Proton Bombardment Research Articles

A facility for cryogenic ion irradiation and in situ characterization of rare-earth barium copper oxide superconducting tapes.

Superconducting magnets based on Rare Earth Barium Copper Oxides (REBCO) offer transformative capabilities in the fields of fusion energy, high energy physics, and space exploration. A challenge shared by these applications is the limited lifetime of REBCO due to radiation damage sustained during operation. Here we present a new ion-beam facility that enables simultaneous cryogenic irradiation and in situ characterization of commercial REBCO tapes. The ion source provides spatially uniform fluxes up to 1018protons/m2s with kinetic energies up to 3.4MeV, in addition to helium and higher-Z species. Using this facility, we can induce uniform damage profiles in the first 10-20 µm of REBCO tapes with less than 0.25 appm of hydrogen implanted in REBCO after a dose of 1020protons/m2. The tape can be held between 20 and 300K with an accuracy of ±0.1K and is connected to a four-point probe measuring the critical current, Ic, and critical temperature, Tc, before, during, and after irradiation with transport current ranging from 100 nA to 100A, and a typical voltage noise less than 0.1 μV. These capabilities are presently used to study the effect of irradiation temperature on REBCO performance change during and after proton bombardment, to assess the possibility of Ic and Tc recovery after irradiation through thermal annealing, and to explore the instantaneous and recoverable suppression of Ic and Tc observed during irradiation.

Influence of electrical field on the susceptibility of gallium nitride transistors to proton irradiation

Radiation susceptibility of electronic devices is commonly studied as a function of radiation energetics and device physics. Often overlooked is the presence or magnitude of the electrical field, which we hypothesize to play an influential role in low energy radiation. Accordingly, we present a comprehensive study of low-energy proton irradiation on gallium nitride high electron mobility transistors (HEMTs), turning the transistor ON or OFF during irradiation. Commercially available GaN HEMTs were exposed to 300 keV proton irradiation at fluences varying from 3.76 × 1012 to 3.76 × 1014 cm2, and the electrical performance was evaluated in terms of forward saturation current, transconductance, and threshold voltage. The results demonstrate that the presence of an electrical field makes it more susceptible to proton irradiation. The decrease of 12.4% in forward saturation and 19% in transconductance at the lowest fluence in ON mode suggests that both carrier density and mobility are reduced after irradiation. Additionally, a positive shift in threshold voltage (0.32 V and 0.09 V in ON and OFF mode, respectively) indicates the generation of acceptor-like traps due to proton bombardment. high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy analysis reveal significant defects introduction and atom intermixing near AlGaN/GaN interfaces and within the GaN layer after the highest irradiation dose employed in this study. According to in-situ Raman spectroscopy, defects caused by irradiation can lead to a rise in self-heating and a considerable increase in (∼750 times) thermoelastic stress in the GaN layer during device operation. The findings indicate device engineering or electrical biasing protocol must be employed to compensate for radiation-induced defects formed during proton irradiation to improve device durability and reliability.

Void Formation and Radiation‐Induced Ion Migration in Perovskite Solar Cells under 10 MeV Proton Radiation

Perovskite solar cell (PSC) technology is a promising candidate for space applications because of its high power‐to‐weight ratio, low‐cost fabrication process, and good tolerance to high‐energy particle radiation. In this work, perovskite films and resultant high‐efficiency PSCs are assessed under 10 MeV proton radiation at fluences in the range 1e12–1e14 p cm−2, which are equivalent to 1 to 100 years in geostationary orbit (GEO) without any shielding or cover. For the first time, void formation and material ablation are detected on perovskite films, indicating structural damage of the materials under the proton radiation. Furthermore, ions inside the devices especially Au and Pb ions are displaced to underlying layers under the proton bombardment. These lead to the degradation of PSCs to ≈89% of the initial performance (from 24.1% to 21.4%) at the highest dose. The experimental results are supported by previous simulation works with a good fit in all optoelectronic parameters. This study provides insights into the degradation mechanism of PSCs under proton radiation and paves the way for the utilization of PSCs in space applications.

