Abstract We employ a probabilistic mesoscopic description to draw conceptual and quantitative analogies between Brownian motion and late-time fluctuations of thermal correlation functions in generic chaotic systems respecting ETH. In this framework, thermal correlation functions of ‘simple’ operators are described by stochastic processes, which are able to probe features of the microscopic theory only in a probabilistic sense. We apply this formalism to the case of semiclassical gravity in AdS3, showing that wormhole contributions can be naturally identified as moments of stochastic processes. We also point out a ‘Matryoshka doll’ recursive structure in which information is hidden in higher and higher moments, and which can be naturally justified within the stochastic framework. We then re-interpret the gravitational results from the boundary perspective, promoting the OPE data of the CFT to probability distributions. The outcome of this study shows that semiclassical gravity in AdS can be naturally interpreted as a mesoscopic description of quantum gravity, and a mesoscopic holographic duality can be framed as a moment-vs.-probability-distribution duality.
Nuclear and particle physics. Atomic energy. Radioactivity
XuanLong-50 (EXL-50) is the first medium-size spherical torus (ST) in China, with the toroidal field of 0.5 T at a major radius of 50 cm. Central Solenoid (CS)—free and non-inductive current drive via electron cyclotron resonance heating (ECRH) were the main physics research issue for EXL-50. Plasma currents from 50 kA to 180 kA were routinely achieved in EXL-50, with the current flattops sustained for up to or beyond 2 s. The current drive effectiveness on EXL-50 reached as high as 1 A W ^−1 for low-density discharges using 28 GHz ECRH alone for heating power less than 200 kW. The plasma current reached I p > 80 kA for high-density (>5 × 10 ^18 m ^−2 ) discharges with 150 kW 28 GHz ECRH. Higher performance discharge ( I p of about 120 kA and core density of about 1 × 10 ^19 m ^−3 ) was achieved with 150 kW 50 GHz ECRH. The plasma current in EXL-50 was mainly carried by the energetic electrons. The physics mechanisms for the solenoid-free ECRH current drive and the energetic electrons have also been investigated. Preliminary experimental results indicate that 100 kW of lower hybrid current drive waves can drive 20 kA of plasma current. Several boron injection systems were installed and tested in EXL-50, including B _2 H _6 gas puffing, boron powder injection, boron pellet injection. The upgrade of EXL-50, the EXL-50U, has begun experimental research to address these issues of ST proton-boron plasmas over a much wider parameter space.
Nuclear and particle physics. Atomic energy. Radioactivity
Sheng-Han Xiong, Yong-Zhuang Li, Xiao-Mei Kuang
et al.
Abstract In this article, the shadow and the quasinormal modes (QNMs) of an exact asymptotically flat hairy electrically charged black hole solution with a dilaton potential are investigated. Using the constraint equation among the integration constant $$\eta $$ η of the gravitational field, the mass M, the electric charge Q and the coupling constant $$\nu $$ ν between the U(1) field and the dilaton field, we find that the shadow radii, the Lyapunov exponent $$\lambda $$ λ and the coordinate angular velocity $$\Omega _{c}$$ Ω c only significantly affected by $$\nu $$ ν if the Q is close to the extremal value. Especially, near the $$\nu =1$$ ν = 1 critical point the phenomenon exhibits singular enhancement. Furthermore, the QNMs are numerically computed by using the Hatsuda method and verified with the higher-order WKB approximations with the Padé summation. We find that the QNMs are close to that of the low energy limit of the string theory when $$\nu $$ ν is large enough. In the eikonal limit, the real and imaginary parts are proved to be approximated by $$\Omega _{c}$$ Ω c and $$\lambda $$ λ , respectively.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
ZHANG Kaihui, ZHUANG Kun, ZHANG Xinxin, WANG Senshan, DENG Lina, WANG Yongzhan, WANG Yingzhen
