Neutrons provide exceptional insight into materials, owing to their sensitivity to light elements, isotopic composition, magnetic moments, and high-penetration. However, neutron sources are polychromatic and of low brightness. Neutron optics provides a route to address these limitations by focusing, and to date, various types of neutron optics have been developed based on reflection, refraction, diffraction, and magnetism. Notably, compound refractive lenses and Fresnel zone plates have been demonstrated for imaging, yet their severe chromatic aberration under polychromatic beams has prevented their widespread use and limits progress towards true high-resolution neutron microscopy. Here, we demonstrate an achromatic neutron lens for full-field neutron microscopy. This development overcomes the intrinsic sample-detector distance constraint in pinhole-based radiography. The lens magnification enables the use of efficient detection systems without loss of spatial resolution and establishes a pathway towards high-resolution neutron microscopy. We anticipate the neutron achromat will advance a broad range of neutron methods.
The Laue neutron macromolecular crystallography beamline, IMAGINE, at the High Flux Isotope Reactor (HFIR) is undergoing a major upgrade to incorporate the dynamic nuclear polarization (DNP) technique. Upon completion, the new IMAGINE-X instrument is expected to enhance the signal-to-noise ratio of the diffraction data by an order of magnitude. To take full advantage of the benefits of DNP, both a highly polarized neutron beam and a high-efficiency neutron spin flipper are required. We have developed a compact cryogenic spin flipper utilizing the Meissner effect in high-Tc yttrium-barium-copper-oxide superconducting films. The flipper has been successfully tested at two HFIR neutron development beamlines, Larmor and Poplar, with neutron wavelengths of 5.3 and 2.4 Å respectively. At Larmor, a flipping efficiency of 0.995 ± 0.004 was achieved for 5.3 Å neutrons, and at Poplar, efficiency of up to 0.9987 ± 0.0004 was obtained for 2.4 Å neutrons. Both tests demonstrated the flipper's excellent performance and suitability for integration into IMAGINE-X.
In this study, the shielding properties of biodegradable polyhydroxybutyrate composites reinforced with various amounts of gadolinium oxide, ranging from 0 wt% to 25 wt%, against photon and neutron radiation are investigated theoretically using Monte Carlo simulation codes (Geant4 and FLUKA), as well as theoretical software packages (WinXCom and Phy-X). The dosimetric parameters, such as exposure build-up factors, energy absorption build-up factors, and suppression of secondary photon build-up, are computed up to 40 mean free paths, indicating that the addition of gadolinium oxide effectively reduces the build-up of secondary photons within the matrix material. The addition of gadolinium oxide significantly enhances the photon shielding properties, especially for low-energy photons ranging from 50-60 keV. In addition, 60 keV and 600 keV 2D total ionizing dose distributions indicate that the penetration of photons is restricted within the near-surface region of the composite material. The shielding properties of the composite material against neutrons indicate that there is a possibility of lateral diffusion of neutrons, whereas the composite material reinforced with 25 wt% of gadolinium oxide exhibited 99.9% efficiency for the capture of thermal neutrons, which effectively reduces the production of secondary gamma rays due to neutron capture reactions.
The advantage of apertures sharpening the edges of pencil beam scanning proton fields comes with the price of an increased out-of-field dose predominantly mediated by secondary neutrons. The objective of this study was to measure the increase in neutron ambient dose equivalent (H∗n(10) ) for monoenergetic square proton fields collimated by static brass apertures compared to non-collimated fields. The influence of the aperture material, i.e. brass and nickel, on the neutron contamnation was investigated. The experimental results were compared to a Monte Carlo (MC) simulation framework.
Approach: Experiments were conducted in a treatment room of a clinical proton therapy center. The H∗n(10) was measured with three extended-range rem-meters at multiple out-of-field positions at 2 m/1.12 m distance from the isocenter for quasi-monochromatic square proton fields (100, 140, 180 MeV) incident on a 30×30×30 cm3solid water target. The measurement results were compared to the respective calculations with the TOPAS MC simulation framework.
