首页期刊导航|Nuclear instruments and methods in physics research, Section B. Beam interactions with materials and atoms
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Nuclear instruments and methods in physics research, Section B. Beam interactions with materials and atoms
North-Holland
North-Holland
0168-583X
Nuclear instruments and methods in physics research, Section B. Beam interactions with materials and atoms/Journal Nuclear instruments and methods in physics research, Section B. Beam interactions with materials and atoms
Marek ZmeskalPetr BurianMichal KostalTomas Czakqj...
165710.1-165710.7页
查看更多>>摘要：The characteristics of the proton beam produced by the IBA Cyclone 18/9 medical cyclotron were investigated, focusing on its energy and profile. The proton beam energy was measured as 18.25 ± 0.25 MeV using activation foil detectors. The beam profile was characterized using the Timepix3 based detector, revealing a Gaussian distribution with consistent widths and slight asymmetry in the horizontal plane. This study presents a straightforward methodology for evaluating cyclotron beam parameters using activation foils and pixel detectors, providing a tool for optimizing target design and expanding the applications of medical cyclotrons beyond radiopharmaceutical production.
Robert KochStefanie EcknerMarcel GeraldShavkat Akhmadaliev...
165715.1-165715.6页
查看更多>>摘要：Insulated Gate Bipolar Transistors (IGBTs) power devices require high blocking capability, low on-resistance as well as adaptable switching behaviour. The technique presented in this work aims to realize continuous deep (> 40 μm) n-type profiles as field stop structures in high voltage silicon IGBTs (1200 V) to adjust the switching capability. Hydrogen-related donor (HD) defect complexes perform as n-type dopants in single crystalline silicon. Up to now, these IGBT field stop profiles are generated using multiple high energy (up to 2 MeV) implantation steps. In contrast, we achieve continuous deep HD profiles in a single implantation step by inserting a micro-patterned silicon membrane (energy filter) into the primary ion beam at an energy of 2.5 MeV to provide a beam with a broad customized energy distribution. In this work, we investigate how filter structure, implanted fluence φ (from 10~(13) cm~(-2) to 5×10~(15) cm~(-2)) and annealing conditions affect the depth distribution of HD defect complexes. We found that the electrically active dose divided by the implanted fluence before the energy filter, depends on the pattern type of the membrane (long grooves or squares), the implanted fluence and the annealing hold temperature (320 ℃ to 420 ℃).
查看更多>>摘要：Two-phase Ni_(30)Zr_(70) alloy consisting of pure Zr and NiZr_2 phases was irradiated with 100 MeV Au ions at room temperature. Effects of the irradiation on the lattice structure of the alloy were investigated using X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) and positron annihilation lifetime (PAL) measurements. The results showed that the NiZr_2 phase was gradually amorphized, and the Zr phase remained a crystalline even after the irradiation.
查看更多>>摘要：An event involving multiple biomass burning wildfires that occurred in southern and central Mexico during May 2019 was investigated using Particle Induced X-ray Emission (PKE). The event severely affected the Mexico City Metropolitan Area (MCMA), resulting in elevated concentrations of various pollutants, including fine particulate matter (PM2.5), which accumulated in the region over several days. PM_(2.5) mass concentration reached a maximum value of 63 μg/m~3, exceeding the Mexican Air Quality Standard of 45 μg/m~3 in 24 h, in effect in Mexico in 2019. PM2.5 samples were collected during the wildfires episode and analyzed by PIXE to determine their elemental concentrations. Additionally, a high-volume PM_(2.5) sampler operating in parallel provided samples to determine organic carbon (OC) and elemental carbon (EC). Time series of PM_(2.5), OC, and EC, as well as those elements considered respectively good markers of biomass burning (K) and fossil fuel combustion (S and V) were generated. The results revealed trends in accordance with their origin, verifying the presence of particles proceeding from common sources, either from biomass burning or fossil fuel combustion. These results were cross compared with aerosol transport trajectories generated using the HYSPLIT model for computing simple air parcel trajectories, showing to be in agreement. Non-soil (smoke) potassium was estimated using its corresponding enrichment factor before, during, and after the most critical period of the event (May 9-18, 2019), indicating that wildfires were indeed the main contributors to the local atmospheric pollution around the peak of the event. Tracers time series proved to be a very valuable asset to link the pollutants to their sources.
L. PichonQ. LemassonD. Bachiller-PereaC. Pacheco...
165734.1-165734.8页
查看更多>>摘要：We present here the advances on two custom-built software programs for PIXE spectra processing, both of them based on the GUPK package. The first one, named LivePIXE, is a standalone executable that has been implemented in the New AGLAE data acquisition system to process dynamically PIXE spectra during recording, almost in real-time. It allows to verify if the selected area of the object is relevant for the analysis and it provides a first interpretation of the PIXE results in order to orientate further analysis. The second program presented here is an updated version of the TrauPIXE software, which we had previously developed to process series of recorded PIXE spectra. As different X-ray absorbers can be installed in front of the detectors, each element of interest in the sample can be measured with different detection limits and uncertainties. This updated version selects the most precise element concentrations from all the PIXE results. It can also take into account the elemental concentrations obtained simultaneously by PIGE or/and RBS and incorporate them during the PIXE processing and into the final compositional table.
