén waves. Key Points: Pitch angle distributions of electrons are used to establish field‐aligned beams near Callisto from the moon‐magnetosphere interactionClose to the moons, field‐aligned electron are accelerated in regions with changing density and magnetic field to maintain the current flowThere is evidence that at Callisto Alfvén waves could have accelerated electrons along field lines up to several hundreds of keV [ABSTRACT FROM AUTHOR]

Accelerator engineering could benefit from faster and higher-quality physics simulations. Machine learning has emerged as a promising tool for developing accelerator simulation programs that are both fast and accurate. In this study, we propose a surrogate model based on encoder–decoder neural networks. We incorporate physical regularization into the loss function, which allows us to integrate prior physical knowledge into the deep learning network. The advantage of this regularization is that it ensures the results are more consistent with the underlying physical laws. The method was applied to beam dynamics modeling of the medium energy beam transport (MEBT) section in the China Accelerator Facility for Superheavy Elements (CAFe II). The final results indicate that after training, the network maintains a mismatch, emittance difference, and transmission efficiency of approximately 0.01. Our scheme has been demonstrated to be effective in the simulation of the accelerator's beam dynamics. [ABSTRACT FROM AUTHOR]

The use of laser–plasma-based x-ray sources is discussed, with a view to carrying out time-resolved x-ray absorption spectroscopy measurements, down to the femtosecond timescale. A review of recent experiments performed by our team is presented. They concern the study of the nonequilibrium transition of metals from solid to the warm dense regime, which imposes specific constraints (the sample being destroyed after each shot). Particular attention is paid to the description of experimental devices and methodologies. Two main types of x-ray sources are compared, respectively, based on the emission of a hot plasma, and on the betatron radiation from relativistic electrons accelerated by laser. [ABSTRACT FROM AUTHOR]

All-optical Compton sources combine laser-wakefield accelerators and intense scattering pulses to generate ultrashort bursts of backscattered radiation. The scattering pulse plays the role of a small-period undulator (${\sim }1\,\mathrm {\mu }{\rm m}$) in which relativistic electrons oscillate and emit X-ray radiation. To date, most of the working laser-plasma accelerators operate preferably at energies of a few hundreds of megaelectronvolts and the Compton sources developed so far produce radiation in the range from hundreds of kiloelectronvolts to a few megaelectronvolts. However, for such applications as medical imaging and tomography the relevant energy range is 10–100 keV. In this article, we discuss different scattering geometries for the generation of X-rays in this range. Through numerical simulations, we study the influence of electron beam parameters on the backscattered photons. We find that the spectral bandwidth remains constant for beams of the same emittance regardless of the scattering geometry. A shallow interaction angle of $30^{\circ }$ or less seems particularly promising for imaging applications given parameters of existing laser-plasma accelerators. Finally, we discuss the influence of the radiation properties for potential applications in medical imaging and non-destructive testing. [ABSTRACT FROM AUTHOR]

Verification procedures for patient-specific quality assurance (QA) in advanced radiotherapy are laborious and time-consuming. Moreover, it has been shown that these procedures cannot detect some inaccuracies for some particular complex cases due to tissue inhomogeneity and highly modulated plans. Secondary dose calculation verification of radiotherapy plans is an important aspect in patient-specific QA. A suitably optimized software, RadCalc equipped with 3D Monte Carlo Module (MC), was used to dosimetrically verify radiotherapy treatment plans where the measured dose distributions can be inaccurate due to the TPS dose calculation algorithm and/or treatment unit delivery uncertainties. MC Models were built using specific commissioning measurements and then the Additional Radiation to Light Field Offset parameter (Dosimetric Leaf Gap parameter) was tuned to achieve the best dose comparison agreement with phantom patient-specific QA measurements. The results showed a good agreement between the TPS and the simulations. RadCalc MC also allows to better estimate the plan doses in lung cancer patients and to detect the presence of possible inaccuracies due to tissue inhomogeneity, which is not estimable with a homogeneous phantoms. [ABSTRACT FROM AUTHOR]