Conceptional design of an adjustable moderator for BNCT based on a neutron source of 2.8 MeV proton bombarding with Li target

Beam shaping assembly (BSA) is a vital component in Boron Neutron Capture Therapy (BNCT) for obtaining epithermal neutron beams. Several feasible designs of BSA for accelerator-based BNCT (AB-BNCT) neutron source are carried out based on neutrons by bombarding a natural lithium target with 10 mA, 2.8 MeV proton beams. The calculation results demonstrate that a thickness of 45 cm is appropriate for general moderators referring to the therapeutic parameter of Advanced Depth (AD). A series of optimizations are performed and two results are confirmed: One is that employing the configuration of MgF2 and FLUENTAL combined by 1:1 could improve the therapeutic rate (TR) of tumors at a depth of middle region, and the other one is that the TR of superficial tumors can be increased by adding a 5 cm thick boron-11 secondary moderator at the end of general moderators. As a result, an innovative conception of an adjustable moderator is recommended to BNCT. Compared to the MgF2 moderator with a fixed thickness of 45 cm, the TR value can be improved by a maximum of 47.7 % by using the adjustable moderator. Furthermore, the configuration of adjustable moderator has been designed with regulation method for treating tumors of different depths.

Effect of proton irradiation on the cathodoluminescence of gallium nitride films

In this work, we studied the effect of 350 keV proton irradiation with two different fluences of 1013 cm−2 and 1015 cm−2 on the cathodoluminescence (CL) spectrum of GaN. Three lines were observed in the CL spectra of virgin and proton pre-irradiated samples - band edge line (3.4 eV), blue line (2.8 eV) and yellow line (2.15 eV). A strong decrease in the CL intensity for samples pre-irradiated by protons, especially at high proton fluence of 1015 cm−2, is shown. The evolution of the cathodoluminescence spectra during electron irradiation demonstrates a further decrease in all line intensities. It was shown that virgin and proton pre-irradiated GaN samples were not charged under electron irradiation. The cathodoluminescence signal drop can be caused by a decrease in the concentration of initial luminescence centers associated with intrinsic and impurity defects due to their transformation under proton bombardment and electron-stimulated diffusion implanted H+ ions.

A Laboratory Setup for Increasing the Technological Yield of 123I from a 124Xe Target under Proton Bombardment

A Laboratory Setup for Increasing the Technological Yield of 123I from a 124Xe Target under Proton Bombardment

P-309 - Development of Solid Target Technologies for 225Ac Production with Proton Bombardment

P-309 - Development of Solid Target Technologies for 225Ac Production with Proton Bombardment

Achieving stable photodiode characteristics under ionizing radiation with a self-adaptive nanostructured heterojunction CNWs/CdZnTe

This study proposed self-adaptive nanostructured heterojunction UV-VIS-NIR photodiodes carbon nanowalls (CNWs)/cadmium zinc telluride (CdZnTe) exhibiting stable photoelectric characteristics under ionizing radiation conditions. We carried out a comprehensive analysis of the impact of proton radiation with an energy of 1.5 MeV and a total fluence of 1012 protons/cm2 on the properties of CNWs and CdZnTe functional layers, as well as on the main photodiode characteristics of the CNWs/CdZnTe heterojunctions, employing a set of state-of-the-art materials and device characterization techniques. Responsivity and detectivity of the prepared heterojunctions even slightly improve after exposure to harsh ionizing radiation conditions due to the unique radiation-induced self-adaptive features of the CNWs/CdZnTe heterojunction interface. The characteristics of the CNWs/CdZnTe photodiodes before and after high-energy proton bombardment demonstrate excellent stability, which is the key requirement for long-term and reliable operation of optoelectronic devices in space or radioactively contaminated environments.

Excitation functions of proton-induced nuclear reactions on natCaCO3 up to 60 MeV

47Sc could be used in SPECT imaging and is also suitable for targeted therapy of small tumours. Application of 47Sc is quite promising as theranostic with its diagnostic pair 44Sc or 43Sc. Excitation functions for the production of 47Sc and its accompanying impurities through proton bombardment of natural calcium carbonate (natCaCO3) targets were experimentally evaluated and compared with both previous measurements and TALYS predictions. The integral production yields of 47Sc, as well as the main impurities 44m,46,48Sc, were calculated. The consistency of the results with available experimental data was verified for each reaction. The target yield was determined using the measured activity of the produced radionuclides.

