Subjects: Electronics and Communication Technology >> Electron Technology Subjects: Engineering and technical science >> Technology of Instrument and Meter Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties submitted time 2024-04-23
Abstract： In this work, we design and fabricate the transimpedance Amplifier (TIA) following the design mentioned in Ref. cite{Liang2024}. In the TIA, the preamplifier (Pre-Amp) is made of a junction field effect transistor (JFET) that can work at 77 K. The post-amplifier is made of an operational amplifier (OPA). Cascade Pre-Amp and Post-Amp to form the inverting-amplifier (Inv-Amp). The gain-bandwidth product of Inv-Amp with the gain about 50,000 is higher than 10 GHz. With a 1.13 Gohm feedback network, the gain of TIA is 1.13 Gohm and its bandwidth is about 97 kHz. The equivalent input noise voltage power spectral density of TIA is not more than 9 (nV)2/Hz at 10 kHz and 4 (nV)2/Hz at 50kHz, and its equivalent input noise current power spectral density is about 26 (fA)2/Hz at 10 kHz and 240(fA)2/Hz at 50 kHz. The measured transport performances and noise performances of TIA are consistent with the simulations and calculations, verifying the feasibility for the design of low-noise large-bandwidth TIA proposed in Ref. 1 . And, TIA with various performances that meet various needs can be designed according to the design methods in Ref. 1,2 . With the same gain, the bandwidth of the TIA in this work is much larger than the present TIA and its noises are much lower than those of present ones. The TIA in this work is perfect for the cryogenic STM working at 77 K (i.e. liquid nitrogen temperature).
Peer Review Status:
Awaiting Review
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties submitted time 2024-04-22
Abstract： Electron-diffraction patterns with 5-fold rotational symmetry of experimental alloy phases are assumed to be produced by periodic structures. A three-dimensional periodic structures is presented based on two kind polyhedrons. These structures can be used as an atomic model to describe the alloy phases. The Fourier-transform patterns of the models are found to be similar to the corresponding electron-diffraction patterns of these alloy phases along three “symmetry directions”. Details of the motivations and approaches that lead to these models are discussed.
Peer Review Status:Awaiting Review
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2024-04-22
Abstract： The possibility of Lorentz symmetry breaking has been discussed in many models of quantum gravity. In this paper we followed the Lorentz violation model in Ref. 14 to discuss the Doppler frequency shift of photons and the Compton scattering process between photons and electrons, pointing out that following the idea in Ref. 14 we have to modify the usual quantum relation of photons involved in the Doppler effect. But due to the current limited information and knowledge, we couldn’t yet determine the specific expression for the correction coefficient of the quantum relation of photons. However, the phenomenon of spontaneous radiation in a cyclotron maser give us an opportunity to see what the expression for this correction coefficient might look like, as the phenomenon of spontaneous radiation in a cyclotron maser can be explained by the Doppler effect of virtual photons and the Compton scattering process between virtual photons and electrons (or other particles). Therefore, under some restrictive conditions, we construct a very concise expression for this correction coefficient by discussing different cases. And then we used this expression to analyze the wavelength of radiation in the cyclotron maser, which tends to be a limited value at v→c, rather than to be 0 as predicted by the Lorentz model.And we also discussed the inverse Compton scattering phenomenon and found that there is a limit to the maximum
energy that can be obtained by photons in the collision between ultra-high energy particles and low-energy photons, which conclusion is also very different from that obtained from the Lorentz model, in which the energy that can be obtained by the photon tends to be infinite as the velocity of particle is close to c. This paper still inherits the idea in Ref. 14 that the energy and momentum of particles (i.e., any particles, including photons) cannot be infinite, otherwise it will
