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The Pulsed Energetic Electrons for Research (PEER) beamline at the ANSTO Australian Synchrotron comprises a 100 MeV linac injector that is currently being developed for ultra-high dose-rate, very high-energy electron radiotherapy research. Previously, dosimetry studies discovered a lack of reliable charge measurement to the in-air end station, though no change in response was recorded in fast current transformer measurements, the only available diagnostic device for measuring charge. This work describes the process of simulating and then commissioning a purpose-built Faraday cup to ascertain absolute in-air charge measurements at PEER. By combining simulation data with experimental results, the PEER Faraday cup is shown to possess a primary electron capture efficiency of (99.22 ± 0.10)%, with a net capture efficiency due to secondary electron emission of (97.87 ± 0.24)%. These results show the PEER Faraday cup performs as intended and, when scaled against simulations, will be suitable for measuring absolute charge at PEER. [ABSTRACT FROM AUTHOR]

Diffraction radiation is widely used for the nondestructive diagnostics of charged particle beams. In the series of previous works, a method was developed for describing the diffraction radiation of a nonrelativistic particle on a perfectly conducting sphere, based on the method of images well-known from electrostatics. This method allows one to derive the analytic formulas for two main radiation characteristics, i.e., spectral angular density and polarization. The characteristic features of these values allow the possibility of developing, on their basis, new methods for monitoring the parameters of the trajectory of a moving particle in relation to the sphere center. In this work, formulas are obtained that describe the polarization of the coherent diffraction radiation on a metal sphere from a pancake-bunch of charged particles. It is shown that the polarization of the radiation in this case makes it possible to estimate the positions of bunch edges relative to the center of the sphere. This can be used for the nondestructive measurement of characteristic bunch dimensions. [ABSTRACT FROM AUTHOR]

Machine learning deals with creating algorithms capable of learning from the provided data. These systems have a wide range of applications and can also be a valuable tool for scientific research, which in recent years has been focused on finding new diagnostic techniques for particle accelerator beams. In this context, SPARC_LAB is a facility located at the Frascati National Laboratories of INFN, where the progress of beam diagnostics is one of the main developments of the entire project. With this in mind, we aim to present the design of two neural networks aimed at predicting the spot size of the electron beam of the plasma-based accelerator at SPARC_LAB, which powers an undulator for the generation of an X-ray free electron laser (XFEL). Data-driven algorithms use two different data preprocessing techniques, namely an autoencoder neural network and PCA. With both approaches, the predicted measurements can be obtained with an acceptable margin of error and most importantly without activating the accelerator, thus saving time, even compared to a simulator that can produce the same result but much more slowly. The goal is to lay the groundwork for creating a digital twin of linac and conducting virtualized diagnostics using an innovative approach. [ABSTRACT FROM AUTHOR]

The transition radiation of a charged particle in the simplest case of incidence on an infinitely conductive, ideal plane can be described based on the well-known method of images from electrostatics. This method also enables finding the distribution of fields in more complex cases, such as the field of a point particle in the presence of two intersecting conducting planes, the angle between which divides the angle 180° evenly. Based on the method of images, we describe the transition radiation that occurs when a fast charged particle strikes a target consisting of two conducting half-planes intersecting at right angles (from the inside of a dihedral angle). The characteristics of radiation emitted by fast and slow particles are qualitatively examined, and their visual interpretation is given. The possibility of using interference effects arising from radiation for monitoring beams of charged particles is discussed. [ABSTRACT FROM AUTHOR]

The Pulsed Energetic Electrons for Research (PEER) beamline at the ANSTO Australian Synchrotron comprises a 100 MeV linac injector that is currently being developed for ultra-high dose-rate, very high-energy electron radiotherapy research. Previously, dosimetry studies discovered a lack of reliable charge measurement to the in-air end station, though no change in response was recorded in fast current transformer measurements, the only available diagnostic device for measuring charge. This work describes the process of simulating and then commissioning a purpose-built Faraday cup to ascertain absolute in-air charge measurements at PEER. By combining simulation data with experimental results, the PEER Faraday cup is shown to possess a primary electron capture efficiency of (99.22 ± 0.10)%, with a net capture efficiency due to secondary electron emission of (97.87 ± 0.24)%. These results show the PEER Faraday cup performs as intended and, when scaled against simulations, will be suitable for measuring absolute charge at PEER.

The Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser Facility (EuXFEL) is equipped with a multipurpose diagnostic end-station (DES) at the end of the instrument. The imager unit in DES is a key tool for aligning the beam to a standard trajectory and for adjusting optical elements such as focusing lenses or the split-and-delay line. Furthermore, the DES features a bent-diamond-crystal spectrometer to disperse the spectrum of the direct beam to a line detector. This enables pulse-resolved characterization of the EuXFEL spectrum to provide X-ray energy calibration, and the spectrometer is particularly useful in commissioning special modes of the accelerator. Together with diamond-based intensity monitors, the imager and spectrometer form the DES unit which also contains a heavy-duty beamstop at the end of the MID instrument. Here, we describe the setup in detail and provide exemplary beam diagnostic results.

The Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser Facility (EuXFEL) is equipped with a multipurpose diagnostic end-station (DES) at the end of the instrument. The imager unit in DES is a key tool for aligning the beam to a standard trajectory and for adjusting optical elements such as focusing lenses or the split-and-delay line. Furthermore, the DES features a bent-diamond-crystal spectrometer to disperse the spectrum of the direct beam to a line detector. This enables pulse-resolved characterization of the EuXFEL spectrum to provide X-ray energy calibration, and the spectrometer is particularly useful in commissioning special modes of the accelerator. Together with diamond-based intensity monitors, the imager and spectrometer form the DES unit which also contains a heavy-duty beamstop at the end of the MID instrument. Here, we describe the setup in detail and provide exemplary beam diagnostic results. [ABSTRACT FROM AUTHOR]

Machine learning deals with creating algorithms capable of learning from the provided data. These systems have a wide range of applications and can also be a valuable tool for scientific research, which in recent years has been focused on finding new diagnostic techniques for particle accelerator beams. In this context, SPARC_LAB is a facility located at the Frascati National Laboratories of INFN, where the progress of beam diagnostics is one of the main developments of the entire project. With this in mind, we aim to present the design of two neural networks aimed at predicting the spot size of the electron beam of the plasma-based accelerator at SPARC_LAB, which powers an undulator for the generation of an X-ray free electron laser (XFEL). Data-driven algorithms use two different data preprocessing techniques, namely an autoencoder neural network and PCA. With both approaches, the predicted measurements can be obtained with an acceptable margin of error and most importantly without activating the accelerator, thus saving time, even compared to a simulator that can produce the same result but much more slowly. The goal is to lay the groundwork for creating a digital twin of linac and conducting virtualized diagnostics using an innovative approach.

Fast ion beams delivered by tandem Van de Graaff accelerators intrinsically have an energy width, Δ E P / E P , due to the voltage ripple of the accelerator, the production mechanism of the highly charged ions inside the tank of the accelerator, as well as geometrical considerations related to the propagation of the ion beam. The ion beam energy width directly affects the experimental resolution and thus its value should be considered in experiments and the corresponding data analysis. Here, we present a method for determining the energy width of ion beams delivered by tandem Van de Graaff accelerators, based on high resolution Auger projectile electron spectroscopy combined with data analysis via Monte Carlo simulations within the SIMION ion optics package. [ABSTRACT FROM AUTHOR]

The results of a comparison of the autocorrelation functions of coherent transition radiation, which are obtained experimentally using the microtron of Tomsk Polytechnic University and by simulation methods, are discussed. The conditions of the experiment and the mathematical basis of the simulation are described in detail. The comparison shows good agreement between the experimental and simulated data. It is demonstrated that the autocorrelation function of transition radiation depends on the temporal structure of the electron beam and can be used as a precision method for measuring the delay time between electron bunches. [ABSTRACT FROM AUTHOR]

