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Nitrogen-incorporated ultrananocrystalline diamond [(N)UNCD] pyramid tip cathode has been considered as a next-generation high peak current electron source for dielectric laser accelerators as well as other high peak current particle accelerator applications. In this work, we study non-linear photoemission from an (N)UNCD pyramid tip cathode using an ultrafast laser with the pulse length of 150 fs with the central wavelength of 800 nm in the peak intensity range of 10 9 – 10 10 W / cm 2. We demonstrated that as the incident laser intensity increases, the current emitted from the nano-tip first increases as a power function with an exponent of about 5 and then starts to roll over to an exponent of 3. This roll over is attributed to the Coulomb interaction between electrons emitted from the tip also known as the space charge. We also measured the photoemission electron energy spectra that show electrons with energies as high as ∼ 10 eV. Based on the shape of the electron energy spectra, we conclude that the high-energy electrons are thermally emitted electrons due to ultrafast laser heating at the tip of the (N)UNCD pyramid tip cathode. [ABSTRACT FROM AUTHOR]

Particle trajectory and collision simulation is a critical step of the design and construction of novel particle accelerator components. However it requires a huge computational effort which can slow down the design process. We started from a sequential simulation program which is used to study an event called Multipacting. Our work explains the physical problem that is simulated and the implications it can have on the behavior of the components. Then we analyze the original program's operation to find the best options for parallelization. We first developed a parallel version of the Multipacting simulation and were able to accelerate the execution up to ∼ 35 × with 48 or 56 cores. In the best cases, parallelization efficiency was maintained up to 16 cores ( ∼ 95 %) and the speed-up plateaus at around 40–48 cores. When this first parallelization effort was tried for multi-power simulations, we found that parallelism was severely limited with a maximum of 20 × speed-up. For this reason, we introduced a new method to improve the parallelization efficiency for this second use case. This method uses a shared processor pool for all simulations of electrons (OnePool). OnePool improved scalability by pushing the speed-up to over 32 × . [ABSTRACT FROM AUTHOR]

The commissioning of multi-petawatt class laser facilities around the world is gathering pace. One of the primary motivations for these investments is the acceleration of high-quality, low-emittance electron bunches. Here we explore the interaction of a high-intensity femtosecond laser pulse with a mass-limited dense target to produce MeV attosecond electron bunches in transmission and confirm with three-dimensional simulation that such bunches have low emittance and nano-Coulomb charge. We then perform a large parameter scan from non-relativistic laser intensities to the laser-QED regime and from the critical plasma density to beyond solid density to demonstrate that the electron bunch energies and the laser pulse energy absorption into the plasma can be quantitatively described via the Zero Vector Potential mechanism. These results have wide-ranging implications for future particle accelerator science and associated technologies. [ABSTRACT FROM AUTHOR]

The synchrotron is a circular particle accelerator used for high energy physics experiments, material and life science, as well as hadron cancer therapy. After acceleration to the desired energies, particle beams are commonly extracted from the synchrotron using the method of resonant slow extraction. The goal is to deliver a steady particle flux—referred to as spill—to experiments and treatment facilities over the course of seconds while slowly emptying the storage ring. Any uncontrolled intensity fluctuations in the spill are detrimental to the efficiency of beam usage, as they lead to detector pileups or detector interlocks, hindering experiments and cancer treatment. Among the most widely used extraction scheme in medical facilities is the Radio Frequency Knock Out (RF-KO) driven resonant slow extraction, where the stored beam is transversely excited with a radio frequency (RF) field and the spill intensity is controlled by the excitation signal strength. This article presents particle dynamics simulations of the RF-KO system with the focus on finding effective mechanism for minimizing the intensity fluctuations while maintaining a good extraction efficiency and other advantages of KO extraction. An improved beam excitation signal which optimizes these main objectives is found, and is rigorously compared experimentally with other commonly applied techniques. [ABSTRACT FROM AUTHOR]

This letter presents a method for accurately calculating radio frequency (RF) power in a standing wave transmission line system. The proposed approach utilizes two directional couplers in conjunction with a low‐level radio frequency control system. RF power is determined through the application of proposed equations derived from amplitude and phase measurements of coupling signals obtained from the two directional couplers. Experimental validation of the method is conducted using two directional couplers with directivities of 26 and 28 dB, respectively, operating at 162.5 MHz across the entire wavelength. Results indicate that employing a single directional coupler yields average power errors of approximately 6.6% and 5.8%, respectively. However, by implementing the proposed method, the measurement error can be reduced to approximately 1.0%. [ABSTRACT FROM AUTHOR]

Copper-based alloys designed to combine high electronic and thermal conductivities with high mechanical strength find a wide range of applications in different fields. Among the principal representatives, strongly diluted CuAg alloys are of particular interest as innovative materials for the realization of accelerating structures when the use of high-gradient fields requires increasingly high mechanical and thermal performances to overcome the limitations induced by breakdown phenomena. This work reports the production and optical characterization of CuAg crystals at low Ag concentrations, from 0.028% wt to 0.1% wt, which guarantee solid solution hardening while preserving the exceptional conductivity of Cu. By means of Fourier Transform Infrared (FTIR) micro-spectroscopy experiments, the low-energy electrodynamics of the alloys are compared with that of pure Cu, highlighting the complete indistinguishability in terms of electronic transport for such low concentrations. The optical data are further supported by Raman micro-spectroscopy and SEM microscopy analyses, allowing the demonstration of the full homogeneity and complete solubility of solid Ag in copper at those concentrations. Together with the solid solution hardening deriving from the alloying process, these results support the advantage of strongly diluted CuAg alloys over conventional materials for their application in particle accelerators. [ABSTRACT FROM AUTHOR]

