Quantum Beam Science

12 pages, 2579 KiB

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

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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 KiB

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

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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 KiB

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

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

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