Purpose: Radiation-induced lung injury (RILI) is strongly associated with various clinical conditions and dosimetric parameters. Former studies have led to reducing radiotherapy (RT) doses to the lung and have favored the discontinuation of tamoxifen during RT. However, the monocentric design and variability of dosimetric parameters chosen have limited further improvement. The aim of our study was to assess the incidence of RILI in current practice and to determine clinical and dosimetric risk factors associated with RILI occurrence. Material and methods: Data from 3 out of the 10 top recruiting centers in CANTO-RT, a subset of the CANTO prospective longitudinal cohort (NCT01993498), were retrospectively analyzed for RILI occurrence. This cohort, which recruited invasive cT0-3 cN0-3 M0 breast cancer patients from 2012 to 2018, prospectively recorded the occurrence of adverse events by questionnaires and medical visits at the end of, and up to 60months after treatment. RILI adverse events were defined in all patients by the association of clinical symptoms and compatible medical imaging. Results: RILI was found in 38/1565 (2.4%) patients. Grade II RILI represented 15/ 38 events (39%) and grade III or IV 2/38 events (6%). There were no grade V events. The most frequently used technique for treatment was 3D conformational RT (96%). In univariable analyses, we confirmed the association of RILI occurrence with pulmonary medical history, absence of cardiovascular disease medical history, high pT and pN, chemotherapy use, nodal RT. All dosimetric parameters were highly correlated and had close predictive value. In the multivariable analysis adjusted for chemotherapy use and nodal involvement, pulmonary medical history (OR=3.05, p<0.01) and high V30 Gy (OR=1.06, p=0.04) remained statistically significant risk factors for RILI occurrence. V30 Gy >15% was significantly associated with RILI occurrence in a multivariable analysis (OR=3.07, p=0.03). Conclusion: Our study confirms the pulmonary safety of breast 3D RT in CANTO-RT. Further analyses with modern radiation therapy techniques such as IMRT are needed. Our results argue in favor of a dose constraint to the ipsilateral lung using V30 Gy not exceeding 15%, especially in patients presenting pulmonary medical history. Pulmonary disease records should be taken into account for RT planning. [ABSTRACT FROM AUTHOR]

Objective. This study aimed at investigating through Monte Carlo simulations the limitations of a novel hybrid Cerenkov-scintillation detector and the associated method for irradiation angle measurements. Approach. Using Monte Carlo simulations, previous experimental irradiations of the hybrid detector with a linear accelerator were replicated to evaluate its general performances and limitations. Cerenkov angular calibration curves and irradiation angle measurements were then compared. Furthermore, the impact of the Cerenkov light energy dependency on the detector accuracy was investigated using the energy spectra of electrons travelling through the detector. Main results. Monte Carlo simulations were found to be in good agreement with experimental values. The irradiation angle absolute mean error was found to be less than what was obtained experimentally, with a maximum value of 1.12° for the 9 MeV beam. A 0.4% increase of the ratio of electrons having an energy below 1 MeV to the total electrons was found to impact the Cerenkov light intensity collected as a function of the incident angle. The effect of the Cerenkov intensity variation on the measured angle was determined to vary according to the slope of the angular calibration curve. While the contribution of scattered electrons with a lower energy affects the detector accuracy, the greatest discrepancies result from the limitations of the calculation method and the calibration curve itself. Significance. A precise knowledge of the limitations of the hybrid detector and the irradiation angle calculation method is crucial for a clinical implementation. Moreover, the simulations performed in this study also corroborate hypotheses made regarding the relations between multiple Cerenkov dependencies and observations from the experimental measurements. [ABSTRACT FROM AUTHOR]

A growing body of scientific evidence indicates that exposure to low dose ionizing radiation (< 2 Gy) is associated with a higher risk of developing radioinduced cancer. Additionally, it has been shown to have significant impacts on both innate and adaptive immune responses. As a result, the evaluation of the low doses inevitably delivered outside the treatment fields (out-of-field dose) in photon radiotherapy is a topic that is regaining interest at a pivotal moment in radiotherapy. In this work, we proposed a scoping review in order to identify evidence of strengths and limitations of available analytical models for out-offield dose calculation in external photon beam radiotherapy for the purpose of implementation in clinical routine. Papers published between 1988 and 2022 proposing a novel analytical model that estimated at least one component of the out-of-field dose for photon external radiotherapy were included. Models focusing on electrons, protons and Monte-Carlo methods were excluded. The methodological quality and potential limitations of each model were analyzed to assess their generalizability. Twenty-one published papers were selected for analysis, of which 14 proposed multi-compartment models, demonstrating that research efforts are directed towards an increasingly detailed description of the underlying physical phenomena. Our synthesis revealed great inhomogeneities in practices, in particular in the acquisition of experimental data and the standardization of measurements, in the choice of metrics used for the evaluation of model performance and even in the definition of regions considered out-of-the-field, which makes quantitative comparisons impossible. We therefore propose to clarify some key concepts. The analytical methods do not seem to be easily suitable for massive use in clinical routine, due to the inevitable cumbersome nature of their implementation. Currently, there is no consensus on a mathematical formalism that comprehensively describes the out-of-field dose in external photon radiotherapy, partly due to the complex interactions between a large number of influencing factors. Out-of-field dose calculation models based on neural networks could be promising tools to overcome these limitations and thus favor a transfer to the clinic, but the lack of sufficiently large and heterogeneous data sets is the main obstacle. [ABSTRACT FROM AUTHOR]