Space heat pipe reactors have the advantages of miniaturization, long life, and strong environmental adaptability, and have broad application prospects in the aerospace field. This study focused on a high-enrichment space heat pipe reactor KRUSTY-HEU proposed by Los Alamos National Laboratory. While maintaining the reactivity, the volume was optimized by adding moderator materials to reduce the control rod’s volume and the reflector thickness to decrease spacecraft launch costs and launch loads. In terms of moderator selection, zirconium hydride was selected by comparing the moderator materials commonly used in space reactor with yttrium hydride. For moderator configuration, three schemes including a moderator located inside the core, in the middle, and dispersed in fuel were proposed, and reactivity and safety were analyzed. Three schemes added the same amount of moderator, and the scheme with the largest initial excess reactivity was selected. The results show that the scheme of moderator located inside the core is better than the other two schemes, and the minimum reflector thickness is 8.69 cm, which is 3.11 cm less than before, and the volume is reduced by about 30%. And the reactor remains subcritical state when the control rod is fully inserted and in an unexpected dropping accident. The neutronics and thermal-mechanics were carried out for the optimized scheme. The results show that the fuel temperature has little influence on the reactivity, besides the reactivity do not change with the change of moderator temperature. Moving reflector can control the reactivity effectively, the differential value of the reflector control is highest when the radial reflector moves about 20 cm. The reactivity caused by burnup is small, when the reactor runs for 15 years, the reactivity is basically unchanged, due to the low power of 4.3 kW. During normal operation, the core temperature and thermal displacement are not much different from before, and the maximum thermal stress is about 200 MPa at the interface of moderator and core, which exceeds the yield limit of core material. The thermal stress is effectively reduced to about 63.3 MPa within the yield limit of the material by adding a gap between the moderator and the core. Single pipe failure analysis shows that core temperature, displacement and thermal stress have changed, but it do not affect its safety. In summary, the moderator located inside the core scheme proposed in this study can effectively reduce the volume of KRUSTY-HEU, and the thermal-mechanical coupling characteristics show that the optimized core still has high safety and stability.
Refers to: “D. Sagatov, “Comparative analysis of copper X-radiation intensity with LiF and KBr crystals”, tbusphys, vol. 2, no. 1, p. 0007, Jan. 2024. doi: 10.54355/tbusphys/2.1.2024.0007” In the originally published version of this article, the Methods section lacked detailed information about the experimental apparatus specifications, data acquisition process, and statistical analysis. The following corrections have been made: Section 2 (Methods): - The revised text now includes specific details of the experimental setup: manufacturer and model of the HUBER X-ray diffraction system, goniometer configuration, collimator aperture, scan parameters, and data acquisition software (SPEC Control Software). - Additional details have been added on repeated measurements (triplicate readings), calculation of mean values, standard deviations, and propagation of error for wavelength and energy estimations. - Statistical reliability criteria (<2% relative uncertainty) have been introduced to validate the results. Minor textual clarifications were made to improve reproducibility and accuracy of the described procedure. Additionally, the following references have been updated: “Fitted empirical reference cross sections for K-shell ionization by protons / H. Paul, J. Sacher // Atomic Data and Nuclear Data Tables. — 1989. — Vol. 42, No. 1. — P. 105–156” has been replaced with “Empirical K-shell ionization cross-sections of elements from 4Be to 92U by proton impact / A. Kahoul, M. Nekkab, B. Deghfel // Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. — 2008. — Vol. 266, No. 23. — P. 4969–4975. https://doi.org/10.1016/j.nimb.2008.09.008”; “Cross Sections for K‐shell X‐ray Production by Hydrogen and Helium Ions in Elements from Beryllium to Uranium / G. Lapicki // Journal of Physical and Chemical Reference Data. — 1989. — Vol. 18, No. 1. — P. 111–218. https://doi.org/10.1063/1.555838” have been replaced with “Feasibility study of thin films deposited on a self-supporting carbon grid substrate target on the measurement of atomic inner-shell ionization cross-sections impacted by 3-30 keV electrons / Z. C. Qian, Y. Wu, C. H. Chang, Y. Yuan, C. S. Mei, J. J. Zhu, K. Moharram // EPL. — 2017. — Vol. 118, No. 1. — Article number. 