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Spectral, Angular and Polarizing Properties of Semiconductor Photodiodes Covering the Near-Infrared to Soft X-Ray Range

Journal Description

Quantum Beam Science

Quantum Beam Science is an international, peer-reviewed, open access journal on research derived from beam line facilities and related techniques published quarterly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, ESCI (Web of Science), CAPlus / SciFinder, Inspec, Astrophysics Data System, and other databases.
Journal Rank: CiteScore - Q2 (Nuclear and High Energy Physics)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 31.8 days after submission; acceptance to publication is undertaken in 6.7 days (median values for papers published in this journal in the second half of 2025).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Journal Cluster of Atomic, Molecular, and Optical (AMO) Physics: Entropy, Photonics, Atoms, Lights, Optics, Plasma, Physics, Quantum Beam Science and Lasers.

Impact Factor: 1.7 (2024); 5-Year Impact Factor: 1.5 (2024)

Imprint Information Journal Flyer Open Access ISSN: 2412-382X

Latest Articles

21 pages, 74312 KB

Open AccessArticle

Investigation of Spark-Plasma Erosion-Based Micro-Hole Drilling of SS316L and Ti-6AL-4V for Precision Biomedical Applications

by Pallab Sarmah, Promod Kumar Patowari and Kapil Gupta

Quantum Beam Sci. 2026, 10(2), 11; https://doi.org/10.3390/qubs10020011 - 5 May 2026

This research investigated the performance of spark-plasma erosion-based machining, also known as electrical discharge machining, for micro-hole drilling in SS316L and Ti-6Al-4V under various spark-plasma formation conditions, with 27 experimental combinations of capacitance, voltage, and electrode feed rate. Spark-plasma conditions at various discharge [...] Read more.

This research investigated the performance of spark-plasma erosion-based machining, also known as electrical discharge machining, for micro-hole drilling in SS316L and Ti-6Al-4V under various spark-plasma formation conditions, with 27 experimental combinations of capacitance, voltage, and electrode feed rate. Spark-plasma conditions at various discharge energies were found to play a major role in influencing machining time and overcut, which were considered two responses to evaluate machining performance. Increasing the voltage from 80 to 180 V at 100 pF decreased machining time from 2553 s to 564 s for SS316L and from 2608.2 s to 570.6 s for Ti-6Al-4V, but it increased overcut from 6 to 17.5 µm and from 8 to 22 µm, respectively. At 10,000 pF and 180 V, machining times of 51.6 s (SS316L) and 62.4 s (Ti-6Al-4V) were obtained, with maximum overcut values of 62.5 µm and 73.5 µm, respectively. Analysis of variance revealed that voltage strongly controlled machining time (~64%), while capacitance dominated overcut (64–69%). Ti-6Al-4V required 5–20% more machining time and exhibited a higher overcut due to its lower thermal conductivity and higher strength. The experimental observations indicated consistent plasma formation and favorable spark to achieve the required geometric accuracy and process productivity for the fabrication of high-quality biomedical components from SS316L and Ti-6Al-4V. Full article

(This article belongs to the Section Engineering and Structural Materials)

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20 pages, 6734 KB

Open AccessArticle

Time-Scale Mismatch as a Fundamental Constraint in Quantum Beam–Matter Interactions

by Abbas Alshehabi

Quantum Beam Sci. 2026, 10(2), 10; https://doi.org/10.3390/qubs10020010 - 8 Apr 2026

Quantum beams-including X-rays, synchrotron radiation, electrons, neutrons, ions, and ultrafast photon sources-are indispensable tools for probing the structure, dynamics, and electronic properties of matter. The excitation time scale

τ_{e x c}

is defined operationally as the characteristic temporal interval governing externally imposed [...] Read more.

Quantum beams-including X-rays, synchrotron radiation, electrons, neutrons, ions, and ultrafast photon sources-are indispensable tools for probing the structure, dynamics, and electronic properties of matter. The excitation time scale

τ_{e x c}

is defined operationally as the characteristic temporal interval governing externally imposed energy deposition events within the interaction volume, such as pulse duration, bunch spacing, or beam dwell time. Interpretation of beam–matter interactions has traditionally relied on steady-state or quasi-equilibrium assumptions, implicitly presuming that intrinsic material relaxation processes can accommodate externally imposed excitation. Recent advances in high-brightness synchrotron sources, X-ray free-electron lasers (XFELs), and pulsed electron beams increasingly operate in regimes where this assumption is strained, and systematic nonequilibrium effects, radiation damage, and irreversible transformations are reported even under routine experimental conditions. This work examines the role of time-scale mismatch between beam-driven energy deposition and intrinsic material relaxation as a governing constraint in beam–matter interactions. Analyzing the hierarchy of excitation, electronic relaxation, phonon coupling, and thermal diffusion time scales, the analysis introduces a dimensionless mismatch parameter

