Proton Microprobe Research Articles

Continuous ion beam-induced luminescence (IBIL) spectroscopy of air-borne particulate matter hourly collected from the atmosphere

We investigated the applicability of Ion Beam Induced Luminescence (IBIL) analysis for identifying biological components in sequentially collected airborne particulate matter (PM) samples obtained using the automated sampler. A series of micro-IBIL spectroscopies were performed on a PTFE (polytetrafluoroethylene) membrane tape filter from the Atmospheric Environmental Regional Observation System (AEROS) during a highly concentrated air pollution event on 26–27 March 2020, collected at Ota, Japan (36.290°n, 139.381°e) using an external 3 MeV proton microprobe. IBIL at typical wavelengths associated with organic compounds such as NADH and riboflavin were identified through the series of IBIL analyses, which is a key factor for identifying existence of organic pollutions, or bioaerosols. The decay times of the IBIL indicate that the peak measured is due to organic compounds rather than inorganic particles or ambient substances. These results suggest that micro-IBIL spectroscopy can be used to identify bioaerosols in hourly collected AEROS PTFE membrane tape filters taken from the atmosphere.

Characterization of hourly-collected airborne particulate matters from an automated sampling unit of the atmospheric environmental regional observation system by in-air micro-PIXE analysis

We investigated element composition ratios in two sets of sequentially collected airborne particulate matter (PM) samples obtained through the automatic sampler of the Atmospheric Environmental Regional Observation System (AEROS). A series of micro-PIXE analyses and imaging were performed on a PTFE (Polytetrafluoroethylene) membrane tape filter corresponding to two hourly time slots through a high-concentration air pollution event from 26th to 27th March 2020 sampled at Ota, Japan (36.290° N, 139.381° E) by utilizing an external 3 MeV proton microprobe. Latent variables of sequentially collected PM samples were analyzed by the non-linear least square method and classified by those clustering driven by house-made data analysis software. Micro-PIXE imaging effectively confirmed the presence of large elemental agglomerations on the PTFE membrane tape filter of AEROS that often appeared as outliners in data analysis.

Exploring New Methods to Study and Moderate Proton Beam Damage for Multimodal Imaging on a Single Tissue Section.

Characterizing proton beam damage in biological materials is of interest to enable the integration of proton microprobe elemental mapping techniques with other imaging modalities. It is also of relevance to obtain a deeper understanding of mechanical damage to lipids in tissues during proton beam cancer therapy. We have developed a novel strategy to characterize proton beam damage to lipids in biological tissues based on mass spectrometry imaging. This methodology is applied to characterize changes to lipids in tissues ex vivo, irradiated under different conditions designed to mitigate beam damage. This work shows that performing proton beam irradiation at ambient pressure, as well as including the application of an organic matrix prior to irradiation, can reduce damage to lipids in tissues. We also discovered that, irrespective of proton beam irradiation, placing a sample in a vacuum prior to desorption electrospray ionization imaging can enhance lipid signals, a conclusion that may be of future benefit to the mass spectrometry imaging community.

EPMA and PIXE Analyses of High Grade Metamorphic Rocks

Background/Objectives: The demand for exact quantification analyses in complex ore assemblages is increasing rapidly as mineral processing studies become more sophisticated. In response to this need, an Electron Micro Probe Analysis and Proton Induced X-ray Emission complementary based analytical tool procedure for the chemical characterization of minerals was employed to study the metamorphic rocks. Methods : In this work, we compare the quantitative analysis of high-grade metamorphic rocks by proton induced X-ray emission (PIXE) with that of the previous analyses by electron probe microanalysis (EPMA). During this investigation, the PIXE analytical method on a nuclear microprobe was added to the previously well-known EPMA for the chemical quantification of high-grade metamorphic rocks from the Charnockite Hill, Visakhapatnam, A.P., India. For the evolution and geochemical characterization of the metamorphic rocks, the above two methods are compared and discussions are made with respect to certain elements. Findings: Particle-induced X-ray emission is well-matched except for certain elements for the chemical characterization of metamorphic rocks belonging to earth material samples. This comparison with EPMA demonstrates the elemental quantification characteristics for such analyses. Not only is an exploratory study of proton induced X-ray emission benefit presented, but also a synopsis of comparison with electron probe microanalysis aimed at a responsible reply to metamorphic rock analytical questions. Novelty: The complementary technique, especially EPMA, is required to fill the elemental gaps that are not determined in the case of matrix complex charnockite compositional analysis by PIXE with 3MeV and a Si (Li) detector. Keywords: Electron and Proton Microprobes; Complementary Techniques; Metamorphic Rocks; Elemental Analysis