One of the most prominent applications of modern particle accelerators is the generation of radiation. In a synchrotron or an x-ray free electron laser (XFEL), high energy electrons oscillating in periodic magnetic structures emit bright x rays. In spite of their scientific appeal that will remain evident for many decades, one limitation of synchrotrons and XFELs is their typical mile-long size and their cost, which often limits access to the broader scientific community. This tutorial reviews the principles and prospects of using plasmas produced by intense lasers as particle accelerators and x-ray light sources, as well as some of the applications they enable. A plasma is an ionized medium that can sustain electrical fields many orders of magnitude higher than that in conventional radio frequency accelerator structures and can be used to accelerate electrons. When short, intense laser pulses are focused into a gas, it produces electron plasma waves in which electrons can be trapped and accelerated to GeV energies. This process, laser-wakefield acceleration (LWFA), is analogous to a surfer being propelled by an ocean wave. Many radiation sources, from THz to gamma-rays, can be produced by these relativistic electrons. This tutorial reviews several LWFA-driven sources in the keV-MeV photon energy range: betatron radiation, inverse Compton scattering, bremsstrahlung radiation, and undulator/XFEL radiation. X rays from laser plasma accelerators have many emerging applications. They can be used in innovative and flexible x-ray imaging and x-ray absorption spectroscopy configurations, for use in biology, industry, and high-energy density science. [ABSTRACT FROM AUTHOR]

Purpose. The aim of this paper is the presentation of the complex activity realized by the medical physicists involved in the radiotherapy practice, starting from the preparation of the technical documentation necessary for the medical equipments authorization, until the physical and clinical dosimetry measurements, quality assurance (QA), and also the realization/ evaluation/approval of the treatment plan. Materials and method. Medical linear accelerators (LINAC), equipments for dosimetry measurements, and specific softwares were used. Results. After the preparation of authorization documentation and obtaining the specific licenses for the medical equipments, there were performed the physical dosimetry measurements according to the international guidelines for three linear accelerators, photons’ beams (with energy of 6 MV, and 15 MV), and electrons’ beams (with energy of 4 MeV, 6 MeV, 9 MeV, 12 MeV and 15 MeV). Further, there were realized some tests, proposed in the IAEATECDOC-1583(1) report of the International Atomic Energy Agency (IAEA), using the CIRS THORAX phantom, a special device for clinical dosimetry, having 8 localizations associated with 8 different density structures; those structures are situated at different depths and distances from the central axis. The prescribed dose taken into consideration was 200 cGy/ fraction; dose values calculated using the specific softwares based on the numerical models were compared with the values measured using ionization chamber and the further results were evaluated according to the acceptance protocols (variation/deviation threshold is between ±2% and ±4%). Also, for all the three linear accelerators the IAEA external periodic audit “Dose Quality” was performed. The follow-up and the clinical dosimetry measurements were realized for all radiological equipments, taking into consideration different tumor localizations, in accordance with the medical prescription: dose (D) per fraction (Fr.), Dmax for PTV (planning target volume) and the specific dose for organ at risk (OAR). Conclusions. Medical physicists’ activities are very complex, the specialists having the professional mission to assure constantly that radiotherapy equipments are properly used according to the radiological norms. Also, they perform physical and clinical dosimetry for quality assurance in radiotherapy practice. Independent of its source, the radiation can produce radiological incidents or accidents, therefore the entire professional activity of the medical physicist must be efficient and efficacious developed. The measurements results are situated in the acceptance standards of 2-4%. Dose rate verification is a very important step because a possible dose rate variation of the equipments may induce monitor units variation calculated with TPR. With the aim to obtain valid results, it is important to use ionization chambers calibrated at time intervals specified in their calibration certificates. Treatment plans calculated with numerical algorithms may also be verified through manual calculation, taking into consideration the medium’s density in the reference point. [ABSTRACT FROM AUTHOR]

