11B Ions Research Articles

Nanogram-scale boron isotope analysis through micro-distillation and Nu Plasma 3 MC-ICP-MS

The determination of boron isotopes (δ11B) represents a powerful tool for a variety of applications such as the reconstruction of past ocean pH and atmospheric pCO2 from the analysis of marine biogenic carbonates. In recent years, MC-ICP-MS has gained popularity over other techniques thanks to its superior sample throughput and high ionization efficiency. This study evaluates, for the first time, the performance of the Nu Instruments Plasma 3 MC-ICP-MS for measuring δ11B using different sample introduction systems and detector configurations. The main goal is to provide a detailed methodology for nanogram-scale boron isotope analysis through a straightforward approach that can be easily adopted. Boron (B) purification from the carbonate matrix was performed through micro-distillation, using a temperature of 95 °C and a minimum heating duration of 15 h, allowing the full recovery of B from up to 3 mg of carbonate mass. We attained blank values (on average 14 ± 6 pg, 1 SD, n = 27) comparable to the lowest micro-distillation blanks reported in the literature. Three sample introduction systems were tested, and the 30 μL min−1 nebuliser system outperformed the 50 and 170 μL min−1 systems in terms of signal intensity per mass of B. Two detector configurations were used based on the total boron signal intensity achieved: (1) FC11/FC12, with two Faraday cups fitted to 1011 Ω and 1012 Ω amplifier resistors to detect 11B and 10B ion beams, respectively, and (2) FC12/IC, with which we investigated, for the first time, the feasibility of combining an ion counter for detecting 10B, and a Faraday cup fitted to a 1012 Ω amplifier for 11B. The FC12/IC configuration provided accurate results compared to the use of two Faraday cups for total boron signals lower than 0.35 V (∼12 ng of B in the analysed solution). The proposed analytical procedure was validated through the analysis of several reference materials with varying boron amounts, including clam JCt-1, coral JCp-1, NIST RM 8301 Foram and Coral solutions, and boric acid ERM-AE121. Furthermore, the long-term reproducibility was assessed with two in-house standards (coral CLD-1 and foraminifera GINF-1), providing values of 25.68 ± 0.23 ‰ (2SD, n = 53; with 14–36 ng of B) and 14.90 ± 0.16 ‰ (2SD, n = 12; with 11–16 ng of B), respectively.

Ultrafast probing of plasma ion temperature in proton–boron fusion by nuclear resonance fluorescence emission spectroscopy

Aneutronic fusion reactions such as proton–boron fusion could efficiently produce clean energy with quite low neutron doses. However, as a consequence, conventional neutron spectral methods for diagnosing plasma ion temperature would no longer work. Therefore, finding a way to probe the ion temperature in aneutronic fusion plasmas is a crucial task. Here, we present a method to realize ultrafast in situ probing of 11B ion temperature for proton–boron fusion by Doppler broadening of the nuclear resonance fluorescence (NRF) emission spectrum. The NRF emission is excited by a collimated, intense γ-ray beam generated from submicrometer wires irradiated by a recently available petawatt (PW) laser pulse, where the γ-ray beam generation is calculated by three-dimensional particle-in-cell simulation. When the laser power is higher than 1 PW, five NRF signatures of a 11B plasma can be clearly identified with high-resolution γ-ray detectors, as shown by our Geant4 simulations. The correlation between the NRF peak width and 11B ion temperature is discussed, and it is found that NRF emission spectroscopy should be sensitive to 11B ion temperatures Ti > 2.4 keV. This probing method can also be extended to other neutron-free-fusion isotopes, such as 6Li and 15N.

Influence from the electronic shell structure on the range distribution during channeling of 40–300 keV ions in 4H-SiC

Ion implantation is performed in 4H-SiC with 11B, 27Al, 31P, 51V, 71Ga, and 75As ions using energies between 40 and 300 keV at various fluences along the [000-1] or the ⟨11-2-3⟩ axes. Secondary ion mass spectrometry is utilized to determine the depth distribution of the implanted elements. A Monte Carlo binary collision approximation (MC-BCA) code for crystalline targets is then applied to explain the influence of the electronic shell structure on electronic stopping and the obtained channeled ion depth distributions. The results show that, as the atomic number increases in a row of the periodic table, i.e., as the ionic radius decreases and the electron clouds densify, the interaction with the target electrons increases and the range is reduced. The decreased range is particularly pronounced going from 27Al to 31P. The reduction in channeling depth is discussed in terms of electronic shells and can be related to the ionic radii, as defined by Kohn–Sham. It is shown that these shell effects in channeled implantations can easily be included in MC-BCA simulations simply by modifying the screening length used in the local treatment of electronic stopping in channels. However, it is also shown that, for vanadium ions with an unfilled d-shell, this simple model is insufficient to predict the electronic stopping in the channels.