A novel design methodology based on a current-tunable magnetic focusing system that can flexibly switch between Brillouin and immersive flow focusing modes is presented in this paper. Such a magnetic system, which comprises cascaded solenoid coils and pole pieces, could be used in beam optics systems of vacuum tubes, particle accelerators, and free-electron lasers. Although the profile of this magnetic system is not brand new, the novel way proposed in this paper to establish and manipulate such a system to fit versatile purposes has never been reported in the literature to the best of the authors' knowledge. The specific structure of the magnetic system should be optimized, starting from the immersive flow focusing mode together with the electron gun design, which will be determined on successful optimization. According to our analysis, such systems could be transformed into the Brillouin bunching mode by simply adjusting the coil currents without modifying the hardware. To verify such an approach, single-beam and multi-beam optical systems are demonstrated in this paper. Moreover, the beam radius in such systems could also be conveniently adjusted via a similar technique. [ABSTRACT FROM AUTHOR]

Ultrashort-pulse laser processing of copper is performed in air to reduce the secondary electron yield (SEY). By UV (355 nm), green (532 nm), and IR (1064 nm) laser-light induced surface modification, this study investigates the influence of the most relevant experimental parameters, such as laser power, scanning speed, and scanning line distance (represented as accumulated fluence) on the ablation depth, surface oxidation, topography, and ultimately on the SEY. Increasing the accumulated laser fluence results in a gradual change from a Cu 2 O to a CuO-dominated surface with deeper micrometer trenches, higher density of redeposited surface particles from the plasma phase, and a reduced SEY. While the surface modifications are less pronounced for IR radiation at low accumulated fluence (< 1000 J/cm 2), analogous results are obtained for all wavelengths when reaching the nonlinear absorption regime, for which the SEY maximum converges to 0.7. Furthermore, independent of the extent of the structural transformations, an electron-induced surface conditioning at 250 eV allows a reduction of the SEY maximum below unity at doses of 5×10-4 C/mm 2. Consequently, optimization of processing parameters for application in particle accelerators can be obtained for a sufficiently low SEY at controlled ablation depth and surface particle density, which are factors that limit the surface impedance and the applicability of the material processing for ultrahigh vacuum systems. The relations between processing parameters and surface features will provide guidance in treating the surface of vacuum components, especially beam screens of selected magnets of the Large Hadron Collider or of future colliders. [ABSTRACT FROM AUTHOR]

Studies of the radiation tolerance and electrical behavior of gallium nitride (GaN) based devices are important for the next generation of high-power and high-voltage electronics that may be subjected to harsh environments such as nuclear reactor and fusion facilities, particle accelerators, and post-denotation environments. In this work, we study the behavior of Ga-polar and N-polar GaN Schottky diodes before and after exposure to fast and thermal + fast neutrons. Temperature-dependent current–voltage (I–V) and circular transmission line method (CTLM) measurements were used to study the electrical characteristics. A strong reduction in reverse leakage current and an increase in differential resistance in forward bias were observed after neutron irradiation. Thermionic emission (TE), Frenkel–Poole (FP) emission, and Fowler–Nordheim (FN) tunneling models were used to explain the forward and reverse I–V characteristics pre- and post-irradiation. The study confirms that Ga-polar and N-polar GaN Schottky diodes exhibit different electrical responses to fast and thermal neutron irradiations. The reverse bias characteristics of N-polar diodes are less affected after the fast neutron irradiation compared to Ga-polar diodes, while in the forward bias region, the electrical behavior after fast and thermal neutron irradiations is similar in Ga-polar and N-polar diodes. The results indicate that the role of orientation should be considered in the design of GaN-based radiation-tolerant electronics. [ABSTRACT FROM AUTHOR]

Metal photocathodes are widely utilized as electron sources for particle accelerators for their ease of use, high durability, and fast response time. However, the high work function (WF) and low quantum efficiency (QE) typically observed in metals necessitate the use of high power deep UV lasers. Metal oxide ultra-thin films on metals offer a route to photocathodes with a lower WF and improved QE while maintaining photocathode durability and response time. We show how the photocathode performance of an Ag(100) single crystal is enhanced by the addition of an ultra-thin MgO film. The film growth and WF reduction of 1 eV are characterized, and the QE and mean transverse energy (MTE) are measured as a function of illumination wavelength. An eightfold increase of QE is achieved at 266 nm without adding to MTE through additional surface roughness, and the resistance of the photocathode to O 2 gas is greatly improved. [ABSTRACT FROM AUTHOR]

The article focuses on the potential of a muon collider to revolutionize particle physics, exploring its feasibility, technical hurdles, and its capacity to address key inquiries such as elucidating the Higgs mechanism, which explains how particles acquire mass, investigating dark matter, and probing supersymmetry. Topics include the challenges in building a muon collider, its advantages over conventional colliders, and its implications for addressing fundamental questions in particle physics.

In classical electrodynamics, the well-known Lorentz force law falls short of providing a satisfactory result for the trajectory of point-like charged particles when considering that particle's own self-force. While there have been many historical attempts, Gralla, Harte and Wald developed a new model for classical charged particles that is free from pathologies while being consistent with Maxwell's equations and conserves stress-energy. Expanding upon this approach, we derive a relativistically correct, modified Lorentz force law in vector form, which includes radiation reaction, and spin- and magnetic moment-dependent correction terms, suitable to be included in classical electrodynamics lectures and beam dynamics simulation tools. As by-products we obtain evolution equations for mass, spin angular momentum and the radiated power. We compare the new equations to the classical ones and use the new equations to conduct numerical simulations, showing that the results are free of any nonphysical artifacts, and which might be possible to test in future experiments at particle accelerators. The new equations foster improved insight into beam dynamics. [ABSTRACT FROM AUTHOR]

