This work reevaluates the ion detection efficiency of the Jet Counter nanodosimeter working with low-pressure nitrogen. SIMION simulations were used to model the trajectories of ions during their extraction from the interaction chamber. The study examined the relationship between efficiency vs. extraction voltage, gas density, and temperature. The highest detection efficiency (approximately 60%) was achieved at a high extraction voltage and low temperature. The findings were then used as a parameter in the Monte Carlo modeling of the Jet Counter operations, and the results were compared with experimental results, showing satisfactory agreement.
Precise evaluation of a gamma-ray’s interaction position in scintillator detectors is important for their application in medical and industrial imaging. Two approaches can be pursued in achieving this goal: pixelated detectors or monolithic detectors coupled to pixelated readouts. Here, we present the design of a thin monolithic position-sensitive detector for low-energy gamma-rays. Two distinct position-evaluation methods were developed and assessed in terms of accuracy, precision, and imaging capabilities. An analytical model based on a curve-fitting procedure established a performance baseline. A neural network model showed superior performance, offering notable improvements in both accuracy and precision. Qualitative evaluation of the imaging results provided insights into the inherent advantages and limitations of both models. The results demonstrate the ability of a thin monolithic scintillator detector to generate images that significantly surpass the resolution of the readout array for low-energy gamma-ray imaging.
To make precision particle mass measurements in charged spectrometers detailed understanding of the influence of detector effects is critical. In this paper the influence of detector-related uncertainties on the determination of the parent particle mass in two-body decays is investigated. It is shown how the dependence of observed mass shifts on the sum and difference of the daughter particle momenta can be used to determine the physical causes of a bias more rigorously than the ad hoc rules that are often adopted. The approach is illustrated using the case of measuring the Λ hyperon mass. This observable is of interest because our current knowledge relies on information from a single experiment that has not been updated to account for changes in the value of the K_s^0 mass used for calibration. With the approach developed in the paper it shown that the LHCb experiment has the capability to make a measurement of the Λ mass with systematic uncertainties from the tracking system controlled to 0.7keV/c^2. This allows a total precision of 2.2keV/c^2 to be achieved, dominated by the knowledge of the K_s^0 mass used for calibration. This would improve the current knowledge of the Λ hyperon mass by a factor of three.
We report on a novel design for a HPGe-BGO pair spectrometer with the aim to enhance the performance of existing HPGe detectors for high-energy γ-rays. In addition, the BGO shield as a standalone detector allows for a use with the selective detection of positron annihilation. The compact geometry was optimized to use it with ELIADE, the HPGe array at VEGA (ELI-NP). We present the design, results from two commissioning runs with high-energy γ-rays and an outlook to future applications.
This paper presents a comprehensive overview of the Machine Detector Interface (MDI) design developed for the FCC-ee Feasibility Study. It highlights novel studies related to the lightweight interaction region, including a mechanical model of the vacuum chambers, integration of the vertex detector, the MDI alignment system, and assessments of machine-induced backgrounds. The small beam pipe radius and thickness, as well as the high power to be dissipated, require state-of-the-art mechanical design. The integration of all mechanical elements and detectors is challenging, necessitating careful studies to allow fulfilling conflicting requirements. The optimisation of the machine detector interface against formidable backgrounds is presented.
This paper mainly studied the safety detection of pesticide residues of agricultural products. The agricultural products studied were capsicums from Haidong City, Qinghai Province, China. Ten kinds of organophosphate pesticides (OPPs) were detected by the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). The results showed that the method had the best detection performance when using 1% glacial acetic acid-acetonitrile solvent as extraction agent and 0.6gMgSO4+0.1gPSA+0.1GGCB as purification agent. The average recovery rate of ten OPPs was between 75.94% and 118.78%, and the relative standard deviation (RSD) was between 1.01% and 3.25%. In the actual detection of 216 capsicum samples, only methidathion was detected twice, the detection range was 0.0018-0.0026 mg/kg, and the maximum residue limit was 0.2 mg/kg; all ten kinds of OPPs were within the standard limits. The results show that this method can detect ten kinds of OPPs in agricultural products and can be applied in practice.