13001. https://doi.org/10.1209/0295-5075/118/13001”; “Energy-loss effect in inner-shell Coulomb ionization by heavy charged particles / W. Brandt, G. Lapicki // Physical Review A. — 1981. — Vol. 23, No. 4. — P. 1717–1729” have been replaced with “Theoretical models to calculate stopping and ionization ratios of H2+ molecules in solid targets / C. D. Archubi, N. R. N. Arista // Physical Review A. — 2019. — Vol. 99, No. 3. — Article number 032702. https://doi.org/10.1103/PhysRevA.99.032702”; “Specific conductance of the molten LiF-KCl and LiF-KBr systems / C. Xu, G. Liu, N. Chen // Jinshu Xuebao/Acta Metallurgica Sinica. — — Vol. 20, No. 5. — P. b320–b322.” Have been replaced with “Phase Assemblage of the Li+,Na+,K+||F–,Cl–,Br– Five-Component Reciprocal System and Its LiF–KCl–KBr–NaBr–NaCl Stable Pentatope / A.V. Burchakov, I. K. Garkushin, U. A. Emel’yanova Russian Journal of Inorganic Chemistry. — 2023. — Vol. 68, No. 7. — P.889–897. https://doi.org/10.1134/S003602362360082X”. These amendments do not affect the scientific results, discussion, or conclusions of the paper but enhance methodological transparency.
Abstract In principle, the local cosmic void can be simply modeled by the spherically symmetric Lemaitre–Tolman–Bondi (LTB) metric. In practice, the real local cosmic void is probably not spherically symmetric. In this paper, to reconstruct a more realistic profile of the local cosmic void, we divide it into several segments. Each segment with certain solid angle is modeled by its own LTB metric. Meanwhile, we divide the 1048 type Ia supernovae (SNIa) of the Pantheon Survey into corresponding subsets according to their distribution in the galactic coordinate system. Obviously, each SNIa subset can only be used to reconstruct the profile of one segment. Finally, we can patch together an irregular profile for the local cosmic void with the whole Pantheon sample. Note that, the paucity of each data subset lead us to focus on the inner part of each void segment and assume that the half radii of the void segments are sufficient to constrain the whole segment. We find that, despite $$2\sigma $$ 2 σ signals of anisotropy limited to the depth of the void segments, the constraints on every void segment are consistent with $$\Lambda $$ Λ CDM model at 95% CL. Moreover, our constraints are too weak to challenge the cosmic homogeneity and isotropy.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
The effect of Ag nanoparticles (NPs) on the optical and optoelectronic properties of films based on graphene oxide has been studied. In the presence of Ag NPs, the morphology, as well as the thickness of graphene oxide films, were not changed. When Ag NPs were added, a change in the shape and position of the absorption bands and Raman spectra of graphene oxide was observed. It is shown that with the addition of Ag NPs, the G band of graphene oxide shifts to low frequencies, which may be the result of the absence of separate double bonds, while the ID/IG ratio was not changed, as did the number of Gr layers. In the absorption spectrum of the films, along with the absorption band of graphene oxide, a shoulder was registered, which can be associated with the absorption of Ag NPs. The optical density of Gr films with plasmonic NPs is higher than without them. Measurements of the optoelectronic characteristics showed that, in the presence of Ag NPs, an increase in the values of the photocurrent of graphene oxide is observed. The sensitivity of graphene oxide films was increased by almost 20 times when plasmonic NPs were added to them, and the detection ability increased by 25 times.
The results obtained can be used in the development of new photosensitive devices for optoelectronic and applications.