A wire scanner designed to measure the spatial characteristics of beams of relativistic and nonrelativistic charged particles, as well as beams of X-ray and gamma radiation, is proposed. The scanner contains several wires of different materials located along the beam axis and capable of moving across the beam. During scanning, characteristic X-ray radiation is generated in the wires under the action of the beam, the spectra of which are recorded by an energy-dispersive X-ray detector. Determination of the transverse profiles of the studied beam consists in measuring the radiation-intensity dependence on the impact parameter of the wires. Matching of the obtained profiles with specific wires is performed according to the energy of characteristic X-ray radiation. The data obtained during scanning allows determination of the transverse dimensions, shape, trajectory, divergence and emittance of the beam. [ABSTRACT FROM AUTHOR]

For the characterisation of an electric propulsion system, the determination of the thrust has a crucial role. The thrust of an Indium FEEP Multiemitter (IFM) Nano Thruster laboratory model is measured directly with a thrust balance and indirectly via beam diagnostics. Both measurements are carried out simultaneously to enable mutual verification with high accuracy. The novel mN-torsion thrust balance by FOTEC resolves six different thrust magnitudes, ranging from 10 μ N to 1 N. It is based on the so-called force-feedback method using a voice coil actuator to determine the thrust, which leads to an accuracy of better than 2 %. The indirect thrust measurements were performed with a high-precision beam diagnostics system by FOTEC. A semi-circular diagnostics arm equipped with 23 digital Faraday cups is used to measure the ion current density distribution of the entire beam. The thrust results of both systems show an agreement with a deviation less than 5 % for thruster operation points ranging from 50 to 450 μ N. This proves that the performance of a FEEP thruster can be characterised very precisely by indirect trust measurements. • Presentation of FOTEC's newly developed high-precision mN-thrust balance for electric propulsion thrusters. • FEEP thruster beam characterisation using FOTEC's high-precision digital beam diagnostics system. • High degree of agreement between direct and indirect thrust measurements. [ABSTRACT FROM AUTHOR]

A uniformly moving charged particle generates transition radiation when moving in an inhomogeneous medium (in particular, when crossing the interface between two media) and diffraction radiation when moving near medium inhomogeneities without crossing their boundaries. Both diffraction and transition radiation can be used to detect particles and monitor beams in accelerators. While methods based on the transition radiation of particles for diagnostics of both relativistic and nonrelativistic beams are widespread, the application of diffraction radiation for these goals remains the subject of research. Diffraction-radiation generation weakly perturbs the motion of a particle beam, which makes it possible to develop nondestructive beam-diagnostics methods. The description of the diffraction radiation of a nonrelativistic charged particle for a conducting sphere was constructed earlier by means of the image method known from electrostatics. The method for finding the parameters of particle flight by the sphere was proposed within the framework of this approach; it used a single point detector recording the intensity and polarization of diffraction radiation. Here we propose a scheme with three detectors that solves the same problem without recording the radiation polarization. [ABSTRACT FROM AUTHOR]

A new multi-pinhole Faraday cup (MPFC) device was designed, fabricated and tested to measure ion beam uniformity over a range of centimeters. There are 32 collectors within the device, and each of those is used as an individual Faraday cup to measure a fraction of the beam current. Experimental data show that the device is capable of measuring a charged particles distribution - either in the form of a raster scanned focused beam or a defocused beam.

