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2. Note on a Paper by J. Spanier Concerning Monte Carlo Estimators
- Author
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MacMillan, D. B.
- Published
- 1967
3. National Academy of Sciences: Abstracts of Papers Presented at the Annual Meeting, 24-26 April 1961, Washington, D.C.
- Published
- 1961
4. Abstracts of Papers Presented at the Washington Meeting
- Published
- 1933
5. Abstracts of Papers Communicated to the Royal Society of London
- Published
- 1938
6. Abstracts of Papers Communicated to the Royal Society of London
- Published
- 1938
7. DETECTION OF PHOSPHOLIPIDS ON PAPER CHROMATOGRAMS BY NEUTRON ACTIVATION.
- Author
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JOHNSON P, WEBER EJ, CARTER HE, and KROBER MS
- Subjects
- Activation Analysis, Chromatography, Neutrons, Phospholipids
- Published
- 1965
8. Viral and Microbial Threats - a joint position paper by Analytical Research Infrastructures of Europe (ARIE)
- Author
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Cicchetti, Gregor, van Daalen, Mirjam, Gleizes, Pierre-Emmanuel, Leonard, Gordon, Redlich, Britta, Schertler, Gebhard, Toimil Morales, Maria Eugenia, and Wacklin-Knecht, Hanna
- Subjects
high magnetic field ,protons ,Laserlab ,EMFL ,electrons ,neutrons ,COVID-19 ,DREAM ,RADIATE ,viral threats ,microbial threats ,FELIX Infrared and Terahertz Spectroscopy ,research infrastructures ,Coronavirus ,LENS ,ions ,photons ,Inspire Project ,lasers ,LEAPS - Abstract
Analytical Research Infrastructures of Europe (ARIE) join forces to face threats such as COVID-19 and potential future crises. With this paper, the ARIE enhanced its cross-border, multidisciplinary collaboration to offer Europe a strong and valid weapon against the present COVID-19 challenge and other potential viral and microbial threats., {"references":["Shin et al. (2020) DOI: 10.1038/s41586-020-2601-5","Zhou et al. (2020) DOI:10.1038/s41594-020-0480-y","M. Eckermann/T. Salditt (2020) DOI: 10.7554/eLife.60408"]}
- Published
- 2020
9. (Keynote Paper) Mono-Domain Ferrites and Their Implications.
- Author
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van der Zaag, P. J.
- Subjects
- *
MAGNETIC structure , *MAGNETIC domain , *FERRITES , *MAGNETIC domain walls , *DOMAIN walls (String models) , *GRAIN size , *PERMEABILITY - Abstract
Neutron depolarization experiments have shown that the intragranular magnetic domain structure of polycrystalline ferrites exhibits a marked grain size dependence. Below a grain size of around $3~\mu \text{m}$ , the magnetic domain structure changes from the two-domain to the mono-domain state. Ferrites composed of mono-domain grains exhibit low dissipation at megahertz frequencies. This is attributed to the absence of intragranular domain wall movement, i.e., a microscopic origin for dissipation in ferrites has been identified. The implications of this clear observation and evidence for a transition from the mono- to two-domain state in ferrites for micromagnetic theory when a single particle becomes monodomain, as well as for the initial permeability mechanisms in polycrystalline ferrites, are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Neutron Activation Paper Chromatographic Analysis of Phospholipids in Human Liver and Bile
- Author
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Sillén, Lars
- Published
- 1961
- Full Text
- View/download PDF
11. JUNO distributed computing system.
- Author
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Zhang, Xiaomei
- Subjects
NEUTRINOS ,NEUTRONS ,DISTRIBUTED computing ,DATA management ,COMPUTER networks - Abstract
The Jiangmen Underground Neutrino Observatory (JUNO) [1] is a multipurpose neutrino experiment and the determination of the neutrino mass hierarchy is its primary physics goal. JUNO is going to start data taking in 2024 and plans to use distributed computing infrastructure for the data processing and analysis tasks. The JUNO distributed computing system has been designed and built based on DIRAC [2]. Since last year, the official Monte Carlo (MC) production has been running on the system, and petabytes of massive MC data have been shared among JUNO data centers through this system. In this paper, an overview of the JUNO distributed computing system will be presented, including workload management system, data management, and condition data access system. Moreover, the progress of adapting the system to support token-based AAI [3] and HTTP-TPC [4] will be reported. Finally, the paper will mention the preparations for the upcoming JUNO data-taking. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Research on the Effect of Fracture Angle on Neutron Logging Results of Shale Gas Reservoirs.
- Author
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Zhang, Xueang, Yang, Zhichao, and Li, Xiaoyan
- Subjects
SHALE gas reservoirs ,GAS condensate reservoirs ,SHALE gas ,THERMAL neutrons ,PETROPHYSICS ,NATURAL gas storage ,NEUTRONS ,NEUTRON temperature ,NEUTRON diffusion - Abstract
Fracture structures are important natural gas transport spaces in shale gas reservoirs, and their storage state in shale gas reservoirs seriously affects gas production and extraction efficiency. This work uses numerical modeling techniques to investigate the logging response law of the thermal and epithermal neutrons in the gas-containing fracture environment at various angles, applying neutron logging as a technical method. To increase the precision of the evaluation of the natural gas storage condition in shale gas reservoirs, the angle of the fractures' neutron logging data is analyzed. It is found that even in an environment with the same porosity of the fractures, there are significant differences in the logging results due to the different angles of the fracture alignment: 1. the neutron counts in the high-angle (70–90°) fracture environment are 2.25 times higher than in the low-angle (0–20°), but the diffusion area of the neutrons is only 10.58% of that in the low-angle (0–20°); 2. in the neutron energy spectrum, neutron counts are spreading to the high-energy region (7–13 MeV) along with the increase in the angle of the fracture, and the feature is especially prominent in the approximately vertical (60–90°) fracture environment, which is an increase of 528.12% in comparison with the counts in the approximately horizontal angle (0–30°) environment. The main reason for these differences is the variation in the volume of the fracture within the source radiation. This volumetric difference results from the variation in fracture angles (even though the fracture porosity is the same). In view of the above phenomenon, this paper proposes the concept of "effective fracture volume", which can intuitively reflect the degree of influence of fracture angle on neutron logging results. Further, based on the unique characteristics of shale gas reservoirs and neutrons, this paper provides important theoretical support for the modification of the porosity of the field operation, the evaluation of the physical characteristics of the gas endowment space, and the assessment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Biomarker dosimetry of acute low level of thermal neutrons and radiation adaptive response effect on rats.
- Author
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Awad MM, Abdelgawad MH, Aboelezz E, and Ereiba KT
- Subjects
- Animals, Rats, Male, Superoxide Dismutase metabolism, Lipid Peroxidation radiation effects, Radiometry methods, Dose-Response Relationship, Radiation, DNA Damage radiation effects, Adaptation, Physiological radiation effects, Catalase metabolism, Glutathione metabolism, Glutathione blood, Comet Assay, Oxidative Stress radiation effects, Electron Spin Resonance Spectroscopy methods, Biomarkers metabolism, Neutrons
- Abstract
In this paper, we demonstrated the biological effects of acute low-dose neutrons on the whole body of rats and investigated the impact of that level of neutron dose to induce an in vivo radio-adaptive response. To understand the radio-adaptive response, the examined animals were exposed to acute neutron radiation doses of 5 and 10 mSv, followed by a 50 mSv challenge dose after 14 days. After irradiation, all groups receiving single and double doses were kept in cages for one day before sampling. The electron paramagnetic resonance (EPR) method was used to estimate the radiation-induced radicals in the blood, and some hematological parameters and lipid peroxidation (MDA) were determined. A comet assay was performed beside some of the antioxidant enzymes [catalase enzyme (CAT), superoxide dismutase (SOD), and glutathione (GSH)]. Seven groups of adult male rats were classified according to their dose of neutron exposure. Measurements of all studied markers are taken one week after harvesting, except for hematological markers, within 2 h. The results indicated lower production of antioxidant enzymes (CAT by 1.18-5.83%, SOD by 1.47-17.8%, and GSH by 11.3-82.1%). Additionally, there was an increase in red cell distribution width (RDW) (from 4.61 to 25.19%) and in comet assay parameters such as Tail Length, (from 6.16 to 10.81 µm), Tail Moment, (from 1.17 to 2.46 µm), and percentage of DNA in tail length (DNA%) (from 9.58 to 17.32%) in all groups exposed to acute doses of radiation ranging from 5 to 50 mSv, respectively. This emphasizes the ascending harmful effect with the increased acute thermal neutron doses. The values of the introduced factor of radio adaptive response for all markers under study reveal that the lower priming dose promotes a higher adaptation response and vice versa. Ultimately, the results indicate significant variations in DNA%, SOD enzyme levels, EPR intensity, total Hb concentration, and RDWs, suggesting their potential use as biomarkers for acute thermal neutron dosimetry. Further research is necessary to validate these measurements as biodosimetry for radiation exposure, including investigations involving the response impact of RAR with varied challenge doses and post-irradiation behavior., (© 2024. The Author(s).)