Resistive strips Micromegas are employed in the ATLAS New Small Wheel project. They have already been installed and operate in the experimental cavern of the ATLAS experiment at CERN. This work attempts to describe the mechanism of the surface electric charge spread on a resistive strip of the Micromegas detector and the created transient electric field leading to the suppression of the spark rate in the amplification region. The electric field spatial mapping is calculated versus time by using the accurate 3-layer geometry as a function of the resistive layer thickness around its value used in Micromegas detectors. We also used the approximated method based on 2-layer geometry to investigate its discrepancy from the accurate one.
Generating high output powers while achieving narrow line single mode lasing are often mutual exclusive properties of commercial laser diodes. For this reason, efficient and scalable amplification of narrow line laser light is still a major driving point in modern laser system designs. Commonly, injection locking of high-power semiconductor laser diodes are used for this purpose. However, for many laser diodes it is very challenging to achieve stable operation of the injection locked state due to a complex interplay of non-linearities and thermal effects. Different approaches of active or passive stabilization usually require a large overhead of optical and electrical equipment and are not generally applicable. In our work we present an active, periodically applied stabilization scheme which is generally applicable, technically easy to implement and extremely cost-effective. It is based on the externally synchronized automatic acquisition of the optimal injection state. Central to our simple but powerful scheme is the management of thermalization effects during lock acquisition. By periodical relocking, spectrally pure amplified light is maintained in a quasi-CW manner over long timescales. We characterize the performance of our method for laser diodes amplifying 671 nm light and demonstrate the general applicability by confirming the method to work also for laser diodes at 401 nm, 461 nm and 689 nm. Our scheme enables the scaled operation of injection locks, even in cascaded setups, for the distributed amplification of single frequency laser light.
We develop a new algorithm to estimate the temperature of a nonneutral plasma in a Penning-Malmberg trap. The algorithm analyzes data obtained by slowly lowering a voltage that confines one end of the plasma and collecting escaping charges, and is a maximum likelihood estimator based on a physically-motivated model of the escape protocol presented in (Beck in Measurement of the magnetic and temperature dependence of the electron-electron anisotropic temperature relaxation rate. PhD thesis, 1990). Significantly, our algorithm may be used on single-count data, allowing for improved fits with low numbers of escaping electrons. This is important for low-temperature plasmas such as those used in antihydrogen trapping. We perform a Monte Carlo simulation of our algorithm, and assess its robustness to intrinsic shot noise and external noise. The assumptions in this paper allow for a lower bound for measurable plasma temperatures of approximately 3 K for plasmas of length 1 cm , with approximately 100 particle counts needed for an accuracy of ± 10 % .
In contrast to conventional E-mode resonance accelerators, H-mode DTLs provide for compact linac sections and have been established as highly efficient resonators during the last decades. Thus, H-mode structures are widely applied for heavy-ion acceleration with medium beam energies because of their outstanding capability to provide high acceleration gradients with relatively low energy consumption. To build upon those advantages, an alternating phase focusing beam dynamics layout has been applied to provide for a resonance accelerator design without internal lenses, which allows for eased commissioning, routine operation, maintenance, and potential future upgrades. The features of such a channel are going to be demonstrated on the example of two interdigital H-mode cavities, separated by an external quadrupole triplet. This setup provides for heavy ion (mass-to-charge ratio A/z≤ 6 ) acceleration from 300 keV/u to 1400 keV/u and is used as an injector part of the superconducting continuous wave accelerator HELIAC. Hence, this promising approach generally enables effective and compact routine operation for various applications, such as super heavy ion research, material science, and radio biological applications such as heavy-ion tumor therapy.