Introduction: The presence of neutron contamination in medical linear accelerators poses a significant challenge in radiation therapy. Numerous studies have addressed the estimation of neutron levels, often relying on electronic equipment to extract simulation results. This study introduces an innovative neutron detection method that eliminates the need for electrical system with complex circuit. Material and Methods: Neutron contamination arises in VARIAN linear accelerators through the interaction of energetic photons with heavier elements in the accelerator head, such as Tungsten. The primary objective of this study is to investigate neutron contamination in the VARIAN linear accelerators using a Thick Gas Electron Multiplier (THGEM) detector in the Self-Quenching Streamer (SQS) mode through Monte Carlo simulation. The detection system designed in this study involves of two main parts. 1- Conversion material to convert neutrons to protons. 2- THGEM in SQS mode to detect protons. In this structure, the detection of protons gives an estimate of neutron contamination. Results: The findings indicate that, in the designed detection system, a distance of 0.5 cm from the converter is an optimal location for the THGEM. When the THGEM's minimum voltage is set at 700 volts, SQS mode occurs in most THGEM holes. Conclusion: The simple structure is one of the advantages of detection system in this research. Its costeffectiveness, featuring fewer electrical tolerances, lightweight design, and adaptability in various sizes are additional advantages, making it a viable option for neutron contamination detection. [ABSTRACT FROM AUTHOR]

The direction of particle accelerator development is ever-increasing beam quality, currents and repetition rates. This poses a challenge to traditional diagnostics that directly intercept the beam due to the mutual destruction of both the beam and the diagnostic. An alternative approach is to infer beam parameters non-invasively from the synchrotron radiation emitted in bending magnets. However, inferring the beam distribution from a measured radiation pattern is a complex and computationally expensive task. To address this challenge we present SYRIPY (SYnchrotron Radiation In PYthon), a software package intended as a tool for performing inference of synchrotron-radiationbased diagnostics. SYRIPY has been developed using PyTorch, which makes it both differentiable and able to leverage the high performance of GPUs, two vital characteristics for performing statistical inference. The package consists of three modules: a particle tracker, Lienard-Wiechert solver and Fourier optics propagator, allowing start-to-end simulation of synchrotron radiation detection to be carried out. SYRIPY has been benchmarked against SRW, the prevalent numerical package in the field, showing good agreement and up to a 50x speed improvement. Finally, we have demonstrated how SYRIPY can be used to perform Bayesian inference of beam parameters using stochastic variational inference. [ABSTRACT FROM AUTHOR]

The document provides a comprehensive list of upcoming conferences and events related to X-ray spectrometry, chemical analysis, and materials research. These events will take place in different locations worldwide from 2024 to 2028. Notable conferences mentioned include the Nano tech 2024 conference in Tokyo, the APS March Meeting 2024 in Minneapolis, the ACS Spring 2024 conference in New Orleans, and the European Conference on X-ray Spectrometry 2024 in Athens. Researchers and professionals interested in these fields can use this list to find relevant conferences and meetings to attend or gather information from, fostering collaboration and knowledge sharing. [Extracted from the article]

We report the detection of a γ -ray bubble spanning at least 100 deg 2 in ultra-high energy (UHE) up to a few PeV in the direction of the star-forming region Cygnus X, implying the presence super PeVatron(s) accelerating protons to at least 10 PeV. A log-parabola form with the photon index Γ (E) = (2.71 ± 0.02) + (0.11 ± 0.02) × log 10 (E / 10 TeV) is found fitting the gamma-ray energy spectrum of the bubble well. UHE sources, "hot spots" correlated with very massive molecular clouds, and a quasi-spherical amorphous γ -ray emitter with a sharp central brightening are observed in the bubble. In the core of ∼ 0.5 ° , spatially associating with a region containing massive OB association (Cygnus OB2) and a microquasar (Cygnus X-3), as well as previously reported multi-TeV sources, an enhanced concentration of UHE γ -rays is observed with 2 photons at energies above 1 PeV. The general feature of the bubble, the morphology, and the energy spectrum, are reasonably reproduced by the assumption of a particle accelerator in the core, continuously injecting protons into the ambient medium. [ABSTRACT FROM AUTHOR]

The superconducting magnets of future particle accelerators will be exposed to high irradiation doses at cryogenic temperatures. To investigate the effect of irradiation temperature and atmosphere on the aging behavior, we have characterized the changes in thermomechanical properties of six epoxy resins for potential use in superconducting magnets after irradiation up to 20 MGy in ambient air, inert gas, and liquid helium. Based on the results obtained by Dynamic Mechanical Analysis (DMA), we discuss the effect of irradiation temperature and the presence of oxygen. The irradiation temperature can have a strong influence on the rates at which cross-linking and chain scission occur. [ABSTRACT FROM AUTHOR]

Context. The colliding-wind region in binary systems made up of massive stars allows us to investigate various aspects of shock physics, including particle acceleration. Particle accelerators of this kind are mainly identified thanks to their synchrotron radio emission and dubbed particle-accelerating colliding-wind binaries. Aims. Our objective is first to validate the notion that obtaining snapshot high-resolution radio images of massive binaries constitutes a relevant approach to unambiguously identifying particle accelerators. Second, we intend to exploit these images to characterise the synchrotron emission of two specific targets, HD 167971 and HD 168112, which are known particle accelerators. Methods. We traced the radio emission from the two targets at 1.6 GHz with the European Very Long Baseline Interferometry (VLBI) Network, with an angular resolution of a few milli-arcseconds. Results. Our measurements allowed us to obtain images for both targets. For HD 167971, our observation occurs close to apastron, at an orbital phase where the synchrotron emission is at minimum. For HD 168112, we resolved for the very first time the synchrotron emission region. The emission region appears slightly elongated, in agreement with the expectations for a colliding-wind region. In both cases, the measured emission is significantly stronger than the expected thermal emission from the stellar winds, lending strong support to their non-thermal nature. Conclusions. Our study offers a significant contribution to the still poorly addressed question of high angular resolution radio imaging of colliding-wind binaries. We show that snapshot VLBI measurements constitute an efficient approach to investigate these objects, with promising results in terms of the identification of additional particle accelerators, coupled with their applicability in revealing long-period binaries. [ABSTRACT FROM AUTHOR]