make some physical scenarios meaningless, and this view is also from the idea in some quantum gravity models. When the parameter Q characterizing the degree of deviation from the Lorentz model is equal to 0, all the results and conclusions in this paper will return to the case as in the Lorentz model, so this paper also provides us with a possible experimental scheme to determine the value of Q in Ref. 14 , although it still requires extremely high experimental energy.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Celestial Mechanics Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2024-04-20
Abstract： This article presents a brief introduction to a systematic improvement in celestial dynamics theory through the introduction of a new symmetrical form of particle dynamics equation. For open multi-body systems where it is challenging to find a highly accurate inertial reference frame, approximations of inertial frames need to be introduced. However, the new symmetric equation can be applied to any translational reference frame, thus avoiding the need for inertial reference frame approximations and enhancing the accuracy of theoretical predictions. In the case of bound multi-body systems, the traditional approach involves introducing a center of mass reference frame, applying Newton’s second law in this frame, and then transforming it back to the actual reference frame, such as the perturbation equation of the solar system’s planets. Conversely, applying the new symmetric equation allows for the direct derivation of planetary perturbation equations. Furthermore, by considering temporary thrust or impact forces acting on planets, or to further enhance computational precision, even considering any external forces acting on the bound system, then a new correction equation has been established for the planetary perturbation equation that can be further imposed with non-perturbative interactions.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2024-04-18
Abstract： Based on the dinuclear system model, the calculated evaporation residue cross sections matched well with the current experimental results. The synthesis of superheavy elements Z = 121 was systematically studied through combinations of stable projectiles with Z = 21–30 and targets with half-lives exceeding 50 d. The influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in detail. The reactions 254Es (46Ti, 3n) 297121 and 252Es (46Ti, 3n) 295121 were found to be experimentally feasible for synthesizing superheavy element Z = 121, with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV, respectively.
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties submitted time 2024-04-17
Shuqiang He
Yi-Feng Zheng
Guosheng Shi
Yi-Jie Xiang
Meihui Xiao
Qituan Zhang
Yue-Yu Zhang
Haiping Fang
Abstract： The identification of new materials with superconducting properties is the pursuit in the realm of superconductivity research. Here, excitedly, we show that the simplest salt daily used can be made a superconductor at normal pressure only by adjusting its stoichiometry of Na and Cl as Na3Cl at normal pressure based on first-principles calculations. This bulk stable abnormal Na-Cl stoichiometric crystal of 3:1, the first ‘magic’ ratio, includes metallic (Na) atoms in the core as well as hybridization of ionic and metallic bonding, facilitating the electron-phonon-coupling for superconductivity with a critical temperature Tc of 0.13 K. The flat bands and van Hove singularities near the Fermi level produce large densities of states, similar to H3S and LaH10, which is beneficial for the emergence of superconductivity. The crystal composed of with abnormal Na-Cl magic stoichiometry is a precisely tunable, purely sodium and chloride-based, three-dimensional bulk superconductor, which is therefore an ideal material for designing and understanding abnormal stoichiometric crystals. The methodology of constructing this bulk abnormal crystal may be general to almost all elements, which could lead to insights into the physics of other conventional superconductors and even high-critical-temperature superconductors.