Initial radiation DNA damage observed in prematurely condensed chromosomes of G2-phase human lymphocytes and analytical model of ion tracks

In the present work, we have adopted the premature chromosome condensation (PCC) technique to study the initial DNA damage in order to distinguish between the biological and physical components of the dose-effect curves. We have studied G2-chromatid breaks in human lymphocytes, isochromatid-type breaks as well as chromatid exchanges at two different sampling times: directly after irradiation (t0) and 12 hours later (t12). The lymphocyte samples have been exposed to 150 MeV and spread out Bragg peak (SOBP) proton beams, 22 MeV/u 11B ions and for comparison to 60Co γ rays. Dose-response curves for both types of breaks have been determined. We have shown that t0 G2-chromatid breaks follow linear-quadratic dependence for all studied cases and could be used for estimation of the effective ion track radius. A comparison to the expected physical track radii leads to the conclusion that the biological repair mechanism considerably prevails the physical effect of the overlapping ion tracks even at the time t0. The results have been also compared to the dose-effect curves previously obtained in our chromosome aberrations study.Graphical abstract

Modeling of chromosome aberration response functions induced by particle beams with different LET.

This study is based on our already published experimental data (Kowalska et al. in Radiat Environ Biophys 58:99-108, 2019) and is devoted to modeling of chromosome aberrations in human lymphocytes induced by 22.1MeV/u 11B ions, 199MeV/u 12C ions, 150MeV and spread-out Bragg peak (SOBP) proton beams as well as by 60Co γ rays. The curvature of the dose-effect curves determined by the linear-quadratic model was considered in the frame of a simple analytical approach taking into account increase in the irradiation dose due to overlapping interaction regions of ion tracks. The model enabled to estimate effective interaction radius which could be compared with the physical expectations. The results were also compared to the Amorphous Track Structure Model of Katz which allows to get some additional information about the ion track structure. The analysis showed that the curvature of the experimental dose-effect curves mainly results from highly efficient repair processes of the DNA damage.

Boron vacuum-arc ion source with LaB6 cathode.

We describe a pulsed vacuum arc ion source with a lanthanum hexaboride (LaB6) cathode for high-dose selective implantation of 10B and 11B isotope ions. The design and main parameters of the source and its plasma generator are described, and research data are reported on the formation, transport, and magnetic separation of 10B and 11B ions extracted from the erosion plasma of a vacuum arc discharge. Cathode spots are initiated by flashover across an alumina ceramic block of diameter ∼2.5 mm located at the center of the working cathode. The design of the trigger system provides rather uniform cathode erosion, and the cathode dimensions (diameter of 14 mm, length of ∼15 mm) ensure long-term operation of the source. The plasma generator operates at a pulse repetition rate of up to 10 Hz with a discharge current pulse width of 280 µs. At an arc current of 130 A, the source provides an ion beam of a rectangular cross section of 0.6 × 6 cm2 with an energy of 25 keV and amplitude up to 75 mA. A mass analyzer magnet was used for mass-to-charge separation.

Механізми реакції 13C(11B,7Li)17O при енергії іонів 11B 45 МеВ

Механізми реакції 13C(11B,7Li)17O при енергії іонів 11B 45 МеВ

The Influence of Physical Characteristics of Accelerated Heavy Ions on the Formation and Repair of DNA Double-Strand Breaks

The kinetics of formation and elimination of γH2AX/53ВР1 foci induced by accelerated 11B, 20Ne, and 15N ions with different physical characteristics in human skin fibroblasts have been investigated. The results of the elimination kinetics for radiation-induced γH2AX/53BP1 foci (RIF) reveal that a decrease in the energy and an increase of the linear energy transfer (LET) of the particles reduce the efficiency of doublestrand break (DSB) repair. An investigation into the structure of RIF induced by accelerated 20Ne and 11B ions with various physical parameters shows significant differences in the nature of the RIF that is formed. It is found that 20Ne ions with a high density of δ rays in tracks (Z*2/β2 = 1454) induce larger clustered γH2AX/53BP1 foci with a more complex structure than 11B ions with a lower density of δ rays in tracks (Z*2/β2 = 494), which indicates the formation of more severe complex damage to genetic structures, first and foremost, DNA DSBs.