Proton microprobe analysis with 3 MeV and Si (Li) detector at Z < 17 elements in charnockite composition

The low Z elements in the matrix charnockite composition are the problem, according to proton induced X-ray emission analysis with 3 MeV energy and a Si (Li) detector. The charnockite composition analysis with a proton microprobe is affected by the energy of the ion beam, the X-ray yield of a number of atoms, the ionisation cross-section, the energy-dependent detection efficiency of the semiconductor detectors used, and several other aspects. It's difficult to compute the absolute concentration of component Z < 17 in an unknown charnockite matrix. As a result, modifying the dimensions of the detector, window, or incident proton beam energy can be used to evaluate light elemental sensitivity. Low Z elements in charnockite matrix materials can also be discovered using complementary analytical methods.

Novel Approach to Tooth Chemistry. Quantification of the Dental-Enamel Junction.

The dentin-enamel junction (DEJ) is known for its special role in teeth. Several techniques were applied for the investigation of the DEJ in human sound molar teeth. The electron (EPMA) and proton (PIXE) microprobes gave consistent indications about the variability of elemental concentrations on this boundary. The locally increased and oscillating concentrations of Mg and Na were observed in the junction, in the layer adhering to the enamel and covering roughly half of the DEJ width. The chemical results were compared with the optical profiles of the junction. Our chemical and optical results were next compared with the micromechanical results (hardness, elastic modulus, friction coefficient) available in the world literature. A strong correlation of both result sets was proven, which testifies to the self-affinity of the junction structures for different locations and even for different kinds of teeth and techniques applied for studies. Energetic changes in tooth strictly connected with crystallographic transformations were calculated, and the minimum energetic status was discovered for DEJ zone. Modeling of both walls of the DEJ from optical data was demonstrated. Comparing the DEJ in human teeth with the same structure found in dinosaur, shark, and alligator teeth evidences the universality of dentin enamel junction in animal world. The paper makes a contribution to better understanding the joining of the different hard tissues.

Automation of multi-modal beam focusing of an MeV sub-microprobe for ion beam analysis

We have developed an automatic beam-focusing system to reduce the experimental configuration time for a sub-micrometer-scaled beam probe of MeV ions with various analytical applications. Parasitic aberration due to misalignment and astigmatism must be eliminated or minimized to obtain an ideal beam spot size of less than 1 × 1 µm2, because astigmatism from excitation error and axial misalignment broaden the beam. The system involves a two-stage process of contrast and phase-difference detection that includes an automated minimization algorithm for astigmatism. The process can identify misalignments of axial rotation by measuring the line profiles of a fine mesh grid. The contrast method focused a proton microprobe to approximately 1 μm2 within 30 min, without the need for manual control when rotational misalignment was not present, while the phase-difference method successfully reduced the rotational error of lenses.

Processing of AC-coupled n-in-p pixel detectors on MCz silicon using atomic layer deposited aluminium oxide

We report on the fabrication of capacitively (AC) coupled n+-in-p pixel detectors on magnetic Czochralski silicon substrates. In our devices, we employ a layer of aluminium oxide (Al2O3) grown by atomic layer deposition (ALD) as dielectric and field insulator, instead of the commonly used silicon dioxide (SiO2). As shown in earlier research, Al2O3 thin films exhibit high negative oxide charge, and can thus serve as a substitute for p-stop/p-spray insulation implants between pixels. In addition, they provide far higher capacitance densities than SiO2 due to their high dielectric constant, permitting more efficient capacitive coupling of pixels. Furthermore, metallic titanium nitride (TiN) bias resistors are presented as an alternative to punch-through or poly-Si resistors.Devices obtained by the above mentioned process are characterized by capacitance–voltage and current–voltage measurements, and by 2 MeV proton microprobe. Results show the expected high negative charge of the Al2O3 dielectric, uniform charge collection efficiency over large areas of pixels, and acceptable leakage current densities.