Peer Review Status:Awaiting Review
Subjects: Engineering and technical science >> Physics Related Engineering and Technology Subjects: Engineering and technical science >> Technology of Instrument and Meter Subjects: Electronics and Communication Technology >> Electron Technology Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology submitted time 2024-04-16
Abstract： In this work, a design of transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. The TIA with the tip-sample component in CryoSTM is called as CryoSTM-TIA. With transimpedance gain of 1 Gohm, the bandwidth of the CryoSTM-TIA is larger than 200 kHz. The distinctive feature of the proposed CryoSTM-TIA is that its pre-amplifier is made of a single cryogenic high electron mobility transistor (HEMT), so the apparatus equivalent input noise current power spectral density at 100 kHz is lower than 6 (fA)2/Hz. In addition, bias-cooling method can be used to in-situ control the density of the frozen DX- centers in the HEMT doping area, changing its structure to reduce the device noises. With this apparatus, fast scanning tunneling spectra measurements with high-energy-resolution are capable to be performed. And, it is capable to measure scanning tunneling shot noise spectra (STSNS) at the atomic scale for various quantum systems, even if the shot noise is very low. It provides a powerful tool to investigate novel quantum states by measuring STSNS, such as detecting the existence of Majorana bound states in the topological quantum systems.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2024-04-15
Abstract： The search for chiral magnetic effects (CME) in relativistic heavy-ion collisions helps us to understand CP symmetry breaking in strong interactions and the topological nature of the quantum chromodynamic (QCD) vacuum. A two-plane method was proposed based on the fact that the background and signal of CME have different correlations relative to the spectator plane and the participant plane. Using a multiphase transport model with different input strengths of CME, we revisit the two-plane method in isobar collisions at √sNN = 200 GeV. The relative correlations of the CME signal and background to two different planes were found to be different, which is inconsistent with the assumptions made in the current experimental measurements. The difference arises from the decorrelation of the CME relative to the spectator and participant planes, which originates from the final state interactions. Our finding suggests that the current experimental measurements may overestimate the fraction of the CME signal in the final state in relativistic heavy-ion collisions.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-12
Abstract： A systematic comparison of the odd-$A$ cobalt isotopes $^{53-65}$Co’s negative parity halo states energy level structures indicates a level inversion between $9/2^-$ and $11/2^-$ in $^{55}$Co, and suggests that $^{53,57}$Co might exhibit strong collective effects. Shell model calculations based on the GXPF1A effective interaction reproduce well these nuclei’s halo state energy levels, along with the corresponding experimental values for magnetic moments and electric quadrupole moments. The shell model results show that the dominant proton configuration component in the ground state $7/2^-$ wave functions of $^{53-65}$Co is $ pi left(1f_{7/2} right)^7$. The excited states $9/2^-$ and $11/2^-$ in $^{55}$Co involve a competition between $1f_{7/2}$ proton excitation and $1f_{7/2}$ neutron excitation, leading to a possible level inversion between the $9/2^-$ and $11/2^-$ states. Moreover, using the Constrained Hartree-Fock (CHF) method to study the quadrupole deformation characteristics of $^{53,55,57}$Co, and combining the average occupancy numbers and configurations obtained from shell model calculations, the reasons why the excited state energies of $^{55}$Co are higher compared to other Co isotopes were analyzed.
Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics Subjects: Astronomy >> Astrophysical processes submitted time 2024-04-11
Abstract： The electromagnetic fields of point sources with time varying charges moving in the vacuum are derived using the Liénard-Wiechert potentials. The properties of the propagation velocities and the Doppler effect are discussed based on their far fields. The results show that the velocity of the electromagnetic waves and the velocity of the sources cannot be added like vectors; the velocity of electromagnetic waves of moving sources are anisotropic in the vacuum; the transverse Doppler shift is intrinsically included in the fields of the moving sources and is not a pure relativity effect caused by time dilation. Since the fields are rigorous solutions of the Maxwell’s equations, the findings can help us to abort the long-standing misinterpretations concerning about the classic mechanics and the classic electromagnetic theory. Although it may violate the theory of the special relativity, we show mathematically that, when the sources move faster than the light in the vacuum, the electromagnetic barriers and the electromagnetic shock waves can be clearly predicted using the exact solutions. Since they cannot be detected by observers in the region outside their shock wave zones, an intuitive and reasonable hypothesis can be made that the superluminal sources may be considered as a kind of electromagnetic blackholes.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2024-04-10
Abstract： A theory of quantum reference frame is considered in the paper, the induced Ricci flow of quantum spacetime and gravity theory are discussed by considering the second order moment of the quantum fluctuation of the reference frame. We also discuss the cosmic acceleration (cosmological constant problem), radial acceleration discrepancy of galaxies, inflation in the early universe, and the origin of spacetime entropy. Finally, we propose some possible predictions of the theory.
