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Quantum Beam Sci., Volume 9, Issue 3 (September 2025) – 6 articles

Cover Story (view full-size image): For the first time, a mixture of lead telluride and lead/tellurium oxides produced by high-energy milling is used as a precursor to form various PbTe structures under electron beam irradiation (EBI). When conditions favor rapid transformation, the high internal energy of the multiphase mixture allows EBI to trigger immediate physical and chemical changes. These changes lower the Gibbs free energy barrier, enabling the formation of PbTe quantum dots, nanocrystals, nanoparticles, and grain-like structures with a sintered appearance, along with a small amount of non-stoichiometric phases. Post-irradiation imaging reveals morphological changes in PbTe, demonstrating its potential for thermoelectric applications due to their crystallinity and nanostructured features. View this paper

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11 pages, 758 KB

Open AccessFeature PaperArticle

Measurement of the ³³S(n,α)³⁰Si Thermal Cross-Section with Slow Neutrons at ILL

by Javier Praena, Begoña Fernández, Miguel Macías, Ignacio Porras, María Pedrosa-Rivera, Hanna Koivunoro, Marta Sabaté-Gilarte and Fernando Arias de Saavedra

Quantum Beam Sci. 2025, 9(3), 27; https://doi.org/10.3390/qubs9030027 - 22 Sep 2025

Viewed by 203

Abstract

This work is focused on an accurate experimental determination of the thermal ³³S(n,

α

)³⁰Si cross-section. This cross-section is a critical parameter for the potential use of ³³S as a cooperative target in boron neutron capture therapy [...] Read more.

This work is focused on an accurate experimental determination of the thermal ³³S(n,

α

)³⁰Si cross-section. This cross-section is a critical parameter for the potential use of ³³S as a cooperative target in boron neutron capture therapy or to understand its role in the stellar nucleosynthesis of ³⁶S. At present, there are large discrepancies in this experimental value; therefore, in this work we measured it relative to the ¹⁰B(n,

α

)⁷Li standard cross-section at the high flux reactor of the Institut Laue-Langevin. The experimental setup was based on a double-sided silicon strip detector. Two ³³S samples were used. One ¹⁰B sample was used as reference. Particular attention was taken to the characterization of the mass thickness of the samples before and after the experiment because of the high volatility of ³³S. Such work was already published in a dedicated paper. A cross-check of the ¹⁰B sample was carried out with the neutron flux monitor at the n_TOF-CERN facility. The obtained cross-section of (280 ± 33) mb is significantly higher than the existing data. Full article

(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2025)

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20 pages, 4666 KB

Open AccessFeature PaperArticle

Strain and Electric Field Engineering for Enhanced Thermoelectric Performance in Monolayer MoS₂: A First-Principles Investigation

by Li Sun, Ensi Cao, Wentao Hao, Bing Sun, Lingling Yang and Dongwei Ao

Quantum Beam Sci. 2025, 9(3), 26; https://doi.org/10.3390/qubs9030026 - 18 Aug 2025

Viewed by 617

Abstract

Optimizing thermoelectric (TE) performance in two-dimensional materials has emerged as a pivotal strategy for sustainable energy conversion. This study systematically investigates the regulatory mechanisms of uniaxial strain (−2% to +2%), temperature (300–800 K), and out-of-plane electric fields (0–1.20 eV/Å) on the thermoelectric properties of monolayer MoS₂ via first-principles calculations combined with Boltzmann transport theory. Key findings reveal that uniaxial strain modulates the bandgap (1.56–1.86 eV) and carrier transport, balancing the trade-off between the Seebeck coefficient and electrical conductivity. Temperature elevation enhances carrier thermal excitation, boosting the power factor to 28 × 10¹⁰ W·m⁻¹·K⁻²·s⁻¹ for p-type behavior and 27 × 10¹⁰ W·m⁻¹·K⁻²·s⁻¹ for n-type behavior at 800 K. The breakthrough lies in the exceptional suppression of lattice thermal conductivity (κ₁) by out-of-plane electric fields—at 1.13 eV/Å, κ₁ is reduced to single-digit values (W·m⁻¹·K⁻¹), driving ZT to ~4 for n-type MoS₂ at 300 K. This work demonstrates that synergistic engineering of strain, temperature, and electric fields effectively decouples the traditional trade-off among the Seebeck coefficient, conductivity, and thermal conductivity, providing a core optimization pathway for 2D thermoelectric materials via electric field-mediated κ₁ regulation. Full article

(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2025)

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14 pages, 12986 KB

Open AccessArticle

Validation of an EGSnrc Monte Carlo Model of a 10 MV Photon Beam for Varian Clinac iX Linac, Including Flattening and Flattening-Free Modes

by Wafa M. Al-Saleh

Quantum Beam Sci. 2025, 9(3), 25; https://doi.org/10.3390/qubs9030025 - 14 Aug 2025