Nuclear and particle physics. Atomic energy. Radioactivity, Thermodynamics
The 6th International Nuclear Chemistry Congress (INCC-6, https:// incc-6. lzqid ian. com) was held in 29th Aug-2nd Sept. 2022 in Lanzhou, China, and organized by Lanzhou University in cooperation with the Institute of Modern Physics, Chinese Academy of Science. The INCC is one of the series of international conferences in nuclear and radiochemistry, which was launched in 2005 by the International Nuclear Chemistry Society (INCS). The last three INCC were held in Sicily, Italy in Sep. 2011(3rd –INCC), Meresias Beach, Brazil in Sep. 2014 (4th-INCC) and in Gothenburg, Sweden, in Sep. 2017 (5th-INCC), respectively. The INCC-6 was proposed to be held in Sept. 2020 in Lanzhou, China as the regular frequency of every 3 years. However, the COVID-19 pandemic occurred in the beginning of 2020, the conference has to be postponed for a few times until Aug. 2022. Since the pandemic was still not yet over, and travel restriction makes it difficult to be organized as a fully face-toface conference. It was therefore held as a hybrid conference of both on-line and on-site. The topics of the INCC-6 covers all aspects of nuclear and radiochemistry. In total, 186 abstracts were accepted and 193 presentations including 6 plenary, 34 invited, 72 oral and 81 posters were given in the conference by the researchers and students from 62 institutions in 19 countries, such as Canada, China, Czech Republic, Finland, France, Germany, Hungary, Japan, Korea, Lithuanian, Italy, Poland, Russia, Slovakia, Singapore, Switzerland, the Netherland, United kingdom and United States of America (Fig. 1). More than 300 people attended the conference including about 130 on-site participants (Fig. 2). In the opening session, Prof. Chunhua Yan, the president of Lanzhou University, gave a warm welcome speech with a brief introduction of Lanzhou University, the president of the INCS, prof. Flavia Groppi gave a speech with a briefly introduction of the background and status of the INCS (Fig. 3). Six lectures in different topics in nuclear and radiochemistry were presented in the plenary session on 29th Aug. Prof. Zhifang Chai from Institute of High Energy Physics, Chinese Academy of Sciences reviewed the history, status and progress of nuclear and radiochemistry in China with his 60 years scientific career as example. Prof. Amares Chatt from Dalhousie University, Canada presented applications of nuclear analytical techniques in environmental, biological and medical research with a title on “speciation analysis using reactor neutrons and synchrotron radiation”. Prof. Yuichiro Nagame from Japan Atomic Energy Agency presented an overview on chemistry of heavy elements entitled on “chemistry of heavy actinides using their low-energy ion beam”. Prof. Xiaolin Hou from Lanzhou University and Institute of Earth Environment, China presented research progress on environmental radioactivity and radioecology in China entitled on “Environmental radioactivity in China: level, distribution and sources”. Prof. Xiaoyuan (Shawn) Chen from National University of Singapore presented an overview and progress in radiopharmaceutics entitled on “cancer radiotheranostics”. Prof. Thomas Albrecht-Schönzart from Florida University, USA presented a new progress on nuclear chemistry entitled on “the Quest for californium (II)” (Fig. 4). Overall 34 invited lectures on the new progresses of different aspects of nuclear and radiochemistry were presented in 12 conference sessions. In the computing chemistry of radionuclides, a lecture on Theoretical actinide chemistry: progress and perspectives was presented by Prof. Jun Li. In the topic of nuclear chemistry, 2 lectures on chemical studies of the heaviest known elements: niobium (element 113), flerovium (element 114) and moscovium (element 115) by prof. Christoph E. Düllmann, and Pentavalent americium: preparation, stabilization and separation by prof. Chao Xu were presented. In the topic of separation materials and technology in nuclear and radiochemistry, 6 lectures entitled on Harvesting exotic radionuclides at PSI by Dr. Dorothea Schumann, Spontaneous multi-scale supramolecular assembly * Xiaolin Hou houxl@lzu.edu.cn