Λ = \frac{τ_{r e l}}{τ_{e x c}}

, which quantifies the competition between externally imposed excitation and intrinsic relaxation processes in beam–matter interactions. The resulting framework provides a unified physical interpretation of beam-induced damage, signal distortion, dose dependence, and nonlinear response across quantum beam modalities, framing these effects as consequences of forced nonequilibrium dynamics rather than technique-specific artifacts. Full article

(This article belongs to the Section Radiation Scattering Fundamentals and Theory)

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25 pages, 6783 KB

Open AccessArticle

Spectral, Angular and Polarizing Properties of Semiconductor Photodiodes Covering the Near-Infrared to Soft X-Ray Range

by Terubumi Saito

Quantum Beam Sci. 2026, 10(2), 9; https://doi.org/10.3390/qubs10020009 - 3 Apr 2026

Some windowless semiconductor photodiodes can detect not only photons but also charged particles, cover a wide spectral range including a part of the ionizing radiation region and, thus, play important roles for synchrotron radiation experiments. To understand the spectral, angular and polarizing properties [...] Read more.

Some windowless semiconductor photodiodes can detect not only photons but also charged particles, cover a wide spectral range including a part of the ionizing radiation region and, thus, play important roles for synchrotron radiation experiments. To understand the spectral, angular and polarizing properties of semiconductor photodiodes, complex amplitude coefficients of transmittance or reflectance are calculated based on rigorous formulation using Fresnel equations with complex optical constants of the composing materials, whose validity was verified by comparison with experiments. Concrete examples of the behavior on the complex plane are shown as a function of complex optical constants, film thickness, angle of incidence and the wavelength. The results show that the optical properties of the layered system are sensitive to its layer thickness, the angle of incidence and the wavelength in the ultraviolet region where optical indices of the composing materials steeply change. It has been shown that oblique incidence photodiodes are useful as polarization-sensitive devices, and that the graphical technique using the amplitude coefficients expressed on the complex plane is effective and powerful to search for optimal conditions for complex optical constants, film thickness and/or angle of incidence. Full article

(This article belongs to the Special Issue Quantum Beam and Its Applications for Quantum Technologies)

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13 pages, 347 KB

Open AccessFeature PaperArticle

Vorticity of Twisted Electron Fields: Role of the Energy–Momentum Tensor

by Andrei Afanasev, Carl E. Carlson and Asmita Mukherjee

Quantum Beam Sci. 2026, 10(2), 8; https://doi.org/10.3390/qubs10020008 - 25 Mar 2026

Electron fields (and more generally spinor fields) with a vortex structure in free space that allows them to have arbitrary integer orbital angular momentum along the direction of motion have been studied for some time. We point out that there are several ways [...] Read more.

Electron fields (and more generally spinor fields) with a vortex structure in free space that allows them to have arbitrary integer orbital angular momentum along the direction of motion have been studied for some time. We point out that there are several ways to calculate the local velocity of the electron field, defined as the ratio of momentum density to energy density, and that all but one show a singular vorticity at the vortex line. That one, using the Dirac bilinear current with no derivatives, is the only one so far (to our knowledge) studied in the literature in this context and we further show how to understand an apparent conflict in the existing results. The momentum densities corresponding to the three possible velocity fields give different physical results, in particular regarding the electron induced quantum superkicks given to small electron-absorbing test objects. Full article

(This article belongs to the Section Radiation Scattering Fundamentals and Theory)

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Graphical abstract

20 pages, 236653 KB

Open AccessArticle

Periodic Noise Reduction in Neutron Imaging

by Shilin Wang, Tianhao Wang, Chao Zhou, Sen Yang and Xin Tong

Quantum Beam Sci. 2026, 10(1), 7; https://doi.org/10.3390/qubs10010007 - 2 Mar 2026

Periodic structures that may exist within the neutron imaging detector can introduce periodic noise into the imaging results, directly degrading image quality and further affecting the performance of deconvolution. This periodic noise appears as four-pointed star-shaped peaks in the amplitude spectrum of the [...] Read more.