Peer Review Status:Awaiting Review
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2024-04-10
Abstract： Artificial Neural Network (ANN) has become a powerful tool in the field of scientific research with its powerful information encapsulation ability and convenient variational optimization method. In particular, there have been many recent advances in computational physics to solve variational problems. Deep neural network (DNN) is used to represent the wave function to solve quantum many-body problems using variational optimization. In this work we used a new Physics-Informed Neural Network (PINN) to represent the Cumulative Distribution Function (CDF) of some classical problems in quantum mechanics and to obtain their ground state wave function and ground state energy through the CDF. By benchmarking against the exact solution, the error of the results can be controlled at a very low level. This new network architecture and optimization method can provide a new choice for solving quantum many- body problems.
Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics Subjects: Electronics and Communication Technology >> Optoelectronics and Laser Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2024-04-08
Abstract： The Einstein’s theory of special relativity is based on his two postulates. The first is that the laws of physics are the same in all inertial reference frames. The second is that the velocity of light in the vacuum is the same in all inertial frames. The theory of special relativity is considered to be supported by a large number of experiments. This paper revisits the two postulates according to the new interpretations to the exact solutions of moving sources in the laboratory frame. The exact solutions are obtained using the classic Maxwell’s theory, which clearly show that the propagation velocity of the electromagnetic waves of moving sources in the vacuum is not isotropic; the propagation velocity of the electromagnetic waves and the moving velocity of the sources cannot be added like vectors; the transverse Doppler effect is intrinsically included in the fields of the moving sources. The electromagnetic sources are subject to the Newtonian mechanics, while the electromagnetic fields are subject to the Maxwell’s theory. We argue that since their behaviors are quite different, it is not a best choice to try to bind them together and force them to undergo the same coordinate transformations as a whole, like that in the Lorentz transformations. Furthermore, the Maxwell’s theory does not impose any limitations on the velocity of the electromagnetic waves. To assume that all objects cannot move faster than the light in the vacuum need more examinations. We have carefully checked the main experiment results that were considered as supporting the special relativity. Unfortunately, we found that the experimental results may have been misinterpreted. We here propose a Galilean-Newtonian-Maxwellian relativity, which can give the same or even better explanations to those experimental results.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2024-04-08
Abstract： The study of nuclear isoscalar giant monopole resonance (ISGMR) is an important way to constrain nuclear incompressibility coefficient $K_ infty$, which provides important information for the understanding of nuclear astrophysics phenomena. At present, there is a serious discrepancy in the unified descriptions of the ISGMR in Pb and Sn isotopes, which prevents us from the accurate determination of $K_ infty$. In this paper, we reviewed the recent progress in understanding this problem within the framework of quasiparitcle random phase approximation as well as quasiparticle-vibration coupling models.
Subjects: Physics >> Nuclear Physics submitted time 2024-04-01
Abstract： Using two nuclear models, i) the relativistic continuum Hartree-Bogoliubov (RCHB) theory
and ii) the Weizs acker-Skyrme (WS) model WS$^ ast$,
the performances of nine kinds of kernel functions in the kernel ridge regression (KRR) method
are investigated by comparing the accuracies of describing the experimental nuclear charge
radii and the extrapolation abilities.
It is found that, except the inverse power kernel, other kernels can reach the same level
around 0.015-0.016~fm for these two models with KRR method.
The extrapolation ability for the neutron rich region of each kernel depends on the trainning data.
Our investigation shows that the performances of the power kernel and Multiquadric kernel are
better in the RCHB+KRR calculation, and the Gaussian kernel is better in the WS$^ ast$+KRR calculation.
In addition, the performance of different basis functions in
the radial basis function method is also investigated for comparison.
The results are similar to the KRR method.
The influence of different kernels on the KRR reconstruct function is discussed
by investigating the whole nuclear chart.
At last, the charge radii of some specific isotopic chains have been investigated
by the RCHB+KRR with power kernel and the WS$^ ast$+KRR with Gaussian kernel.