Main results: Collimating the edges of 10 × 10 cm2 fields with apertures increased the H∗n(10) on average by 23%. This increase was up to 74% in lateral direction to the initial beam and up to 6% in forward direction. With a reduction of H∗n(10) down to 50% and 33% on average, nickel proved to be more favorable than brass. Placing a range-shifter upstream of the aperture is more favorable compared to the downstream placement since the H∗n(10) was on average 20% lower. Considering the associated uncertainties, the simulations and experiments agreed well with an average deviation of 11.7% (1% to 34%).
Significance: Concluding, the increase of H∗n(10) caused by apertures sharpening scanned proton field edges is small to moderate with 23% on average. Neutron contamination can be reduced by material selection and the arrangement of beam-shaping devices. TOPAS is suited for the application under consideration.
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Cesium lead bromide (CsPbBr3) is a fully inorganic halide perovskite material known for its excellent optoelectronic properties, offering significant advantages for applications in aerospace and nuclear fields. To evaluate its radiation hardness under neutron exposure, the transport process of 1-14 MeV neutrons in CsPbBr3 was simulated using the Geant4 Monte Carlo toolkit. This study focuses on the primary damage characteristics, systematically analyzing the primary knock-on atom (PKA) spectrum and non-ionizing energy loss (NIEL). The simulation results indicate that most PKAs are distributed in the low-energy range. As the incident neutron energy increases, PKA types become more diverse, introducing transmutation products such as 77-81Se, 133Xe, 76As, and 205Hg. Furthermore, a distinct anomaly is observed at lower neutron energies (∼3 MeV), where the displacement of Pb atoms exhibits a localized peak directly attributed to its prominent (n, n) elastic scattering resonance, although the overall macroscopic damage remains heavily dominated by the Br sublattice. Crucially, the calculated NIEL, number of displaced atoms (Nd), and displacements per atom (dpa) exhibit a non-monotonic dependence on incident neutron energy, initially increasing and then decreasing beyond ∼10 MeV. This trend is primarily driven by the transition from elastic to inelastic scattering dominance, coupled with increased ionizing energy partitioning at higher PKA energies. This paper provides fundamental data on the primary damage state of CsPbBr3, establishing an essential source term basis for subsequent multiscale simulations of defect evolution.
Nuclear mass is a key indicator of how the nuclear shell structure evolves. The recent mass measurement study of neutron-rich lanthanum isotopes [Jaries et al., Phys. Rev. Lett. 134, 042501 (2025)PRLTAO0031-900710.1103/PhysRevLett.134.042501] reveals the presence of a distinct prominence in their two-neutron separation energies. However, its presence has been called into question based on the results of another mass determination [Liu, Ph.D. thesis, University of Notre Dame, 2025, 10.7274/28766600.v1.]. In this Letter, we report an effort to clarify these contradictory results through the use of the simultaneous mass-lifetime measurement of the neutron-rich lanthanum isotope ^{149}La using a multireflection time-of-flight mass spectrograph combined with a β-TOF detector. The peak corresponding to a β-decaying state was observed in the time-of-flight spectra at a position of 221(6)  keV/c^{2} lighter than the reported ^{149}La mass in Jaries et al., but our measured result is in excellent agreement with the mass value reported in Liu. We have concluded that this peak is the ground state of ^{149}La. With this, the previously reported distinct prominence in the two-neutron separation energies disappears, while a new kink structure, similar to that in the cerium isotopes, appears. Comparison with theoretical models suggests that a nuclear shape transition from octupole deformation to another type of deformation occurs around N=91 and is likely the cause of this kink structure.
Using the time-of-flight technique, we measured the beta-delayed neutron emission of ^{132}Cd. From our large-scale shell model (LSSM) calculation using the N^{3}LO interaction [Z. Y. Xu et al., Phys. Rev. Lett. 131, 022501 (2023)PRLTAO0031-900710.1103/PhysRevLett.131.022501], we suggest the decay is dominated by the transformation of a neutron in the g_{7/2} orbital, deep below the Fermi surface, into a proton in the g_{9/2} orbital. We compare the beta-decay half-lives and neutron branching ratios of nuclei with Z<50 and N≥82 obtained with our LSSM with those of leading "global" models such as finite-range droplet model (FRDM). Our calculations match known half-lives and neutron branching ratios well and suggest that current leading models overestimate the yet-to-be-measured half-lives. Our model, backed by the ^{132}Cd decay data presented here, offers robust predictive power for nuclei of astrophysical interest such as r-process waiting points.