Periodic structures that may exist within the neutron imaging detector can introduce periodic noise into the imaging results, directly degrading image quality and further affecting the performance of deconvolution. This periodic noise appears as four-pointed star-shaped peaks in the amplitude spectrum of the frequency domain. However, the distribution of honeycomb-like noise structures in neutron imaging results makes it difficult to detect using conventional thresholding methods. We propose a method that applies a dilation operation before threshold detection to enhance the contrast between peaks and the surrounding areas. Then, a notch filter is used to smooth the peaks containing noise information, thereby removing the periodic noise structure. This approach effectively eliminates honeycomb structures of approximately 40 micrometers and improves the image quality after deconvolution processing. Full article

(This article belongs to the Section Spectroscopy Technique)

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21 pages, 2223 KB

Open AccessFeature PaperArticle

Simulating Neutron Diffraction from Deformed Mosaic Crystals in McStas

by Daniel Lomholt Christensen, Sandra Cabeza, Thilo Pirling, Kim Lefmann and Jan Šaroun

Quantum Beam Sci. 2026, 10(1), 6; https://doi.org/10.3390/qubs10010006 - 4 Feb 2026

Monochromator and analyzer systems that rely on bent single crystals are in use throughout the neutron scattering community. An adequate component for the simulation of such crystals was missing in the widely used neutron simulation software package McStas. The newly developed component Monochromator_bent [...] Read more.

Monochromator and analyzer systems that rely on bent single crystals are in use throughout the neutron scattering community. An adequate component for the simulation of such crystals was missing in the widely used neutron simulation software package McStas. The newly developed component Monochromator_bent, which fills this gap, is introduced. It can serve as a model for crystal monochromators and analyzers of various kinds, including the bent perfect crystals, mosaic crystals, and crystals combining mosaicity with bending. The performance of the component is tested at several configurations and compared with the results of another simulation program, SIMRES. Validation is carried out using analytical calculations and the McStas NCrystal_sample component for the case of unbent crystals. Excellent agreement in all tests and good performance in terms of computing speed has been found. The component has been included in the present distribution of McStas 3.5. Full article

(This article belongs to the Section Instrumentation and Facilities)

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17 pages, 3608 KB

Open AccessReview

Optimized Neutronics Designs of the Indonesian Experimental Power Reactor/RDE (Comprehensive Review and Future Challenges)

by Peng Hong Liem

Quantum Beam Sci. 2026, 10(1), 5; https://doi.org/10.3390/qubs10010005 - 2 Feb 2026

In this paper, several optimized design results of the HTGR-based 10 MWth Reaktor Daya Eksperimental (RDE) (Experimental Power Reactor), so far conducted, are reviewed and compared from the neutronics, reactor types, refueling schemes, and fuel cycle points of view. The review covers the [...] Read more.

In this paper, several optimized design results of the HTGR-based 10 MWth Reaktor Daya Eksperimental (RDE) (Experimental Power Reactor), so far conducted, are reviewed and compared from the neutronics, reactor types, refueling schemes, and fuel cycle points of view. The review covers the multipass and once-through-then-out (OTTO) pebble-bed cores, as well as block/prismatic type cores with several fuel shuffling options. As for the fuel cycle, uranium and thorium fuels are considered. The fuel burnup performance and power distribution are evaluated and compared among other important design parameters. Reactor physics codes, nuclear data libraries, and calculation models and procedures used for the design and analysis are reviewed, and challenges for future improvements are discussed. Full article

(This article belongs to the Section Instrumentation and Facilities)

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10 pages, 5092 KB

Open AccessFeature PaperArticle

A Compact Heat Sink Compatible with a Ka-Band Gyro-TWT with Non-Superconducting Magnets

by Shaohang Ji, Boxin Dai, Zewei Wu, Wei Jiang, Xin Chen, Binyang Han, Jianwei Zhou, Qianqian Chen, Guo Liu, Yelei Yao, Jianxun Wang and Yong Luo

Quantum Beam Sci. 2026, 10(1), 4; https://doi.org/10.3390/qubs10010004 - 22 Jan 2026

This paper presents a thermal management solution for a Ka-band gyrotron traveling wave tube (gyro-TWT) with non-superconducting magnets. At present, the miniaturization and non-superconductivity of gyro-TWT have become a trend, but miniaturization leads to a significant increase in power density and a severe [...] Read more.

This paper presents a thermal management solution for a Ka-band gyrotron traveling wave tube (gyro-TWT) with non-superconducting magnets. At present, the miniaturization and non-superconductivity of gyro-TWT have become a trend, but miniaturization leads to a significant increase in power density and a severe limitation in heat sink volume, which critically limits power capacity. To address this challenge, a joint microwave–thermal management evaluation model is used to investigate the heat transfer process and identify the crucial factors constraining the power capacity. A cylindrical heat sink with narrow rectangular grooves is introduced. Based on this, the cooling efficiency has been enhanced through structural optimization. The beam–wave interaction, electrothermal conversion, and heat conduction processes of the interaction circuit are analyzed. The compact heat sink achieves a 1.2-fold increase in coolant utilization and reduces the overall volume by 27.4%. Meanwhile, this heat sink improves the cooling performance and power capability of the gyro-TWT effectively. At 29 GHz, the gyro-TWT achieves a pulse power of 150 kW. Simulation results show that the maximum temperature is 348 °C at a 45% duty cycle, reduced by 159 °C. The power capacity of the Ka-band gyro-TWT increases by 40.6%. Full article