- Published
- 2024
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14. A Nuclear Data Evaluation Pipeline for the Fast Neutron Energy Range – using heteroscedastic Gaussian processes to treat model defects.
- Author
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Göök, Alf, Andersson-Sundén, Erik, Hansson, Joachim, and Sjöstrand, Henrik
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NUCLEAR reactions ,NUCLEAR energy ,HETEROSCEDASTICITY ,GAUSSIAN processes ,NEUTRONS - Abstract
In this paper, we discuss the development of a nuclear data evaluation pipeline, based around the TALYS code system. The pipeline focuses on the evaluation of the fast neutron energy range, above the resolved resonances. A strong focus in development lies on automation and reproducibility, as well as the efficient use of large-scale computational infrastructure, to enable rapid testing of new algorithms and modified assumptions. Several novel concepts for nuclear data evaluation methodology are implemented. A particular problem in evaluating the neutron-induced reaction cross-section using TALYS, relates to the intermediate energy range. While TALYS only predicts the smooth energy-averaged cross-section, experiments reveal unresolved resonance-like structures. In this paper, we explore ways to treat this type of model defect using heteroscedastic Gaussian processes to automatically determine the distribution of experimental data around an energy-averaged cross-section curve. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
15. Correlation Between the Direction of Prompt Neutrons and Fragments in the Fission Process as a Tool for Studying Rotation Effect.
- Author
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Berikov, Daniyar, Ahmadov, Gadir, Kopatch, Yuri, Nuruyev, Sabuhi, Mendibayev, Kairat, and Ahmadov, Farid
- Subjects
NEUTRONS ,NUCLEAR fission ,NEUTRON beams ,ANGULAR distribution (Nuclear physics) ,STATISTICAL correlation - Abstract
This paper investigates the possibility of restoring the trajectory of fission fragments using thick targets that are opaque to the fragments, by analyzing the angular distribution of prompt neutrons. Employing thick targets in experimental studies with low-intensity neutron beams accelerate the accumulation of statistics, thereby facilitating the study of subtle effects, such as the rotation (ROT) effect which sheds light on the deformation and rotational behavior of fission fragments. The paper details the experimental techniques used, presents the results of neutron yield measurements from the fission of
235 U with cold and “warm” (60 meV) neutrons in the range of angles from 0 to 360( (in 22.5( increments). The analysis of these is also presented. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
16. Wide-Bandgap Semiconductors for Radiation Detection: A Review.
- Author
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Capan, Ivana
- Subjects
WIDE gap semiconductors ,RADIATION ,X-ray detection ,ALPHA rays ,THERMAL neutrons ,GALLIUM nitride ,NEUTRONS - Abstract
In this paper, an overview of wide-bandgap (WBG) semiconductors for radiation detection applications is given. The recent advancements in the fabrication of high-quality wafers have enabled remarkable WBG semiconductor device applications. The most common 4H-SiC, GaN, and β-Ga
2 O3 devices used for radiation detection are described. The 4H-SiC and GaN devices have already achieved exceptional results in the detection of alpha particles and neutrons, thermal neutrons in particular. While β-Ga2 O3 devices have not yet reached the same level of technological maturity (compared to 4H-SiC and GaN), their current achievements for X-ray detection indicate great potential and promising prospects for future applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
17. Burnup-Dependent Neutron Spectrum Behaviour of a Pressurised Water Reactor Fuel Assembly.
- Author
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Mweetwa, Bright Madinka and Margulis, Marat
- Subjects
NUCLEAR fuels ,NEUTRONS ,THERMAL neutrons ,RESEARCH reactors ,NUCLEAR reactors - Abstract
Understanding the behaviour of a neutron spectrum with burnup is important for describing various phenomena associated with reactor operation. The quest to understand the neutron spectrum comes with a lot of questions. One question that is usually asked by students is: Does the neutron spectrum harden or soften with burnup? Most textbooks used by students do not provide a definite answer to this question. This paper seeks to answer this question using a 3D model of a standard 17 × 17 pressurised water reactor fuel assembly. Two cases were studied using the Serpent Monte Carlo code: the first considered the fuel assembly with constant boron concentration (traditionally found in many published papers), and the second considered boron iteration (where the boron concentration was reduced with burnup). Neutron spectra for the two cases at beginning of life and end of life were compared for spectral shifts. In addition, thermal spectral indices were used to assess spectrum hardening or softening with burnup. Spectral shifts to lower energies were observed in the thermal region of the neutron spectrum, whereas the fast region experienced no spectral shift. There was an increase in thermal spectral indices indicating that the spectrum became soft with burnup. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
18. Characterization of 3D micro-structured TIMEPIX detectors for neutron imaging.
- Author
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Polo, Matteo, Mendicino, Roberto, Quaranta, Alberto, and Dalla Betta, Gian-Franco
- Subjects
DETECTORS ,NEUTRONS ,X-rays ,RADIATION ,CLUSTER analysis (Statistics) - Abstract
Neutron imaging provides additional information to X-ray imaging and can be used in many applications, for example, nuclear engineering, non-industrial diagnostics and homeland security. This paper presents the latest development results of a new 3D structured pixel detector for thermal neutron detection and imaging. The device is based on Medipix/Timepix read-out chip family. The detector, without converter materials, was initially tested in the laboratory with a 241Am source, to simulate events that are induced by reaction products of active material in the silicon bulk. Thanks to the analysis of the size of event clusters and deposited energy, α particles and noise signals were discriminated. The detector was also tested with β and γ sources, to study the effect of other radiation on the device. These results can be useful as a starting point for future experiments, where a neutron source will be used, after filling the cavities with active materials, such as 6Li or 10B. In this paper, the results of the characterization and a comparison between experimental data and Monte Carlo simulations are shown. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