The study of relativistic electron–positron pair plasmas is both of fundamental physics interest and important to understand the processes that shape the magnetic field dynamics, particle acceleration, and radiation emission in high-energy astrophysical environments. Although it is highly desirable to study relativistic pair plasmas in the laboratory, their generation and control constitutes a critical challenge. Significant experimental and theoretical progress has been made over recent years to explore the use of intense lasers to produce dense relativistic pair plasma in the laboratory and study the basic collective plasma processes associated with these systems. Important challenges remain in terms of improving the number of pairs, system size, and control over the charge neutrality required to establish laboratory platforms that can expand our understanding of relativistic pair plasma and help validate underlying models in conditions relevant to high-energy astrophysical phenomena. We highlight recent progress in this field, discuss the main challenges, and the exciting prospects for studying relativistic pair plasmas and astrophysics relevant instabilities in the laboratory in the near future. [ABSTRACT FROM AUTHOR]

By focusing conventional 1-TW 40-fs laser pulses into a dense 450-μm-long nitrogen gas cell, we demonstrate the feasibility of routinely generating electron beams from laser wakefield acceleration (LWFA) with primary energies scaling up to 10 MeV and a high charge in excess of 50 pC. When electron beams are generated with a charge of ≈30 pC and a beam divergence of ≈40 mrad from the nitrogen cell having a peak atom density of 7.6 × 10 18 cm−3, increasing the density inside the cell by 25%—controlled by tuning the backing pressure of fed nitrogen gas—can induce defocusing of the pump pulse that leads to a twofold increase in the output charge but with a trade-off in beam divergence. Therefore, this LWFA scheme has two preferred regimes for acquiring electron beams with either lower divergence or higher beam charge depending on a slight variation of the gas/plasma density inside the cell. Our results identify the high potential for implementing sub-millimeter nitrogen gas cells in the future development of high-repetition-rate LWFA driven by sub-TW or few-TW laser pulses. [ABSTRACT FROM AUTHOR]

Various weight fractions (ranging from 0 to 30 wt percent, at 5 wt percent intervals) of microcrystalline wood charcoal powder (75µm) were used to generate polyester-based particle reinforced composites. The developed wood charcoal (WC) particles reinforced polyester matrix composites were successfully characterized quantitatively, qualitatively, and functionally using an energy dispersive x-ray spectrophotometer (EDXRF), scanning electron microscope (SEM) enhanced with ancillary EDS for elemental identification capability and Fourier transform infrared spectrometer (FTIR). Fe2O3, CaO, CuO, ZnO and Iron, calcium, copper, zinc are the major oxides and elements discovered in wood charcoal by EDXRF. The characteristics of reinforced polymer composites were found to be improved by these elements and oxides. The key elements revealed by EDXRF analysis were also validated by EDS elemental mapping. SEM images demonstrated that composites supplemented with microcrystalline wood charcoal had high interfacial adhesion and interlocking due to even dispersion of the filler particles. FTIR functional characterization indicated interactions of the microcrystalline wood charcoal fillers with the polyester matrix molecules as modest shifts in the frequency bands of functional groups commonly found in unsaturated polyester resin. [ABSTRACT FROM AUTHOR]