We investigated the feasibility on the application of a superconducting radio frequency (SRF) niobium cavity to an accelerator-based neutron source for boron neutron capture therapy (BNCT). Neutron source is the key component of BNCT and adopting rf-linac based neutron source realizes a medical care system sufficient to be compact, which can be installed in a hospital and to generate intensive neutron yields that the BNCT requires. However, it is still desirable to improve the efficiency of input power on neutron yields and the achievable accelerate field gradient. SRF accelerator technology potentially allows us to enhance the performance because of its prominent lower ohmic loss and higher sustainable accelerating fields. This paper presents a first feasibility study on the application of a SRF niobium cavity to an accelerator-based neutron source for BNCT, assuming that a superconducting radio frequency quadrupole (SC-RFQ) composed of pure bulk niobium at 4.2 K accelerates the proton/deuteron beams to a beryllium or lithium target for the neutron production of BNCT via ^{7}Li(p,n)^{7}Be, ^{9}Be(p,n)^{9}B, or ^{9}Be(d,n)^{10}B. The following beam parameters were used: beam energy of 2.5 MeV (for Li target)/5 MeV (for Be target), ion source current (50 keV, CW 30 mA), normalized beam emittance of 0.02 cm mrad, and resonance frequency of 325 MHz (for proton)/162.5 MHz (for deuteron). Based on these conditions, we evaluated the feasibility on the following three criteria: comparison of the cooling capacity of the refrigerator to the amount of heat, power consumption of AC, and size of the BNCT system. First, we evaluated the amount of heat generated in a cryomodule by adding the ohmic loss of SC-RFQ Q_{rf}, beam losses in SC-RFQ Q_{b}, heat penetration into the cryomodule Q_{ext}, and beam losses of molecular ion beams and poor quality beams emitted from the ion-source at/near the RFQ entrance Q_{emit}. In this study, we typically regarded Q_{ext} as 20 W at 4.2 K and considered a new low-energy beam transport system that can suppress Q_{emit} to 0. In addition, Q_{rf} and Q_{b} were numerically evaluated by beam simulation and electromagnetic calculation. The obtained results revealed that the sum of the heat amounts could be sufficiently suppressed below the typical cooling capacity of a commercially available helium refrigerator. Second, we compared the ac power consumption of BNCT between a conventional and SC-BNCT systems, which indicated that the BNCT system adopting the SRF cavity effectively reduced the ac power consumption of SC-BNCT by almost 1/4 times. Third, the length of the SC-RFQ could be shortened by adjusting the peak surface E-field, as compared to conventional existing RFQs such as J-PARC, SNS, and IFMIF. Eventually, this study demonstrated that the application of the SRF cavity for the rf-linac-based neutron source of BNCT is feasible, and thus provides a foundation for the future development of design for next-generation BNCT systems.
Nuclear and particle physics. Atomic energy. Radioactivity
As a part of SPIRAL1 upgrade, several experiments were carried out to understand the transport of 1+ (monocharged) ion beam through the SP1 ECR charge breeder ion source and to investigate the physical processes involved in charge breeding. Ion beam transport simulations were performed to reproduce the trends of the experimental results (charge breeding efficiency versus 1+ beam injection energy ΔV) by transporting the 1+ beam through a potential map that reflects the presence of the ECR (electron cyclotron resonance) plasma. The role of Coulomb collisions in the capture of 1+ beam leads to a necessary detailed analysis for an accurate description of the charge breeding process. This was done by using a full six-dimensional (6D) phase space Monte Carlo charge breeding (MCBC) code. MCBC models Coulomb collisions of the injected 1+ beam in an ECR plasma and atomic processes (ionization and charge exchange). A simplified background ECR plasma model is implemented in the code to reproduce the trends of three different experiments (interaction of Na^{1+} with He plasma, K^{1+} with He plasma and K^{1+} with O_{2} plasma). The model is able to reproduce the low charge state (1+ and 2+) experimental trends by tuning each plasma parameter (plasma density, plasma ion temperature and electron temperature) independently. The estimated plasma parameters obtained from each case are presented and their contribution in charge breeding process are discussed.