This work presents a theoretical assessment of photon attenuation and preliminary fast-neutron shielding indicators for six tellurite-based glass compositions containing Bi2O3, WO3, Nb2O5, Gd2O3, and As2O3. The selected literature-based compositions span densities from 4.596 to 6.996 g/cm3 and were evaluated over the photon energy range of 15 keV to 15 MeV using the Phy-X/PSD platform. The calculated shielding parameters include the mass attenuation coefficient (MAC), linear attenuation coefficient (μ), half-value layer (HVL), mean free path (MFP), radiation protection efficiency (RPE%), effective atomic number (Zeff), and fast neutron removal cross section (FNRCS). The present work provides a comparative theoretical benchmark for evaluating the influence of composition, density, high-Z absorption-edge behavior, photon attenuation characteristics, and fast-neutron removal indicators across different tellurite glass networks under consistent computational conditions. The results indicate that WO3 and Bi2O3-rich glasses, particularly TWA1 and TNB2, exhibit comparatively favorable attenuation performance among the investigated samples. At 0.04 MeV, TWA1 showed μ = 106.2 cm-1, HVL = 0.007 cm, and MFP = 0.009 cm, compared with μ = 14.8 cm-1 and HVL = 0.047 cm for ordinary concrete, suggesting comparatively improved theoretical thickness efficiency in the low-energy region. At 0.511 MeV, TWA1 exhibited the lowest HVL among the present glasses (0.937 cm), with RPE ≈ 52.2% at 1 cm thickness. The calculated FNRCS values ranged from 0.08 to 0.095 cm-1, with TNB2 showing the highest value. Within the limitations of the present theoretical framework, these findings provide comparative guidance for future experimental and Monte Carlo transport evaluation of lead-free tellurite glasses for radiation shielding applications.
Boron Neutron Capture Therapy is dependent on localized energy deposition of alpha particles and lithium nuclei. However, deviations and inconsistencies in cellular responses to neutron beams are frequently reported in radiobiological studies. This technical note investigates dosimetric impact of the overlying medium thickness on a [Formula: see text] cellular array using Monte Carlo method. [Formula: see text]B concentrations ranging from 0 to 80 ppm were evaluated to explicitly quantify energy partitioning between the cytoplasm and nucleus. Our findings demonstrate that minor variations in the aqueous medium layer severely attenuate the thermal neutron flux, leading to a marked decrease in the absolute dose deposited in the cellular targets. Specifically, increasing the medium thickness from 100 μm to 800 μm resulted in a [Formula: see text] reduction in the total cellular dose at 80 ppm. These results highlight the critical necessity of controlling and reporting fluid levels in BNCT in vitro experiments to prevent dosimetric variations and ensure reproducible biological outcomes.
Boron neutron capture therapy (BNCT) requires sustained, high intratumoral concentrations of 10B with minimal normal tissue exposure. However, small-molecule agents such as sodium borocaptate (BSH) and p-boronophenylalanine (BPA) often exhibit insufficient tumor selectivity and retention. In this study, we designed a covalent conjugate of BSH with an amphiphilic styrene-maleic acid copolymer (SMA), termed BSH-SMA, as a polymer-based boron carrier for tumor-retentive boron delivery. The BSH-SMA conjugate was synthesized via a thioester linkage and evaluated for boron loading, hydrodynamic diameter, interaction with albumin under purified-protein conditions, and pH-responsive behavior. Biodistribution was measured in tumor-bearing mice. Thermal neutron irradiation was performed 12 h post-injection, corresponding to the peak tumor boron concentration. In vitro, BSH-SMA showed interaction with albumin under purified-protein conditions, as indicated by size-exclusion chromatography, and exhibited an acid-enhanced association, manifested by increased turbidity at tumor-relevant pH values. In vivo, the conjugate achieved tumor-preferential boron delivery with a high tumor-to-normal tissue ratio. Upon neutron irradiation, BSH-SMA significantly suppressed tumor growth compared with controls. Hematoxylin and eosin staining revealed no obvious histopathological changes in the liver or kidneys. These results support the potential of BSH-SMA as a polymeric boron carrier for tumor-selective boron delivery and BNCT under the present experimental conditions.