Coherent synchrotron radiation (CSR) is generated when the electron bunch length is in the order of the magnitude of the wavelength of the emitted radiation. The self-interaction of short electron bunches with their own electromagnetic fields changes the longitudinal beam dynamics significantly. Above a certain current threshold, the micro-bunching instability develops, characterized by the appearance of distinguishable substructures in the longitudinal phase space of the bunch. To stabilize the CSR emission, a real-time feedback control loop based on reinforcement learning (RL) is proposed. Informed by the available THz diagnostics, the feedback is designed to act on the radio frequency (RF) system of the storage ring to mitigate the micro-bunching dynamics. To satisfy low-latency requirements given by the longitudinal beam dynamics, the RL controller has been implemented on hardware (FPGA). In this article, a real-time feedback loop architecture and its performance is presented and compared with a software implementation using Keras-RL on CPU/GPU. The results obtained with the CSR simulation Inovesa demonstrate that the functionality of both platforms is equivalent. The training performance of the hardware implementation is similar to software solution, while it outperforms the Keras-RL implementation by an order of magnitude. The presented RL hardware controller is considered as an essential platform for the development of intelligent CSR control systems. [ABSTRACT FROM AUTHOR]

Electrostatic beam position monitors (pickup stations) are among the main methods for obtaining information on the properties of an electron beam in electron cooling systems. In the case of low electron energies, the space charge of the beam can have a substantial effect on the interpretation of the experimental data. This study is devoted to experimentally investigating changes in the amplitude of the sum signal at pickup stations, which can be associated with the formation of space-charge waves arising along the electron beam. Space-charge waves are excited by applying an alternating voltage to the near-cathode (control) electrode. [ABSTRACT FROM AUTHOR]

A novel active focusing system was developed for enhancing the irradiation performance of the 18 MeV medical cyclotron in operation at the Bern University Hospital in view of the production of non-conventional medical radioisotopes using solid targets. In several cases, such as the production of 43 Sc and 44 Sc, the beam has to be kept stable within a very small target of about 5 mm diameter. For this purpose, we conceived and realized an apparatus based on a compact focusing and steering magnet system followed by a two-dimensional beam monitoring detector and a specific feedback software that drives the magnet to optimize the beam for a given irradiation set-up. We report on the design, realization and validation beam tests performed using the research beam transfer line of the Bern cyclotron. We demonstrated that the beam spot can be kept on target thanks to the fact that the system automatically reacts to perturbations. Compactness is one of the key features of this system, allowing its use in accelerator facilities with limited space, such as medical cyclotrons for radioisotope production. [ABSTRACT FROM AUTHOR]

Radiochromic films are mainly used for two-dimensional dose verification in photon, electron, and proton therapy treatments. Moreover, the radiochromic film types available today allow their use in a wide dose range, corresponding to applications from low-medical diagnostics to high-dose beam profile measurements in charged particle medical accelerators. An in-depth knowledge of the characteristics of radiochromic films, of their operating principles, and of the dose reading techniques is of paramount importance to exploit all the features of this interesting and versatile radiation detection system. This short review focuses on these main aspects by considering the most recent works on the subject. [ABSTRACT FROM AUTHOR]

Electro-optic sampling (EOS) is widely used as a technique to measure THz-domain electric field pulses such asthe self-fields of femtosecond electron beams. We present an EOS-based approach for single-shot spectral measurement that excels in simplicity (compatible with fiber integration) and bandwidth coverage (overcomes the laser bandwidth limitation), allowing few-fs electron beams or single-cycle THz pulses to be characterized with conventional picosecond probes. It is shown that the EOS-induced optical sidebands on the narrow-bandwidth optical probe are spectrally-shifted replicas of the THz pulse. An experimental demonstration on a 0-3 THz source is presented.

A compact beam-position monitor was constructed using a linear contact image sensor attached to a plastic scintillator and tested using a 230 MeV proton beam. The results indicate that the beam position can be obtained in real-time, and the beam position with a precision of up to 0.03 mm. The compactness and high precision of the device hold considerable potential for it to be used as a beam-position monitor and offline, daily quality assurance monitor in hadron therapy. • The method can provide a high precision and high resolution beam position for flash irradiation in particle therapy in real-time. • The method using contact image sensor with scintillator does not require a long focal length for camera and it is free of image distortion. • The method can be integrated into medical particle accelerator for feedback control and daily quality assurance.