The charge radii and most of the specific features in these isotopic chains
can be reproduced after considering the KRR method.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-28
Abstract： Charge exchange reactions with the intermediate energy can be used to study the complex structure of atomic nuclei from the respect of spin-isospin excitation. By utilizing the radioactive beam line at the Institute of Modern Physics, Chinese Academy of Sciences, charge exchange reaction experiments in inverse kinematics can expand the target nuclides to be studied to neutron-rich nuclei and even unstable nuclei. Based on this, a detector system for charge exchange reaction experiments has been designed, which mainly consists of a 3He gas target, TPC and CsI(Tl) arrays, where the TPC and CsI(Tl) arrays form a ΔE-E system. Using simulation software such as Geant4 and Garfield++, the operating conditions of the TPC were optimized, the kinematic intervals and the basic design of the detector for the experimental study were determined, and the particle discrimination ability of the detection system was investigated. Based on the simulation, the detection system was built.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-27
Abstract： Background: The propagation and power deposition process of ion cyclotron waves in plasma is the key to ICRH.
Purpose: The purpose of this study is to evaluate the effect of single absorption assumption and non-single absorption assumption on ion cyclotron wave coupling and heating in the EAST.
Methods: Under different antenna current phases, the simulation results of the EAST 3D full vacuum chamber ICRH program and the 1/4 vacuum chamber ICRH program were compared.
Results: When the antenna current phase is (0 π 0 π), there is a significant difference between the simulation results of the two models.
Conclusion: The ion cyclotron wave propagating multiple times in the toroidal direction is the main reason for the difference in results. For fusion devices, the applicability of the single absorption assumption needs further systematic research.
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties submitted time 2024-03-26
Abstract： Under typical circumstances, it is commonly believed that solutions carrying a single type of charge are either non-existent or unstable. We have investigated the principles of high-concentration charged solution preparation techniques, employing methods such as electrostatic attraction, gravity separation, positive feedback, and self-powered mechanisms to effectively separate anions and cations in solution. Through electrostatic repulsion and the use of electrostatic separation networks, the partition of homoelectric ions has been achieved. Through water and electric separation, the capability for sustained accumulation of single-charge species has been attained, thus overcoming application bottlenecks and establishing evidence for the existence of charged solutions. We have proposed voltage limits and predicted phenomena such as electrostatic boiling, topological ice crystals, and strange ice crystals, thereby opening new perspectives and possibilities for enriching the understanding and research of electrostatics and electrochemistry. The introduction of the high-concentration charged solution and its controllable preparation are expected to facilitate or pioneer research in various fields including seawater desalination, wastewater treatment, hydrovoltaic power generation, and topological ice crystals, etc. This advancement holds the potential to rectify relevant discussions in textbooks. Implementing the dual electrostatic method for self-powered desalination and purification, coupled with wind, solar, and pumped hydro storage technologies, can aid in mitigating the intermittency and waste of wind and solar power, thus advancing the cause of seawater for land.
Peer Review Status:Awaiting Review
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology submitted time 2024-03-23
Abstract： To predict the fractal decoded image quality more efficiently, an accumulated collage error coefficient (ACEC) based method was proposed in this study. Firstly, the definition of ACEC was introduced to describe the relationship among the upper bound, lower bound, and actual value of the accumulated collage error of all range blocks. Moreover, the definition and monotonicity of the relative error of ACEC were also defined and discussed. While the relative error of ACEC reaches a relatively small value, the average collage error (ACER) can be estimated approximately, and then the encoding process can be terminated to directly predict the peak signal-to-noise ratio (PSNR) quality of decoded images. Experimental results show that compared with the previous method, the proposed method can predict the decoded image quality more accurately with fewer computations.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2024-03-22
Abstract： Meson beam and nucleus collision experiments have played an important role in the field of nuclear physics and particle physics at medium and high energies, especially in the study of hadron spectroscopy, where a series of important experimental measurements have been achieved. In this paper, several typical meson beam experiments in the world are summarized, including J-PARC experiment in Japan, COMPASS experiment, AMBER experiment and HIKE experiment planned at CERN, GlueX experiment and EIC project at JLab in the United States. Furthermore, parameters of secondary meson beam are estimated based on HIAF facility in China, and physical measurements are discussed. Through the investigation of these experimental projects, the purpose is to provide some inspiration and reference for the further planning and construction of meson beam experimental equipment in China and the related research on hadron physics.
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