Three-dimensional localization of neutron-emitting materials is crucial for minimizing personnel radiation exposure during nuclear decommissioning and nuclear safety activities. To address this challenge, this study proposes a localization method based on double-scattering principle and a dedicated reconstruction algorithm. This study is comprised of two main parts. First, a double-layer scintillator array detector was designed. Its key parameters were optimized to achieve a balance between coincidence detection efficiency and spatial resolution. Second, a three-dimensional localization algorithm was developed. This algorithm determines the optimal imaging plane and reconstructs a heatmap, leading to three-dimensional localization. The performance of the double-scattering imaging system was evaluated via simulations. The results demonstrated that the neutron source can be localized within a defined spatial area with centimeter-level accuracy. This study provides a practical solution for the three-dimensional localization of neutron-emitting materials and demonstrates its significant application potential in the field of nuclear decommissioning.
Boron neutron capture therapy (BNCT) enables localized tumor ablation while minimizing damage to surrounding tissues, offering advantages for treating anatomically challenging sites. However, current boron carriers, such as sodium borocaptate (10BSH), suffer from inadequate tumor specificity. Herein, the present study details the design, synthesis, and preclinical evaluation of a novel small-molecule boron-10-enriched carrier, which was synthesized by covalent bond coupling 4-carboxy-3-fluorophenylboronic acid (FPBA) to 10BSH (FPBA-BSH), achieving a boron content of approximately 25 wt.%. FPBA-BSH efficiently penetrated the blood-brain barrier and demonstrated pronounced accumulation in orthotopic gliomas, achieving a boron concentration of 75.4 μg-B/g-tumor tissue, which was 4.2- and 3.7-fold higher than those with boronophenylalanine (BPA) and BSH, respectively. Moreover, FPBA-BSH exhibited markedly improved tumor selectivity, with tumor-to-normal tissue (T/N) and tumor-to-blood ratios of 52.0 and 7.2, respectively. The T/N ratio was approximately 19.3- and 14.1-fold greater than those observed for BPA and BSH. In the melanoma model, FPBA-BSH achieved an intratumor boron concentration of 114.4 μg-B/g-tumor tissue, representing 8.4- and 9.9-fold increases compared with BPA and BSH, respectively. Correspondingly, the T/N and tumor-to-blood ratios reached 135.1 and 8.6, indicating substantially enhanced tumor targeting and retention. The T/N ratio achieved with FPBA-BSH was approximately 26.0- and 34.6-fold higher than those obtained with BPA and BSH, respectively. Consistent with its superior tumor selectivity, FPBA-BSH-mediated BNCT induced pronounced tumor-selective cytotoxicity and markedly inhibited tumor growth in both orthotopic glioma and melanoma models compared with BPA, BSH, and untreated controls. These findings demonstrate that FPBA-BSH represents a promising small-molecule boron delivery agent with substantial potential for clinical BNCT applications.
Boron neutron capture therapy (BNCT) is an emerging targeted radiotherapy technology that enables precise eradication of tumor cells. The development of efficient boron carriers is crucial for the advancement of BNCT technology. Notably, biomolecular carriers currently represent the only class of drug carriers that has achieved market approval (e.g., boronophenylalanine [BPA] in Japan), underscoring their pivotal role in clinical applications. Their outstanding biocompatibility, high payload capacity, and tumor-targeting capabilities align closely with the stringent requirements of BNCT drug delivery. For instance, amino acid-based carriers (such as BPA) utilize L-type amino acid transporter 1 (LAT1) for tumor-specific accumulation; nucleoside prodrugs are activated by thymidine kinase 1 (TK1) and incorporated into tumor DNA; carbohydrate-based carriers improve solubility and targeting through glucose transporters (GLUTs); peptide carriers facilitate cellular uptake via receptor-mediated endocytosis or cell-penetrating peptides; and liposomes leverage the enhanced permeability and retention (EPR) effect together with active-targeting modifications for enhanced tumor delivery. Nevertheless, delivering ultrahigh doses of boron remains a major challenge. Biomacromolecules, particularly albumin-based systems, have garnered increasing attention because of their excellent biosafety and high boron-loading potential, offering promising avenues for overcoming dose delivery barriers in BNCT. This review systematically summarizes the recent advances in biomolecular carriers for BNCT and highlights emerging applications of protein-based boron carriers, addressing a notable gap in the comprehensive review of biomolecular strategies within the BNCT drug delivery field.