(This article belongs to the Section Radiation Scattering Fundamentals and Theory)

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22 pages, 1849 KB

Open AccessReview

Key Considerations for Treatment Planning System Development in Electron and Proton FLASH Radiotherapy

by Chang Cheng, Gaolong Zhang, Nan Li, Xinyu Hu, Zhen Huang, Xiaoyu Xu, Shouping Xu and Weiwei Qu

Quantum Beam Sci. 2026, 10(1), 3; https://doi.org/10.3390/qubs10010003 - 8 Jan 2026

The global cancer burden continues to increase worldwide. Among the various treatment options, radiotherapy (RT), which employs high-energy ionizing radiation to destroy cancer cells, is one of the primary modalities for cancer. However, increasing the absorbed dose to the target volume also increases [...] Read more.

The global cancer burden continues to increase worldwide. Among the various treatment options, radiotherapy (RT), which employs high-energy ionizing radiation to destroy cancer cells, is one of the primary modalities for cancer. However, increasing the absorbed dose to the target volume also increases the risk of damage to surrounding healthy tissues. This radiation-induced toxicity to normal tissues limits the desirable dosage that can be delivered to the tumor, thereby constraining the effectiveness of radiation therapy in achieving tumor control. FLASH radiotherapy (FLASH-RT) has emerged as a promising technique due to its biological advantages. FLASH-RT involves the delivery of radiation at an ultra-high dose rate (≥40 Gy/s). Unlike conventional RT, FLASH-RT achieves comparable tumor control rates while significantly reducing damage to surrounding normal tissues, a phenomenon known as the FLASH effect. Although the mechanism behind the FLASH effect is not fully understood, this approach shows considerable promise for future cancer treatment. The development of specialized treatment planning systems (TPS) becomes imperative to facilitate the clinical implementation of FLASH-RT from experimental studies. These systems must account for the unique characteristics of FLASH-RT, including ultra-high dose rate delivery and its distinctive radiobiological effects. Critical reassessment and optimization of treatment planning protocols are essential to fully leverage the therapeutic potential of the FLASH effect. This review examines key considerations for the TPS development of electron and proton FLASH-RT, including electron and proton FLASH techniques, biological models, crucial beam parameters, and dosimetry, providing essential insights for optimizing TPS and advancing the clinical implementation of this promising therapeutic modality. Full article

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

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14 pages, 2516 KB

Open AccessArticle

Temperature and Fluence Dependence Investigation of the Defect Evolution Characteristics of GaN Single Crystals Under Radiation with Ion Beam-Induced Luminescence

by Xue Peng, Wenli Jiang, Ruotong Chang, Hongtao Hu, Shasha Lv, Xiao Ouyang and Menglin Qiu

Quantum Beam Sci. 2026, 10(1), 2; https://doi.org/10.3390/qubs10010002 - 4 Jan 2026

To investigate the in situ irradiation effects of gallium nitride at varying temperatures, we combined ion beam-induced luminescence spectroscopy with variable-temperature irradiation using a home-built IBIL system and a GIC4117 2 × 1.7 MV tandem accelerator. Unlike previous static studies—limited to post-irradiation or [...] Read more.

To investigate the in situ irradiation effects of gallium nitride at varying temperatures, we combined ion beam-induced luminescence spectroscopy with variable-temperature irradiation using a home-built IBIL system and a GIC4117 2 × 1.7 MV tandem accelerator. Unlike previous static studies—limited to post-irradiation or single-temperature luminescence—we in situ tracked dynamic luminescence changes throughout irradiation, directly capturing the real-time responses of luminescent centers to coupled temperature-dose variations—a rare capability in prior work. To clarify how irradiation and temperature affect the luminescent centers of GaN, we integrated density functional theory (DFT) calculations with literature analysis, then resolved the yellow luminescence band into three emission centers via Gaussian deconvolution: 1.78 eV associated with C/O impurities, 1.94 eV linked to VGa, and 2.2 eV corresponding to CN defects. Using a single-exponential decay model, we further quantified the temperature- and dose-dependent decay rates of these centers under dual-variable temperature and dose conditions. Experimental results show that low-temperature irradiation such as at 100 K suppresses the migration and recombination of V_Ga/C_N point defects, significantly enhancing the radiation tolerance of the 1.94 eV and 2.2 eV emission centers; meanwhile, it reduces non-radiative recombination center density, stabilizing free excitons and donor-bound excitons, thereby improving near-band-edge emission center resistance. Notably, the 1.94 eV emission center linked to gallium vacancies exhibits superior cryogenic radiation tolerance due to slower defect migration and more stable free exciton/donor-bound exciton states. Collectively, these findings reveal a synergistic regulation mechanism of temperature and radiation fluence on defect stability, addressing a key gap in static studies, providing a basis for understanding degradation mechanisms of gallium nitride-based devices under actual operating conditions (coexisting temperature fluctuations and continuous radiation), and offering theoretical/experimental support for optimizing radiation-hardened gallium nitride devices for extreme environments such as space or nuclear applications. Full article