19. Modelling of a SiC Based Detector for the Interpretation of 14.1 MeV Neutrons Measurements.
- Author
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Potiron, Quentin, Destouches, Christophe, Dubus, Léo, Houry, Michael, Llido, Olivier, Lyoussi, Abdallah, Ottaviani, Laurent, and Reynard-Carette, Christelle
- Subjects
NEUTRONS ,SILICON carbide ,RADIATION ,MONTE Carlo method ,SEMICONDUCTORS - Abstract
Wide-bandgap semiconductor-based fast neutron detectors such as silicon carbide (SiC) seem to be a promising concept to meet the implementation requirements as well as the performance specifications for fusion and fission environments such as radiation hardness as well as thermal and mechanical stabilities. Beyond the problem of integration of the device in constrained environments, the issue of the quantitative response of the device in a mixed radiation field must be addressed. Therefore, the characterisation of the detector performances, according to the energy of the neutrons is a key first step needed for neutron detection and monitoring in mixed radiation environments with high levels of gammas and fast and thermal neutron fluxes emissions at large energy scales. This paper presents the interpretation of 14.1 MeV neutron measurements using a numerical model developed with the GEANT4 MonteCarlo transport code. The methodology used for a first attempt to estimate the fluence rate of incident neutrons is exposed and a calculation versus experiment ratio is determined. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. Alignment facility and software for single-crystal time-of-flight neutron spectroscopy
- Author
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Christopher D. Frost, Russell A. Ewings, Zihao Liu, Chris Stock, H. Lane, and J. Paul Attfield
- Subjects
Physics - Instrumentation and Detectors ,Materials science ,Nuclear engineering ,FOS: Physical sciences ,02 engineering and technology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,pole figures ,Software ,0103 physical sciences ,characterization ,Neutron ,Spallation ,physics.ins-det ,010302 applied physics ,Condensed Matter - Materials Science ,business.industry ,neutrons ,Materials Science (cond-mat.mtrl-sci) ,Instrumentation and Detectors (physics.ins-det) ,021001 nanoscience & nanotechnology ,Research Papers ,cond-mat.mtrl-sci ,Neutron spectroscopy ,Characterization (materials science) ,Time of flight ,Neutron source ,0210 nano-technology ,business ,Spallation Neutron Source - Abstract
An instrument and software algorithm is described for the purpose of characterization of large single crystals at the Alignment Facility (ALF) of the ISIS spallation neutron source. We describe a method for both characterizing the quality of the sample and also aligning it in a particular scattering plane. We present a software package written for this instrument and demonstrate its utility by way of an example of the structural characterization of large singles crystals of Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$. We suggest extensions and modifications of characterization instruments for future improved beamlines. It is hoped that this software will be used by the neutron user community for pre characterizing large single crystals for spectroscopy experiments and that future facilities will include such a facility as part of the spectroscopy suite at spallation neutron sources., (6 pages, 7 figures, to be published in Journal of Applied Crystallography); The software package can be found at https://github.com/CSTOCK3/ALF-Analysis-Software. Please email comments to the authors
- Published
- 2021
21. 50th anniversary and recent decade achievements of the Hokkaido University Neutron Source (HUNS) facility with cold-fast neutrons and high-energy electrons/X-rays.
- Author
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Sato, Hirotaka, Kamiyama, Takashi, Nagakura, Hiroki, Sato, Ko-ichi, Ohnuma, Masato, and Furusaka, Michihiro
- Subjects
NEUTRONS ,X-rays ,ASTROPHYSICS ,BIOLOGY ,CRYSTALLINITY - Abstract
In this paper, present status, scientific strategy, recent decade achievements and future perspectives of HUNS with cold, thermal, epithermal, fast neutrons and high-energy electrons/X-rays are presented. Time-of-flight small-angle cold neutron scattering with SAXS is useful for extended-duration materials and foods analysis. Irradiations using fast neutrons, thermal neutrons, 32 MeV electrons and MeV-class X-rays are used for not only soft error test of system-level semiconductor devices but also astrophysics and medical biology. Time-of-flight neutron imaging can accept big sample, system-level sample and many samples for crystalline microstructure and temperature analyses in steel, car and cultural heritage research fields. The reasons of such great activities are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
22. Proposal for determining absolute biological effectiveness of boron neutron capture therapy—the effect of 10B(n,α)7Li dose can be predicted from the nucleocytoplasmic ratio or the cell size
- Author
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Yuki Tamari, Minoru Suzuki, Hiroki Tanaka, Shin-ichiro Masunaga, Koji Ono, and Tsubasa Watanabe
- Subjects
inorganic chemicals ,Health, Toxicology and Mutagenesis ,Boron Neutron Capture Therapy ,Lithium ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Radiation sensitivity ,Cell Line, Tumor ,Regular Paper ,medicine ,Relative biological effectiveness ,Animals ,Humans ,Radiology, Nuclear Medicine and imaging ,Radiosensitivity ,Biology ,Boron ,Cell Nucleus ,Neutrons ,Radiation ,Chemistry ,business.industry ,Melanoma ,Dose-Response Relationship, Radiation ,medicine.disease ,BPA ,Neutron temperature ,D0 ,cell size ,Neutron capture ,Dose–response relationship ,030220 oncology & carcinogenesis ,BSH, N/C ratio ,Cell survival curve ,Nuclear medicine ,business ,Relative Biological Effectiveness ,boron-neutron dose - Abstract
The relationship between the radiation dose delivered to a tumor and its effect is not completely predictable. Uncertainty in the estimation of the boron concentration in a tumor, variation in the radiation sensitivity of the tumor cells, and the complexity of the interactions between the four types of radiation comprising the boron neutron capture therapy (BNCT) dose contribute to this uncertainty. We reanalyzed the data of our previous papers to investigate the variation in radiosensitivity of tumor cells to the 10B(n,α)7Li dose: the dose generated by the reaction of thermal neutrons and 10B, hereafter the ‘boron-neutron dose’. The radiosensitivities of five tumors (EL4, SAS/neo, SAS/mp53, SCCVII and B16-BL6 melanoma) were examined. For the combination of p-boron-L-phenylalanine (BPA: C9H12BNO4) with neutron irradiation, D0, the cell survival curve for the boron-neutron dose was the smallest for the SAS/neo, followed by the EL4, SAS/mp53, SCCVII and B16-BL6 melanoma, in that order. For the combination of mercaptoundecahydrododecaborate (BSH: Na2B12H11SH) with neutron irradiation, D0 was the smallest for the EL4, followed by the SAS/neo, B16–BL6melanoma, SAS/mp53 and SCCVII, in that order. The relationships between these D0 values and the nucleocytoplasmic ratios (Xncs) or cell size indices (Xcs) obtained by histopathological microslide image were as follows: (D0 = 0.1341Xnc–1.586, R2 = 0.9721) for all tumor types with BPA-BNCT, and D0 = 0.0122Xcs–0.1319 (R2 = 0.9795) for four tumor types (all except the B16-BL6 melanoma) with BSH-BNCT. Based on these results, we proposed a new biologically equivalent effectiveness factor: the absolute biological effectiveness (ABE) factor. The ABE factor is Gy/D0. Thus, the ABE dose is the physical dose multiplied by the ABE factor, and refers to the dose needed to decrease the cell survival rate to e–ABE dose/Gy.
- Published
- 2018
23. YC-1 sensitizes the antitumor effects of boron neutron capture therapy in hypoxic tumor cells
- Author
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K. Ichise, Yuki Wada, Mariko Sato, Katsumi Hirose, Yoshihiro Takai, Ken Takeda, Takahiro Kato, Takaomi Harada, and Masahiko Aoki
- Subjects
Radiation-Sensitizing Agents ,Indazoles ,Cell Survival ,Phenylalanine ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,Antineoplastic Agents ,Boron Neutron Capture Therapy ,Deferoxamine ,YC-1 ,Oxygen ,Large Neutral Amino Acid-Transporter 1 ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Cell Line, Tumor ,Neoplasms ,Gene expression ,Regular Paper ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,RNA, Small Interfering ,Boron ,hypoxia-inducible factor 1α ,Neutrons ,Gene knockdown ,Radiation ,Hypoxic tumor ,hypoxia ,Hypoxia (medical) ,Hypoxia-Inducible Factor 1, alpha Subunit ,Cell Hypoxia ,chemistry ,Cell culture ,030220 oncology & carcinogenesis ,MCF-7 Cells ,Cancer research ,AcademicSubjects/SCI00960 ,medicine.symptom ,medicine.drug - Abstract
The uptake of boron into tumor cells is a key factor in the biological effects of boron neutron capture therapy (BNCT). The uptake of boron agents is suppressed in hypoxic conditions, but the mechanism of hypoxia-induced modulation of suppression of boron uptake is not clear. Therefore, we evaluated whether hypoxia-inducible factor 1α (HIF-1α) contributes to attenuation of the antitumor effects of BNCT in hypoxic tumor cells. We also tested whether YC-1, a HIF-1α-targeting inhibitor, has therapeutic potential with BNCT. To elucidate the mechanism of attenuation of the effects of BNCT caused by hypoxia, deferoxamine (DFO) was used in experiments. Cells were incubated in normal oxygen, hypoxic conditions (1% O2) or 5 μM DFO for 24 h. Then, cells were treated with 10B-boronophenylalanine (BPA) for 2 h and boron accumulation in cells was evaluated. To clarify the relationship between HIF-1α and L-type amino acid transporter 1 (LAT1), gene expression was evaluated by a using HIF-1α gene knockdown technique. Finally, to improve attenuation of the effects of BNCT in hypoxic cells, BNCT was combined with YC-1. Boron uptake was continuously suppressed up to 2 h after administration of BPA by 5 μM DFO treatment. In cells treated with 5 μM DFO, LAT1 expression was restored in HIF-1α-knocked down samples in all cell lines, revealing that HIF-1α suppresses LAT1 expression in hypoxic cells. From the results of the surviving fraction after BNCT combined with YC-1, treatment with YC-1 sensitized the antitumor effects of BNCT in cells cultured in hypoxia.