Cyclotron production of 43Sc and 44gSc from enriched 42CaO, 43CaO, and 44CaO targets.

Introduction: 43Sc and 44gSc are both positron-emitting radioisotopes of scandium with suitable half-lives and favorable positron energies for clinical positron emission tomography (PET) imaging. Irradiation of isotopically enriched calcium targets has higher cross sections compared to titanium targets and higher radionuclidic purity and cross sections than natural calcium targets for reaction routes possible on small cyclotrons capable of accelerating protons and deuterons. Methods: In this work, we investigate the following production routes via proton and deuteron bombardment on CaCO3 and CaO target materials: 42Ca(d,n)43Sc, 43Ca(p,n)43Sc, 43Ca(d,n)44gSc, 44Ca(p,n)44gSc, and 44Ca(p,2n)43Sc. Radiochemical isolation of the produced radioscandium was performed with extraction chromatography using branched DGA resin and apparent molar activity was measured with the chelator DOTA. The imaging performance of 43Sc and 44gSc was compared with 18F, 68Ga, and 64Cu on two clinical PET/CT scanners. Discussion: The results of this work demonstrate that proton and deuteron bombardment of isotopically enriched CaO targets produce high yield and high radionuclidic purity 43Sc and 44gSc. Laboratory capabilities, circumstances, and budgets are likely to dictate which reaction route and radioisotope of scandium is chosen.

Neutron Generated during Proton Bombardment in Water Molecule

Neutron Generated during Proton Bombardment in Water Molecule

18F]Tosyl fluoride as a versatile [18F]fluoride source for the preparation of 18F-labeled radiopharmaceuticals

Positron emission tomography (PET) is an in vivo imaging technology that utilizes positron-emitting radioisotope-labeled compounds as PET radiotracers that are commonly used in clinic and in various research areas, including oncology, cardiology, and neurology. Fluorine-18 is the most widely used PET-radionuclide and commonly produced by proton bombardment of 18O-enriched water in a cyclotron. The [18F]fluoride thus obtained generally requires processing by azeotropic drying in order to completely remove H2O before it can be used for nucleophilic radiofluorination. In general, the drying step is important in facilitating the radiofluorination reactions and the preparation of 18F-labeled PET radiotracers. In this communication, we have demonstrated the feasibility of using [18F]tosyl fluoride ([18F]TsF) as a versatile [18F]fluoride source for radiofluorination to bypass the azeotropic drying step, and we have developed a continuous flow solid-phase radiosynthesis strategy to generate [18F]TsF in a form that is excellent for radiofluorination. [18F]TsF shows high reactivity in radiofluorination and provides the features suitable for preparing PET radiotracers on a small scale and exploring novel radiolabeling technologies. Thus, using [18F]TsF as a [18F]fluoride source is a promising strategy that facilitates radiofluorination and provides a convenient and efficient solution for the preparation of 18F-labeled radiopharmaceuticals that is well matched to the emerging trends in PET imaging technologies.

Shielding Assessment and Optimization of the Target Station for Medical Isotope Production Based on Superconducting Proton Linac

In response to the worldwide shortage of 99mTc supply caused by the combined consequence from both decommissioning and maintenance of research reactors worldwide, the Institute of Modern Physics (IMP) of the Chinese Academy of Science and Lanzhou University have launched a collaboration to research and develop a 99mTc production solution based on the 25 MeV high-intensity superconducting proton linear accelerator. Radiation from high-current proton bombardment must be evaluated and considered carefully at the design stage to meet radiation protection (RP) policy and requirements of the shielding for the key device. This work employed FLUKA to conduct the shielding assessment of both prompt and residual radiation fields in several iterations, based on a prototype of the high-power target system. The prompt dose rates outside the target station are lower than the institution’s limit. The residual dose rates inside the station fall below 100 μSv/h at 64 h after the end of beam (EOB); the dominant source term is then the target chamber. The service life of the main actuator is expected to be extended by 2.7 times with the current partial shielding design. The simulation accelerating techniques are applied to balance the accuracy of results and the progress of the project at the same time, which is referential to the shielding assessment of large-scale nuclear facilities. The results can also be used in further study and construction of the target station.

