High-energy Radiation Sources Research Articles

X-ray science using the ESRF—extremely brilliant source

The Extremely Brilliant Source (EBS), the first high-energy 4th-generation synchrotron radiation source, constructed at the ESRF and based upon the novel concept of a Hybrid Multi-Bend Achromat (HMBA), has started user operation on August 25th, 2020. We report here on selected recent scientific results exploiting the greatly improved performances of this novel X-ray source.

Photon emission and radiation reaction effects in surface plasma waves in ultra-high intensities

Manipulating and harnessing plasmonic phenomena in the ultra-relativistic regime reveal promising prospects for the use of surface plasma waves (SPW) to create high-energy particle and radiation sources in the next generation of multi-petawatt lasers. Indeed, relativistic high-charge electron bunches can be produced by SPW excited by ultra-high intensity femtosecond lasers impinging on a periodically modulated solid-density target. In this regime, there is good evidence that SPW excitation survives and that the produced electron bunches experience strong acceleration, thus emitting large amounts of electromagnetic radiation. Therefore, extending the study to ultra-high laser intensities (I>1021 W/cm2), the use of a resonant grating for SPW generation represents an interesting alternative to light sources, as the energy lost by electrons due to radiation emission is transferred to high-energy γ photons. In addition, we show that using a laser with wavefront rotation coupled with a tailored blazed grating improves photon emission in the ultra-relativistic regime of interaction.

Role of Low-Energy (

We demonstrate for the first time that Galactic cosmic rays with energies as high as ∼1010 eV can trigger a cascade of low-energy (<20 eV) secondary electrons that could be a significant contributor to the interstellar synthesis of prebiotic molecules whose delivery by comets, meteorites, and interplanetary dust particles may have kick-started life on Earth. For the energetic processing of interstellar ice mantles inside dark, dense molecular clouds, we explore the relative importance of low-energy (<20 eV) secondary electrons-agents of radiation chemistry-and low-energy (<10 eV), nonionizing photons-instigators of photochemistry. Our calculations indicate fluxes of ∼102 electrons cm-2 s-1 for low-energy secondary electrons produced within interstellar ices due to attenuated Galactic cosmic-ray protons. Consequently, in certain star-forming regions where internal high-energy radiation sources produce ionization rates that are observed to be a thousand times greater than the typical interstellar Galactic ionization rate, the flux of low-energy secondary electrons should far exceed that of nonionizing photons. Because reaction cross sections can be several orders of magnitude larger for electrons than for photons, even in the absence of such enhancement, our calculations indicate that secondary low-energy (<20 eV) electrons are at least as significant as low-energy (<10 eV) nonionizing photons in the interstellar synthesis of prebiotic molecules. Most importantly, our results demonstrate the pressing need for explicitly incorporating low-energy electrons in current and future astrochemical simulations of cosmic ices. Such models are critically important for interpreting James Webb Space Telescope infrared measurements, which are currently being used to probe the origins of life by studying complex organic molecules found in ices near star-forming regions.

Contemporary Applications of Cherenkov Imaging in Radiation Therapy

Cherenkov radiation (CR) is produced from all high energy radiation sources and is part of the dose delivery process in tissue. As such, CR is a direct indicator of the dose delivery process and in recent years the ability to image and measure CR has provided a number of ways to help with radiotherapy dosimetry and delivery tracking. This review provides an overview of the fundamental physical principles of CR production and the radiation transport in tissue, along with applications of imaging CR that have seen significant development in the past few years.

Scientific programme at the Laser Laboratory for Acceleration and Applications

In recent years, laser-driven accelerators have emerged as a promising technology for the development of compact and cost-effective sources of high-energy particles and radiation. Here, we introduce our research programme at the Laser Laboratory for Acceleration and Applications, which focusses on high-power laser systems, development of high-repetition rate targetry, and biomedical applications of laser-based accelerators. Our recent results include the generation of high-energy proton and ion beams through laser-plasma acceleration, which have potential applications in materials activation for medical imaging. We have also investigated the feasibility of using laser-driven X-rays and ion beams for radiobiological research, including FLASH therapy and hadron therapy.