Simple Summary: This manuscript is entitled "MR-LINAC, a new partner in radiation oncology: current landscape" in response to your invitation to collaborate on the Special Issue on "Hypofractionated Radiotherapy in Cancer Treatments". The main contribution of this review is to provide an update on the scientific evidence regarding the role of new technology in radiation oncology: the MR-LINAC. These data are relevant because there have been important advances in the management of different pathologies with this LINAC, principally high dose and SBRT, with promising results in recent years. Technological advances in radiation oncology are oriented towards improving treatment precision and tumor control. Among these advances, magnetic-resonance-image-guided radiation therapy (MRgRT) stands out, with technological advances to deliver targeted treatments adapted to a tumor's anatomy on the day while minimizing incidental exposure to organs at risk, offering an unprecedented therapeutic advantage compared to X-ray-based IGRT delivery systems. This new technology changes the traditional workflow in radiation oncology and requires an evolution in team coordination to administer more precise treatments. Once implemented, it paves the way for newer indication for radiation therapy to safely deliver higher doses than ever before, with better preservation of healthy tissues to optimize patient outcomes. In this narrative review, we assess the technical aspects of the novel linear accelerators that can deliver MRgRT and summarize the available published experience to date, focusing on oncological results and future challenges. [ABSTRACT FROM AUTHOR]

The National Synchrotron Radiation Research Center (NSRRC) celebrated its 30th anniversary in October 2023. The event brought together pioneers in the synchrotron radiation field, current and retired NSRRC staff, users, and government officials. The NSRRC has made significant contributions to Taiwan's synchrotron light source development, with the Taiwan Light Source (TLS) being the first synchrotron accelerator in Taiwan and the third globally. The NSRRC has also established collaborations with international research institutions and has expanded its engagements within and beyond the realm of science. The center aims to continue enhancing its facilities and infrastructure to support frontier scientific exploration. [Extracted from the article]

Objectives: The high accuracy alignment requirements of particle accelerators present a great challenge to measurement techniques. Due to the advantages of large volume, high precision and three-dimensional measurement of laser tracker, it is necessary to carry out the research on the measurement accuracy by laser tracker in particle accelerators. Methods: First, this paper studied the measurement accuracy of laser tracker itself, introduced the expression and test method of the accuracy, derived the calculation formula and explained its specific meaning of rated accuracy, which provided a theoretical basis for the measurement application and data processing. Then, the linear control network was taken as a representative for the accuracy analysis of control network by laser tracker in particle accelerator, and a measurement activity was implemented in the linac of China Spallation Neutron Source facility, two groups were assigned to survey with different laser trackers during the same period. Results: By analyzing the adjustment precision of each group and the coordinate deviations between the two groups, the weakest transversal accuracy of 200 m linear control network was confirmed and better than 0.2 mm. Moreover, in order to make a quick evaluation of the accuracy of linear control network, a method was proposed to estimate the accuracy with the network simplified to traverse network, and the rule of the weakest point accuracy was acquired that was proportional to the square root of the third power of length. Conclusions: These studies can provide guidance for accuracy analysis and scheme design of alignment in particle accelerators. [ABSTRACT FROM AUTHOR]

Conditions that maximize the performance of an accelerator-driven system related to particle beam and energy and accelerator type are analyzed. The toolkit Geant4 simulated the interaction of protons and ions with masses up to 20Ne and energies from 0.2 to 2 GeV/n. The beam intensity considered is 1.5 × 1016 p/s. The core of the reactor is modeled as an assembly of fuel rods surrounding a cylindrical beryllium converter, with a criticality coefficient of 0.985 and lead-bismuth eutectic coolant. Lower enrichment generates better utilization of fuel (20% to 25% from the initial actinide mass can fission in a cycle keeping neutron damage in clad below 200 displacements per atom). Data on particle fluence and energy released obtained from the simulation are used to calculate total electric power produced and isotope evolution. Power spent to accelerate the beam depends on accelerator type and is calculated by scaling from data on accelerator efficiency for a reference particle. Optimal proton energy is ~1.5 GeV when the beam is accelerated in a linac with energy gain G ~ 14 and is 0.75 to 1 GeV in the case of a cyclotron (G ~ 12). Ion beams starting with 4He realize higher G values than protons: 20 to 50 in a linac and 15 to 35 in a cyclotron. [ABSTRACT FROM AUTHOR]

The existence of a violation of the Charge-Parity (CP) symmetry in the laws of physics is one of the cornerstone conditions for the generation of a matter–antimatter imbalance necessary to the creation of a matter-dominated universe. The first experimental evidence of the fact that this symmetry is broken in nature was obtained in 1964 in the observations of the decays of neutral kaon mesons. The magnitude of CP violation in the quark sector was measured with an increasing precision exploring also decays of other mesons. However, CP violation in the quark sector alone is not sufficient to explain the formation of matter-dominated universe, and additional sources are required. One such potential source is the lepton sector, where the CP violation could be observed by studying neutrino oscillations with neutrino beams generated by particle accelerators. This article reviews the present efforts in this direction. The results obtained in the ongoing experiments, T2K in Japan and NOvA in USA, are discussed. Additionally, the search for leptonic CP violation is one of the key goals in the programs of future experiments, DUNE in USA and Hyper-Kamiokande in Japan. These experiments and their prospects for its discovery are also presented. [ABSTRACT FROM AUTHOR]

