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Liang, Ruibin, Jessica M. J. Swanson, Mårten Wikström i Gregory A. Voth. "Understanding the essential proton-pumping kinetic gates and decoupling mutations in cytochrome c oxidase". Proceedings of the National Academy of Sciences 114, nr 23 (23.05.2017): 5924–29. http://dx.doi.org/10.1073/pnas.1703654114.
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Cytochrome c oxidase (CcO) catalyzes the reduction of oxygen to water and uses the released free energy to pump protons against the transmembrane proton gradient. To better understand the proton-pumping mechanism of the wild-type (WT) CcO, much attention has been given to the mutation of amino acid residues along the proton translocating D-channel that impair, and sometimes decouple, proton pumping from the chemical catalysis. Although their influence has been clearly demonstrated experimentally, the underlying molecular mechanisms of these mutants remain unknown. In this work, we report multiscale reactive molecular dynamics simulations that characterize the free-energy profiles of explicit proton transport through several important D-channel mutants. Our results elucidate the mechanisms by which proton pumping is impaired, thus revealing key kinetic gating features in CcO. In the N139T and N139C mutants, proton back leakage through the D-channel is kinetically favored over proton pumping due to the loss of a kinetic gate in the N139 region. In the N139L mutant, the bulky L139 side chain inhibits timely reprotonation of E286 through the D-channel, which impairs both proton pumping and the chemical reaction. In the S200V/S201V double mutant, the proton affinity of E286 is increased, which slows down both proton pumping and the chemical catalysis. This work thus not only provides insight into the decoupling mechanisms of CcO mutants, but also explains how kinetic gating in the D-channel is imperative to achieving high proton-pumping efficiency in the WT CcO.
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Shematovich, V. I. "Atmospheric Loss of Atomic Oxygen during Proton Aurorae on Mars". Solar System Research 55, nr 4 (lipiec 2021): 324–34. http://dx.doi.org/10.1134/s0038094621040079.
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Abstract— For the first time, the calculations of the penetration of protons of the undisturbed solar wind into the daytime atmosphere of Mars due to charge exchange in the extended hydrogen corona (Shematovich et al., 2021) are used allowing us to determine self-consistently the sources of suprathermal oxygen atoms, as well as their kinetics and transport. An additional source of hot oxygen atoms—collisions accompanied by the momentum and energy transfer from the flux of precipitating high-energy hydrogen atoms to atomic oxygen in the upper atmosphere of Mars—was included in the Boltzmann kinetic equation, which was solved with the Monte-Carlo kinetic model. As a result, the population of the hot oxygen corona of Mars has been estimated; and it has been shown that the proton aurorae are accompanied by the atmospheric loss of atomic oxygen, which is evaluated within a range of (3.5–5.8) × 107 cm–2 s–1. It has been shown that the exosphere becomes populated with a substantial amount of suprathermal oxygen atoms with kinetic energies up to the escape energy, 2 eV. The atomic oxygen loss rate caused by a sporadic source in the Martian atmosphere—the precipitation of energetic neutral atoms of hydrogen (H‑ENAs) during proton aurorae at Mars—was estimated by the self-consistent calculations according to a set of the Monte-Carlo kinetic models. These values turned out be comparable to the atomic oxygen loss supported by a regular source—the exothermic photochemical reactions (Groeller et al., 2014; Jakosky et al., 2018). It is currently supposed that the atmospheric loss of Mars due to the impact of the solar wind plasma and, in particular, the fluxes of precipitating high-energy protons and hydrogen atoms during solar flares and coronal mass ejections may play an important role in the loss of the neutral atmosphere on astronomic time scales (Jakosky et al., 2018).
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Jones, S. B., T. S. Nonnenmacher, E. Atkin, G. J. Barker, A. Basharina-Freshville, C. Betancourt, S. B. Boyd i in. "Off-Axis Characterisation of the CERN T10 Beam for low Momentum Proton Measurements with a High Pressure Gas Time Projection Chamber". Instruments 4, nr 3 (28.07.2020): 21. http://dx.doi.org/10.3390/instruments4030021.