This work presents GN-Vision, a novel dual γ -ray and neutron imaging system, which aims at simultaneously obtaining information about the spatial origin of γ -ray and neutron sources. The proposed device is based on two position sensitive detection planes and exploits the Compton imaging technique for the imaging of γ -rays. In addition, spatial distributions of slow- and thermal-neutron sources (<100 eV) are reconstructed by using a passive neutron pin-hole collimator attached to the first detection plane. The proposed gamma-neutron imaging device could be of prime interest for nuclear safety and security applications. The two main advantages of this imaging system are its high efficiency and portability, making it well suited for nuclear applications were compactness and real-time imaging is important. This work presents the working principle and conceptual design of the GN-Vision system and explores, on the basis of Monte Carlo simulations, its simultaneous γ -ray and neutron detection and imaging capabilities for a realistic scenario where a 252 Cf source is hidden in a neutron moderating container.
We have developed a Yb-doped fiber amplifier (YDFA) using fusion splicing, and characterized its performance with numerical simulation, achieving a continuous output of above 10 W of 1064 nm light. The device has been conceptualized to have a configuration as simple as possible; a strategy for using fiber amplifiers in harsh environments where quick repairs and replacements may become necessary at unexpected times.
HVE-400 ion implanter is special ion implantation equipment for semiconductor materials boron and phosphorus doping. The ion source and extraction deflection system are at high voltage platform, while the corresponding control system is at ground voltage position. The control signals and measurement signals of various parameters at the high-voltage end need to be transmitted between ground voltage and high voltage through optical fibers to isolate high voltage. Upgrading is carried out due to the aging of the optical fiber transmission control and monitoring system, which cannot work stably. The transformation replaces the original distributed single-point control method with an advanced distributed centralized control method, and integrates all control and monitoring functions into an industrial control computer for digital operation and display. In the computer software, two kinds of automatic calculation of ion mass number are designed. After upgrading, the implanter high-voltage platform control and monitoring system features digitalization, centralized control, high reliability, strong anti-interference, fast communication speed, and easy operation.
We present a stabilization technique developed to lock and dynamically tune the resonant frequency of a moderate finesse Fabry-Pérot (FP) cavity used in precision atom-cavity quantum electrodynamics (QED) experiments. Most experimental setups with active stabilization either operate at one fixed resonant frequency or use transfer cavities to achieve the ability to tune the resonant frequency of the cavity. In this work, we present a simple and cost-effective solution to actively stabilize an optical cavity while achieving a dynamic tuning range of over 100 MHz with a precision under 1 MHz. Our unique scheme uses a reference laser locked to an electro-optic modulator (EOM) shifted saturation absorption spectroscopy (SAS) signal. The cavity is locked to the PDH error signal obtained from the dip in the reflected intensity of this reference laser. Our setup provides the feature to efficiently tune the resonant frequency of the cavity by only changing the EOM drive without unlocking and re-locking either the reference laser or the cavity. We present measurements of precision control of the resonant cavity frequency and vacuum Rabi splitting (VRS) to quantify the stability achieved and hence show that this technique is suitable for a variety of cavity QED experiments.
During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.
Proton therapy systems produce large fluxes of energetic secondary particles when tailoring the beam energy and transverse profile to the specificities of each irradiation plan. A Low Activation Concrete (LAC) mix is foreseen for parts of the shielding of the Ion Beam Applications (IBA) Proteus® One (P1) compact system at the ProtherWal proton therapy centre in Charleroi, Belgium, to limit the long-term activation of the concrete shielding. To experimentally monitor the long-term activation and validate the beneficial impact of the LAC mix, a setup of four removable cores to be placed at critical locations in the cyclotron vault is optimised. We report on the experimental and simulation monitoring setup design. Our validated BDSIM/FISPACT-II methodology combines particle tracking and Monte-Carlo particle-matter interactions simulations using Beam Delivery Simulation (BDSIM) and the computation of the activation using FISPACT-II. We show that the evaluation of the short-term activation of the cores is essential to the measurement analysis. We detail a hybrid workflow based on numerical simulations that uses logging data of the workloads of the clinical and research beam production and experimental measurements to evaluate and monitor the short- and long-term activation at any point during the centre lifetime and decommissioning period. The activation of the cores using a realistic foreseen irradiation pattern is studied, allowing for the characterisation of the measurement process and radiation protection considerations related to the measurement campaign. The final experimental setup and the supporting online simulation tools are discussed in detail.