Simple Summary: Ultra-high dose rate (UHDR) irradiation in proton therapy has mostly been performed using a cyclotron system so far. In this study, we present our approach to achieve an ultra-high dose rate for a clinical synchrotron proton therapy system and its dosimetric specifications. We demonstrated that it is feasible to adapt an existing clinical synchrotron-based proton therapy system and reach ~100 nA nozzle beam. UHDR dose rate (>40 Gy/s) was reached with the tested spot scanning patterns. The maximum dose per spill depends on the field size and is limited by the maximum charge extraction per spill. A beam monitoring ion chamber is currently being incorporated into the beam control system to improve system reproducibility and expand the irradiation area. Background: This study aims to present the feasibility of developing a synchrotron-based proton ultra-high dose rate (UHDR) pencil beam scanning (PBS) system. Methods: The RF extraction power in the synchrotron system was increased to generate 142.4 MeV pulsed proton beams for UHDR irradiation at ~100 nA beam current. The charge per spill was measured using a Faraday cup. The spill length and microscopic time structure of each spill was measured with a 2D strip transmission ion chamber. The measured UHDR beam fluence was used to derive the spot dwell time for pencil beam scanning. Absolute dose distributions at various depths and spot spacings were measured using Gafchromic films in a solid-water phantom. Results: For proton UHDR beams at 142.4 MeV, the maximum charge per spill is 4.96 ± 0.10 nC with a maximum spill length of 50 ms. This translates to an average beam current of approximately 100 nA during each spill. Using a 2 × 2 spot delivery pattern, the delivered dose per spill at 5 cm and 13.5 cm depth is 36.3 Gy (726.3 Gy/s) and 56.2 Gy (1124.0 Gy/s), respectively. Conclusions: The synchrotron-based proton therapy system has the capability to deliver pulsed proton UHDR PBS beams. The maximum deliverable dose and field size per pulse are limited by the spill length and extraction charge. [ABSTRACT FROM AUTHOR]

Simple Summary: Stereotactic body radiation therapy (SBRT) can be safely delivered for the treatment of localized prostate cancer. High-dose-per-fraction treatments require precise and rapid delivery of the radiation dose to the tumor, and any potential margin expansion must be balanced against the risk of increased toxicity. Since significant intrafraction prostate displacement can have a relevant impact on an extreme-hypofractionated regimen, real-time monitoring has emerged as a strategy to avoid the excessive exposure of healthy tissue or insufficient target coverage, but it requires continuous investment of resources and time. In real-world clinical practice, the utilization of organ motion management devices is not always feasible for all patients. Thus, our strategy has often been to mitigate the impact of intrafraction motion by shortening the delivery time without compromising the quality of the treatment. This was achieved through optimal patient preparation, flattening filter-free (FFF) beams, adequate margins, and a reduction in the number of arcs in the VMAT technique. This study aimed to comprehensively present data on treatment optimization in linac-based SBRT for localized prostate cancer at a single institution. Moreover, the dosimetric quality and treatment efficiency of single-arc (SA) versus dual-arc (DA) VMAT planning and delivery approaches were compared. Re-optimization was performed on twenty low-to-intermediate-risk- (36.25 Gy in 5 fractions) and twenty high-risk (42.7 Gy in 7 fractions) prostate plans initially administered with the DA FFF-VMAT technique in 2021. An SA approach was adopted, incorporating new optimization parameters based on increased planning and clinical experience. Analysis included target coverage, organ-at-risk (OAR) sparing, treatment delivery time, and the pre-treatment verification's gamma analysis-passing ratio. The SA optimization technique has consistently produced superior plans. Rectum and bladder mean doses were significantly reduced, and comparable target coverage and homogeneity were achieved in order to maintain a urethra protection strategy. The mean SA treatment delivery time was reduced by 22%; the mean monitor units increased due to higher plan complexity; and dose measurements demonstrated optimal agreement with calculations. The substantial reduction in treatment delivery time decreased the probability of prostate motion beyond the applied margins, suggesting potential decrease in treatment-related toxicity and improved target coverage in prostate SBRT. Further investigations are warranted to assess the long-term clinical outcomes. [ABSTRACT FROM AUTHOR]

The work is devoted to the dosimetric studies of a low-intensity beam for the implementation of proton radiography on the proton therapy complex Prometeus. In contrast to therapy, radiography using proton beams requires low particle fluxes, less than 1 × 106 protons/(s cm2). The controlled uniform extraction of beams of such intensity at therapeutic accelerators is a significant challenge, and it requires the development of innovative approaches. This study is part of a series of studies on the Russian medical proton synchrotron for implementing the extraction of low-intensity beams. The paper presents data on the key parameter of the extracted beam—the absorbed dose—when performing radiographic plans with a scanning beam. It also provides a quantitative analysis based on computer simulation of the spatial characteristics of proton images obtained using the extracted beam parameters. [ABSTRACT FROM AUTHOR]

The results of the Oxygen 5+ beam dynamics simulation in the regular section of a 7,5 MeV/u linear accelerator are presented. Linear accelerator LU-1 consists of several ion sources, RFQ section (Radio Frequency Quadrupole) and two groups of identical IH (Interdigital H-type) cavities. Beam transport between the accelerating sections is done via low energy (LEBT) line, two medium energy MEBT-1 and MEBT-2 lines, and high energy (HEBT) line that transfers the beam to the booster synchrotron or a beam dump. This paper contains the results on Oxygen 5+ A/Z = 3.2 beam dynamics end-to-end simulation in the LU-1 sections (LEBT, RFQ, MEBT-1, MEBT-2 beam transport lines and both groups of IH cavities). [ABSTRACT FROM AUTHOR]