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We present studies of proton fluxes in the T10 beamline at CERN. A prototype high pressure gas time projection chamber (TPC) was exposed to the beam of protons and other particles, using the 0.8 GeV/c momentum setting in T10, in order to make cross section measurements of low energy protons in argon. To explore the energy region comparable to hadrons produced by GeV-scale neutrino interactions at oscillation experiments, i.e., near 0.1 GeV of kinetic energy, methods of moderating the T10 beam were employed: the dual technique of moderating the beam with acrylic blocks and measuring scattered protons off the beam axis was used to decrease the kinetic energy of incident protons, as well as change the proton/minimum ionising particle (MIP) composition of the incident flux. Measurements of the beam properties were made using time of flight systems upstream and downstream of the TPC. The kinetic energy of protons reaching the TPC was successfully changed from ∼0.3 GeV without moderator blocks to less than 0.1 GeV with four moderator blocks (40 cm path length). The flux of both protons and MIPs off the beam axis was increased. The ratio of protons to MIPs vary as a function of the off-axis angle allowing for possible optimisation of the detector to select the type of required particles. Simulation informed by the time of flight measurements show that with four moderator blocks placed in the beamline, (5.6 ± 0.1) protons with energies below 0.1 GeV per spill traversed the active TPC region. Measurements of the beam composition and energy are presented.
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Roy, S., R. Bandyopadhyay, Y. Yang, T. N. Parashar, W. H. Matthaeus, S. Adhikari, V. Roytershteyn i in. "Turbulent Energy Transfer and Proton–Electron Heating in Collisionless Plasmas". Astrophysical Journal 941, nr 2 (1.12.2022): 137. http://dx.doi.org/10.3847/1538-4357/aca479.
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Abstract Despite decades of study of high-temperature weakly collisional plasmas, a complete understanding of how energy is transferred between particles and fields in turbulent plasmas remains elusive. Two major questions in this regard are how fluid-scale energy transfer rates, associated with turbulence, connect with kinetic-scale dissipation, and what controls the fraction of dissipation on different charged species. Although the rate of cascade has long been recognized as a limiting factor in the heating rate at kinetic scales, there has not been direct evidence correlating the heating rate with MHD-scale cascade rates. Using kinetic simulations and in situ spacecraft data, we show that the fluid-scale energy flux indeed accounts for the total energy dissipated at kinetic scales. A phenomenology, based on disruption of proton gyromotion by fluctuating electric fields that are produced in turbulence at proton scales, argues that the proton versus electron heating is controlled by the ratio of the nonlinear timescale to the proton cyclotron time and by the plasma beta. The proposed scalings are supported by the simulations and observations.
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Li, Li-Li, Fu-Hu Liu, Muhammad Waqas, Rasha Al-Yusufi i Altaf Mujear. "Excitation Functions of Related Parameters from Transverse Momentum (Mass) Spectra in High-Energy Collisions". Advances in High Energy Physics 2020 (10.06.2020): 1–21. http://dx.doi.org/10.1155/2020/5356705.
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Transverse momentum (mass) spectra of positively and negatively charged pions and of positively and negatively charged kaons, protons, and antiprotons produced at mid-(pseudo)rapidity in various collisions at high energies are analyzed in this work. The experimental data measured in central gold-gold, central lead-lead, and inelastic proton-proton collisions by several international collaborations are studied. The (two-component) standard distribution is used to fit the data and extract the excitation function of effective temperature. Then, the excitation functions of kinetic freeze-out temperature, transverse flow velocity, and initial temperature are obtained. In the considered collisions, the four parameters increase with the increase of collision energy in general, and the kinetic freeze-out temperature appears at the trend of saturation at the top Relativistic Heavy Ion Collider and the Large Hadron Collider.
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Martiryan, D. A. "SELECTION OF COINCIDENCE ELECTRON-PROTON EVENTS IN NUCLEI INTERACTION". Proceedings of the YSU A: Physical and Mathematical Sciences 53, nr 1 (248) (15.04.2019): 53–59. http://dx.doi.org/10.46991/pysu:a/2019.53.1.053.