Dose dependent modifications in structural, magnetic and optical properties of gamma-irradiated nanocrystalline Gd3Fe5O12 garnet

Different γ-radiation doses can be used to study stability and phase changes. The Gd3Fe5O12 samples were prepared using combustion method with glycine as fuel. Decomposition occurred after γ-irradiation at a dose of (20 kGy) into three crystalline phases, Fe2GdO4, GdFeO3 and Gd3Fe5O12. Uv–vis spectra were studied to investigate Gd3Fe5O12 absorption measurements. It was found that the difference in optical energy band was dependent on gamma-dose. Photoluminescence measurements at room temperature using 310 nm wavelength excitation were studied and three emission bands peaking at different wavelengths were observed. SEM images indicate that Gd3Fe5O12 is forming in addition to other phases. Our research is important to understand the stability and performance of the garnet based devices used near high-energy radiation sources.

XIDER: a novel X-ray detector for the next generation of high-energy synchrotron radiation sources

Next-generation sources of synchrotron radiation pose significant challenges for 2D pixelated X-ray detectors, such as at the ESRF Extremely Brilliant Source (EBS), the first fourth-generation high-energy synchrotron facility. In particular, scattering and diffraction experiments require fast detectors with a high dynamic range, from single photon sensitivity to pile-up conditions under very high photon fluxes. Furthermore, in the case of high-energy applications, the high-Z sensor materials needed for efficient photon detection introduce other difficulties. Leakage current, bias- and flux-induced polarisation, and afterglow all must be carefully managed for the detector system to reach the required specifications. The XIDER project aims to fulfil the needs of the above-mentioned applications by implementing a novel incremental digital integration readout scheme. XIDER detectors seek to operate efficiently under the high-flux EBS beam of up to 100 keV photons, with a time resolution that can cope with near-continuous and pulsed beams. Simultaneously, non-constant leakage current contributions can be removed for noise-free single photon detection, resulting in a very high dynamic range. This contribution presents the recent developments of the XIDER project, including the first characterisation measurements with cadmium telluride sensors.

Isolated attosecond X-ray pulses from superradiant thomson scattering by a relativistic chirped electron mirror

Time-resolved investigation of electron dynamics relies on the generation of isolated attosecond pulses in the (soft) X-ray regime. Thomson scattering is a source of high energy radiation of increasing prevalence in modern labs, complementing large scale facilities like undulators and X-ray free electron lasers. We propose a scheme to generate isolated attosecond X-ray pulses based on Thomson scattering by colliding microbunched electrons on a chirped laser pulse. The electrons collectively act as a relativistic chirped mirror, which superradiantly reflects the laser pulse into a single localized beat. As such, this technique extends chirped pulse compression, developed for radar and applied in optics, to the X-ray regime. In this paper we theoretically show that, by using this approach, attosecond soft X-ray pulses with GW peak power can be generated from pC electron bunches at tens of MeV electron beam energy. While we propose the generation of few cycle X-ray pulses on a table-top system, the theory is universally scalable over the electromagnetic spectrum.

Development of a Dual-Modality Gamma-ray/Fast Neutron Imaging System for Air Cargo Inspection

High-energy radiation sources have provided a strong security inspection capability using a non-invasive imaging system. The use of multiple radiation sources in one imaging system can also lead to a more powerful system that can classify various materials compared to using a single radiation source. The Advanced Radiation Technology Institute of Korea Atomic Energy Research Institute has developed an air cargo inspection system using multiple radiation sources such as fast neutrons and gamma-rays to classify the plastics, metals, and organics among various sample materials. The fast neutron beam with an energy of 14.1 MeV, generated using the D-T neutron generator, and the gamma-ray beam with an energy of 6 MeV, generated by an electron linear accelerator, are projected onto the vertically aligned scintillator-based radiation detectors. The neutron and gamma-ray images of a cargo container moved by a motorized linear translation stage are acquired, and the image data processing shows good material classification results. In this paper, we describe a multi-radiation imaging system for air cargo inspection and investigate its material classification capability using various sample materials.