- Published
- 2020
24. Microdosimetric quantities of an accelerator-based neutron source used for boron neutron capture therapy measured using a gas-filled proportional counter
- Author
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Naonori Hu, Ryohei Uchida, Yoshinori Sakurai, Hiroki Tanaka, Keita Okazaki, and Takushi Takata
- Subjects
Materials science ,tissue equivalent proportional counter ,Health, Toxicology and Mutagenesis ,Monte Carlo method ,Proportional counter ,Radiation ,030218 nuclear medicine & medical imaging ,Nuclear physics ,03 medical and health sciences ,0302 clinical medicine ,Regular Paper ,Relative biological effectiveness ,Humans ,Computer Simulation ,Radiology, Nuclear Medicine and imaging ,Irradiation ,Neutrons ,accelerator-based neutron source ,Absorption, Radiation ,Radiotherapy Dosage ,microdosimetry ,Neutron capture ,Gamma Rays ,boron neutron capture therapy ,030220 oncology & carcinogenesis ,Absorbed dose ,Neutron source ,Gases ,Particle Accelerators ,Monte Carlo Method ,Relative Biological Effectiveness - Abstract
Boron neutron capture therapy (BNCT) is an emerging radiation treatment modality, exhibiting the potential to selectively destroy cancer cells. Currently, BNCT is conducted using a nuclear reactor. However, the future trend is to move toward an accelerator-based system for use in hospital environments. A typical BNCT radiation field has several different types of radiation. The beam quality should be quantified to accurately determine the dose to be delivered to the target. This study utilized a tissue equivalent proportional counter (TEPC) to measure microdosimetric and macrodosimetric quantities of an accelerator-based neutron source. The micro- and macro-dosimetric quantities measured with the TEPC were compared with those obtained via the the particle and heavy ion transport code system (PHITS) Monte Carlo simulation. The absorbed dose from events >20 keV/μm measured free in air for a 1-h irradiation was calculated as 1.31 ± 0.02 Gy. The simulated result was 1.41 ± 0.07 Gy. The measured and calculated values exhibit good agreement. The relative biological effectiveness (RBE) that was evaluated from the measured microdosimetric spectrum was calculated as 3.7 ± 0.02, similar to the simulated value of 3.8 ± 0.1. These results showed the PHITS Monte Carlo simulation can simulate both micro- and macro-dosimetric quantities accurately. The RBE was calculated using a single-response function, and the results were compared with those of several other institutes that used a similar method. However, care must be taken when using such a single-response function for clinical application, as it is only valid for low doses. For clinical dose ranges (i.e., high doses), multievent distribution inside the target needs to be considered.
- Published
- 2020
25. A machine learning decision criterion for reducing scan time for hyperspectral neutron computed tomography systems.
- Author
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Tang, Shimin, Venkatakrishnan, Singanallur V., Chowdhury, Mohammad S. N., Yang, Diyu, Gober, Megan, Nelson, George J., Cekanova, Maria, Biris, Alexandru S., Buzzard, Gregery T., Bouman, Charles A., Skorpenske, Harley D., and Bilheux, Hassina Z.
- Subjects
IMAGE reconstruction algorithms ,ARTIFICIAL neural networks ,MACHINE learning ,COMPUTER systems ,NEUTRONS ,GOLDEN ratio - Abstract
We present the first machine learning-based autonomous hyperspectral neutron computed tomography experiment performed at the Spallation Neutron Source. Hyperspectral neutron computed tomography allows the characterization of samples by enabling the reconstruction of crystallographic information and elemental/isotopic composition of objects relevant to materials science. High quality reconstructions using traditional algorithms such as the filtered back projection require a high signal-to-noise ratio across a wide wavelength range combined with a large number of projections. This results in scan times of several days to acquire hundreds of hyperspectral projections, during which end users have minimal feedback. To address these challenges, a golden ratio scanning protocol combined with model-based image reconstruction algorithms have been proposed. This novel approach enables high quality real-time reconstructions from streaming experimental data, thus providing feedback to users, while requiring fewer yet a fixed number of projections compared to the filtered back projection method. In this paper, we propose a novel machine learning criterion that can terminate a streaming neutron tomography scan once sufficient information is obtained based on the current set of measurements. Our decision criterion uses a quality score which combines a reference-free image quality metric computed using a pre-trained deep neural network with a metric that measures differences between consecutive reconstructions. The results show that our method can reduce the measurement time by approximately a factor of five compared to a baseline method based on filtered back projection for the samples we studied while automatically terminating the scans. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Research on the Measurement Method of the Prompt Neutron Decay Constant Based on LHS-DMD-Rossi-Alpha.
- Author
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Li, Junguang, Xie, Jinsen, Deng, Nianbiao, Zhang, Erpin, Wu, Zhiqiang, Tong, Ji, and Yu, Tao
- Subjects
DECAY constants ,NEUTRONS ,LATIN hypercube sampling ,VALUE engineering - Abstract
In response to the significant dependency on empirical judgment in measuring the prompt neutron decay constant with the traditional Rossi-alpha method and the issue of requiring an excessive number of detectors with the DMD-Rossi-alpha method, this paper introduces a calculation method for the prompt neutron decay constant based on a combination of Latin Hypercube Sampling (LHS), Dynamic Mode Decomposition (DMD), and the Rossi-alpha method. Initially, the method uses LHS to expand the sample dataset of neutron noise data to reduce the number of detectors required. It then employs the Rossi-alpha method to construct a Rossi-alpha distribution model from neutron noise data. Finally, it utilizes DMD for feature extraction from the Rossi-alpha distribution model, thereby determining the prompt neutron decay constant. Research findings demonstrate that, by simulating the KUCA facility using RMC3.5 in a near-critical state, the relative error of the α value calculated by the LHS-DMD-Rossi-alpha method model is 9% less than that calculated by the Rossi-alpha method. This approach, capable of enhancing the precision of measuring the prompt neutron decay constant with just a single detector, holds significant theoretical value and engineering significance for the advancement of reactor physics and experimental techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. High-Precision Visual Servoing for the Neutron Diffractometer STRESS-SPEC at MLZ.