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The main goal of this analysis is to study momentum (or kinetic energy) distribution of the backward going protons using data from CLAS EG2 experiment at Jefferson Lab. In this experiment scattering of a 5.014 GeV electron beam off various nucleus targets, ranging from deuterium to lead, have been recorded. The analysis includes selection of events in the reaction $ A(e, e^{\prime}, P_{back}) X $, where $ P_{back} $ is a proton scattered above 90° either in the lab coordinate frame or with respect to the direction of the interacting virtual photon, then performing required corrections and studying the protons momentum distribution as a function of energy transfer. In this paper identification of electron-proton events is presented.
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Kalytka, V. A. "Nonlinear Quantum Phenomena During the Polarization of Nanometer Layers of Proton Semiconductors and Dielectrics". Izvestiya of Altai State University, nr 4(120) (10.09.2021): 35–42. http://dx.doi.org/10.14258/izvasu(2021)4-05.
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This paper investigates the influence of the structure and parameters of the degenerate quasi-discrete energy spectrum of relaxers (protons) on the mechanism of nonlinear quantum diffusion polarization in nanoscale layers of hydrogen bonded crystals (HBC) in a wide range of parameters of fields (100 kV/m - 1000 MV/m) and temperatures (0-1550 K). The temperature dependence of the quantum transparency of the parabolic potential barrier for protons in HBC is calculated using the Gibbs quantum canonical distribution for the ensemble of non-interacting protons (ideal proton gas balanced with the ions of anion sub-lattice) moving in an onedimensional potential field of a crystalline lattice (in the field of hydrogen bonds) with a zone structure distributed by energy levels. The influence of "zero" oscillations of protons on the temperature dependences of the proton subsystem kinetic coefficients in HBC is considered. It is revealed that proton tunneling influences the nonlinear space-charge polarization kinetics in HBC at high (150-550 K) and ultrahigh (550-1550 K) temperatures when crystalline layer thickness ranges from 1 to 10 nm. The results of theoretical studies (based on earlier experiments) are bound to be prospective for the prediction of HBC-class (KDP, DKDP) ferroelectrics properties, studying the second-order nonlinear optical effects of femtosecond lasers, and the development of memory cells for non-volatile high-speed memory devices.
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Sengbusch, Evan R., i Thomas R. Mackie. "Maximum kinetic energy considerations in proton stereotactic radiosurgery". Journal of Applied Clinical Medical Physics 12, nr 3 (12.04.2011): 122–31. http://dx.doi.org/10.1120/jacmp.v12i3.3533.
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Baliukin, I. I., V. V. Izmodenov i D. B. Alexashov. "Energetic pickup proton population downstream of the termination shock as revealed by IBEX-Hi data". Monthly Notices of the Royal Astronomical Society 509, nr 4 (14.12.2021): 5437–53. http://dx.doi.org/10.1093/mnras/stab3214.
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ABSTRACT Pickup protons originate as a result of the ionization of hydrogen atoms in the supersonic solar wind, forming the suprathermal component of protons in the heliosphere. While they are being picked by the heliospheric magnetic field and convected into the heliosheath, the pickup protons may suffer stochastic acceleration from the solar wind turbulence in the region from the Sun up to the heliospheric termination shock, where they can also experience shock-drift acceleration or reflection from the cross-shock potential. These processes create a high-energy tail in the pickup ion energy distribution. The properties of this energetic pickup proton population are still not well defined, in spite of the fact that they are vital for models that simulate energetic neutral atom fluxes. We consider two scenarios for the pickup proton velocity distribution downstream of the heliospheric termination shock (a filled shell with an energetic power-law tail, and bi-Maxwellian). Based on a numerical kinetic model and observations of the energetic neutral atom fluxes from the inner heliosheath by the IBEX-Hi instrument, we characterize the pickup proton distribution and provide estimations of the properties of the energetic pickup proton population downstream of the termination shock.
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Tenerani, Anna, Carlos González, Nikos Sioulas, Chen Shi i Marco Velli. "Dispersive and kinetic effects on kinked Alfvén wave packets: A comparative study with fluid and hybrid models". Physics of Plasmas 30, nr 3 (marzec 2023): 032101. http://dx.doi.org/10.1063/5.0134726.