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

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12 pages, 1690 KB

Open AccessArticle

Fast and Accurate Pixel Calibration of Tof Neutron Diffractometers with Machine Learning

by Albert P. Song and Ke An

Quantum Beam Sci. 2026, 10(1), 1; https://doi.org/10.3390/qubs10010001 - 25 Dec 2025

At a spallation neutron source, neutron pulses of varying energies are generated, and the detection of neutrons by instrument detectors is recorded as time-of-flight from the emission of the neutron pulse to its arrival at specific detector pixels with high time resolution. The [...] Read more.

At a spallation neutron source, neutron pulses of varying energies are generated, and the detection of neutrons by instrument detectors is recorded as time-of-flight from the emission of the neutron pulse to its arrival at specific detector pixels with high time resolution. The flight path of neutrons from the moderator to the sample and then to the detector must be precisely calibrated at the detector-pixel level using standard powders, so the neutron events from all pixels can be time-focused to produce high-resolution diffraction patterns. Modern time-of-flight neutron diffractometers at spallation neutron sources are equipped with two-dimensional detectors with millimeter-scale pixelations. The number of pixels in a diffraction instrument can reach millions, which makes a single-pixel-level calibration process time-consuming or even impossible with conventional refinement or fitting approaches. Here we present a machine-learning-aided calibration process using a train-and-predict approach, in which machine learning models are trained on the relationship between an individual pixel time-of-flight diffraction pattern and its diffraction constant. These models use a portion of the available pixels for training, and a good model then predicts the diffraction constants precisely and rapidly for large sets of pixel diffraction patterns. Full article

(This article belongs to the Section Instrumentation and Facilities)

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12 pages, 2152 KB

Open AccessFeature PaperArticle

A Compact Cryogenic Environment for In Situ Neutron Diffraction Under Mechanical Loading

by Dunji Yu, Yan Chen, Harley Skorpenske and Ke An

Quantum Beam Sci. 2025, 9(4), 36; https://doi.org/10.3390/qubs9040036 - 5 Dec 2025

Cited by 1

Understanding the deformation mechanisms of materials at cryogenic temperatures is crucial for cryogenic engineering applications. In situ neutron diffraction is a powerful technique for probing such mechanisms under cryogenic conditions. In this study, we present the development of a compact cryogenic environment (CCE) [...] Read more.

Understanding the deformation mechanisms of materials at cryogenic temperatures is crucial for cryogenic engineering applications. In situ neutron diffraction is a powerful technique for probing such mechanisms under cryogenic conditions. In this study, we present the development of a compact cryogenic environment (CCE) designed to facilitate in situ neutron diffraction experiments under mechanical loading at temperatures as low as 77 K with a maximum cooling rate of 6 K/min. The CCE features a polystyrene foam cryogenic chamber, aluminum blocks serving as neutron-transparent cold sinks, a liquid nitrogen dosing system for cryogen delivery, a nitrogen gas flow control system for thermal management, a process controller for temperature control, and a pair of thermally isolated grip adapters for mechanical testing. The CCE achieves reliable temperature control with minimal neutron attenuation. Utilizing this setup, we conducted three in situ neutron diffraction tensile tests on a 316L stainless steel at 77, 173, and 298 K, respectively. The results highlight the pronounced effects of cryogenic temperatures on the material’s deformation mechanisms, underscoring both the significance of cryogenic deformation studies and the effectiveness of the CCE. Full article

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

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18 pages, 2011 KB

Open AccessFeature PaperArticle

Implementation and Applications of a Precision Weak-Field Sample Environment for Polarized Neutron Reflectometry at J-PARC

by Takayasu Hanashima, Kazuhiro Akutsu-Suyama, Yoshimasa Ohe, Satoshi Kasai, Hiroshi Kira, Azusa N. Hattori, Ai I. Osaka, Hidekazu Tanaka, Jun-Ichi Suzuki and Kazuhisa Kakurai

Quantum Beam Sci. 2025, 9(4), 35; https://doi.org/10.3390/qubs9040035 - 3 Dec 2025

Polarized neutron reflectometry (PNR) analyzes surface and interfacial structures of materials. For the SHARAKU reflectometer at the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Research Complex, precise measurements under weak magnetic fields, which are critical for modern spintronics, have [...] Read more.