Electronic components must be tested to allow for safe and reliable missions in radiation environments. The METU Defocusing Beamline (METU-DBL) was installed in the R&D room at the Particle Accelerator Facility (PAF) of Turkish Energy, Nuclear and Mineral Research Agency (TENMAK). This facility was established in accordance with the European Space Agency (ESA), European Space Components Coordination (ESCC), No: 25100 standard to conduct proton irradiation tests for electronic components and various materials to be used in the space environment. METU-DBL uses beam elements such as quadrupole magnets to amplify the beam and collimators to reduce the flux, as per the specifications of the standard. A pretest setup was constructed, and this system was operated for a total of 17 hours for three months before the METU-DBL final design was assembled. The first protective collimator is made of stainless steel 316L and was used during the period of pretests. As a result of these irradiations, the emerged radioisotopes in the collimator were observed and measured in situ with a NaI detector. These measurements were compared with the FLUKA simulations 120 days after the last irradiation. Among fourteen radioisotopes, only six of them with activity above 1.0×101 Bq/cm3 were matched. [ABSTRACT FROM AUTHOR]

The laser wakefield acceleration in bubble regime is now a promising method for producing high-quality electron beams, which is crucial to the development of the next-generation compact and low-cost particle accelerators. In this paper, we demonstrate the possibility of controlling particle injection and electron beam quality in sub-petawatt laser pulse interaction with simple plasma waveguides with a radially step-like density profile. Fully relativistic particle-in-cell calculations for different laser intensities indicate that by considering a sufficiently low electron density for a central plasma channel to ensure both increased acceleration length and formation of a well-structured bubble, one can optimize the surrounding plasma density and central channel diameter to reach the best injection conditions and produce a high-quality monoenergetic electron beam with improved peak energy and reduced energy spread. Calculations are performed for 33 fs, 140–315 TW laser pulses interacting with a ∼2 cm long plasma waveguide. It is demonstrated that by using the proposed scheme in optimized conditions, monoenergetic electron beams with peak energies 3–4 GeV and energy spreads less than 1.5% can be obtained in a single acceleration length of 1.85 cm. The beam charge and conversion efficiency of laser energy into the beam energy were also enhanced to values around 195 pC and 14.7%, respectively. [ABSTRACT FROM AUTHOR]

The recently observed FLASH effect describes the observation of normal tissue protection by ultra-high dose rates (UHDR), or dose delivery in a fraction of a second, at similar tumor-killing efficacy of conventional dose delivery and promises great benefits for radiotherapy patients. Dedicated studies are now necessary to define a robust set of dose application parameters for FLASH radiotherapy and to identify underlying mechanisms. These studies require particle accelerators with variable temporal dose application characteristics for numerous radiation qualities, equipped for preclinical radiobiological research. Here we present the dresden platform, a research hub for ultra-high dose rate radiobiology. By uniting clinical and research accelerators with radiobiology infrastructure and know-how, the dresden platform offers a unique environment for studying the FLASH effect. We introduce its experimental capabilities and demonstrate the platform's suitability for systematic investigation of FLASH by presenting results from a concerted in vivo radiobiology study with zebrafish embryos. The comparative pre-clinical study was conducted across one electron and two proton accelerator facilities, including an advanced laser-driven proton source applied for FLASH-relevant in vivo irradiations for the first time. The data show a protective effect of UHDR irradiation up to 10 5 Gy / s and suggests consistency of the protective effect even at escalated dose rates of 10 9 Gy / s . With the first clinical FLASH studies underway, research facilities like the dresden platform, addressing the open questions surrounding FLASH, are essential to accelerate FLASH's translation into clinical practice. [ABSTRACT FROM AUTHOR]

Since the late '80s, CERN has pioneered the development of niobium thin film radio-frequency (RF) cavities deposited on copper substrates for several particle accelerator applications. However, niobium thin film cavities historically feature a progressive performance degradation as the accelerating field increases. In this study, we describe a temperature mapping system based on contact thermometry, specially designed to obtain temperature maps of niobium-coated copper cavities and, consequently, study the mechanisms responsible for performance degradation. The first temperature maps on a niobium/copper 1.3 GHz cavity are reported along with its RF performance. In addition to some hotspots displayed in the temperature maps, we surprisingly observed a temperature decrease in a limited portion of the cavity cell as the accelerating field increased. This may shed new light on understanding the heat dissipation of niobium thin film cavities in liquid helium-I, which might be exploited to improve the RF cavity performance. [ABSTRACT FROM AUTHOR]

Simple Summary: In the past year, there have been improvements in cancer treatment, especially for cancers that have spread throughout the body. However, treating tumors that spread to the brain, causing brain metastases, is still a challenge. The brain has extra protection that makes it hard for helpful medications to reach it. That's why local treatments like stereotactic radiosurgery, a precise way of using radiation to treat tumors, are important for addressing brain metastases. Nowadays, even multiple metastases can be treated simultaneously with stereotactic radiosurgery. Different techniques, such as the Gamma Knife that treats metastases one by one, and single-isocenter techniques that can treat many metastases at once using a traditional radiation device called a linear accelerator, are used for this purpose. This article compares the advantages and disadvantages of these treatments by examining other articles published on the topic. The advancement of systemic targeted treatments has led to improvements in the management of metastatic disease, particularly in terms of survival outcomes. However, brain metastases remain less responsive to systemic therapies, underscoring the significance of local interventions for comprehensive disease control. Over the past years, the threshold for treating brain metastases through stereotactic radiosurgery has risen. Yet, as the number of treated metastases increases, treatment complexity and duration also escalate. This trend has made multi-isocenter radiosurgery treatments, such as those with the Gamma Knife, challenging to plan and lengthy for patients. In contrast, single-isocenter approaches employing linear accelerators offer an efficient and expeditious treatment option. This review delves into the literature, comparing different linear-accelerator-based techniques with each other and in relation to dedicated systems, focusing on dosimetric considerations and feasibility. [ABSTRACT FROM AUTHOR]