Boron neutron capture therapy (BNCT) has emerged as a promising therapeutic modality in cancer treatment, demonstrating the ability to selectively eliminate cancer cells through the 10B(n,α)7Li nuclear reaction with minimal side effects on normal tissues. As a binary, target-specific therapeutic modality for malignancies, BNCT critically depends on novel boron delivery carriers that exhibit high tumor affinity and prolonged intratumoral retention. Although several boron carriers have received Food and Drug Administration approval for clinical investigation, leading carriers such as L-p-boronophenylalanine (BPA) and sodium borocaptate (BSH) continue to require high infusion doses and exhibit limited tumor selectivity and affinity, short systemic half-lives, and limited in vivo stability. These challenges have stimulated extensive global research into novel boron-10 carriers and innovative carrier platforms, including amino acids, sugars, porphyrin derivatives, nucleotides, and a variety of nanocarrier systems. This review provides a systematic classification of high-abundance boron-10 carriers, critically examines radio-boron research, and evaluates the potential integration of BNCT into clinical diagnostics and advanced cancer treatment protocols. By detailing the current status of novel boron-10 carriers, this review further aims to elucidate critical challenges and opportunities in BNCT drug development, ultimately providing a theoretical foundation for next-generation BNCT interventions.
An equimolar N-methylacetamide-water (NMA-W) mixture was re-examined by combining molecular dynamics (MD) simulations, DFT-based Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) analyses, and data-driven reconstruction of previously reported neutron scattering functions of the NMA-W liquid. MD simulations, using an AMBER-based force field for NMA and the SPC/E model for water, reproduce reasonably well the experimental structure factors and pair correlation functions of the liquid. In parallel, a Random Forest Regressor is employed as a nonparametric data-driven reconstruction tool, showing that the main features of the structural data can be represented as a continuous numerical representation of the scattering vector Q, providing a continuous numerical representation for comparison purposes. Three representative NMA-water clusters previously identified as the most probable local arrangements governing the liquid structure are further analyzed using NBO and Atoms-in-Molecules (AIM) approaches. The analysis provides additional information on hydrogen-bond electronic structure, including charge-transfer effects, electron density at bond critical points, and topological characteristics of intermolecular interactions. Comparison with MD-derived lifetimes shows that stronger electronic interactions do not always correspond to longer-lived hydrogen bonds, reflecting the role of local network topology and dynamical fluctuations.
Sialoblastoma is a rare, aggressive pediatric salivary gland tumor often refractory to conventional therapies, which carry significant risks of growth impairment in children. We report the 52-month follow-up of a 6-year-old girl with recurrent sialoblastoma treated with two sessions of boron neutron capture therapy (BNCT). She achieved a 23-month complete response after the first session and a sustained partial response following the second. Dosimetric analysis using a conservative α/β ratio of 2.0 Gy for late-responding tissues showed that the equivalent dose in 2-Gy fractions to the mandible area was approximately 4.3 Gy-Eq. This is substantially below the 15 Gy threshold recognized for skeletal impairment. Our findings suggest that BNCT is a highly selective salvage option that effectively controls refractory pediatric tumors while preserving craniofacial development.
Pixelated detectors based on inorganic scintillation materials are widely used in radiation detection systems for medical imaging and many other fields of science and technology. A substantial application is X-ray scanning using flat-panel detectors (FPDs) for both fluorography and mammography. In this article, the detection properties of the monolithic planar ceramic scintillation elements are reported for the first time. A high-light yield (Gd,Y)3Al2Ga3O12:Ce,Mg garnet-type scintillation material was used to form square-shaped pixels, while a material of similar composition was used as a substrate. Green bodies were successfully fabricated by a digital light processing (DLP) 3D printing method. Subsequent debinding and pressureless high-temperature sintering resulted in composite elements consisting of two layers with different chemical compositions. The lower bulk layer consisted of transparent, non-luminescent garnet, whereas the upper pixelated layer, with pixel dimensions of 230 × 230 µm, was made of scintillation material. The spatial resolution of the matrices under UV light and alpha-particle excitation was evaluated. It was confirmed that the spatial resolution of the matrices produced by the developed technology is approximately 0.4 times the pixel size. The proven ability of the integrated technology of inorganic scintillation matrix production opens the way for future improvement in spatial resolution through optimizing the printed pixel dimensions.