Polarized neutron reflectometry (PNR) analyzes surface and interfacial structures of materials. For the SHARAKU reflectometer at the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Research Complex, precise measurements under weak magnetic fields, which are critical for modern spintronics, have long been challenging. To address this issue, we developed a precise weak-field sample environment equipped with a newly designed coil system. The magnetic field at the sample position can be applied within the surface/interface plane, either in the scattering plane (horizontal configuration) or perpendicular to it (vertical configuration). The horizontal configuration achieved high polarization efficiency across a stable field range, whereas the vertical configuration enabled the experiments to cross zero into negative fields. We demonstrated the instrument’s capability by resolving the remanent magnetic structure of an Fe film. Its applicability to soft matter was proven through analysis of a cellulose thin film with roughness using magnetic contrast variation PNR. In this case, precise weak-field control is essential to tune the magnetic contrast from the reference layer beneath the soft film. These results establish the system as a versatile platform for future PNR and polarized off-specular scattering experiments across a wide range of materials. Full article

(This article belongs to the Section Instrumentation and Facilities)

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13 pages, 2712 KB

Open AccessArticle

Temporal Variation in Nano-Enhanced Laser-Induced Plasma Spectroscopy (NELIPS)

by Ashraf EL Sherbini and AbdelNasser Aboulfotouh

Quantum Beam Sci. 2025, 9(4), 34; https://doi.org/10.3390/qubs9040034 - 28 Nov 2025

The NELIPS acronym stands for Nano-Enhanced Laser-Induced Plasma Spectroscopy. Within this framework, the temporal variation in the enhanced plasma emissions from pure nanomaterials with respect to corresponding bulk materials was monitored as a function of delay time in the range from 1 to [...] Read more.

The NELIPS acronym stands for Nano-Enhanced Laser-Induced Plasma Spectroscopy. Within this framework, the temporal variation in the enhanced plasma emissions from pure nanomaterials with respect to corresponding bulk materials was monitored as a function of delay time in the range from 1 to 5–11 μs. Six different pure nanomaterials were employed including silver, zinc, aluminum, titanium, iron, and silicon. Radiation from pulsed Nd: YAG laser at wavelength 1064 nm was used to induce both bulk and pure nanomaterial plasmas under similar experimental conditions. Plasma emissions from both targets were monitored via optical emission spectroscopy technique (OES). The spectral line intensities (Signal-To-Noise ratio S/N) from the pure nanomaterial plasma turns out to decline in a constant logarithmic manner but at a slower rate than that from the corresponding bulk material plasma. Consequently, the measured average enhanced emission from different nanomaterials features an increase in an exponential manner with delay time. This trend of increase was accounted for via mathematical elaboration of enhanced emission based on the measured Signal-To-Noise data. Plasma parameters (electron density and temperature) were precisely measured at each delay time as well. Full article

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

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18 pages, 4770 KB

Open AccessFeature PaperReview

Japanese Sword Studies Using Neutron Bragg-Edge Transmission and Computed Tomography

by Yoshiaki Kiyanagi, Kenichi Oikawa, Yoshihiro Matsumoto, Joseph Don Parker, Kenichi Watanabe, Hirotaka Sato and Takenao Shinohara

Quantum Beam Sci. 2025, 9(4), 33; https://doi.org/10.3390/qubs9040033 - 24 Nov 2025

Japanese swords have a history of more than one thousand years and are recognized as metallic art objects. The sword-making process is not clearly understood, especially for old swords made before about 1600 A.D. Knowledge of structural information such as crystallite sizes and [...] Read more.

Japanese swords have a history of more than one thousand years and are recognized as metallic art objects. The sword-making process is not clearly understood, especially for old swords made before about 1600 A.D. Knowledge of structural information such as crystallite sizes and anisotropy is important to understand the sword characteristics and the sword-making process. Bragg-edge transmission imaging is a useful noninvasive method that can extract this structural information continuously over a wide area of the sword. Neutron CT is powerful enough to detect quenched areas, voids, and precipitates. Using both methods, we measured more than 10 swords and obtained information on the two-dimensional crystallite size distribution, anisotropy parameter, lattice plane spacing, and quenched regions. Comparison of the results indicated the following features: the crystallite size distributions showed two patterns: an almost uniform distribution of small-sized crystallites, and mixed distributions of large- and small-sized crystallites. The patterns were observed in different eras and places. The preferred orientation showed different patterns, and strain areas due to quenching were observed in many swords. The quenched area showed a trend that the quenching was weaker for old swords than newer ones. CT images showed the boundaries of the quenched regions and a void in the layered structure for one sword, for which a layered structure was confirmed. Full article

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

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65 pages, 2194 KB

Open AccessFeature PaperReview

Advances in Pulsed Liquid-Based Nanoparticles: From Synthesis Mechanism to Application and Machine Learning Integration

by Begench Gurbandurdyyev, Berdimyrat Annamuradov, Sena B. Er, Brayden Gross and Ali Oguz Er

Quantum Beam Sci. 2025, 9(4), 32; https://doi.org/10.3390/qubs9040032 - 5 Nov 2025

Cited by 2

Pulsed liquid-based nanoparticle synthesis has emerged as a versatile and environmentally friendly approach for producing a wide range of nanomaterials with tunable properties. Unlike conventional chemical methods, pulsed techniques—such as pulsed laser ablation in liquids (PLAL), electrical discharge, and other energy-pulsing methods—enable the [...] Read more.