- Author
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Landesberger, Martin, Kedilioglu, Oguz, Wang, Lijiu, Gan, Weimin, Kornmeier, Joana Rebelo, Reitelshöfer, Sebastian, Franke, Jörg, and Hofmann, Michael
- Subjects
INDUSTRIAL robots ,DIGITAL twins ,NEUTRON diffraction ,NEUTRONS ,SURGICAL robots ,DIFFRACTOMETERS - Abstract
With neutron diffraction, the local stress and texture of metallic components can be analyzed non-destructively. For both, highly accurate positioning of the sample is essential, requiring the measurement at the same sample location from different directions. Current sample-positioning systems in neutron diffraction instruments combine XYZ tables and Eulerian cradles to enable the accurate six-degree-of-freedom (6DoF) handling of samples. However, these systems are not flexible enough. The choice of the rotation center and their range of motion are limited. Industrial six-axis robots have the necessary flexibility, but they lack the required absolute accuracy. This paper proposes a visual servoing system consisting of an industrial six-axis robot enhanced with a high-precision multi-camera tracking system. Its goal is to achieve an absolute positioning accuracy of better than 50 μ m. A digital twin integrates various data sources from the instrument and the sample in order to enable a fully automatic measurement procedure. This system is also highly relevant for other kinds of processes that require the accurate and flexible handling of objects and tools, e.g., robotic surgery or industrial printing on 3D surfaces. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Correction: Chakin et al. Tritium Desorption Behavior and Microstructure Evolution of Beryllium Irradiated at Low Temperature Up to High Neutron Dose in BR2 Reactor. J. Nucl. Eng. 2023, 4 , 552–564.
- Author
-
Chakin, Vladimir, Rolli, Rolf, Gaisin, Ramil, and van Renterghem, Wouter
- Subjects
TRITIUM ,BERYLLIUM ,LOW temperatures ,NEUTRON irradiation ,HIGH temperatures ,NEUTRONS ,DESORPTION - Abstract
This document is a correction notice for a published paper titled "Tritium Desorption Behavior and Microstructure Evolution of Beryllium Irradiated at Low Temperature Up to High Neutron Dose in BR2 Reactor." The authors have made several corrections to the figures, tables, and text in the paper. The changes include removing and adding figures, correcting correlations, clarifying the tritium content in irradiated beryllium, and updating the data availability statement. The authors state that these corrections do not affect the scientific conclusions of the paper. [Extracted from the article]
- Published
- 2024
- Full Text
- View/download PDF
29. Data Assimilation using Non-invasive Monte Carlo Sensitivity Analysis of Reactor Kinetics Parameters.
- Author
-
Kleedtke, N., Hutchinson, J., Cutler, T., Michaud, I., Rising, M.E., Hua, M., Alwin, J., Grosskopf, M.J., Vander Wiel, S., Neudecker, D., and Thompson, N.
- Subjects
CRITICALITY (Nuclear engineering) ,NEUTRONS ,SENSITIVITY analysis ,NUCLEAR physics experiments - Abstract
Accurately predicting the criticality of an experiment before interacting with the experimental components is very important for criticality safety. Radiation transport software can be utilized to calculate the effective neutron multiplication factor of a nuclear system. Because of the integral nature of the effective neutron multiplication factor, the value calculated contains various sources of nuclear-data induced uncertainty. The sensitivity analysis and data assimilation technique presented in this paper exhibit one possible method of identifying and reducing the effective neutron multiplication factor nuclear-data induced uncertainty. The results presented in this work show that it is possible to use relative sensitivity coefficients of the prompt neutron decay constant and the effective delayed neutron fraction to
239 Pu nuclear data to reduce nuclear-data induced uncertainties in the effective neutron ultiplication factor. This work has been utilized by members of the Los Alamos National Laboratory project EUCLID (Experiments Underpinned by Computational Learning for Improvements in Nuclear Data) for optimally designing a new experiment, which will be used to reduce compensating errors in239 Pu nuclear data. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
30. Uncertainty Considerations that Impact the Use of Dosimetry Metrics in Modern Semiconductors.
- Author
-
Griffin, Patrick
- Subjects
RADIATION dosimetry ,NEUTRONS ,SEMICONDUCTORS ,UNCERTAINTY ,AVIONICS - Abstract
The use of calculated dosimetry metrics is a crucial element in predicting neutron damage to modern semiconductors under various conditions, e.g., control electronics in avionic systems, satellite sensors, or power output from solar panels. These dosimetry metrics have little value unless they are accompanied by a quantified uncertainty. This paper outlines a mathematical framework that captures the response models for most semiconductor damage metrics and addresses some of the challenges faced in quantifying the relevant sources of uncertainty. The energy-dependent correlations in the damage functions are a critical underpinning in propagating the uncertainty back to a measured quantity. Significant issues are associated with "model defect" in some of the models used, i.e., assumptions in the model form that are not easily considered in the uncertainty estimate. Other issues relate to fundamental differences between the experimental measured quantity and the calculated metric used to represent the damage mode. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
31. DETECTION OF PHOSPHOLIPIDS ON PAPER CHROMATOGRAMS BY NEUTRON ACTIVATION
- Author
-
P, JOHNSON, E J, WEBER, H E, CARTER, and M S, KROBER
- Subjects
Neutrons ,Chromatography ,Phospholipids ,Activation Analysis - Published
- 1965
32. Evaluation of a new neutron energy spectrum unfolding code based on an Adaptive Neuro-Fuzzy Inference System (ANFIS)
- Author
-
Seyed Abolfazl Hosseini and Iman Esmaili Paeen Afrakoti
- Subjects
Normalization (statistics) ,Light ,Computer science ,Health, Toxicology and Mutagenesis ,02 engineering and technology ,01 natural sciences ,Bin ,Spectral line ,Fuzzy Logic ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Regular Paper ,Radiology, Nuclear Medicine and imaging ,Computer Simulation ,ANFIS ,unfolding ,neutron pulse height distribution ,Neutrons ,Adaptive neuro fuzzy inference system ,Radiation ,Americium ,Artificial neural network ,010308 nuclear & particles physics ,Inverse problem ,Neutron temperature ,252Cf ,Neutron source ,020201 artificial intelligence & image processing ,Neural Networks, Computer ,Algorithm ,neutron energy spectrum ,241Am-9Be ,Algorithms - Abstract
The purpose of the present study was to reconstruct the energy spectrum of a poly-energetic neutron source using an algorithm developed based on an Adaptive Neuro-Fuzzy Inference System (ANFIS). ANFIS is a kind of artificial neural network based on the Takagi–Sugeno fuzzy inference system. The ANFIS algorithm uses the advantages of both fuzzy inference systems and artificial neural networks to improve the effectiveness of algorithms in various applications such as modeling, control and classification. The neutron pulse height distributions used as input data in the training procedure for the ANFIS algorithm were obtained from the simulations performed by MCNPX-ESUT computational code (MCNPX-Energy engineering of Sharif University of Technology). Taking into account the normalization condition of each energy spectrum, 4300 neutron energy spectra were generated randomly. (The value in each bin was generated randomly, and finally a normalization of each generated energy spectrum was performed). The randomly generated neutron energy spectra were considered as output data of the developed ANFIS computational code in the training step. To calculate the neutron energy spectrum using conventional methods, an inverse problem with an approximately singular response matrix (with the determinant of the matrix close to zero) should be solved. The solution of the inverse problem using the conventional methods unfold neutron energy spectrum with low accuracy. Application of the iterative algorithms in the solution of such a problem, or utilizing the intelligent algorithms (in which there is no need to solve the problem), is usually preferred for unfolding of the energy spectrum. Therefore, the main reason for development of intelligent algorithms like ANFIS for unfolding of neutron energy spectra is to avoid solving the inverse problem. In the present study, the unfolded neutron energy spectra of 252Cf and 241Am-9Be neutron sources using the developed computational code were found to have excellent agreement with the reference data. Also, the unfolded energy spectra of the neutron sources as obtained using ANFIS were more accurate than the results reported from calculations performed using artificial neural networks in previously published papers.