Verifying the accuracy of the dose calculation algorithm is considered one of the most critical steps in radiotherapy treatment for delivering an accurate dose to the patient. This work aimed to evaluate the dosimetric performance of the treatment planning system (TPS) algorithms; the AAA (v. 15.6), AXB (v. 15.6) and eMC (v. 15.6) following the AAPM medical physics practice guideline 5.a (MPPG 5.a) validation tests package in a Varian iX Linear Accelerator (Linac). A series of tests were developed based on the MPPG 5.a. on a Varian's Eclipse TPS (v. 15.6) (Varian Medical Systems). First, the basic photon and electron tests were validated by comparing the TPS calculated dose with the measurements. Next, for heterogeneity tests, we verified the Computed Tomography number to electron density (CT-to-ED) curve by comparing it with the baseline values, and TPS calculated point doses beyond heterogeneous media were compared to the measurements. Finally, for IMRT/VMAT dose validation tests, clinical reference plans were re-calculated on ArcCheck's virtual phantom (Sun Nuclear Corporation, Melbourne, FL, USA) and exported to the Linac for delivery using the ArcCheck dosimetry system. All validation tests were evaluated following the MPPG 5.a recommended tolerances. In basic dose validation tests, the TPS calculated depth dose profiles agreed well with the measurements, with a minimum gamma passing rate of 95% at 2%/2 mm criteria. However, disagreements are seen in the build-up and penumbra region. Results for most point doses in homogeneous water phantoms were within the MPPG 5.a tolerance. For the heterogeneity tests, the CT-to-ED curve was established, and calculated point doses were all within 3% of the measurements for heterogeneous media for both photon algorithms at three energies. These results are within the MPPG5.a the recommended tolerance of 3%. Moreover, for electron beams, the differences between the calculated and measured point doses averaged 5% and 7%, but were just within the MPPG 5.a tolerance of 7%. For IMRT and VMAT validation tests using a gamma criteria of a 2%/2 mm, IMRT plans showed maximum and minimum passing rates of 98.2% and 97.4%, respectively. Whereas VMAT plans showed maximum and minimum passing rates of 100% and 94.3%, respectively. We conclude that the dosimetric accuracy of the Eclipse TPS (v15.6) algorithm is adequate for clinical use. The MPPG 5.a tests are valuable for evaluating dose calculation accuracy and are very useful for TPS upgrade checks, commissioning tests, and routine TPS QA. [ABSTRACT FROM AUTHOR]

Plasma waves are considered to be a unique feature of space plasmas which have a universal presence. Plasma waves are observed in almost all solar system objects such as the Sun, planets, planetary satellites, interplanetary medium, etc. Plasma waves are predicted to exist in the interstellar medium, etc. Plasma waves can exist around the comets also. The interaction of solar radiation with the neutral cometary surroundings results in the formation of a plasma environment around a comet which is capable of sustaining plasma waves. Plasma waves are observed around comets Giacobini–Zinner, Halley, Grigg–Skjellerup, Borrelly, and Churyumov–Gerasimenko. Some other comets such as Humason, Brorsen–Metcalf, Wirtanen, etc. also have a plasma environment but the existence of plasma waves there is yet to be investigated. In this review paper, the plasma waves observed around five main comets are discussed [ABSTRACT FROM AUTHOR]

The low energy (2.8 kJ, 25 μF, 15 kV, 120 kA) AECS PF-2 Mather-type plasma focus device operated with nitrogen filling gas is used to study of the high energetic electrons beams effect on the pure tin material inserted on the copper anode tip. The operational gas pressure ranges from 0.2 mbar to 1.2 mbar. For each plasma focus discharge, the current and voltage waveforms are recorded using Rogowski coil and Ohm voltage divider, respectively. Two five channel BPX65 PIN photodiodes X-ray spectrometers (DXS) with appropriate filters are managed to estimate the X-ray yield emitted from the tin (Sn) insert (tin L-series X-ray 3.04–4.474 keV window) at the axial and radial directions. The signals of current, voltage and the temporal evolution of X-rays generated in the AECS PF-2 plasma focus device are simultaneously recorded and then analyzed for different experimental conditions. As the X-ray emission from plasma focus has a shot-to-shot variation, so for each value of gas pressure 3–10 successful shots are performed. The obtained results show that the X-ray yield decreases with increasing pressure from 0.2 to 1.2 mbar. The peak X-ray yield is found to be 0.4 J at the pressure of 0.2 mbar with efficiency ∼0.014% and the lowest values are at the highest pressure of 1.2 mbar. It can be concluded that the X-ray emission from AECS PF-2 plasma focus device depends on the pinch plasma parameters, the generated electron beam properties and the tin insert. • The AECS PF-2 device is used to study of the x-ray yield from the tin insert. • The x-ray yield decreases with increasing pressure from 0.2 to 1.2 mbar. • The maximum yield is found to be 0.4 J (at 0.2 mbar). [ABSTRACT FROM AUTHOR]