Pulsed liquid-based nanoparticle synthesis has emerged as a versatile and environmentally friendly approach for producing a wide range of nanomaterials with tunable properties. Unlike conventional chemical methods, pulsed techniques—such as pulsed laser ablation in liquids (PLAL), electrical discharge, and other energy-pulsing methods—enable the synthesis of high-purity nanoparticles without the need for toxic precursors or stabilizing agents. This review provides a comprehensive overview of the fundamental mechanisms driving nanoparticle formation under pulsed conditions, including plasma–liquid interactions, cavitation, and shockwave dynamics. We discuss the influence of key synthesis parameters, explore different pulsed energy sources, and highlight the resulting effects on nanoparticle size, shape, and composition. The review also surveys a broad spectrum of material systems and outlines advanced characterization techniques for analyzing synthesized nanostructures. Furthermore, we examine current and emerging applications in biomedicine, catalysis, sensing, energy, and environmental remediation. Finally, we address critical challenges such as scalability, reproducibility, and mechanistic complexity, and propose future directions for advancing the field through hybrid synthesis strategies, real-time diagnostics, and machine learning integration. By bridging mechanistic insights with practical applications, this review aims to guide researchers toward more controlled, sustainable, and innovative nanoparticle synthesis approaches. Full article

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

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13 pages, 6797 KB

Open AccessFeature PaperArticle

Multi-Scale PbSe Structures: A Complete Transformation Using a Biphasic Mixture of Precursors

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

Quantum Beam Sci. 2025, 9(4), 31; https://doi.org/10.3390/qubs9040031 - 14 Oct 2025

With the recently acquired knowledge of the use of a multiphase mixture of precursors under electron beam irradiation (EBI), new possibilities were opened for this technique. In the present work, we obtained quantum dots, nanocrystals, nanoparticles, and grains of PbSe with a sintered [...] Read more.

With the recently acquired knowledge of the use of a multiphase mixture of precursors under electron beam irradiation (EBI), new possibilities were opened for this technique. In the present work, we obtained quantum dots, nanocrystals, nanoparticles, and grains of PbSe with a sintered appearance using a biphasic mixture of PbSe and PbSeO₃ under EBI. High-energy milling was used to obtain the biphasic mixture of precursors, which is composed of agglomerates with sizes ranging from ~400 to ~1700 nm, but nanoparticles were also present. The structural details of the biphasic mixture were studied using X-ray diffraction and the Rietveld method. The driving force of the EBI caused instantaneous physical and chemical changes due to the high internal energy of the biphasic mixture of precursors. The abrupt release of high internal energy, due to localized heating effects during EBI, gave way to the formation of multi-scale PbSe structures. Large particles with a sintered appearance formed near the electron beam impact point and in regions between ~800 nm and ~1400 nm, while well-defined faceted nanostructures were predominantly observed beyond ~1400 nm. The latter tended to be surrounded by {200} facets as the main growth direction. Furthermore, coalescence was anticipated to occur during EBI. It occurred simultaneously with the sublimation mechanism when the particle size was below the critical size of 10 nm. Multi-scale PbSe structures, obtained via EBI, are promising for developing thermoelectric devices due to their crystallinity and nanostructured features. Full article

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

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12 pages, 1523 KB

Open AccessArticle

Methodological Approach to the Characterization of Single-Photon Sources Using a Hanbury Brown–Twiss Interferometer in a Laser-Excited Fluorescence Microscope

by Sergey Mikushev and Aleksei Kalinichev

Quantum Beam Sci. 2025, 9(4), 30; https://doi.org/10.3390/qubs9040030 - 13 Oct 2025

The development of quantum-enhanced technologies requires single-photon sources, as well as methods for their characterization and verification. Here, we describe a methodology for measuring the correlation function of a single-photon source using an experimental setup that comprises a laser-excited fluorescence microscope equipped with [...] Read more.