Abstract A novel probe for the measurement of forces exerted by a beam of ions and neutral atoms on a small target is described. The force probe is intended for various applications: First, diagnostics of thruster plumes of electric spacecraft propulsion engines, in particular the determination of the spatial distribution of the momentum in an exhaust beam, and second, the study of sputtering of solid targets by means of the related momentum transfer. The instrument makes use of a sensitive cantilever whose elastic deflection is measured interferometrically along two axes and enables that way a simultaneous measurement of two independent components of the force vector. The present contribution focuses on setup and calibration of the probe. Example measurements with obliquely irradiating ion beams are performed.

A new method for the experimental study of ionization loss of relativistic negatively charged particles moving in a crystal in the channeling regime using a semiconductor surface-barrier detector with smoothly tunable thickness of the depleted layer is proposed. The thickness of the depleted layer in a flat semiconductor detector can be smoothly regulated by the value of the bias voltage applied to the detector. Therefore, the energy distribution of the ionization loss of relativistic particles which cross the detector and move in the channeling regime in the detector crystal can be measured along the path of the particles by varying the bias voltage of the detector and the dechanneling length can be found. Available literature data on experimental and theoretical researches of the dechanneling length are reviewed. The significant disagreement between the experimental and theoretical data is noted. Comparison of experimental data obtained by the detector-target with smoothly tunable thickness of the depleted layer with calculations can help to develop theoretical description of the dynamics of motion of negatively charged particles channeling in a crystal. A better understanding of the dechanneling length properties can be useful in the production of positrons and other particles such as neutrons by an electron beam in crystals, as well as in the development of crystalline undulators, and in the crystal-based extraction of electron beams from a synchrotron. [ABSTRACT FROM AUTHOR]

The final as-built version of the DTL4 Faraday cup for the ESS proton accelerator is presented; the beam-interceptive device acted as beam dump to support the commissioning and tuning of the ESS proton accelerator up to the DTL4 section. The DTL4 Faraday cup was designed, optimized and validated via MCNPX/ANSYS simulations in order to dump [21, 74] MeV protons, proton pulses up to 50 μ s long, repetition rates up to 14 Hz and an unprecedented proton beam current up to 62.5 mA. The maximum volumetric power density was computed to be 20 GW/cm3 and 25 MW/cm3 for 21 MeV and 74 MeV protons, respectively. During the DTL4 commissioning, the DTL4 Faraday cup absorbed and safely dissipated the proton beam power, measured in real-time the proton beam current as well as the pulse duration. Examples of measured proton pulses are included to demonstrate the transport and acceleration of the high-power proton beam all the way down to the ESS DTL4 section. The control system for the data acquisition, operation under vacuum, motion control and cooling water system was based on EPICS. The operational parameters are presented following the results of thermo-mechanical calculations. In the most demanding operational condition, the predicted temperature of the core was around 1010 °C. The cooling water temperature was continuously monitored and remained below 23 °C during the operational period. Neutronics simulations were performed in order to quantify the activation, residual dose rates, radiation shielding and necessary decay time to be waited after the end of the commissioning. After four weeks of decay, a residual dose rate of 1.1 mSv/h was measured at 30 cm from the device. The DTL4 Faraday cup and its shielding were uninstalled in order to proceed with the installation of the DTL5 section. The Faraday cup is planned to be permanently installed in the DTL4 intertank once the DTL5 section is in place. [ABSTRACT FROM AUTHOR]

Laser-driven acceleration of particle beams is an emerging modality under research for biomedical applications. The spatially resolved diagnostics of laser-accelerated proton bunches is crucial for their application. The RadEye detector, featuring up to 10 cm x 5 cm area of online complementary metal-oxide-semiconductor (CMOS) detector made of 48 μm pixels, is established for x-ray, proton and ion beam diagnostics. We exploit the usually undesired ‘Image lag’ phenomenon of incomplete pixel reset to generate 2D-images with a larger dynamic range than the single frame range of 12-bit. Using 532 nm laser pulses and computer simulations for single-slit diffraction, calibration factors to stack multiple readouts were successfully derived to quantitatively reconstruct spatial information about an optical beam and hence extend the dynamic range of the detector compared to a single frame. The final goal is focus quantification for a permanent magnet quadrupole system for protons and terawatt (TW-class) laser focus diagnostics.