Radiation Monitoring Using Personal Dosimeter Devices in Terms of Long-Term Compliance and Creating a Culture of Safety

IntroductionRadiation-emitting devices are commonplace in the hospital with their ability to produce imaging for diagnoses, However, they hold a risk for device operators due to radiation exposure. Hospital systems have programs where physicians exposed to radiation are required to wear dosimeters to help record total radiation over time. Dosimetry readings over standardized recommendations can lead to hospital image issues and disciplinary action for physicians. This study aimed to discover the true values recorded on dosimeters with radiation exposure and discuss effective ways to encourage compliance with dosimeter usage.MethodologyThe study was completed over a course of 12 months with physicians from three different hospitals. Selection criteria included physicians considered to be “radiation workers” including those who operate x-ray machines, fluoroscopy units, unsealed and sealed isotopes, or those exposed to other sources of gamma or high-energy beta radiation. Two Plan-Do-Study-Act (PDSA) cycles were implemented. The first cycle was the first six months of the study and the second cycle was the second six months of the study. The first PDSA cycle had planned dosimeter reading check-ins every month. After this cycle ended, physicians were sent a survey anonymously asking if they had ever intentionally left behind their dosimeter. In the second PDSA cycle, a planned policy change was put into action where penalties for physicians who went over the recommended dosage were stopped. A monthly educational meeting where a discussion on the risks of radiation as well as protective mechanisms was implemented instead. The same monthly check-ins for dosimeter reading monitoring were employed again with the same survey regarding dosimeter adherence and usage being sent out at the end of the second cycle. Run charts were created to determine whether the policy change showed statistically significant differences in dosimetry readings.ResultsProtocol changes led to statistically significant (p<0.05) differences in radiation exposure recorded throughout the hospital systems. The primary PDSA cycle readings showed that hospital systems one (n=118), two (n=71), and three (n=32) had readings of 3.90 mSv, 2.55 mSv, and 2.02 mSv, respectively, which were all under the annual recommended dose limit of 10 mSv maximum per six months. However, an average of 94.4% (n=221) of physicians across all hospitals admitted to not using the dosimeter. In the second PDSA cycle after the policy change, the radiation doses were higher with an increase in the average cumulative dose at hospital system one of 255%, 328% at system two, and 323% at system three. Hospital systems one and two were both over the yearly limit of 20.0 mSv (7.70 mSv over for system one and 1.86 mSv over for system two) while system three remained under. The number of physicians who stated they always used the dosimeter during the second PDSA cycle increased to 83.9% in-hospital system one, 90.2% in-hospital system two, and 93.8% in-hospital system three.ConclusionCreating a culture of safety is critical for physician compliance. A comfortable work environment without unreasonable consequences creates an environment where physicians can focus on their health and safety while also doing what is in the workplace’s best interest. This culture can best be made with more collaboration between administrative staff and workers to create a trustworthy experience in hospital systems.

Detailed study of extended γ-ray morphology in the vicinity of the Coma cluster with Fermi Large Area Telescope

ABSTRACT Galaxy clusters can be sources of high-energy (HE) γ-ray radiation due to the efficient acceleration of particles exceeding EeV energies. At present, though, the only candidate for emitting HE γ-rays is the Coma cluster, towards which an excess of γ-ray emission has been detected by the Fermi Large Area Telescope (Fermi-LAT). Using ∼12.3 yr of Fermi-LAT data, we explored the region of the Coma cluster between energies 100 MeV and 1 TeV by detailed spectral and morphological analysis. In the region of the Coma cluster, we detected diffuse γ-ray emission of energies between 100 MeV and 1 TeV with a 5.4σ extension significance and a 68 per cent containment radius of $0.82^{+0.10}_{-0.05}$ degrees derived with a two-dimensional homogeneous disc model. The corresponding γ-ray spectrum extends up to ∼50 GeV, with a power-law index of Γ = 2.23 ± 0.11 and flux of $\mathrm{(3.84\pm 0.67)\times 10^{-12}\, erg\, cm^{-2}\, s^{-1}}$. Using energy arguments we show that point-like sources such as radiogalaxies and star-forming galaxies are unlikely to explain the emission, and more likely, the emission is produced in the Coma cluster. Besides, we also identified three point-like sources in the region. However, because of limited statistics, we could neither exclude nor confirm the contribution of three point-like sources to the total emissions.