The development of quantum-enhanced technologies requires single-photon sources, as well as methods for their characterization and verification. Here, we describe a methodology for measuring the correlation function of a single-photon source using an experimental setup that comprises a laser-excited fluorescence microscope equipped with a Hanbury Brown–Twiss intensity interferometer as one of the detection systems. Measurements of the response function of the device and the reference samples are performed. The second-order autocorrelation function of the exciton state of GaAs quantum dots in AlGaAs nanowires is obtained and reveals a single-photon emission. Full article

(This article belongs to the Section Spectroscopy Technique)

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19 pages, 4096 KB

Open AccessFeature PaperReview

Review of VHEE Beam Energy Evolution for FLASH Radiation Therapy Under Ultra-High Dose Rate (UHDR) Dosimetry

by Nikolaos Gazis and Evangelos Gazis

Quantum Beam Sci. 2025, 9(4), 29; https://doi.org/10.3390/qubs9040029 - 9 Oct 2025

Very-high-energy electron (VHEE) beams, ranging from 50 to 300 or 400 MeV, are the subject of intense research investigation, with considerable interest concerning applications in radiation therapy due to their accurate energy deposition into large and deep-seated tissues, sharp beam edges, high sparing [...] Read more.

Very-high-energy electron (VHEE) beams, ranging from 50 to 300 or 400 MeV, are the subject of intense research investigation, with considerable interest concerning applications in radiation therapy due to their accurate energy deposition into large and deep-seated tissues, sharp beam edges, high sparing properties, and minimal radiation effects on normal tissues. The very-high-energy electron beam, which ranges from 50 to 400 MeV, and Ultra-High-Energy Electron beams up to 1–2 GeV, are considered extremely effective for human tumor therapy while avoiding the spatial requirements and cost of proton and heavy ion facilities. Many research laboratories have developed advanced testing infrastructures with VHEE beams in Europe, the USA, Japan, and other countries. These facilities aim to accelerate the transition to clinical application, following extensive simulations for beam transport that support preclinical trials and imminent clinical deployment. However, the clinical implementation of VHEE for FLASH radiation therapy requires advances in several areas, including the development of compact, stable, and efficient accelerators; the definition of sophisticated treatment plans; and the establishment of clinically validated protocols. In addition, the perspective of VHEE for accessing ultra-high dose rate (UHDR) dosimetry presents a promising procedure for the practical integration of FLASH radiotherapy for deep tumors, enhancing normal tissue sparing while maintaining the inherent dosimetry advantages. However, it has been proven that a strong effort is necessary to improve the main operational accelerator conditions, ensuring a stable beam over time and across space, as well as compact infrastructure to support the clinical implementation of VHEE for FLASH cancer treatment. VHEE-accessing ultra-high dose rate (UHDR) perspective dosimetry is integrated with FLASH radiotherapy and well-prepared cancer treatment tools that provide an advantage in modern oncology regimes. This study explores technological progress and the evolution of electron accelerator beam energy technology, as simulated by the ASTRA code, for developing VHEE and UHEE beams aimed at medical applications. FLUKA code simulations of electron beam provide dose distribution plots and the range for various energies inside the phantom of PMMA. Full article

(This article belongs to the Section Instrumentation and Facilities)

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27 pages, 2979 KB

Open AccessReview

Review of EDM-Based Machining of Nickel–Titanium Shape Memory Alloys

by Sujeet Kumar Chaubey and Kapil Gupta

Quantum Beam Sci. 2025, 9(4), 28; https://doi.org/10.3390/qubs9040028 - 26 Sep 2025

Cited by 2

Shape memory alloy (SMA) materials are valued for their shape memory effect, superelasticity, and biocompatibility, making them an ideal choice for applications in biomedical, aerospace, and actuator fields. Nickel–titanium (NiTi) SMA is a promising biomedical material. It is widely used in the manufacture [...] Read more.

Shape memory alloy (SMA) materials are valued for their shape memory effect, superelasticity, and biocompatibility, making them an ideal choice for applications in biomedical, aerospace, and actuator fields. Nickel–titanium (NiTi) SMA is a promising biomedical material. It is widely used in the manufacture of biomedical instruments, devices, implants, and surgical tools. However, its complex thermo-mechanical behavior and poor machinability pose challenges for conventional machining. To manufacture high-quality nitinol parts, traditional machining processes are being replaced by advanced machining technologies. Electric discharge machining (EDM) is an advanced machining technique whose mechanism of material removal involves erosion caused by plasma formation and spark generation. It has proven effective for processing difficult-to-machine materials. This review summarizes EDM and its variants, including hybrid EDM, with a focus on machining NiTi-SMA materials for biomedical, aerospace, microelectromechanical systems, and automotive applications, and systematically explores key factors such as process parameters, material removal mechanisms, surface integrity, tool wear, and optimization strategies. This review begins with an introduction to nitinol (i.e., NiTi-SMA) and its variants, followed by an in-depth discussion of plasma formation, spark generation mechanisms, and other key aspects of EDM. It then provides a detailed analysis of notable past research on the machining of NiTi SMA materials using EDM and its variants. This paper concludes with insights into future research directions, aiming to advance EDM-based machining of SMA materials and serve as a valuable resource for researchers and engineers in the field. Full article

(This article belongs to the Section Engineering and Structural Materials)

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