Nuclear point mass effects in the interaction of energetic ion with carbon nanotubes

We have calculated deposited energies of various energetic ions in carbon nanotubes, to study nuclear point mass effects, with the help of a static Monte Carlo (MC) simulation program. As a result of nuclear point mass effects, we show that at the same incident energy, the ion-deposited energy maximizes, while its mass has intermediate mass values, such as 11B, 12C and 14N ion masses, under hundreds keV 4He, 11B, 12C, 14N, 20Ne, 28Si and 40Ar ion irradiations of a thin-walled carbon nanotube. We also show that at the same incident energy, the coordination defect number maximizes, while its mass has an intermediate mass (20Ne) value, under hundreds keV 4He, 20Ne and 40Ar ion irradiations of the thin-walled nanotube. We derive an ion-deposited energy formula to analyze these maximum phenomena, and compare the MC simulation results with the MD (molecular dynamics) ones.

“Phoswich Wall”: A charged-particle detector array for inverse-kinematic reactions with the Gretina/GRETA γ-ray arrays

A high-efficiency, forward-hemisphere detector system for light charged particles and low-Z heavy ions, as obtained in an accelerator experiment, is described. It consists of four 8×8 pixel multianode photomultiplier tubes with 2.2-mm thick CsI(Tl) and 12-μm thick fast-plastic scintillation detectors. Its phoswich structure allows individual Z resolution for 1H, 4He, 7Li, 4He+4He, 9Be, 11B, 12C, and 14N ions, which are target-like fragments detected in strongly inverse kinematics. The device design has been optimized for use with a 4π γ-ray array, and the main applications are transfer reactions and Coulomb excitation. A high-angular resolution for the detection of the target-like fragments is achieved which permits angular distributions to be measured in the rest frame of the projectile-like fragment with a resolution of ~2°.

Atomistic State of Hydrogen Trapped by Vacancies and Formation of H-associated Vacancy Clusters in Nb as Observed by the Channelling Method

In order to study hydrogen-defect interactions, the effects of ion irradiation and annealing on the lattice location of hydrogen dissolved in Nb, NbH0.023, have been investigated at room temperature by the channelling method utilizing a nuclear reaction 1H(11B,α)αα with a 2 MeV 11B+ beam. By irradiation at room temperature with a dose of about 1.4 × 1016/cm2 of about 2 MeV 11B ions, the lattice location changes from the original tetrahedral (T) site (T-1 state) to the Ttr site, which is displaced from a T site by 0.45–0.55 A towards its nearest neighbour lattice point. The Ttr-site occupancy remains the same even for an approximately three times higher irradiation dose. On subsequent annealing at 523 K for 1 h, the site occupancy changes to the occupancy of (55–70)% of H atoms at T sites (T-2 state) and (30–45)% of them at random (R) sites. By additional irradiation with a dose of about 1.4 × 1016/cm2 at room temperature subsequent to the annealing, the site occupancy changes to the occupancy of (35–50)% at T + (50–65)% at R or (30–40)% at T + (10–20)% at Ttr + (50–60)% at R. It is concluded that the irradiation-induced site change to the Ttr site is a result of the trapping of hydrogen by monovacancies, i.e., the formation of H-vac. complex-1. Most of the H atoms in the T-2 state are not free hydrogen, but associated with more vacancies, for which hydrogen located at a T site in a tetrahedron consisting of four vacancies (tetravacancy), i.e., H-4vac. complex-2, is proposed. The R-site occupancy corresponds to hydrogen in a H-associated larger vacancy cluster complex-3. It is demonstrated that the complex-1 does not act as a nucleus, whereas the complex-2 acts as a nucleus for the growth to the H-associated larger vacancy cluster complex-3 by trapping more irradiation-introduced vacancies at room temperature.

Isotopic mass effects for low-energy channeling in a silicon crystal

Monte Carlo (MC) simulations have been used to study the low-energy channeling of 10B and 11B ions along the [100] axis in Si crystal. MC simulations show that the critical angle ΨC ≈ 15.3(keV/E)1/2 (in degrees) for the channeling of isotopic 10B ions and ΨC=14.5(keV/E)1/2 (in degrees) for the channeling of isotopic 11B ions, where E is the incident energy. This means that (ΨC for 10B ions/ΨC for 11B ions)≈ (15.3/14.5)≈ (11/10)1/2.