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world's largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 Z TeV, where Z is the atomic number. ALICE is one of the experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is being considered to collide a portion of the beam halo, split using a bent crystal inserted in the transverse hierarchy of the LHC collimation system, with an internal target placed a few metres upstream of the existing detector. This study is carried out as a part of the Physics Beyond Collider effort at CERN. Fixed-target collisions offer many physics opportunities related to hadronic matter and the quark-gluon plasma to extend the research potential of the CERN accelerator complex. Production of physics events depends on the particle flux on the target. The machine layout for the fixed-target experiment is developed to provide a flux of particles on the target high enough to exploit the full capabilities of the ALICE detector acquisition system. This paper summarises the fixed-target layout consisting of the crystal assembly, the target and the downstream absorbers. We discuss the conceptual integration of these elements within the LHC ring, the impact on ring losses, and expected performance in terms of particle flux on target. [ABSTRACT FROM AUTHOR]

Workbench-size particle accelerators, enabled by Nb3Sn-based superconducting radio-frequency (SRF) cavities, hold the potential of driving scientific discovery by offering a widely accessible and affordable source of high-energy electrons and x-rays. Thin-film Nb3Sn RF superconductors with high quality factors, high operation temperatures, and high-field potentials are critical for these devices. However, surface roughness, non-stoichiometry, and impurities in Nb3Sn deposited by conventional Sn-vapor diffusion prevent them from reaching their theoretical capabilities. Here we demonstrate a seed-free electrochemical synthesis that pushes the limit of chemical and physical properties in Nb3Sn. Utilization of electrochemical Sn pre-deposits reduces the roughness of converted Nb3Sn by five times compared to typical vapor-diffused Nb3Sn. Quantitative mappings using chemical and atomic probes confirm improved stoichiometry and minimized impurity concentrations in electrochemically synthesized Nb3Sn. We have successfully applied this Nb3Sn to the large-scale 1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at multiple operation temperatures, notably lower than vapor-diffused cavities. Our smooth, homogeneous, high-purity Nb3Sn provides the route toward high efficiency and high fields for SRF applications under helium-free cryogenic operations. [ABSTRACT FROM AUTHOR]

Simple Summary: Magnetic resonance imaging (MRI) has several advantages over computerized tomography (CT) in the treatment planning of central nervous system (CNS) malignancies. The adoption of hybrid MRI and linear accelerators (MRLs) has allowed for more effective tumor control and reduced unnecessary neurotoxicity through precise daily adaptations. In this review, we provide a summary of the evidence for MRLs in the management of various CNS tumors. Additionally, we discuss the potential of multiparametric MRI and genomically guided radiotherapy to enhance patient outcomes. Magnetic resonance imaging (MRI) provides excellent visualization of central nervous system (CNS) tumors due to its superior soft tissue contrast. Magnetic resonance-guided radiotherapy (MRgRT) has historically been limited to use in the initial treatment planning stage due to cost and feasibility. MRI-guided linear accelerators (MRLs) allow clinicians to visualize tumors and organs at risk (OARs) directly before and during treatment, a process known as online MRgRT. This novel system permits adaptive treatment planning based on anatomical changes to ensure accurate dose delivery to the tumor while minimizing unnecessary toxicity to healthy tissue. These advancements are critical to treatment adaptation in the brain and spinal cord, where both preliminary MRI and daily CT guidance have typically had limited benefit. In this narrative review, we investigate the application of online MRgRT in the treatment of various CNS malignancies and any relevant ongoing clinical trials. Imaging of glioblastoma patients has shown significant changes in the gross tumor volume over a standard course of chemoradiotherapy. The use of adaptive online MRgRT in these patients demonstrated reduced target volumes with cavity shrinkage and a resulting reduction in radiation dose to uninvolved tissue. Dosimetric feasibility studies have shown MRL-guided stereotactic radiotherapy (SRT) for intracranial and spine tumors to have potential dosimetric advantages and reduced morbidity compared with conventional linear accelerators. Similarly, dosimetric feasibility studies have shown promise in hippocampal avoidance whole brain radiotherapy (HA-WBRT). Next, we explore the potential of MRL-based multiparametric MRI (mpMRI) and genomically informed radiotherapy to treat CNS disease with cutting-edge precision. Lastly, we explore the challenges of treating CNS malignancies and special limitations MRL systems face. [ABSTRACT FROM AUTHOR]

Since the late '80s, CERN has pioneered the development of niobium thin film radio-frequency (RF) cavities deposited on copper substrates for several particle accelerator applications. However, niobium thin film cavities historically feature a progressive performance degradation as the accelerating field increases. In this study, we describe a temperature mapping system based on contact thermometry, specially designed to obtain temperature maps of niobium-coated copper cavities and, consequently, study the mechanisms responsible for performance degradation. The first temperature maps on a niobium/copper 1.3 GHz cavity are reported along with its RF performance. In addition to some hotspots displayed in the temperature maps, we surprisingly observed a temperature decrease in a limited portion of the cavity cell as the accelerating field increased. This may shed new light on understanding the heat dissipation of niobium thin film cavities in liquid helium-I, which might be exploited to improve the RF cavity performance. [ABSTRACT FROM AUTHOR]

Laser-induced surface structuring is a promising method to suppress electron mulitpacting in the vacuum pipes of particle accelerators. Electrons are scattered inside the rough surface structure, resulting in a low Secondary Electron Yield (SEY) of the material. However, laser processing of internal pipe surfaces with a large aspect ratio is technologically challenging in terms of laser beam guidance and focusing. We present a 532 nm ultrashort-pulse laser setup to process the inner parts of 15 m long beam vacuum tubes of the Large Hadron Collider (LHC). Picosecond pulses at a repetition rate of 200 kHz are guided through an optical fiber toward an inchworm robot traveling inside the beam pipe. The system was installed, characterized, and tested for reliability. First surface treatments achieved the required scan precision. Cu2O-dominated nano-features were observed when processing at high average laser power (5 W) and slow scanning speed (5 mm s−1) in nitrogen flow, and the maximum SEY of copper was decreased from 2.1 to 0.7. [ABSTRACT FROM AUTHOR]