- Published
- 2018
33. Atoms made from marshmallows
- Author
-
Allen, Barbara
- Published
- 2000
34. Proton therapy for non-squamous cell carcinoma of the head and neck: planning comparison and toxicity
- Author
-
Maho Yamada, Y. Hattori, Hiroyuki Ogino, Toshiyuki Toshito, Shingo Hashimoto, K. Nakajima, Kensuke Hayashi, Yuta Shibamoto, Yo Kuroda, Yoshihide Okumura, Chihiro Omachi, Jun-etsu Mizoe, and Hiromitsu Iwata
- Subjects
Adult ,Male ,X-ray intensity-modulated radiotherapy ,non-squamous cell carcinoma of the head and neck ,Health, Toxicology and Mutagenesis ,medicine.medical_treatment ,030218 nuclear medicine & medical imaging ,passive-scattering proton therapy ,03 medical and health sciences ,0302 clinical medicine ,Weight loss ,Proton Therapy ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Basal cell ,Radiometry ,Head and neck ,Pencil-beam scanning ,Proton therapy ,Aged ,Aged, 80 and over ,Neutrons ,Radiation ,patient-specific aperture system ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Regular Papers ,Dose-Response Relationship, Radiation ,pencil beam scanning ,Middle Aged ,Radiation therapy ,Oncology ,quality of life ,Head and Neck Neoplasms ,Non squamous ,030220 oncology & carcinogenesis ,Toxicity ,Female ,medicine.symptom ,business ,Nuclear medicine - Abstract
To investigate optimal treatment planning using proton beams for non-squamous cell carcinoma of the head and neck (NSCHN), the dose distributions of plans involving pencil beam scanning (PBS) with or without a patient-specific aperture system (PSAS), passive-scattering proton therapy (PSPT) and X-ray intensity-modulated radiotherapy (IMRT) were compared. As clinical results, toxicities of PBS with PSAS, including changes in quality of life, were reported. Between April 2014 and August 2016, a total of 30 patients were treated using PBS with PSAS. In 20 patients selected at random, the dose distributions of PBS with or without the PSAS, PSPT and IMRT plans were compared. Neutron exposure by proton therapy was calculated using a Monte Carlo simulation. Toxicities were scored according to CTCAE ver. 4.0. Patients completed EORTC quality of life survey forms (QLQ-C30 and QLQ-HN35) before and 0–12 months after proton therapy. The 95% conformity number of PBS with the PSAS plan was the best, and significant differences were detected among the four plans (P < 0.05, Bonferroni tests). Neutron generation by PSAS was ~1.1-fold higher, but was within an acceptable level. No grade 3 or higher acute dermatitis was observed. Pain, appetite loss and increased weight loss were more likely at the end of treatment, but recovered by the 3 month follow-up and returned to the pretreatment level at the 12 month follow-up. PBS with PSAS reduced the penumbra and improved dose conformity in the planning target volume. PBS with PSAS was tolerated well for NSCHN.
- Published
- 2019
35. Structure of voltage-dependent anion channel-tethered bilayer lipid membranes determined using neutron reflectivity
- Author
-
Susan K. Buchanan, Sergei Y. Noskov, Tatiana K. Rostovtseva, David P. Hoogerheide, Hirsh Nanda, and Adam J. Kuszak
- Subjects
Neutrons ,0301 basic medicine ,Protein Conformation ,Voltage-Dependent Anion Channel 1 ,Bilayer ,Lipid Bilayers ,Protein reconstitution ,Nitrilotriacetic acid ,Substrate (chemistry) ,Hydrogen-Ion Concentration ,Molecular Dynamics Simulation ,Research Papers ,Mice ,Neutron Diffraction ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,Membrane protein ,Structural Biology ,Monolayer ,Biophysics ,Animals ,Lipid bilayer ,Integral membrane protein - Abstract
Neutron reflectivity (NR) has emerged as a powerful technique to study the structure and behavior of membrane proteins at planar lipid interfaces. Integral membrane proteins (IMPs) remain a significant challenge for NR owing to the difficulty of forming complete bilayers with sufficient protein density for scattering techniques. One strategy to achieve high protein density on a solid substrate is the capture of detergent-stabilized, affinity-tagged IMPs on a nitrilotriacetic acid (NTA)-functionalized self-assembled monolayer (SAM), followed by reconstitution into the lipids of interest. Such protein-tethered bilayer lipid membranes (ptBLMs) have the notable advantage of a uniform IMP orientation on the substrate. Here, NR is used to provide a structural characterization of the ptBLM process from formation of the SAM to capture of the detergent-stabilized IMP and lipid reconstitution. The mitochondrial outer-membrane voltage-dependent anion channel (VDAC), which controls the exchange of bioenergetic metabolites between mitochondria and the cytosol, was used as a model β-barrel IMP. Molecular dynamics simulations were used for comparison with the experimental results and to inform the parameters of the physical models describing the NR data. The detailed structure of the SAM is shown to depend on the density of the NTA chelating groups. The relative content of detergent and protein in surface-immobilized, detergent-stabilized VDAC is measured, while the reconstituted lipid bilayer is shown to be complete to within a few percent, using the known atomic structure of VDAC. Finally, excess lipid above the reconstituted bilayer, which is of consequence for more indirect structural and functional studies, is shown to be present.
- Published
- 2018
36. Cosmological Implications of Light Element Abundances: Theory
- Author
-
Schramm, David N.
- Published
- 1993
37. A Novel Semiautomatic Interpretation Model for Impulse Neutron Oxygen Activation Time Spectrum Data.
- Author
-
Dong, Yong, Li, Mengxia, and Liao, Ruiquan
- Subjects
NEUTRONS ,OXYGEN ,TIME ,TRANSLATORS ,ALGORITHMS - Abstract
The existing interpretation models for the time spectrum of impulse neutron oxygen activation require interpreters to select the peak range or background range manually from the time spectrum curve, and there is no adaptive interpretation model that can determine the peak range or background range. In this paper, an adaptive selection rule for background segment is proposed, and a semiautomatic interpretation model is constructed by combining background segment interpretation model. Firstly, the interpretation operator selects the time spectrum curve, then the algorithm program adaptively determines the background segment according to the rules, and then calculates and displays the transit time and volume flow according to the background segment interpretation model. The processing results of the measured data show that the interpretation model in this paper not only retains the interpretation precision of the background interpretation model, but also reduces the labor intensity of the interpretation operator, realizing the semiautomatic interpretation of the time spectrum. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. Restoration of Photographs by Neutron Activation
- Author
-
Ostroff, Eugene
- Published
- 1966
39. Intersections of ultracold atomic polarons and nuclear clusters: how is a chart of nuclides modified in dilute neutron matter?
- Author
-
Hiroyuki Tajima, Hajime Moriya, Wataru Horiuchi, Eiji Nakano, and Kei Iida
- Subjects
CLUSTER theory (Nuclear physics) ,POLARONS ,NEUTRONS ,ULTRACOLD neutrons ,EQUATIONS of state ,NUCLIDES ,NUCLEAR matter - Abstract
Neutron star observations, as well as experiments on neutron-rich nuclei, used to motivate one to look at degenerate nuclear matter from its extreme, namely, pure neutron matter. As an important next step, impurities and clusters in dilute neutron matter have attracted special attention. In this paper, we review in-medium properties of these objects on the basis of the physics of polarons, which have been recently realized in ultracold atomic experiments. We discuss how such atomic and nuclear systems are related to each other in terms of polarons. In addition to the interdisciplinary understanding of in-medium nuclear clusters, it is shown that the quasiparticle energy of a single proton in neutron matter is associated with the symmetry energy, implying a novel route toward the nuclear equation of state from the neutron-rich side. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Two-energy group neutron diffusion model in spherical reactors.
- Author
-
Momani, Shaher, Shqair, Mohammed, Batiha, Iqbal M., Abu-Sei'leek, Mohammed H. E., Alshorm, Shameseddin, and El-Azeem, S. A. Abd
- Subjects
NEUTRON diffusion ,EULER method ,NEUTRON temperature ,NEUTRONS ,FRACTIONAL calculus - Abstract
This paper investigates the neutron diffusion model with two energy groups in spherical reactors. In particular, the integer-order two energy groups neutron diffusion model in spherical reactors is resolved using the Laplace transform method by regarding the spherical radius r as a time domain. Next, we transform the neutron diffusion model into fractional-order versions using the Caputo differentiator, resulting in what is referred to as the fractional-order two-energy-group neutron diffusion model. To address this fractional-order system, we introduce a novel approach to reduce a system of 2a -order to a duplicated system of a -order, where 0 <α 1. This converted system is then solved using one of the recent modifications of the fractional Euler method called the Modified Fractional Euler Method (MFEM). Several numerical simulations are depicted to verify our findings. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Isotopic variations of Sm, Gd, Er and Yb found in planetary materials caused by neutron-capture reactions in nature.