Background and objective: The oncogenic effect of ionizing radiation is widely known. Sarcomas developing after radiation therapy (RT), termed "iatrogenic disease of success", represent a growing problem, since the advancements in cancer management and screening programs have increased the number of long-term cancer survivors. Although many patients have been treated with radiation therapy, only few data are available on radiation-induced sarcomas (RIS). Methods: We examined the medical and radiological records of 186 patients with histologically proven soft tissue and bone sarcomas, which referred to IRCCS CROB Centro di Riferimento Oncologico della Basilicata from January 2009 to May 2022. Among them, seven patients received a histological diagnosis of secondary RIS, according to Cahan's criteria. Clinicopathological features and treatment follow-up data of RIS patients were retrospectively analyzed. Results: Among these secondary RIS, five arose in irradiated breast cancer (5/2,570, 0.19%) and two in irradiated head and neck cancer (2/1,986, 0.10%) patients, with a mean onset latency time of 7.3 years. The histology of RIS was one desmoid tumor, two angiosarcomas, one chondrosarcoma, two leiomyosarcomas, and one undifferentiated pleomorphic sarcoma. Out of the seven RIS, one received radiotherapy, one received electrochemotherapy (ECT), one received a second-line chemotherapy, three were subjected to three lines of chemotherapy, and one underwent radiofrequency ablation, chemotherapy, and ECT. Median survival time is 36 months. No significant survival differences were found stratifying patients for age at RT, latency time, and age at RIS diagnosis. Conclusions: RIS represents a possible complication for long-survivor cancer patients. Therefore, adherence to a strict follow-up after the radiation treatment is recommended to allow early diagnosis and optimal management of RIS patients. After the planned follow-up period, considering the long-term risk to develop a RIS, a specific multispecialty survivorship care plan could be of benefit for patients. [ABSTRACT FROM AUTHOR]

Laser plasma accelerators (LPA) offer an exciting possibility to deliver high energy, high brightness electrons beams in drastically smaller distance scales than is typical for conventional accelerators. As such, LPAs draw considerable attention as potential drivers for next generation light sources and for a compact linear collider. In order to asses the viability of an LPA source for a particular application, the brightness of the source should be properly characterized. In this paper, we present charge dependent transverse emittance measurements of LPA sources using both ionization injection and shock induced density down ramp injection, with the latter delivering smaller transverse emittances by a factor of two when controlling for charge density. The single shot emittance method is described in detail with a discussion on limitations related to second order transport effects. The direct role of space charge is explored through a series of simulations and found to be consistent with experimental observations. [ABSTRACT FROM AUTHOR]

• Photocarrier radiometry (PCR) with superior signal-to-noise was employed to evaluate the carrier transport parameters of silicon solar cell irradiated by energetic particles. • Damage coefficients for lifetime and diffusion lengths were obtained through the PCR results. • The diffusion length maps for the irradiated solar cell and non-irradiation solar cell were compared. Radiation damage induced by energetic particles such as protons and electrons beams could cause permanent deterioration of electrical characteristics of the semiconductor material, which is one of the primary reasons for failures of the space solar cells. This paper discusses the degradations of carrier lifetime and diffusion length of c-Si solar cell with low-level energy (<1 MeV) electron and proton irradiations using Photocarrier Radiometry (PCR) methodology. A theoretical one-dimensional two-layer PCR model was used to evaluate these two parameters of the c-Si solar cells. Monte Carlo Simulations (MCS) were employed to analyze the radiation damage of c-Si solar cell induced by electron and proton irradiations at different energies. Experimental investigations on PCR signals of c-Si solar cells irradiated by electron and proton beams were presented. The results show that the carrier lifetime and diffusion length are dramatically reduced due to the radiation damage induced by the low-level energy electron and proton irradiation. [ABSTRACT FROM AUTHOR]

Cherenkov emission (CE) is a visible blueish light emitted in water mediums irradiated by most radiotherapy treatment beams. However, CE is produced anisotropically which currently imposes a geometrical constraint uncertainty for dose measurements. In this work, polarization imaging is proposed and described as a method enabling precise 2D dose measurements using CE. CE produced in a water tank is imaged from four polarization angles using a camera coupled to a rotating polarizer. Using Malus' law, the polarized component of CE is isolated and corrected with Monte Carlo calculated CE polar and azimuthal angular distributions. Projected dose measurements resulting from polarization-corrected CE are compared to equivalent radiochromic film measurements. Overall, agreement between polarized corrected CE signal and films measurements is found to be within 3%, for projected percent depth dose (PPDD) and profiles at the different tested energies (γ : 6 and 18 MV , e - : 6 and 18 MeV ). In comparison, raw Cherenkov emission presented deviations up 60% for electron beam PPDDs and 20% for photon beams PPDDs. Finally, a degree of linear polarization between 29% and 47% was measured for CE in comparison to 0.2 ± 0.3 % for scintillation. Hence, polarization imaging is found to be a promising and powerful method for improved radio-luminescent dose measurements with possible extensions to signal separation. [ABSTRACT FROM AUTHOR]