Nuclear and particle physics. Atomic energy. Radioactivity
Abstract Chiral Separation Effect (CSE) for systems that feature spin 3/2 fermions was considered. For the self-consistent Adler’s model with relativistic massless Rarita-Schwinger fermions (RSA model), we found that the CSE conductivity is five times larger than for massless Dirac fermions. For a model of four-fold band crossing in Rarita-Schwinger-Weyl semimetals, in which massless fermions with quasispin 3/2 exist, we calculated that the CSE conductivity is four times larger than for Weyl fermions. We show that CSE conductivity for any multi-degenerate Fermi point in topological semimetals is proportional to its Chern number and is topologically protected. Along the calculations, we proved an index theorem that relates Chern number of a Fermi-point and spectral asymmetry of the corresponding Landau band structure. The assumption that CSE for any system of chiral fermions is dictated by the corresponding Chern number is found to be correct for RSA model (and for the Dirac fermions).
Nuclear and particle physics. Atomic energy. Radioactivity
Vanessa Sanches Pereira da Silva, José Roberto Ferreira Neto, Silvia Lucas Ferreira da Silva
et al.
Maraging steels are martensitic steels hardened by precipitation of intermetallic compounds in thermal aging, with good machining properties and high strength, fracture toughness and corrosion resistance, being used in aircraft parts and rocket motor-case, tooling applications and nuclear plants. During thermal aging in steam atmosphere a protective and corrosion resistant oxide layer is formed over the bulk. In this work, conventional Bragg-Brentano geometry was used to identify the phases formed in four specimens of maraging steel grade 300 with different surface finishes that were previously solution annealed twice at (950 ± 5) °C for 1 h, air-cooled, and submitted to oxidation process under positive pressure about 1.5 kPa of steam at (480 ± 5) °C for 6 h, followed by forced air-cooling. Diffraction patterns were measured employing CuKα radiation, ranging 20º < 2θ < 85º and the Rietveld method was used to better characterize the structures identified. Through Rietveld refinements it was possible to conclude that the layer formed during heat treatment process is constituted by a transition metallic phase with a quasi-cubic face centered unit cell, and an oxide layer that includes hematite, magnetite and a spinel structure type MFe2O4, where M could be an alloying element, for all analyzed samples.
Medical physics. Medical radiology. Nuclear medicine, Radioactivity and radioactive substances
Abstract We use the replica method to compute the entanglement entropy of a universe without gravity entangled in a thermofield-double-like state with a disjoint gravitating universe. Including wormholes between replicas of the latter gives an entropy functional which includes an “island” on the gravitating universe. We solve the back-reaction equations when the cosmological constant is negative to show that this island coincides with a causal shadow region that is created by the entanglement in the gravitating geometry. At high entanglement temperatures, the island contribution to the entropy functional leads to a bound on entanglement entropy, analogous to the Page behavior of evaporating black holes. We demonstrate that the entanglement wedge of the non-gravitating universe grows with the entanglement temperature until, eventually, the gravitating universe can be entirely reconstructed from the non-gravitating one.
Nuclear and particle physics. Atomic energy. Radioactivity
The international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) is the next generation accelerator complex for fundamental and applied research with antiproton and ion beams. FAIR will provide worldwide unique facilities enabling a wide spectrum of unprecedented forefront research in hadron and nuclear physics, in atomic physics and nuclear astrophysics as well as in applied sciences like materials research, plasma physics and radiation biophysics. Key features of FAIR are intense beams of antiprotons and ions up to the heaviest and even exotic nuclei covering an energy range from rest up to 30 GeV/u. We present a brief overview on the current construction status of the FAIR accelerator facilities and the associated research pillars with emphasis on PANDA . PANDA (antiProton Annihilation in Darmstadt), is the central experiment to fully exploit the physics research potential of the High Energy Storage Ring (HESR) with intense, phase-space cooled, antiprotons up to 15 GeV/c impinging on a variety of fixed targets. The PANDA detector features two spectrometers, the Target Spectrometer with a SC solenoid magnet of 2 T and the Forward Spectrometer with a 2 Tm dipole magnet. In both spectrometers the PANDA collaboration employs a multitude of modern detector technologies to provide tracking, particle identification, calorimetry and muon identification, arranged hermetically close to 4π around the interaction region with additional detectors for coverage of the forward boosted particles. Focusing on the various PANDA detector systems we present an overview of recent developments, the detector construction progress and conclude with an outline for a phased deployment of PANDA at FAIR.