Boosted by the relentless increase in available computational resources, high-throughput calculations based on first-principles methods have become a powerful tool to screen a huge range of materials. The backbone of these studies is well-structured and reproducible workflows efficiently returning the desired properties given chemical compositions and atomic arrangements as sole input. Herein, we present a new workflow designed to compute the stability and the electronic properties of crystalline materials from density-functional theory using the strongly constrained and appropriately normed approximation (SCAN) for the exchange–correlation potential. We show the performance of the developed tool exploring the binary Cs–Te phase space that hosts cesium telluride, a semiconducting material widely used as a photocathode in particle accelerators. Starting from a pool of structures retrieved from open computational material databases, we analyze formation energies as a function of the relative Cs content and for a few selected crystals, we investigate the band structures and density of states unraveling interconnections among the structure, stoichiometry, stability, and electronic properties. Our study contributes to the ongoing research on alkali-based photocathodes and demonstrates that high-throughput calculations based on state-of-the-art first-principles methods can complement experiments in the search for optimal materials for next-generation electron sources. [ABSTRACT FROM AUTHOR]

High Q-factors are of utmost importance to minimize losses of superconducting radio-frequency cavities deployed in continuous wave particle accelerators. This study elucidates the surface treatment that can maximize the Q-factors in high-beta 650 MHz elliptical niobium cavities. State-of-the-art surface treatments are applied in many single-cell cavities, and surface resistance studies are performed to understand the microwave dissipation at this unexplored frequency. The nitrogen doping treatment is confirmed to be necessary to maximize the Q-factors at medium RF fields. We applied this treatment in five-cell high-beta 650 MHz cavities and demonstrated that extremely high Q-factors were obtained at medium RF fields with this treatment. We also demonstrated that adding a cold electropolishing step after N-doping is crucial to push the quench field of multicell cavities to higher gradients. [ABSTRACT FROM AUTHOR]

High electric fields are present in a rapidly growing number of applications, which include elementary particle accelerators, vacuum interrupters, miniature x-ray sources, and satellites. Many of these applications are limited by the breakdown strength of the materials exposed to electric fields. Different methods have been developed to improve the quality of metal electrode surfaces, aiming to increase their breakdown strength. Not many systematical studies have been performed to provide a proper understanding of what contributes to the correlation between the breakdown strength and the quality of the surface. In this work, we apply a novel method for reducing vacuum arc breakdowns by cleaning the electrode surfaces with O and Ar plasma. The method can be used to alter the surfaces of the Cu electrodes in situ, i.e., without exposing them to air between the measurements. This plasma cleaning treatment is shown to reduce the number of surface impurities and to speed up the conditioning process of the samples under high-voltage pulses. Specifically, the first breakdown field was observed to increase by more than 90% after the plasma cleaning. [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 "Synchrotron Radiation Workshop" (SRW) code is a computer program developed by the European Synchrotron Radiation Facility in 1997. It is used for simulating X-ray beamlines and coherence-exploiting experiments at synchrotron light sources. The code allows for the simulation of partially coherent wavefront propagation and the calculation of intensity distributions and coherence lengths. It has been used for electron beam diagnostics and offers brighter and more coherent X-ray beams for scientific experiments. The code is continuously developed and has interfaces with various software platforms. The article provides examples of simulations and mentions ongoing development and support from different organizations and research facilities. [Extracted from the article]

GeV and TeV emission from the forward shocks of supernova remnants (SNRs) indicates that they are capable particle accelerators, making them promising sources of Galactic cosmic rays (CRs). However, it remains uncertain whether this γ -ray emission arises primarily from the decay of neutral pions produced by very-high-energy hadrons, or from inverse-Compton and/or bremsstrahlung emission from relativistic leptons. By applying a semi-analytic approach to non-linear diffusive shock acceleration, and calculating the particle and photon spectra produced in different environments, we parameterize the relative strength of hadronic and leptonic emission. We show that even if CR acceleration is likely to occur in all SNRs, the observed photon spectra may primarily reflect the environment surrounding the SNR: the emission is expected to look hadronic unless the ambient density is particularly low (with proton number density ≲0.1 cm−3) or the photon background is enhanced with respect to average Galactic values (with radiation energy density u rad ≳ 10 eV cm−3). We introduce a hadronicity parameter to characterize how hadronic or leptonic we expect a source to look based on its environment, which can be used to guide the interpretation of current γ -ray observations and the detection of high-energy neutrinos from SNRs. [ABSTRACT FROM AUTHOR]

Cyclotrons are one of the most important sources of radionuclides used in biomedical applications. The production of important radionuclides used in single-photon emission tomography techniques such as 123I, 67Ga, 201Tl, and 111In has been based for decades on cyclotrons, typically proton machines with an energy up to 30 MeV. The extraordinary growth of positron emission tomography (PET) has led to the development of new models and to the installation of numerous cyclotrons, typically accelerating protons in the energy range 10 to 20 MeV. These have been used for the production of the main PET radionuclides, namely, 11C, 13N, 15O, and above all, 18F. Recently, their use has been extended to the production of radiometals, like 68Ga, and even to the direct production of 99mTc. Moreover, cyclotrons are a valuable tool for research and for the education of new scientists. This critical review presents the main manufacturers and briefly discusses the characteristics of the models they currently offer on the market. [ABSTRACT FROM AUTHOR]