Investigation of intrinsic aberrations introduced by the fringing field in the proposed 300 MeV proton microprobe in Harbin

In Harbin, the 300 MeV proton microprobe system with long-length quadrupole lenses, as a component of the Space Environment Simulation Research Infrastructure (SESRI), is under development driven by many applications in space science and proton therapy. Significant challenges have previously been addressed including minimization of ion scattering from collimators and the development of promising focusing systems compatible with the large beam magnetic rigidity. Here the intrinsic aberrations contributed by the fringe field regions of quadrupole lenses in the probe forming lens system are investigated with respect to the model used for the fringe field profile. The investigation compares the rectangular model, commonly used with the matrix method, and a more sophisticated model employing a multiphysics code for the full field profile used with a numerical raytracing method. For computational and constructional efficiency the proposed triplet system of long-length quadruple lenses required to achieve strong focusing was split into three pairs of two identical short quadrupole lenses, forming a sextuplet microprobe system. The comparison of the two fringe field models show large variations in the aberration coefficients of this system, however the rectangular model is suitable for a broad survey of possible systems to identify promising configurations for further optimization.

An Examination of the Composition and Microstructure of Coarse Intermetallic Particles in AA2099-T8, Including Li Detection.

Electron and proton microprobes, along with electron backscatter diffraction (EBSD) analysis were used to study the microstructure of the contemporary Al-Cu-Li alloy AA2099-T8. In electron probe microanalysis, wavelength and energy dispersive X-ray spectrometry were used in parallel with soft X-ray emission spectroscopy (SXES) to characterize the microstructure of AA2099-T8. The electron microprobe was able to identify five unique compositions for constituent intermetallic (IM) particles containing combinations of Al, Cu, Fe, Mn, and Zn. A sixth IM type was found to be rich in Ti and B (suggesting TiB2), and a seventh IM type contained Si. EBSD patterns for the five constituent IM particles containing Al, Cu, Fe, Mn, and Zn indicated that they were isomorphous with four phases in the 2xxx series aluminium alloys including Al6(Fe, Mn), Al13(Fe, Mn)4 (two slightly different compositions), Al37Cu2Fe12 and Al7Cu2Fe. SXES revealed that Li was present in some constituent IM particles. Al SXES mapping revealed an Al-enriched (i.e., Cu, Li-depleted) zone in the grain boundary network. From the EBSD analysis, the kernel average misorientation map showed higher levels of localized misorientation in this region, suggesting greater deformation or stored energy. Proton-induced X-ray emission revealed banding of the TiB2 IM particles and Cu inter-band enrichment.

A high excitation magnetic quadrupole lens quadruplet incorporating a single octupole lens for a low spherical aberration probe forming lens system

Abstract This paper describes the design of a new probe forming lens system consisting of a high excitation magnetic quadrupole lens quadruplet that incorporates a single magnetic octupole lens. This system achieves both a high demagnification and a low spherical aberration compared to conventional high excitation systems and is intended for deployment for the Harbin 300 MeV proton microprobe for applications in space science and ion beam therapy. This relative simplicity of the ion optical design to include a single octupole lens minimizes the risks associated with the constructional and operational precision usually needed for the probe forming lens system and this system could also be deployed in microprobe systems that operate with less magnetically rigid ions. The design of the new system is validated with reference to two independent ion optical computer codes.

A study of GeV proton microprobe lens system designs with normal magnetic quadrupole

Abstract High energy proton irradiation has many applications to the study of radiation effects in semiconductor devices, biological tissues, proton tomography and space science. Many applications could be extended and enhanced by use of a high energy proton microprobe. However the design of a GeV proton microprobe must address significant challenges including beam collimation that minimizes ion scattering and the probe forming lens system for ions of high rigidity. Here we address the probe forming lens system design subject to several practical constraints including the use of non-superconducting normal magnetic quadrupole lenses, the ability to focus 1–5 GeV protons into 5 µm diameter microprobes and compatibility with the beam parameters of GeV proton accelerators. We show that 2, 3 and 4 lens systems of lenses with effective lengths up to 0.63 m can be employed for this purpose with a demagnification up to 58 and investigate the probe size limitations from beam brightness, lens aberrations and machining precision.

The design of the 300 MeV proton microprobe system in Harbin

In Harbin, a 300MeV proton microprobe system is under development for many applications in space science studies including upset studies in microelectronic devices, radiation hardness of materials for satellites and radiation effects in human tissues. The microprobe system, as a component of Space Environment Simulation Research Infrastructure (SESRI), will employ a purpose-built synchrotron to provide the proton beam. Our design goal for the 300MeV proton microprobe is for energy spread 0.1%, emittance 10π mm mrad, intensity 109 per pulse and a probe size of 10μm. A magnetic quadrupole lens system will be used to focus the microprobe with a demagnification of 50. This paper presents a systematic investigation of the ion beam optics to optimize the design. The feasibility of the design for the Harbin system is evaluated by comparison with existing microprobe systems designed for high energy ions.