A novel active focusing system was developed for enhancing the irradiation performance of the 18 MeV medical cyclotron in operation at the Bern University Hospital in view of the production of non-conventional medical radioisotopes using solid targets. In several cases, such as the production of 43Sc and 44Sc, the beam has to be kept stable within a very small target of about 5 mm diameter. For this purpose, we conceived and realized an apparatus based on a compact focusing and steering magnet system followed by a two-dimensional beam monitoring detector and a specific feedback software that drives the magnet to optimize the beam for a given irradiation set-up. We report on the design, realization and validation beam tests performed using the research beam transfer line of the Bern cyclotron. We demonstrated that the beam spot can be kept on target thanks to the fact that the system automatically reacts to perturbations. Compactness is one of the key features of this system, allowing its use in accelerator facilities with limited space, such as medical cyclotrons for radioisotope production.

X‐ray photon beam diagnostic imagers are located at 24 positions in the European XFEL beam transport system to characterize the X‐ray beam properties, and to give feedback for tuning and optimization of the electron acceleration and orbit, the undulators, and the X‐ray optics. One year of commissioning allowed experience to be gained with these imagers, which will be reported here. The sensitive Spontaneous Radiation imager is useful for various investigations in spontaneous radiation mode: for undulator adjustments and for low‐signal imaging applications. The high‐resolution Free‐Electron Laser imager, 10 µm spatial resolution, is extensively used for the monitoring of beam position, spot size and shape, gain curve measurements, and also for beam‐intensity monitoring. The wide field‐of‐view pop‐in monitors (up to 200 mm) are regularly used for alignment and tuning of the various X‐ray optical components like mirrors, slits and monochromators, and also for on‐line beam control of a stable beam position at the instruments. The Exit Slit imager after the soft X‐ray monochromator provides spectral information of the beam together with multi‐channel plate based single‐pulse gating. For particular use cases, these special features of the imagers are described. Some radiation‐induced degradation of scintillators took place in this initial commissioning phase, providing useful information for better understanding of damage thresholds. Visible‐light radiation in the beam pipe generated by upstream bending magnets caused spurious reflections in the optical system of some of the imagers which can be suppressed by aluminium‐coated scintillating screens. [ABSTRACT FROM AUTHOR]

A muon linac is under development for the precise measurement of the muon anomalous magnetic moment (g − 2) and electric dipole moment (EDM) with a reaccelerated thermal muon beam. An H− source driven by an ultraviolet light has been developed for the muon acceleration experiment. Prior to the acceleration experiment, a beamline commissioning was performed using this H− beam, since the accelerated muon intensity is very low. We successfully measured the magnetic rigidity, which is essential for identifying the accelerated muons. This H− source is capable of utilizing as a general-purpose beam source for other beamline. [ABSTRACT FROM AUTHOR]

Abstract The design, construction, installation, and testing of a Faraday Cup intended to measure the current of a 3 MeV, 1 μ A electron beam is described. Built as a current monitor for a Møller scattering measurement at the MIT High Voltage Research Laboratory, the device combines a large angular acceptance with the capability to measure a continuous, low energy beam. Bench studies of its performance demonstrate current measurements accurate to the percent level at 1 μ A. The Faraday Cup was designed and constructed at MIT and has been in use at the HVRL since 2017, providing a significantly more detailed measurement of beam current than was previously available. [ABSTRACT FROM AUTHOR]