Propagation of Cosmic Rays in Plasmoids of AGN Jets-Implications for Multimessenger Predictions

After the successful detection of cosmic high-energy neutrinos, the field of multiwavelength photon studies of active galactic nuclei (AGN) is entering an exciting new phase. The first hint of a possible neutrino signal from the blazar TXS 0506+056 leads to the anticipation that AGN could soon be identified as point sources of high-energy neutrino radiation, representing another messenger signature besides the established photon signature. To understand the complex flaring behavior at multiwavelengths, a genuine theoretical understanding needs to be developed. These observations of the electromagnetic spectrum and neutrinos can only be interpreted fully when the charged, relativistic particles responsible for the different emissions are modeled properly. The description of the propagation of cosmic rays in a magnetized plasma is a complex question that can only be answered when analyzing the transport regimes of cosmic rays in a quantitative way. In this paper, therefore, a quantitative analysis of the propagation regimes of cosmic rays is presented in the approach that is most commonly used to model non-thermal emission signatures from blazars, i.e., the existence of a high-energy cosmic-ray population in a relativistic plasmoid traveling along the jet axis. It is shown that in the considered energy range of high-energy photon and neutrino emission, the transition between diffusive and ballistic propagation takes place, significantly influencing not only the spectral energy distribution, but also the lightcurve of blazar flares.

Dynamical Control of Nuclear Isomer Depletion via Electron Vortex Beams.

Some nuclear isomers are known to store a large amount of energy over long periods of time, with a very high energy-to-mass ratio. Here, we describe a protocol to achieve the external control of the isomeric nuclear decay by using electron vortex beams whose wave function has been especially designed and reshaped on demand. Recombination of these electrons into the isomer's atomic shell can lead to the controlled release of the stored nuclear energy. On the example of ^{93m}Mo, we show theoretically that the use of tailored electron vortex beams increases the depletion by 4 orders of magnitude compared to the spontaneous nuclear decay of the isomer. Furthermore, specific orbitals can sustain an enhancement of the recombination cross section for vortex electron beams by as much as 6 orders of magnitude, providing a handle for manipulating the capture mechanism. These findings open new prospects for controlling the interplay between atomic and nuclear degrees of freedom, with potential energy-related and high-energy radiation source applications.

Effect of radiation physics on inherent statistics of glow curves from small samples or low doses

A theory is developed to predict statistical noise in the trap populations of small samples or single grains subjected to high-energy ionizing irradiation. Using a model of the radiation process and a one-trap one-center model of a thermoluminescent (TL) material, the statistical behavior of the number of occupied traps during irradiation is predicted. The model focuses on the inherent physics of the process. Experimental sources of error are not considered. The interaction of radiation with the TL material is modeled in a simple way using the Bethe equation. The trap and center populations in the TL material are modeled both with the conventional phenomenological equations and also the more general Master Equation approach. The theory predicts, as the irradiation process proceeds, the mean, standard deviation, dispersion, skewness, and kurtosis of the probability distribution of occupied traps in the TL material. For the same applied dose, the standard deviation and dispersion of the trap population depend strongly on the type of radiation as well as the shape and orientation of the material. High-energy radiation sources, such as alpha, beta, or gamma rays, are found to produce standard deviations and dispersion much larger than low-energy sources, such as UV radiation. The results are summarized in tables which enable, for useful limiting cases, easy calculation of not just standard deviation but also skewness and kurtosis for various radiation sources and geometries.