Radiation Tolerance of NROM Embedded Products

Radiation tolerance of NROM memories is demonstrated at the level of industrial 4 Mbit memory embedded modules, specifically not designed for operation in radiation harsh environments. The memory fabricated in 0.18 um technology remains fully functional after total ionization doses exceeding 100 krad. The tests were performed by irradiating with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\gamma$</tex></formula> -rays ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$^{60}{\rm Co}$</tex></formula> source) and 10 MeV <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{11}{\rm B}$</tex></formula> ions in active (during programming/erase and read-out) and passive (no bias) modes. Comprehensive statistics were obtained by using large memory arrays and comparison of the data with the parameters of irradiated single cells allowed deep understanding of the physical phenomena in the irradiated NROM devices for both moderate ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&lt;$</tex></formula> 1 Mrad) and large ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&gt;$</tex> </formula> 1 Mrad) TID. The obtained data is currently employed in the design of the new generation of NROM memories, having improved radiation tolerance

Inter-chromosomal variation in aberration frequencies in human lymphocytes exposed to charged particles of LET between 0.5 and 55 keV/μm

Purpose: To investigate the distribution of chromosomal aberrations in chromosomes 2, 8 and 14 induced by charged particles, using the fluorescence in situ hybridisation (FISH) technique.Methods: Irradiation of peripheral blood from six healthy volunteers (four male and two female) was performed at the accelerators of the Joint Institute for Nuclear Research (JINR) in Dubna (Russia). Whole blood samples were irradiated with 2 and 3 Gy of protons (170 MeV/nucleon (n), linear energy transfer (LET) ≈ 0.5 keV/μm), 3.5 Gy of 12C ions (480 MeV/n, LET = 10.6 keV/μm), 3 Gy of 12C ions 500 MeV/n, LET = 12 keV/μm), 4 Gy of 7Li ions (30 MeV/n, LET ≈ 20 keV/μm) and 3 Gy of 11B ions (32 MeV/n, LET ≈ 55 keV/μm). Chromosomal aberrations were analysed in metaphase and prematurely condensed chromosomes (PCC) induced in G2-cells using calyculin A. Chromosomes 2, 8 and 14 were painted in different colours and aberrations scored with the help of an image-analysis system.Results: Chromosome 2 was generally less sensitive than expected on the basis of its DNA content. A higher than expected frequency of exchanges was found in chromosomes 8 and 14. On average, the dicentric frequency in chromosome 2 was higher than the translocation frequency, whereas variable dicentric to translocation ratios were observed in chromosomes 8 and 14. When aberrations in all painted chromosomes were summed up the ratio was close to 1. The frequency of complex aberrations correlated with LET.Conclusion: In lymphocytes of donors studied in this work chromosome 2 appears to be consistently less sensitive to protons and heavy ions than chromosomes 8 and 14. Complex aberrations appear to be a potential marker of radiation quality.

Diffusion of Boron near Projected Ranges of B and BF2 Ions Implanted in Silicon

In this study, we examined the diffusion of boron near the projected ranges of high-dose 11B and BF2 ions implanted in silicon. A buried layer of 10B was formed and the redistribution of 10B was used to monitor the diffusion behavior. Boron precipitation at 850 °C produces the pileup of 10B in the peak region of 11B. The formation of a band of boron clusters was indicated by the accumulation of 10B between the projected range and the diffusion tail of the 11B profiles during annealing at 750 °C, following 11B+ implantation. The 10B redistribution at 750 °C also demonstrated the retardation of transient enhanced diffusion (TED) in the peak region. Under BF2+ implantation, TED retardation near the projected range of 11B is suppressed by the decrease in implantation energy, because the surface proximity effect reduces the density of end-of-range (EOR) defects at low implantation energies. Boron clustering is suppressed in front of the diffusion tail of 11B because only a peak of 10B at the EOR dislocations exists at 750 °C following BF2+ implantation.

Breakdown Behavior of 900-V 4H-SiC Schottky Barrier Diodes Terminated with Boron-Implanted pn-Junction

High-voltage (900 V) 4H-SiC Schottky-barrier diodes (SBD) terminated with guard pnjunction were fabricated and investigated. The guard pn-junction was formed by room temperature boron implantation followed by high temperature annealing. Owing to the transient enhanced boron diffusion during anneal, the depth of guard pn-junction is about 1.7 μm, that is approximately 1 μm deeper than the expected average range of 11B ions in 4H-SiC. The maximum reverse voltage of 4H-SiC SBD produced has been found to be limited by the avalanche breakdown in cylindrical portion of planar pn-junction. The value of the breakdown voltage of 910 V is close to theoretical one calculated for the dopant density = 2.5×1015 cm-3, n-base thickness d = 12.5 μm and junction curvature rj = 1.7 μm. Dynamic (pulse) reverse current-voltage characteristics were measured in the breakdown regime. It was found that dynamic breakdown voltage increases with shortening the pulse duration. Due to homogeneous avalanche breakdown at the edge of the quard pn-junction and high differential resistance in the breakdown regime, the diodes under test are able to withstand, with no degradation, pulse reverse voltage at least 1600 V.