Abstract The Heavy Ion Medical Machine (HIMM) is a compact synchrotron based facility built by the Institute of Modern Physics (IMP) in China. This facility delivers carbon ion beams with kinetic energies up to 400 MeV/u for clinical applications. The beam diagnostics system for HIMM is based on 18 different types of monitors and is used to measure all relevant beam parameters from the ion source to the irradiation therapy terminals which are critical for the commissioning of the accelerator as well as during the regular operation to ensure high up-time of the machine. The control system for all the monitors is designed, developed and implemented globally based on a 3-tier architecture with the aim to achieve a clear separation between front-end devices and their controllers. This paper presents the architecture, the design principle and the implementation of this control system. The beam parameters measured based on the detectors ′ motion control and data acquisition control system are analyzed in detail. Furthermore, this beam diagnostics control system (BDCS) will be transplanted to the next heavy ion medical machine in Lanzhou city on account of the successful application in Wuwei city, the precise beam parameters measurement, and long term operation with high stability and reliability. [ABSTRACT FROM AUTHOR]

Radiochromic films are mainly used for two-dimensional dose verification in photon, electron, and proton therapy treatments. Moreover, the radiochromic film types available today allow their use in a wide dose range, corresponding to applications from low-medical diagnostics to high-dose beam profile measurements in charged particle medical accelerators. An in-depth knowledge of the characteristics of radiochromic films, of their operating principles, and of the dose reading techniques is of paramount importance to exploit all the features of this interesting and versatile radiation detection system. This short review focuses on these main aspects by considering the most recent works on the subject.

The paper considers the issues of manpower training in X-ray mammology. It mentions staff shortage and no special training, which reduces the efficient activities of X-ray mammographic rooms, as well as shortage of training facilities and no unified educational programs within interdisciplinary integration, inadequate technical equipment in the training facilities, the lack of an accounting system for training higher- and mid-level health workers, as well as engineers. Emphasis is placed on that the educational programs must comply with the organizational forms of testing the specialists to be employed. The introduction of a continuous education system should be accelerated to rule out the decay period of specialists’ competence.

Characterization of transverse coherence is one of the most critical themes for advanced X-ray sources and their applications in many fields of science. However, for hard X-ray free-electron laser (XFEL) sources there is very little knowledge available on their transverse coherence characteristics, despite their extreme importance. This is because the unique characteristics of the sources, such as the ultra-intense nature of XFEL radiation and the shot-by-shot fluctuations in the intensity distribution, make it difficult to apply conventional techniques. Here, an extended Young's interference experiment using a stream of bimodal gold particles is shown to achieve a direct measurement of the modulus of the complex degree of coherence of XFEL pulses. The use of interference patterns from two differently sized particles enables analysis of the transverse coherence on a single-shot basis without a priori knowledge of the instantaneous intensity ratio at the particles. For a focused X-ray spot as small as 1.8 µm (horizontal) × 1.3 µm (vertical) with an ultrahigh intensity that exceeds 1018 W cm−2 from the SPring-8 Ångstrom Compact free-electron LAser (SACLA), the coherence lengths were estimated to be 1.7 ± 0.2 µm (horizontal) and 1.3 ± 0.1 µm (vertical). The ratios between the coherence lengths and the focused beam sizes are almost the same in the horizontal and vertical directions, indicating that the transverse coherence properties of unfocused XFEL pulses are isotropic. The experiment presented here enables measurements free from radiation damage and will be readily applicable to the analysis of the transverse coherence of ultra-intense nanometre-sized focused XFEL beams.

Abstract The Rare-isotope Accelerator complex for ON-line experiments (RAON) is an accelerator for heavy ions, such as uranium and oxygen. To correct the beam trajectory in the post-linac with low- β , we developed a beam position monitor. In the post-linac, the beam is accelerated from 0.5 MeV/u to 18.5 MeV/u, and each bunch has an electric charge of less than 10 pC. To achieve higher signal strength and better linearity, we investigated stripline- and button-type beam position monitor (BPM) and designed the BPMs with CST Particle Studio. We have fabricated a button-type BPM. We tested 10 BPMs by using a wire test stand to achieve the characterization of each BPM, including the calibration factor with single-pass H electronics of I-Tech. The developed wire test stand has a stretched wire and is movable in the 2D plane with servomotors. In this paper, we present the results of the design, fabrication, and off-line test of a button-type BPM for a low- β , heavy-ion beam. [ABSTRACT FROM AUTHOR]