查看更多>>摘要：~(48)V is a medical radionuclide applicable for positron emission tomography (PET). It can be produced through α-particle-induced reactions on ~(45)Sc. In this study, we measured the cross sections of these reactions using the stacked-foil activation technique and γ-ray spectrometry. The measured cross sections up to 29 MeV are in good agreement with data above 22 MeV obtained in our previous study. We also calculated the physical thick target yields based on the measured cross sections. The results suggest that a projectile energy of approximately 15 MeV is optimal for achieving nearly saturated ~(48)V production while minimizing the formation of radioactive co-products.
查看更多>>摘要：SiOC is an amorphous ceramic with superior irradiation stability, making it attractive for applications in high-temperature and high-radiation environments. However, its glassy state stability under the synergistic effects of helium introduction and heavy damage cascades, as expected in a reactor, has not yet been fully assessed. In this study, e-gun evaporated SiOC was simultaneously irradiated using 150 keV helium at a 45-degree incident angle and 1.5 MeV silicon self-ions at a normal incident angle, at room temperature, 300 ℃, and 500 ℃, respectively. For all irradiation conditions, high-resolution transmission electron microscopy and electron diffraction analysis across different depths of the film did not reveal any crystallization. However, Si-enriched precipitates appeared, with fewer precipitates observed at the highest irradiation temperature. Surface scanning electron microscopy showed periodic patterning on the surface of both room temperature and 300 ℃ irradiated samples, but not on the 500 ℃ irradiated sample. The study demonstrates the overall excellent amorphization resistance of SiOC.
Rijul R. ChauhanValerie TsvetkovaSeungSu KimTania Kumar...
165737.1-165737.10页
查看更多>>摘要：C_(60), also known as ftillerene or buckminsterfullerene, has a variety of applications across different fields due to its unique molecular structure. Notably, C_(60) can be utilized in a variety of applications, including photodetectors, sensors, lubricants, and coatings. Owing to its high surface area, C_(60) film is particularly well-suited for chemical and biological sensors. For sensor applications, ion beams can be utilized to introduce dangling bonds and vacancies to increase efficiency in trapping molecules. Here, the irradiation response of C_(60) films is studied as a function of fluences of of a 100 keV helium ion beam. The C_(60) film is deposited on a Mica substrate via thermal evaporation of C_(60) powders. The as-deposited film exhibits a periodic topographical pattern formation, which was analyzed using atomic force microscopy. Upon ion irradiation, Raman spectra show an increase in the D/G mode intensity with increased fluences, consistent with previous studies on low-dimensional carbon systems. The D/G mode intensity, however, begins to decrease when damage levels are high enough to reduce the number of six-fold rings, corresponding to amorphization. The threshold amorphization fluence was measured.
Miguel PenaXuemei WangWeilin JiangRijul Chauhan...
165738.1-165738.10页
查看更多>>摘要：Self-ion irradiation has been widely used to simulate neutron damage. One issue of self-ion irradiations is the accuracy of predicted implant profiles and the associated local displacement damage. Experimental validation of ion penetration depth requires ion implantation of isotopes that are significantly low in natural abundance. Such isotopic beams are often obtained using expensive isotope-pure sputtering cathode materials. A pure Ni-62 beam can be produced from natural nickel, but effective separation requires a 90-degree bending magnet. This study demonstrates that an isotopically pure beam can be obtained using natural cathode materials with traditional small angle bending magnets. The key is to use a beam collector after the acceleration tank for mass scanning, with additional separation resolution gained from the long distance between the low-energy magnet and the beam collector. We demonstrate the feasibility of obtaining distinct peaks of Ni-58, Ni-60, Ni-61, and Ni-62 from a natural Ni cathode. Depth profiles for 2 MeV and 3.5 MeV Ni-62 ions were obtained, and show dramatic differences compared to SRIM predictions, which overestimate the ion range by ～100% for 2 MeV and ～30% for 3.5 MeV ions.
查看更多>>摘要：A normalized XRF standardless iterative simulation method (NXSIM) is proposed. Various methods are available to perform quantitative analysis with the XRF method. Many of these methods have laborious and costly processes that require sample preparations, specific reference materials, and repeated measurements. For such reasons, researchers continue to search for methods that provide more accurate and faster results. The main goals of this study are to obtain much faster results with acceptable accuracy by eliminating the need for repeated experimental measurements and reference samples. In this study, XRF spectrometry simulations were carried out with the scattering geometry designed in the MCNP 6.2 code system. The obtained results were used to perform quantitative analysis for experimentally prepared samples. After six samples with different element content and composition were prepared by the press pellet method, XRF spectra were obtained experimentally. Simulations were run with random element weight percentages using the elements in the sample. The elemental compositions of the samples were determined by the iteration method developed from the simulation results and experimental results. According to the results obtained, it has been demonstrated that XRF quantitative analysis can be performed by NXSIM with acceptable precision and accuracy.
NETL
NSTL
Elsevier