A brief overview of ion beam analysis methods and procedures in studies of materials exposed to fusion plasmas in controlled fusion devices with magnetic confinement is presented. The role of accelerator techniques in the examination and testing of materials for fusion applications is emphasised. Quantitative results are based on robust nuclear data sets, i.e. stopping powers and reaction cross-sections. Therefore, the work has three major strands: (i) assessment of fuel inventory and modification of wall materials by erosion and deposition processes; (ii) equipment development to perform cutting-edge research; (iii) determination of nuclear data for selected ion-target combinations. Advantages and limitations of methods are addressed. A note is also given on research facilities with capabilities of handling radioactive and beryllium-contaminated materials.
The existing and future accelerator facilities at GSI and FAIR offer unique opportunities for interdisciplinary research, especially for material science and nanotechnology. On their way through polymers, swift heavy ions with GeV energy deposit enormous energy densities along their trajectory, generating long nanoscopic damage trails known as ion tracks. Ion-track technology utilizes the small track size (few nm) combined with the extensive track length (up to 100 μ m and more) to synthesize and control the geometry of high-aspect-ratio nanostructures such as tailored nanochannels and nanowires. In particular, electrodeposition and ion-track nanotechnology provide an excellent platform for developing unique 3D networks of nanowires with controlled dimensions, composition and crystallographic properties. Here, a summary of recent results obtained on the synthesis and characterization of stable 3D architectures of semiconductor and semimetal nanowires, and their implementation in the fields of photoelectrochemistry and thermoelectrics, is presented.
Accelerator Mass Spectrometry (AMS) adds the techniques of higher energy charged particle acceleration to the basic principles of Isotope Ratio Mass Spectrometry (IRMS) to provide extremely low detection capability (below 1 femtogram) of rare isotopes in samples of natural materials as small as 1 mg. Depending on the element selected and the configuration of the equipment, rare isotope sensitivities can reach less than one part in 10(15). The advantages of this small sample size and high sensitivity for the detection of rare isotopes include a) the economic benefit of collecting, shipping and preparing much smaller samples, and b) the ability to analyse specific chemical compounds within the sample. For the latter advantage, the pathway taken by that compound through a complex system can be more precisely traced or, in the case of radioactive isotopes, more precise chronological information can be provided. The paper is an amplification of material which was presented at the IAEA International Conference on Accelerators for Research and Sustainable Development: novel concepts and technical innovation. It begins with a basic overview of AMS technology, with an emphasis on how the use of higher energy contributes to this enhanced sensitivity, and then provides several examples of new AMS technologies which reduce the energy and space requirements for such systems. Several examples of applications which contribute to the investigation of sustainability in other areas of environmental concern are then briefly described.
The wide variety and ever-growing applications of plasma processes in research and industry require an equally growing diversity and accessibility of suitable plasma diagnostics. The plasma parameters and the tailoring thereof strongly influence the outcome of thin film deposition, plasma etching, or surface treatments, to name only a few. To further enhance the determination of different fluxes of species, their energies, and behaviour influencing a surface process, a custom-built combination of two commonly used diagnostics was developed. With a retarding field energy analyzer, one can obtain the ion energy distribution in a plasma by measuring the current at the collector depending on the applied voltage at the scan grid. A passive thermal probe determines the energy flux density coming from a process plasma by measuring the temperature change of a dummy substrate. In this study, we present a retarding field energy analyzer where a passive thermal probe substitutes the collector. By doing so, we can determine the energy distribution of the charged ions, their energy flux density at a certain potential, and the power deposited onto a substrate. Another advantage is that the thermal probe can even measure the power deposited by incoming (fast) neutrals and of the background gas when the grids keep away the ions. Hence, combining these two powerful diagnostics yields information neither can deliver on their own. The probe has been tested in three different plasma environments: ion beam source, magnetron sputtering and radio frequency discharge plasma.