Direct quantification of rare earth doped titania nanoparticles in individual human cells

There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

The mystery of mercury-layers on ancient coins — A multianalytical study on the Sasanian coins under the Reign of Khusro II

40 Sasanian silver coins of the emperor Khusro II (591–628) belonging to the Coin Collection of the Kunsthistorisches Museum Vienna (KHM) as well as 188 coins of the same emperor acquired at the free coin market were analyzed using micro-X-ray fluorescence analysis (μ-XRF) in the course of the research project “Sylloge Nummorum Sasanidarum”. These studies revealed the presence of mercury in the XRF spectra of a bigger part of the coins. First investigations with complementary techniques showed that the mercury is present as a surface layer. Therefore, further detailed studies were performed on polished sections using the Particle Induced X-ray Emission technique with a proton microprobe (μ-PIXE) that offers quantitative and spatially resolved elemental information with micron resolution, scanning micro-X-ray fluorescence (μ-XRF) analyses for a better understanding of the elemental distribution on the surface and polished sections of the coins and finally confocal micro-XRF (3D μ-XRF or CMXRF) analyses for revealing information on the surface layering and elemental in-depth distribution. The synergistic application of these methods offered detailed and improved information on the structure of the mercury-layer on the surface of the silver coins supporting assumptions dating back to 1976/78 indicating medical treatments using Hg as basis for this phenomenon.

SR-FTIR Coupled with Principal Component Analysis Shows Evidence for the Cellular Bystander Effect.

Synchrotron radiation-Fourier transform infrared (SR-FTIR) microscopy coupled with multivariate data analysis was used as an independent modality to monitor the cellular bystander effect. Single, living prostate cancer PC-3 cells were irradiated with various numbers of protons, ranging from 50-2,000, with an energy of either 1 or 2 MeV using a proton microprobe. SR-FTIR spectra of cells, fixed after exposure to protons and nonirradiated neighboring cells (bystander cells), were recorded. Spectral differences were observed in both the directly targeted and bystander cells and included changes in the DNA backbone and nucleic bases, along with changes in the protein secondary structure. Principal component analysis (PCA) was used to investigate the variance in the entire data set. The percentage of bystander cells relative to the applied number of protons with two different energies was calculated. Of all the applied quantities, the dose of 400 protons at 2 MeV was found to be the most effective for causing significant macromolecular perturbation in bystander PC-3 cells.

Radiation tolerance of ultra-thin PIN silicon detectors evaluated with a MeV proton microbeam

A focused MeV proton beam at the Lund Ion Beam Analysis Facility has been used to induce radiation damage in transmission semiconductor detectors. The damage alters the response of detectors and degrades their charge transport properties. In this work, the radiation tolerance of ultra-thin silicon PIN detectors was studied as a function of proton fluences and detector thickness using a scanning proton microprobe. The investigated detectors had thicknesses ranging between 6.5 and 22μm, and different selected regions of each detector were irradiated with fluence up to 2×1015protons/cm2. The results show that the charge collection efficiency (CCE) decreases as a function of the proton fluence. Compared with non-irradiated regions, the CCE was above 94% at the lowest fluence of 2×1012protons/cm2 for all the detectors studied. Degradation of the devices caused spectral peak shifting toward lower energies. The highest possible fluence of 2.55MeV protons that could be used, causing only minor radiation damage, was 2×1013cm−2 for the thinnest detectors (6.5 and 10μm) and 2×1012cm−2 for the thickest detectors (15 and 22μm).

Multifunction signal detection and data acquisition system for SINAP's scanning proton microprobe

Multifunction signal detection and data acquisition system for SINAP's scanning proton microprobe

Hydrogen microscopy – Distribution of hydrogen in buckled niobium hydrogen thin films

Hydrogen absorption in thin metal films clamped to rigid substrates results in mechanical stress that changes the hydrogen's chemical potential by ΔμH(σ) = −1.124σ kJ/molH for σ measured in [GPa]. In this paper we show that local stress relaxation by the detachment of niobium hydrogen thin films from the substrate affects the chemical potential on the local scale: using coincident proton–proton scattering at a proton microprobe, the hydrogen concentration is determined with μm resolution, revealing that hydrogen is not homogenously distributed in the film. The local hydrogen solubility of the film changes with its local stress state, mapping the buckled film fraction. In niobium hydrogen thin films loaded up to nominal concentrations in the two-phase coexistence region, the clamped film fraction remains in the solid solution phase, while the buckles represent the hydride phase. These results are compared to a simple model taking the stress impact on the chemical potential into account.