We report on the experimental demonstration of single-photon state generation and characterization in an electron microscope. In this aim we have used low intensity relativistic (energy between 60 and 100 keV) electrons beams focused in a ca. 1 nm probe to excite diamond nanoparticles. This triggered individual neutral nitrogen-vacancy centers to emit photons which could be gathered and sent to a Hanbury Brown-Twiss intensity interferometer. The detection of a dip in the correlation function at small time delays clearly demonstrates antibunching and thus the creation of nonclassical light states. Specifically, we have also demonstrated single-photon states detection. We unveil the mechanism behind quantum states generation in an electron microscope, and show that it clearly makes cathodoluminescence the nanometer scale analog of photoluminescence. By using an extremely small electron probe size and the ability to monitor its position with subnanometer resolution, we also show the possibility of measuring the quantum character of the emitted beam with deep subwavelength resolution. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The possibility of using the Gafchromic® EBT films parallel to incident electron beams was assessed in order to facilitate quality assurance tests for electron dose calculation algorithms. Materials and methods: Calibration curves were made for electron energies of 6, 9 and 12MeV. A set-up was suggested for EBT film irradiation parallel to the beam, and the dose measurements were compared to Ionization Chamber (IC) measurements in standard and small electrons beams. A more complex Quality Assurance (QA) set-up was performed with the cylindrical CARPET® phantom in order to test our Treatment Planning System (TPS) (Eclipse, Varian Medical Systems, Palo Alto, California) for the clinical situation of a chest wall electron beam therapy. Two dimensional dose distribution and gamma index results were compared to the calculated distribution given by the TPS. Results: The reproducibility was found to be better than 1.5%. We found that applying strong pressure and aligning carefully the film edge with the phantom surface, as recommended for radiographic films, did not completely eliminate the air gap effect. Adding an ultrasound transmission gel and 2 complementary EBT films on the surface gave satisfactory results. The absolute dose for the reference 10×10cm2 field was always within 1% of IC measurements and for smaller elongated fields (5×10, 4×10 and 3×10cm2) the mean difference was −1.4% for the three energies. The mean difference with the IC measurements in R 100, R 90 and R 50 was 0.9mm for all fields and for the three energies. The mean difference in the width of the 90% and the 50% isodoses at R 100 was 0.6mm. With the CARPET® phantom set-up very good agreement was found in the 2D dose distribution; 99% of the points satisfied the γ <1 criteria (3%–3mm). Conclusion: EBT films parallel to the beam axis could be used for absolute measurements of 2D dose distribution if ultrasound gel and overlying perpendicular films are added on the phantom surface. [Copyright &y& Elsevier]

In this paper, we consider the kinetic regularities of lithium–zinc ferrite synthesis under conditions of heating by a high-energy electron beam of mixtures of initial reagents Fe2O3–Li2CO3–ZnO of bulk density and pressed in a hydraulic press. Radiation-thermal synthesis of the samples was performed using an ILU-6 pulsed electron accelerator by heating them with a 2.4-MeV high-energy electron beam. The samples were heated to 600, 700, and 750°C and held at these temperatures for up to 120 min. For comparison with radiation-thermal synthesis, similar studies were carried out with traditional thermal annealing under the same conditions. An X-ray diffraction analysis of the synthesized samples was performed. The rate of ferrite formation was found to depend on both the heating method and the density of the mixture. Heating the mixture with an electron beam is shown to significantly accelerate the process of obtaining ferrite, which manifests itself in a decrease in the values of the kinetic parameters of the ferrite synthesis. An increase in the rate of ferrite formation under the effect of electrons is due to a significant decrease in the activation energy of the synthesis and a decrease in the pre-exponential factor in the temperature dependence. [ABSTRACT FROM AUTHOR]

In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread. [ABSTRACT FROM AUTHOR]