The decay of the 21.47-MeV stretched resonance in 13C: A precise probe of the open nuclear quantum system description

The decay of the 21.47-MeV stretched resonance in 13C, arising from p3/2→d5/2 nucleon excitation coupled to maximum spin, was investigated in a (p,p′) experiment at 135 MeV proton bombarding energy, performed at the Cyclotron Centre Bronowice (CCB) at IFJ PAN in Krakow. First experimental information on the proton and neutron decay branches from this state was obtained by using coincidence measurement of protons inelastically scattered on a 13C target and γ rays from daughter nuclei, namely, 12B (proton decay) and 12C (neutron decay). The main branches lead to the Jπ=2+, first-excited state at 0.953 MeV in 12B, and to the Jπ=1+, T=1 level at 15.110 MeV in 12C. The results were compared with predictions from the Gamow Shell Model (GSM), which was used to describe the stretched resonance in terms of its energy, width, electromagnetic transition strengths and decay pattern. A very good agreement was obtained between the measured and calculated properties of the 21.47-MeV stretched resonance in 13C, demonstrating the high-quality and precision of the GSM wave function calculations, which include coupling to the resonant and non-resonant particle continuum.

Characteristics of neutron production and concrete activation in cyclotron vaults for self-shielded and non-self-shielded facilities

Currently, 13 radioisotope production cyclotrons with proton energies of 9.6–30 MeV exist in Taiwan. Seven of these cyclotrons have self-shielding designs, and the remaining six cyclotrons are non-self-shielded types. The following (p,xn) nuclear reactions with various targets are involved in their operations: 18O(p,n)18F, 68Zn(p,n)68Ga, 68Zn(p,2n)67Ga, 69Ga(p,2n)68Ge, 100Mo(p,pn)99Mo, 100Mo(p,2n)99mTc, 89Y(p,n)89Zr, 112Cd(p,2n)111In, 203Tl(p,3n)201Pb, 124Xe(p,2n)123Cs, and 15N(p,n)15O. The secondary neutrons accompanying these reactions can induce material activation in the cyclotron components and shield structure to varying degrees. By using the FLUKA Monte Carlo code, the characteristics of neutron yields and the resulting spatial and energy distributions of neutrons in cyclotron vaults were evaluated for various targets in proton bombardment. A systematic assessment of residual long-lived radioactivity in forward and lateral concrete walls was conducted. The result for the 18O(p,n)18F reaction with 18-MeV protons was used as a reference for comparisons of the concrete activation induced by neutrons generated through various production routes. The similarities and differences in activation results for the self-shielded and non-self-shielded cyclotrons are presented and discussed.

THE STUDIES OF THE EXCITATION FUNCTIONS OF REACTIONS WITH EMISSION OF γ - QUANTA INDUCED BY PROTONS WITH ENERGY 200…1800 keV ON NUCLEI OF 10B AND 11B

A systematic study of the relative thick-target yields of prompt γ-rays with the energies of the most suitable for elemental and isotopic analysis for stable boron isotopes following proton bombardment has been carried out at Ep = 200…1800 кeV. The relevant excitation function of γ-emission 429 keV from reaction 10B(p,αγ)7Be, 718 keV from reaction 10B(p,p'γ)10B, 4.439 and 16.106 MeV from reaction 11B(p,γ)12C are depicted and a tables of yields of prompt γ-rays as function of proton bombardment energy are given. The experimental procedure is described. Particular aspects of the measuring techniques are discussed.

Experimental determination of atomic alignment of Mo42, Cd48 , and In49 with differential x-ray intensity ratios by 100–250-keV proton impact