Viewed by 409

Abstract

Modelling of linear accelerators using the Monte Carlo method is critical for precise radiotherapy planning. In addition, detailed and accurate dose estimation to the organ at risk can be assessed and optimized. In this study, EGSnrc Monte Carlo code was utilized to model, tune, and validate a 10 MV photon head model of a Varian Clinac iX linear accelerator for different field sizes, including flattening and flattening-free modes. Gamma analysis was utilized to compare the model with measured data to determine the best parameters for the incident electron on the target. The main results revealed that, for both flattening and flattening-free modes, the incident electron’s optimal energy is 9.5 MeV, with a 0.1 cm circular full width half maximum (FWHM) and a 0.07° angular divergence. The model is suitable for field sizes extending from 1 × 1 to 30 × 30 cm². The comparison of large field sizes, which includes both 20 × 20 and 30 × 30 cm², reflects the accuracy of the geometrical model of the flattening filter. Altering the FWHM has a notable effect on the profile, particularly in the penumbral region, although adjusting the angular divergence has little effect. The dose rate for the flattening filter-free beam compared to the flattening filter beam increased by a factor of four. The validated model demonstrates excellent agreement with measured data. Thus, it can provide accurate dose calculations and can be used in future studies to test treatment accuracy and patient safety, especially for advanced radiotherapy techniques. Full article

(This article belongs to the Section Medical and Biological Applications)

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12 pages, 2579 KB

Open AccessArticle

Fast Transformation of PbTe Using a Multiphase Mixture of Precursors: First Insights

by Hugo Rojas-Chávez, Nina Daneu, Manuel A. Valdés-Madrigal, Guillermo Carbajal-Franco, Marcela Achimovičová and José M. Juárez-García

Quantum Beam Sci. 2025, 9(3), 24; https://doi.org/10.3390/qubs9030024 - 11 Jul 2025

Viewed by 589

Abstract

For the first time, a mixture of PbTe and Pb- and Te-oxides coated with carbon, under electron beam irradiation (EBI), was transformed into quantum dots, nanocrystals, nanoparticles and grains of PbTe with a sintered appearance. A small portion of non-stoichiometric phases was also obtained. By selecting conditions that favor the instantaneous transformation, the Gibbs free energy barrier is lowered for obtaining different PbTe structures. The driving force associated with the high-energy milling requires 4 h of processing time to reach a complete transformation, while a high-energy source kinetically affects precursor surfaces to cause an abrupt global chemical transformation instantly. Importantly, the size of the PbTe structures increases as they approach the irradiation point, implying a growth process that is affected by the local temperature reached during the EBI. Imaging after the EBI process revealed morphological variations in PbTe, which can be attractive for use in thermoelectric materials. The results of this study provide the first insights into electron-beam-induced reactions using a multiphase mixture of precursors. Therefore, it is believed that this proposal can also be applied to obtain other binary semiconductor structures, even ternary ones. Full article

(This article belongs to the Special Issue New Challenges in Electron Beams)

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10 pages, 1130 KB

Open AccessFeature PaperArticle

DNA Damage Induced by Fast Neutron and Gamma Rays Evaluated Using qPCR

by Youichirou Matuo, Miyabi Yanami, Shingo Tamaki, Yoko Akiyama, Yoshinobu Izumi, Fuminobu Sato, Isao Murata and Kikuo Shimizu

Quantum Beam Sci. 2025, 9(3), 23; https://doi.org/10.3390/qubs9030023 - 7 Jul 2025

Viewed by 462

Abstract

We developed a novel dosimetric method using DNA molecules as a radiation sensor. The amount of neutron or gamma rays irradiated DNA damage was determined by evaluating the amount of DNA serving as a template for qPCR. The absorbed doses in the samples were estimated using the tally of the “t-product” in the data from the PHITS Monte Carlo particle transport simulation code. The neutron fluence for each sample was measured using the niobium activation reaction ⁹³Nb (n, 2n) ^92mNb, and the absorbed dose per neutron fluence was estimated to be 7.1 × 10⁻¹¹ Gy/(n/cm²). Based on the PHITS modeling, the effects of neutron beams are attributed to the combination of proton and alpha particle beams. The results from qPCR showed that neutrons caused more DNA damage than gamma rays. The qPCR method demonstrated that neutron irradiation caused 1.13-fold more DNA damage compared to gamma ray irradiation; however, this result did not show a statistically significant difference. This method we developed, using DNA molecules as a radiation sensor, may be useful for biodosimetry. Full article

(This article belongs to the Section Medical and Biological Applications)

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10 pages, 2216 KB

Open AccessArticle

A Solid-State Three-Stage Nd:YVO₄ Laser Amplifier System Based on AOM Pulse Picker-Integrated Modulator

by Zhenyu Li, Yawen Zheng, Zhengtao Zhang, Peipei Lu, Zhen Zeng, Zhongsheng Zhai and Boya Xie

Quantum Beam Sci. 2025, 9(3), 22; https://doi.org/10.3390/qubs9030022 - 1 Jul 2025

Viewed by 651

Abstract

In recent years, ultrafast bursts with high power have been applied in many significant fields. However, the peak power of the pulse train generated by fiber lasers is limited by fiber characteristics from nonlinear effects, which can only be at the level of milliwatt. In this research, the pulse frequency is reduced by an AOM pulse picker-integrated modulator. With M2 and pulse width guaranteed, the frequency of the reduced pulse train is amplified by a solid-state three-stage Nd:YVO₄ amplifier system. Finally, the peak power of the pulse train is increased. The final output pulse repetition rate of the experiment is 1 MHz with a pulse width of 8.09 picoseconds and a peak power of up to 3.7 MW. Full article

(This article belongs to the Section High-Power Laser Physics)

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