- Author
-
Hidaka, Hiroshi
- Subjects
THERMAL neutrons ,LUNAR soil ,LUNAR surface ,SAMARIUM ,PLANETARY science ,YTTERBIUM ,NEUTRON irradiation ,NEUTRONS - Abstract
The isotopic shifts of
149 Sm–150 Sm and157 Gd–158 Gd have often been observed in meteorites and lunar surface materials, because they result from the neutron-capture reactions associated with secondary neutrons produced by cosmic-ray irradiation. While the Sm and Gd isotopic shifts can mainly be used for the estimation of thermal neutron fluences that of167 Er–168 Er has recently been applied in the estimation of epithermal neutron fluences. The systematic isotopic dataset of Sm, Gd and Er helps us to consider the details of planetary materials' cosmic-ray exposure conditions using the balance of the fluences between thermal and epithermal neutrons. This paper reviews a series of isotopic variations of Sm, Gd, and Er in association with neutron-capture reactions for the application of planetary sciences. As a new attempt and possibility for better understanding the neutron fluence and its energy distribution, the use of Yb isotopic variation is then discussed using two different data sources, namely lunar regolith and the Oklo natural reactors. Finally, the preliminary result for the precise isotopic measurement of Yb is presented from the viewpoint of chemical separation and instrumental improvement. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
42. Intersections of ultracold atomic polarons and nuclear clusters: how is a chart of nuclides modified in dilute neutron matter?
- Author
-
Tajima, Hiroyuki, Moriya, Hajime, Horiuchi, Wataru, Nakano, Eiji, and Iida, Kei
- Subjects
CLUSTER theory (Nuclear physics) ,POLARONS ,NEUTRONS ,ULTRACOLD neutrons ,NUCLIDES ,EQUATIONS of state ,NUCLEAR matter - Abstract
Neutron star observations, as well as experiments on neutron-rich nuclei, used to motivate one to look at degenerate nuclear matter from its extreme, namely, pure neutron matter. As an important next step, impurities and clusters in dilute neutron matter have attracted special attention. In this paper, we review in-medium properties of these objects on the basis of the physics of polarons, which have been recently realized in ultracold atomic experiments. We discuss how such atomic and nuclear systems are related to each other in terms of polarons. In addition to the interdisciplinary understanding of in-medium nuclear clusters, it is shown that the quasiparticle energy of a single proton in neutron matter is associated with the symmetry energy, implying a novel route toward the nuclear equation of state from the neutron-rich side. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Isospin-Symmetry Breaking within the Nuclear Shell Model: Present Status and Developments.
- Author
-
Smirnova, Nadezda A.
- Subjects
NUCLEAR shell theory ,NUCLEAR reactions ,EXOTIC nuclei ,RADIOACTIVE decay ,NUCLEAR astrophysics ,ISOBARIC spin ,NEUTRONS ,SYMMETRY breaking - Abstract
The paper reviews the recent progress in the description of isospin-symmetry breaking within the nuclear shell model and applications to actual problems related to the structure and decay of exotic neutron-deficient nuclei and nuclei along the N = Z line, where N is the neutron number and Z the atomic number. The review recalls the fundamentals of the isospin formalism for two-nucleon and many-nucleon systems, including quantum numbers, the spectrum's structure and selection rules for weak and electromagnetic transitions; and at the end, summarizes experimental signatures of isospin-symmetry breaking effects, which motivated efforts towards the creation of a relevant theoretical framework to describe those phenomena. The main approaches to construct accurate isospin-nonconserving Hamiltonians within the shell model are briefly described and recent advances in the description of the structure and (isospin-forbidden) decay modes of neutron-deficient nuclei are highlighted. The paper reviews major implications of the developed theoretical tools to (i) the fundamental interaction studies on nuclear decays and (ii) the estimation of the rates of nuclear reactions that are important for nuclear astrophysics. The shell model is shown to be one of the most suitable approaches to describing isospin-symmetry breaking in nuclear states at low energies. Further efforts in extending and refining the description to larger model spaces, and in developing first-principle theories to deal with isospin-symmetry breaking in many-nucleon systems, seem to be indispensable steps towards our better understanding of nuclear properties in the precision era. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. Study of light hypernuclei in Europe: The hypertriton and nnΛ puzzles.
- Author
-
Rappold, C., Achenbach, P., Alibrahim Alfaki, H., Amjad, F., Armstrong, M., Behr, K.-H., Benlliure, J., Brencic, Z., Dickel, T., Drozd, V., Dubey, S., Ekawa, H., Escrig, S., Feijoo-Fontan, M., Fujioka, H., Gao, Y., Geissel, H., Goldenbaum, F., Graña Gonzalez, A., and Haettner, E.
- Subjects
HYPERFRAGMENTS ,ATOMS ,ION beams ,NEUTRONS ,DATA analysis - Abstract
The current understanding of light hypernuclei, which are sub-atomic nuclei with strangeness, is being challenged and studied in detail by several European research groups and collaborations. In recent years, studies of hypernuclei using high-energy heavy ion beams have reported unexpected results on the three-body hypernuclear state
3 Λ H, named the hypertriton. For some time, reports of a shorter lifetime and larger binding energy than what was previously accepted have created a puzzling situation for its theoretical description; this is known as the "hypertriton puzzle". With the inclusion of the most recent experimental measurements, the current status of the hypertriton puzzle is evolving. Additionally, the possible neutral bound state of a Λ hyperon with two neutrons, nnΛ, has raised questions about our understanding of the formation of light hypernuclei either in bound or resonance states. These results have initiated several ongoing experimental programs all over the world to study these three-body hypernuclear states precisely. We are studying these light hypernuclear states by employing heavy ion beams at 2AGeV on a fixed carbon target with the WASA detector system and the Fragment Separator (FRS) at GSI. The WASA-FRS experimental campaign was performed during the first quarter of 2022, and this paper presents a short overview of the campaign and how it seeks to tackle the hypertriton and nnΛ puzzles. Data analysis is ongoing, and several preliminary results will be reported. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
45. s-process Nuclear Reaction Rates.
- Author
-
Rapagnani, David
- Subjects
NUCLEAR reactions ,NEUTRONS ,LOW energy electron diffraction ,STELLAR dynamics ,SUPERFLUIDITY - Abstract
In stars the
13 C(α, n)16 O and22 Ne(α, n)25 Mg reactions are the two main sources of neutrons for the so-called slow neutron capture process (s-process), which is one of the main mechanisms for the stellar synthesis of heavy elements. About13 C(α, n)16 O, in despite of many efforts in measuring its cross section at the lower energies, only high uncertainty data above the s-process Gamow window (150 keV < Ecm < 230 keV) were available, due mostly to the difficulties on suppress the natural background. Indeed, only recently the LUNA collaboration performed high precision underground measurements of the reaction cross section inside the Gamow window, improving the accuracy of its extrapolation at the lower energies. Again due to natural background, only upper limits for the22 Ne(α, n)25 Mg reaction cross section are currently known in the s-process Gamow window (450 keV < Ecm < 750 keV). For this, the ERC founded project SHADES (Unina/INFN) aims to perform high precision and high sensitivity measurements of the22 Ne(α, n)25 Mg reaction cross section down to the neutron threshold. A sensitivity improvement of at least two orders of magnitude over the state of the art is expected thanks to the low natural background environment of the INFN-LNGS laboratory in Italy, the high beam current of the new LUNAMV accelerator and the Beam Induced Background events suppression performed by SHADES hybrid detectors array. In this paper I will present the LUNA efforts to estimate nuclear reaction rates for13 C(α, n)16 O, with a focus on the R-Matrix analysis performed with the code AZURE2 to extrapolate nuclear reaction rates at stellar energies and the estimate of their uncertainty through Monte Carlo methods. I will also present an overview of the SHADES project to measure22 Ne(α, n)25 Mg in the Gamow window and the first results on the setup commissioning. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
46. Absolute neutron and photon flux characterization in the CNESTEN's TRIGA Mark II research reactor.
- Author
-
Ghninou, H., Gruel, A., Lyoussi, A., Reynard-Carette, C., El Younoussi, C., El Bakkari, B., and Boulaich, Y.