Fouling Prevention in Polymeric Membranes by Radiation Induced Graft Copolymerization.

The application of membrane processes in various fields has now undergone accelerated developments, despite the presence of some hurdles impacting the process efficiency. Fouling is arguably the main hindrance for a wider implementation of polymeric membranes, particularly in pressure-driven membrane processes, causing higher costs of energy, operation, and maintenance. Radiation induced graft copolymerization (RIGC) is a powerful versatile technique for covalently imparting selected chemical functionalities to membranes’ surfaces, providing a potential solution to fouling problems. This article aims to systematically review the progress in modifications of polymeric membranes by RIGC of polar monomers onto membranes using various low- and high-energy radiation sources (UV, plasma, γ-rays, and electron beam) for fouling prevention. The feasibility of the modification method with respect to physico-chemical and antifouling properties of the membrane is discussed. Furthermore, the major challenges to the modified membranes in terms of sustainability are outlined and the future research directions are also highlighted. It is expected that this review would attract the attention of membrane developers, users, researchers, and scientists to appreciate the merits of using RIGC for modifying polymeric membranes to mitigate the fouling issue, increase membrane lifespan, and enhance the membrane system efficiency.

Theoretical analysis and experimental evaluation of vibration isolation system with broadband characteristic for laser tracker

High-energy synchrotron radiation source, as a large scientific device, is under construction in Beijing, China. This device is one of the fourth-generation synchrotron radiation sources with the highest brightness in the world. It will provide an important support platform for basic science and engineering science. As a kind of high-precision large-scale measurement equipment, laser tracker is used mainly in high-energy particle accelerator equipment installation, precision poses dynamic measurement and antenna feed dynamic motion precision engineering measurement field. At the construction site of high energy synchrotron radiation source, the laser tracker is often used to calibrate and pre-collimate the high energy source magnet equipment and carry on the tunnel measurement . However, the laser tracker is easily affected by the vibration of the surrounding environment, and the adverse vibration seriously affects its measurement accuracy and even causes the equipment to damage. In order to effectively control the influence of environmental vibration and ensure good static bearing capacity, a broadband vibration isolator for laser tracker is proposed. It is installed in the leg position of the triangular bracket of the laser tracker, which ensures the vibration isolation performance and good bearing capacity. For the above system, the equivalent single freedom nonlinear dynamic differential equation is established, and the steady-state response solution of the broadband isolator is obtained by using the complex variable-average method. The numerical finite element method is used to verify the correctness of the theoretical model and corresponding calculation results. On this basis, the stability of a nonlinear system is analyzed by harmonic balance method, and the influence of key designing parameter &lt;i&gt;K&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt; on vibration isolation performance is considered. Combined with the complexity of the actual working environment of laser tracker, a variety of typical working conditions are set up for test, including long time static pressure test, vertical impact excitation and lateral displacement excitation tests, to evaluate the static stability and vibration control effect of broadband isolator. The experimental results show that the maximum static displacement of the laser tracker is about 2×10&lt;sup&gt;–5&lt;/sup&gt; m under static pressure in a long time, and the maximum static load is within the allowable error range. When the occasional impacting is triggered, the installation of broadband isolator can make the combination quickly restore stability in about 2.95 s, exhibiting better vibration isolation performance. Under different dynamic loads, by comparing the acceleration frequency response curves of the laser tracker with and without the isolator, in the frequency band below the fundamental frequency of the laser tracker, the attenuation rate of the combined system can be up to about 97% with and without the vibration isolator. In the frequency band above the fundamental frequency, the attenuation rate of the combined system with and without the vibration isolation system can reach up to about 88%, and the effective vibration isolation frequency band is extended. The broadband vibration isolator meets all technical requirements.