Highlights • Beam currents measured by beam stopper and calorimeter of injector are consistent. • 100 keV D+ beam profile could be measured by custom image-intensified CID camera. • The algorithm developed to analyse Allison scanner data provides also D+ fraction. • 100 keV D+ fractions measured by Allison scanner and Doppler Shift are consistent. • D+ beam emittance and potential measured by 4-Grid analyser decreased with Kr gas. Abstract The IFMIF accelerator facility consists of 2 identical linacs, each accelerating a 125 mA CW deuteron beam up to the energy of 40 MeV. In order to reach these unprecedented performances, the Linear IFMIF Prototype Accelerator (LIPAc) is under installation and commissioning at the International Fusion Energy Research Centre (IFERC) in Rokkasho, Japan, in the framework of the IFMIF/EVEDA project, which is part of the Broader Approach (BA) agreement between Japan and EU. The accelerator is designed to validate components up to 125 mA CW deuteron beam at 9 MeV. The accelerator components of LIPAc have been designed and manufactured mainly by European Institutes. The injector and superconducting linac, RFQ, MEBT, Diagnostics Plate, HEBT and beam dump have been developed respectively by CEA-Saclay, INFN-Legnaro and CIEMAT-Madrid and were delivered to Rokkasho between 2013 and 2016. The commissioning of the injector with beam started in November 2014. This paper dealt with the experimental data obtained with the beam diagnostics of the injector. The electrical measurements of the beam intensity on the beam stopper were compared with calorimetric measurements. The beam profiles measured with a CCD camera and a custom image-intensified CID camera are also addressed. The analysis of beam emittance and ion species fractions from data obtained with an Allison scanner is described and the results of species fraction measurements are compared with those obtained by using a deported spectrometer. Finally, the analysis of beam space potential from data obtained with a 4-Grid analyser is presented. [ABSTRACT FROM AUTHOR]

Abstract In the following years the Fermilab Muon Campus will deliver highly polarized muon beams to the storage ring of the Muon g-2 Experiment. The transmission fraction of the storage ring has been shown to depend strongly on the transverse optics of the injected beam. Unfortunately, the current diagnostics in the Muon Campus allow only measurement of the beam configuration space which limits how well propagation can be predicted. This paper demonstrates an experimental technique based on a conventional magnet scan to obtain the Twiss parameters at a point, using only beam profiles such that installation of new equipment is not required. A proof-of-principle experiment is presented which shows that this new method is applicable to the Muon Campus, offering a viable approach to optimization of injection in the Muon g-2 Experiment. [ABSTRACT FROM AUTHOR]

A beam profile monitor (BPM) based on a microchannel plate has been developed for muon beams with low transverse momentum for the measurement of the muon anomalous magnetic moment and electric dipole moment at high precision, with capability of diagnosing muon beams of kinetic energy range from a few keV to 4 MeV. The performance of the BPM has been evaluated using a surface muon beam at J-PARC and additionally with an ultraviolet (UV) light source. It has been confirmed that the BPM has a dynamic range from a few to 1 0 4 muons per bunch without saturation. The spatial resolution of the BPM has been estimated to be less than 0.30 mm. The positron background from muon decays is an obstacle in muon beam profile monitoring and a partial discrimination of the positrons has been achieved under discrete particle conditions. [ABSTRACT FROM AUTHOR]

The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurement faces several challenges: non-zero dispersion, non-Gaussian beam distributions due to effects of the electron cooler and various systematic errors such as closed orbit offsets and inaccurate rms momentum spread estimation. In addition, diffusion processes, such as intra-beam scattering might lead to emittance overestimates. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA. [ABSTRACT FROM AUTHOR]