The Gamma Factory project offers the possibility of creating novel re- search tools by producing relativistic beams of highly ionised atoms in CERN’s accelerator complex and exciting their atomic degrees of freedom by lasers to produce strongly collimated high-energy photon beams. Inten- sity of such beams would exceed by several orders of magnitude the ones offered by the presently operating light sources, in the particularly interest- ing energy domain from about 100 keV to above 400 MeV. In this energy regime, the high-intensity photon beams can be used to produce secondary beams of polarised electrons, polarised positrons, polarised muons, neu- trinos, neutrons and radioactive ions. New research opportunities in many domains of physics, from particle physics through nuclear physics to atomic physics, can be opened by the Gamma Factory scientific programme based on the above primary and secondary beams. Except for basic research, it offers also a possibility for various application studies, e.g. in medical physics and nuclear power.
The mechanical and hydraulic properties of unsaturated clay under nonisothermal conditions have practical implications in geotechnical engineering applications such as geothermal energy harvest, landfill cover design, and nuclear waste disposal facilities. The water menisci among clay particles impact the mechanical and hydraulic properties of unsaturated clay. Molecular dynamics (MD) modeling has been proven to be an effective method in investigating clay structures and their hydromechanical behavior at the atomic scale. In this study, we examine the impact of temperature increase on the capillary force and capillary pressure of the partially saturated clay‐water system through high‐performance computing. The water meniscus formed between two parallel clay particles is studied via a full‐scale MD modeling at different elevated temperatures. The numerical results have shown that the temperature increase impacts the capillary force, capillary pressure, and contact angle at the atomic scale. The capillary force on the clay particle obtained from MD simulations is also compared with the results from the macroscopic theory. The full‐scale MD simulation of the partially saturated clay‐water system can not only provide a fundamental understanding of the impact of temperature on the interface physics of such system at the atomic scale, but also has practical implication in formulating physics‐based multiscale models for unsaturated soils by providing interface physical properties of such materials directly through high‐performance computing.
Abstract We formulate a model of noncommutative four-dimensional gravity on a covariant fuzzy space based on SO(1, 4), that is the fuzzy version of the dS4. The latter requires the employment of a wider symmetry group, the SO(1, 5), for reasons of covariance. Addressing along the lines of formulating four-dimensional gravity as a gauge theory of the Poincaré group, spontaneously broken to the Lorentz, we attempt to construct a four-dimensional gravitational model on the fuzzy de Sitter spacetime. In turn, first we consider the SO(1, 4) subgroup of the SO(1, 5) algebra, in which we were led to, as we want to gauge the isometry part of the full symmetry. Then, the construction of a gauge theory on such a noncommutative space directs us to use an extension of the gauge group, the SO(1, 5)×U(1), and fix its representation. Moreover, a 2-form dynamic gauge field is included in the theory for reasons of covariance of the transformation of the field strength tensor. Finally, the gauge theory is considered to be spontaneously broken to the Lorentz group with an extension of a U(1), i.e. SO(1, 3)×U(1). The latter defines the four-dimensional noncommutative gravity action which can lead to equations of motion, whereas the breaking induces the imposition of constraints that will lead to expressions relating the gauge fields. It should be noted that we use the Euclidean signature for the formulation of the above programme.
Nuclear and particle physics. Atomic energy. Radioactivity