- Subjects
- *
NEUTRONS , *PHOTONS , *NUCLEAR energy , *RADIATION dosimetry , *RADIOISOTOPES - Abstract
The National Center for Nuclear Energy, Sciences and Technology (CNESTEN) located in Rabat, Morocco, operates a 2 MW TRIGA Mark II research reactor. This type of reactor is specially designed to effectively implement the various fields of nuclear research such as neutron activation analysis, neutron radiography, detectors testing, radioisotopes production as well as education and training. In the last few years, a collaboration between the French Atomic Energy and Alternative Energies Commission (CEA) and the CNESTEN was established to expand the utilization of the TRIGA computational model by carrying out new in-situ measurements in order to characterize neutron and photon fields within and beyond the TRIGA reactor core. These new measurements will consolidate the knowledge of neutron and photon fluxes in different irradiation and instrumentation channels. The results of these experiments will also be used to extend the experimental validation of the new developed TRIPOLI-4® computational model of the reactor and to quantify the uncertainties and biases. This paper focuses on the neutron and photon flux characterization of two irradiation channels inside the TRIGA reactor core. Neutron measurements are ensured by activation dosimetry whereas photon measurements are ensured by thermo-luminescent detectors (TLD400 – CaF2: Mn). Based on these techniques, the experiments were carried out during an experimental campaign conducted in June 2022. Preceding the implementation of these measurements, two experimental devices were specifically designed and manufactured to ensure a reproducible positioning of the detectors in the selected irradiation channels. This paper presents the experimental results analysis and the associated uncertainty quantification. These results will be then compared to the calculation ones obtained by the computational models of the TRIGA reactor. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
47. Radioactive Direction of Arrival Estimation Using Neural Networks Approach.
- Author
-
Salomon, Yossi, Vax, Eran, Osowizky, Alon, Knafo, Yakir, Ben David, Nadav, and Vilenchick, Dan
- Subjects
IRRADIATION ,RADIATION ,RADIATION dosimetry ,RADIOLOGY ,NEUTRONS - Abstract
In this paper, we present a comprehensive investigation into improving Direction of Arrival (DOA) estimation for gamma-emitting isotopes using deep neural networks. The direction of arrival estimation is most valuable for Home Land Security (HLS) applications or increased safety in Decontamination and Decommissioning (D&D). Traditional methods, such as beamforming (BF), have limitations in accuracy and sensitivity to noise and background variations. In recent years, data-driven approaches utilizing deep neural networks, including Convolutional Neural Network (CNN) and Gated Recurrent Unit (GRU) models, have shown promise in enhancing DOA estimation. By considering the full energy spectrum and augmenting recorded data, our neural network models outperform traditional BF methods and exhibit greater resilience in diverse background scenarios. The 2-layer CNN model, in particular, achieves up to 40% improvement in estimation accuracy. Our research provides a reliable and data-driven approach for precise DOA estimation with potential applications in nuclear security and safety in D&D. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
48. The MICADO Integrated Gamma Station for Radioactive Waste Packages radiological characterization.
- Author
-
Lepore, L., Gandolfo, G., Marzo, G.A., Cherubini, N., Casagrande, D., Palumbo, E., Ratto, N., Fanchini, E., Pepperosa, A., Giordano, F., and Morichi, M.
- Subjects
GAMMA rays ,RADIOACTIVE substances ,RADIOLOGY ,NEUTRONS ,TOMOGRAPHY - Abstract
The MICADO (Measurement and Instrumentation for Cleaning And Decommissioning Operations) Project of the H2020 Research and Innovation Programme aims to propose a cost-effective solution for non-destructive characterization of nuclear waste, implementing a digitization process that could become a referenced standard facilitating and harmonizing the methodology used for the in-field Waste Management and Dismantling & Decommissioning operations. It employs instruments based on different technologies: an active and passive neutron measurement system, a photo-fission facility, and the 'Integrated Gamma Station'. Within the MICADO Project, an entire work package has been dedicated to the design and realization of the 'Integrated Gamma Station' obtained by combining different gamma detection technologies supporting each other to a comprehensive and effective non-destructive gamma characterization, able to accommodate Radioactive Waste Packages of different sizes. The techniques implemented are i) dosimetry measurements, count rate inspection and raw spectroscopy with the CAEN RadHAND, ii) gamma imaging in open geometry with the CEA Nanopix gamma camera, iii) high resolution gamma spectrometry with the ENEA Tomographic Gamma Scanner (TGS). The latter able to carry out different characterization methodologies, i.e., Open Geometry, Segmented Gamma Scanning, Angular Scanning, and Tomography. This paper describes the layout of the Integrated Gamma Station conceived, its features and detection capabilities, and part of the measurement campaign realized during the MICADO Project. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. Specially developed LR-0 reactor graphite environment for gen IV reactor support and cross-section measurement.
- Author
-
Peltan, Tomas, Vilimova, Eva, Czakoj, Tomas, Matej, Zdenek, Mravec, Filip, Cvachovec, Frantisek, Simon, Jan, Juricek, Vlastimil, and Kostal, Michal
- Subjects
NUCLEAR reactors ,GRAPHITE ,SCINTILLATION counters ,NEUTRONS ,ATOMS - Abstract
This paper is focused on the development of the experimental environment connected to reactor graphite. Regarding its very good neutronic and mechanical properties, graphite will be very important in some new reactor designs, such as high-temperature or molten salt SMR reactors. These new reactor concepts require a new experimental environment as support for further research. In the laboratories of the Research Centre Řež and at the LR-0 reactor, the new experimentally validated graphite environment was created. This large graphite insertion is the largest graphite mono-block, which is possible to assemble at the LR-0 reactor. Sets of experiments for measuring reaction rates of different activation detectors for neutron field mapping were performed. This approach was used for thermal and epithermal region descriptions. For the fast neutron spectrum evaluation, the stilbene scintillation detector was used. All parameters, such as criticality height of moderator level, neutron spectrum, and other parameters for all experiments, were performed using Monte Carlo neutronic codes Serpent and MCNP. The obtained results were finally compared to the measurement of neutron leakage spectra from the graphite cube and graphite cylinder. These specially developed graphite-shaped neutron fields, reactor insertions, and external cube and cylinder with Cf neutron source can be used in the future for validation of not only materials used in SMR reactors but for arbitrary cross-section verification. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
50. The CABRI fast neutrons Hodoscope: CABRI model and signal-to-mass conversion charts.
- Author
-
Chevalier, Vincent and Di Salvo, Jacques
- Subjects
NEUTRONS ,NUCLEAR research ,SIMULATION methods & models ,HYDRAULICS - Abstract
The CABRI experimental pulse reactor, located at the Cadarache nuclear research center, southern France, is devoted to the study of Reactivity Initiated Accidents (RIA). The hodoscope, installed in the CABRI reactor, is a unique online fuel motion monitoring system, operated by IRSN. This equipment is dedicated to the measurement of the fast neutrons emitted by the tested rod, in real time (with a rate of 1ms), during the power pulse. It is one of the distinctive features of the CABRI reactor facility, which is operated by CEA. To support the experimental task around CABRI reactor, by the experimenters who work on the Hodoscope, a Monte Carlo model, using the MORET code, is used by IRSN. This paper presents the main outcomes obtained during the reactor commissioning tests functioning, using Hodoscope results compared to MORET calculations, which proves the validity of the CABRI MORET model. Furthermore, we show how MORET code is used to build the signal-to-mass conversion charts of the Hodoscope. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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