Efficient discrimination of thermal neutrons, fast neutrons, and γ-rays is of great importance for radiation monitoring, nuclear security, and fundamental research. However, conventional plastic scintillators, despite their low cost and fast response, generally suffer from limited neutron/gamma (n/γ) discrimination capability, which motivates the development of advanced scintillation materials and dedicated detection systems. In this work, we developed a polystyrene/poly(methyl methacrylate) (PS/PMMA) blended plastic scintillator that combines the high light yield of PS with the mechanical robustness of PMMA. A boron-containing dopant, bis(pinacolato)diboron (B2Pin2), was introduced together with optimized dye and cross-linker concentrations to enhance neutron sensitivity and overall scintillation performance. To evaluate the detector performance, we further constructed a custom measurement platform consisting of a photomultiplier tube (PMT)-based readout module and a high-speed pulse waveform analysis system. Experiments with a 241Am-Be source demonstrate that the developed scintillator exhibits effective pulse shape discrimination capability, demonstrating statistical discrimination of γ-ray-, fast-neutron-, and thermal-neutron-related event populations within a single detector system.
The trace anomaly of dense matter, Δ≡1/3-P/ϵ, defined through the ratio w≡P/ϵ of pressure P to energy density ϵ, quantifies deviations from conformal symmetry and provides a dimensionless measure of the stiffness of the equation of state (EOS) relevant for both neutron stars and heavy-ion collisions. While Δ(ϵ) has recently been inferred from neutron star observations, we report the first Bayesian extraction of the trace anomaly from collective flow observables in intermediate-energy heavy-ion collisions. By employing transport-model simulations that explicitly decouple the cold matter mean-field potential from thermal effects, we directly constrain the EOS of cold dense matter. Remarkably, the trace anomaly inferred from laboratory flow data agrees quantitatively, within 68% credible intervals, with independent astrophysical posterior bands. This nontrivial agreement demonstrates that heavy-ion collisions and neutron star observations probe the same macroscopic properties in a mutually consistent way, establishing the dense-matter trace anomaly as a composition-insensitive macroscopic bridge observable across widely different physical environments.
The commissioning of medical cyclotrons necessitates a thorough assessment of radioactive waste management systems, operational protocols, and radiological safety. Significant neutron and gamma radiation is generated during cyclotron operation for radionuclide production, which are frequently employed in positron emission tomography (PET) for clinical diagnosis and biological research. This study assesses waste management procedures and radiation risks at the Institute of Nuclear Medical Physics' recently commissioned cyclotron facility. Neutron and gamma dose rates were measured at multiple locations under single-beam (80 μA) and dual-beam (160 μA) operational modes. Calibrated radiation survey meters were used to obtain reliable dose measurements during routine cyclotron operation. While gaseous radionuclides were temporarily housed in the air compression station (ACS) prior to controlled emission through the ventilation stack, liquid radioactive waste was kept in lead-shielded decay tanks to allow controlled radioactive decay prior to disposal. Gamma radiation and stack airflow were continuously monitored to guarantee adherence to workplace safety regulations. Neutron and gamma dose rates within the cyclotron vault increased with beam current, ranging from 45.7 ± 4.2 to 49.0 ± 4.5 mSv h-1 and 50.24 ± 2.56 to 95.51 ± 4.87 mSv h-1, respectively. Effective shielding had been verified by the extremely low radiation levels (≤0.7 μSv h-1) at the vault entrance, console room, and nearby locations. The findings demonstrate that the GE PETtrace Cyclotron facility operates reliably under both single-beam and dual-beam configurations, thereby ensuring robust radiological protection for personnel and the surrounding environment.