Lens-free digital holographic microscopy for cell imaging and tracking by Fresnel diffraction from a phase discontinuity

In this Letter, a very simple, stable, and portable lensless digital holographic (DH) microscopy method is presented relying on the Fresnel diffraction (FD) of light from a phase discontinuity (PD). A phase plate in the transmission or a physical step in the reflection can be employed in the path of the divergent beam of a coherent light source as a component imposing the PD. The recorded diffraction pattern in the vicinity of the PD is a hologram produced by off-axis overlapping of two diffracted waves in both sides of the boundary region with adjustable fringe modulation. To validate the method, measurements are performed on the amplitude and phase specimens as well as on the dynamic processes of water evaporation and 3D tracking of floating cells. A reflective configuration of FD from a physical step can be used as a powerful platform for lensless DH microscopy using high-energy electromagnetic radiation, e.g., x-ray and UV sources for the high-resolution imaging of moving samples.

Identification of 90Sr and 204Tl beta radiation sources by energy distribution with a 3GEM detector

This paper presents the performance of a 3GEM in terms of identification of high and low beta energy radiation sources through the energy distribution of the main beta radiation sources used for industrial application 90Sr and 204Tl. We compare the beta radiation theoretical energy loss into the drift zone with experimental energy distribution at different 3GEM voltages. The experimental results show that the Most Probable Value (MPV) of the fitted Landau distribution obtained from 90Sr and 204Tl obtained a degree of error lower than 14% in comparison to the theoretical calculation. Additionally, high energy beta radiation source (90Sr) is identified in comparison to low energy (204Tl) - taking into account the MPV and sigma values from the fitted Landau distribution. These results are essential to design and implement a new application that utilizes the performance and special characteristics of the 3GEM for beta radiation detection and identification.

Thermal decomposition of Yttrium 2-methylbutyrate in argon

The thermal decomposition of yttrium 2-methylbutyrate (Y(C4H9CO2)3) under argon gas flow has been investigated by means of simultaneous thermogravimetry and differential thermal analysis, FTIR-spectroscopy (solid residue and evolved gas analysis), mass spectrometry, hot-stage optical microscopy and X-ray diffraction with a standard laboratory Cu-tube source as well as with a high-energy synchrotron radiation source. At least one structural transition occurs in the solid state between 100 °C and 160 °C. The decomposition of the Y 2-methylbutyrate salt takes place above 400 °C. A first stage results in the formation of Y2O2CO3 between 400 °C and 490 °C. This decomposition step is accompanied by the release of CO2, a symmetrical ketone (3,5-dimethyl-4-heptanone), as well as probably a terminal alkyne, which could not be unambiguously identified. At higher temperature, Y2O2CO3 is slowly converted to Y2O3 with release of CO2, while some carbonaceous residue is eliminated via combustion. The TG trace reaches the final plateau at about 1200 °C.

Response of PE films to low energy electron beam irradiation

In the past few years low energy electron beam units with energies in the range from 80 to 300 keV have been developed as a convenient and non-expensive alternative to high-energy electron accelerators. Some of these applications like surface decontamination or sterilization of medical supplies need the measurement of the dose in order to be in compliance with regulatory agencies. The demand to have dosimetry systems capable to deliver the irradiation dose using a simple procedure and having an appropriate calibration procedure will grow as these applications increase. Having a dosimeter with a response independent of the energy of the incident radiation would allow to calibrate it using high energy radiation sources and then use it at low-energy electron irradiations. In this paper the response of polyethylene (PE) thin films irradiated with low-energy electrons in the interval from 100 to 200 keV has been investigated with the main purpose of using them as dosimeters in low-energy electron irradiations. The response of the films was obtained from their infrared spectrum measured at their surface using the attenuated total reflectance technique (ATR). Analysis of the data obtained using the statistical technique ANOVA was performed to determine whether the energy of the radiation affects the response of the film. The results show that the response of the films depends on the energy of the electron beam used. The conclusion of this research points out that in order to use the PE film in low-energy electron irradiations the films need to be calibrated under the same conditions in which they will be used.