Analysis of light lithophile elements (Li, Be, B) by laser ablation ICP-MS: Comparison between magnetic sector and quadrupole ICP-MS

We report techniques for in-situ abundance measurements of the light-lithophile elements (LLE; Li, Be, and B) in silicate glasses by laser-ablation inductively coupled mass spectrometry (LA-ICP-MS), and compare the analytical performance of a sector field and quadrupole mass analyzer for these measurements. LA-ICP-MS is shown to be an effective means of determining LLE abundances at spatial scales between 25 and 100 μm. Detection limits depend on instrumental sensitivity and ablation rate, but can be in the low- to sub-ng/g range. Measured ion yields for 7Li, 9Be, and 11B ion, normalized to 43Ca as an internal standard, remain largely constant during ablation, although 11B shows a relative increase once the ablation crater aspect ratio exceeds ~1. Surficial contamination, particularly of B, can be removed rapidly via a short pre-ablation (~20 pulses) immediately prior to analysis. The sector field ICP-MS provided considerable improvements in analytical performance over the quadrupole mass analyzer, although longer magnet settling times result in greater duty cycle losses. Calculated detection limits for a given set of ablation conditions are 20–90 times lower, and useful yields (the ratio of atoms ablated to counts detected) are 20–75 times greater for the sector field instrument. Analysis of reference glasses shows that LA-ICP-MS provides accurate measurements of Li, Be, and B contents in silicate glasses over a range of compositions (komatiite to rhyolite). LA-ICP-MS also offers similar accuracy and precision and marked improvements in sample throughput compared to secondary ion mass spectrometry (SIMS) analysis of LLE abundances, although SIMS has higher useful yield and thus provides better spatial resolution.

Energy straggling of He, Li, and B isotopes in aluminium and silver

The energy straggling of 3He, 4He, 6Li, 7Li, 10B, and 11B ions with MeV energies in Al and Ag have been measured using the 3MV tandem accelerator. The experiment were performed by using a self-support transmission method with a partially-coated detector. Our results show that the experimental data are considerable discrepancy as compared with the Bohr’s values for the Al target at the energies investigated. The experimental measurements for the Al target expect for 3He and 4He ions appear an increasing trend with the ion energy in the lower energy region, but decreasing in the higher energy region. As for the Ag data, the measurements increase slightly with the ion energy increasing. The present results indicate that no significant isotope effect of the energy straggling is observed at all energies reported.

The effects of energy non-monochromaticity of 11B ion beams on 11B diffusion

We have shown that energy contamination introduced by ion beam deceleration technology that is used to increase the beam currents available for low energy boron implants, can affect fabricated junctions adversely. A 4keV 11B beam is extracted and retarded by a potential of −3.5keV for 0.5keV 11B implantation, or by a potential of −3.8keV for 0.2keV 11B implantation. Intentional beam contamination was introduced by turning off the retarding potential to allow the 4keV 11B ions to irradiate Si wafers directly. The percentage of contamination, at levels of 0.1%, 0.2% and 0.3% was introduced. Rapid thermal annealing of all the implanted samples was performed under N2 ambient at 1050°C for 1s. The dopant tail profiles themselves are not significant if the contamination levels are low. However, the much higher damage level coming from high energy contamination increases the transient enhanced diffusion of 11B more than proportionately, resulting in considerable boron diffusion. Energy contamination at a level of 0.1% can extend the profile of 0.5keV 11B implants 10nm deeper after a 1050°C spike annealing. The study shows a highly monoenergetic beam with energy contamination less than 0.1% is required for sub-micron devices.

Excitation of 14C by 45 MeV 11B ions

Angular distributions of the 11B + 14C elastic scattering and inelastic scattering for transitions to a few excited states of 14C were measured at E lab( 11B) = 45 MeV over the full angular range. The data were analyzed within the coupled-channels method. Contributions from one- and two-step transfer reactions were found to be negligible. Quadrupole deformation of the 14C ground state was deduced to be negative, the deformation of the 8.318 MeV (2 +) state was found to be similar to that of the ground state. The single particle model calculations reproduced the experimental data for transition to the 6.094 (1 −) state of 14C much better than the collective model analysis. The fit to this experimental data set was improved when we took into account reorientation of 11B in its ground state and considerably enlarged the radius of the potential binding the neutron to the 13C core. The same procedure was tested against the experimental data for transition to the 1/2 + (3.089 MeV) excited state of 13C, populated in the 11B + 13C scattering at E lab( 11B) = 45 MeV, with the similar effect.