This work aims to study the alignment properties of electron vacancies produced by proton bombardment in the low-energy region from 100 to 250 keV. The alignment parameter ${\mathcal{A}}_{20}$ of $_{42}\mathrm{Mo}, _{48}\mathrm{Cd}$, and $_{49}\mathrm{In}$ ions after ${L}_{3}$ subshell ionization has been investigated experimentally. The typical $L$ x-ray spectra are measured for each target at emission angles from ${115}^{\ensuremath{\circ}}$ to ${155}^{\ensuremath{\circ}}$. The angular dependence of differential intensity ratios ${L}_{\ensuremath{\alpha}}/{L}_{\ensuremath{\beta}1}$ and ${L}_{\ensuremath{\beta}2}/{L}_{\ensuremath{\beta}1}$ is studied as a function of the second-order Legendre polynomial ${P}_{2}(\mathrm{cos}\ensuremath{\theta}$). Our result demonstrates that ${L}_{\ensuremath{\alpha}}$ and ${L}_{\ensuremath{\beta}2}$ lines exhibit anisotropic emission spatially. The anisotropy parameter is converted to the alignment parameter by considering the Coster-Kronig (CK) correction coefficient and anisotropy coefficient. The results are compared with theoretical prediction within the framework of the semiclassical theory of inner-shell ionization, and good agreement is found in general. A small discrepancy around the inflection point of the alignment parameter is attributed to the atomic parameters employed only for single ionization in the CK correction coefficient.

NMB-2 - Production and characterization of high purity radioscandium isotopes, 43,47Sc, of clinical interest from proton bombardment on enriched [46,50Ti]TiO2 targets

NMB-2 - Production and characterization of high purity radioscandium isotopes, 43,47Sc, of clinical interest from proton bombardment on enriched [46,50Ti]TiO2 targets

45Ti targeted tracers for PET imaging of PSMA

PurposePositron Emission Tomography is an important molecular imaging technique for detection and diagnoses of various disease states. This work aims to develop novel titanium-45 (t½ = 3.08 h) PET tracers using Prostate Specific Membrane Antigen (PSMA) targeting vectors for imaging of prostate cancer as proof of concept for this relatively unexplored isotope. ProceduresTitanium-45 was produced on the University of Alabama at Birmingham (UAB) TR24 cyclotron using proton bombardments on natural scandium foils and separated using procedures described previously [1]. After purification, Titanium-45 was used to radiolabel two PSMA-targeting molecules; DFO-DUPA and LDFC-DUPA. Radiochemical yields were determined via radio-high purity liquid chromatography (radioHPLC). The radiolabeled compounds were tested both in vitro and in vivo using PSMA+ cell lines (LNCaP and 22Rv1) and PSMA− cell lines (PC3). ResultsTitanium-45 was produced and purified in yields suitable for research studies. Radiochemical yields of up to 98 ± 1% were achieved with DFO-DUPA and 92 ± 7% with LDFC-DUPA. PSMA specific targeting was observed in vitro in PSMA positive cells (LNCaP (0.6% ± 0.05%) and confirmed by blocking (0.15% ± 0.04%) (P < 0.0001)), compared to uptake in the PSMA negative cells (PC3 (0.07% ± 0.008%)) and confirmed by blocking (0.07% ± 0.01%) (P = 0.5253). In vivo studies demonstrated statistically significant uptake in LNCaP tumors (2.3% ± 0.3% ID/g) compared to PC3 tumor uptake (0.1% ± 0.07%). ConclusionsThis work shows that titanium-45 can be used to radiolabel PSMA targeting compounds with high radiochemical yields. These radiolabeled compounds remain intact in serum for at least two half-lives of titanium-45, showing that these compounds would be appropriate for implementation in the clinical setting. This study shows the feasibility of using titanium-45 as positron emitting radiometal for use in imaging PSMA+ prostate cancer, and illustrates that further research is in this area is warranted.

Effect of low energy proton and He particle irradiation on CsPbBr3 material

In this paper, the effect of proton and He particle bombardment in CsPbBr3 material was investigated by the Monte Carlo simulation including ion range, backscattering, vacancies and sputtering yield. The energies of proton and He particle varied from 50 keV to 180 keV and the particle incidence angles increased from 0o to 89.9o . The calculated results showed that with the increase of incidence energies, the range and vacancies increased, and the backscattering ions and sputtering yield reduced for proton and He particle. Meanwhile, the vacancies, backscattering ions and sputtering yield induced by He particle were much more proton at the same energy. With the increase of incidence angles, the range and vacancies were reduced, and the sputtering yield increased for proton and He particle. Also, it is obvious that the effects of He particle on CsPbBr3 material were much more serious than proton.