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We investigate dispersive and kinetic effects on the evolution of a two-dimensional kinked Alfvén wave packet by comparing results from magnetohydrodynamic (MHD), Hall-MHD, and hybrid simulations of a low- β plasma. We find that the Hall term determines the overall evolution of the wave packet over a characteristic time [Formula: see text] in both fluid and hybrid models. Dispersion of the wave packet leads to the conversion of the wave energy into internal plasma energy. When kinetic protons are considered, the proton internal energy increase has contributions from both plasma compressions and phase space mixing. The latter occurs in the direction parallel to the guiding mean magnetic field, due to protons resonating at the Alfvén speed with a compressible mode forced by the wave packet. Implications of our results for switchbacks observations and solar wind energetics are discussed.
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Shaaban, S. M., M. Lazar, R. A. López i R. F. Wimmer-Schweingruber. "On the interplay of solar wind proton and electron instabilities: linear and quasi-linear approaches". Monthly Notices of the Royal Astronomical Society 503, nr 3 (31.03.2021): 3134–44. http://dx.doi.org/10.1093/mnras/stab075.
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ABSTRACT Important efforts are currently being made to understand the so-called kinetic instabilities, driven by the anisotropy of different species of plasma particles present in the solar wind and terrestrial magnetosphere. These instabilities are fast enough to efficiently convert the free energy of plasma particles into enhanced (small-scale) fluctuations, with multiple implications, regulating the anisotropy of plasma particles. In this paper we use both linear and quasi-linear (QL) frameworks to describe complex unstable regimes, which realistically combine different temperature anisotropies of electrons and ions (protons). Thus various instabilities are parametrized, for example the proton and electron firehose, electromagnetic ion cyclotron and whistler instabilities, showing that their main linear properties are markedly altered by the interplay of anisotropic electrons and protons. Linear theory may predict the strong competition of two instabilities of different natures when their growth rates are comparable. In the QL phase, wave fluctuations grow and saturate at different levels and temporal scales, in comparison to results for the individual excitation of the proton or electron instabilities. In addition, the cumulative effects of the combined proton- and electron-induced fluctuations can markedly stimulate the relaxation of their temperature anisotropies. Only whistler fluctuations inhibit the efficiency of proton firehose fluctuations in the relaxation of anisotropic protons. These results offer valuable premises for further investigations in numerical simulations to decode the full spectrum of kinetic instabilities resulting from the interplay of anisotropic electrons and protons in space plasmas.
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Rizzato, C. M., M. C. Nemes, J. N. Maki, M. P. Pato i M. E. Spina. "Kinetic coefficients in inelastic high-energy proton-nucleus collisions". Journal of Physics G: Nuclear and Particle Physics 16, nr 2 (1.02.1990): 261–69. http://dx.doi.org/10.1088/0954-3899/16/2/015.
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Finkelstein, Y., R. Moreh, F. Bianchini i P. Vajeeston. "Anisotropy of the proton kinetic energy in ice Ih". Surface Science 679 (styczeń 2019): 174–79. http://dx.doi.org/10.1016/j.susc.2018.09.010.
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Waqas, Muhammad, Huai-Min Chen, Guang-Xiong Peng, Abd Al Karim Haj Ismail, Muhammad Ajaz, Zafar Wazir, Ramoona Shehzadi, Sabiha Jamal i Atef AbdelKader. "Study of Kinetic Freeze-Out Parameters as a Function of Rapidity in pp Collisions at CERN SPS Energies". Entropy 23, nr 10 (19.10.2021): 1363. http://dx.doi.org/10.3390/e23101363.
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We used the blast wave model with the Boltzmann–Gibbs statistics and analyzed the experimental data measured by the NA61/SHINE Collaboration in inelastic (INEL) proton–proton collisions at different rapidity slices at different center-of-mass energies. The particles used in this study were π+, π−, K+, K−, and p¯. We extracted the kinetic freeze-out temperature, transverse flow velocity, and kinetic freeze-out volume from the transverse momentum spectra of the particles. We observed that the kinetic freeze-out temperature is rapidity and energy dependent, while the transverse flow velocity does not depend on them. Furthermore, we observed that the kinetic freeze-out volume is energy dependent, but it remains constant with changing the rapidity. We also observed that all three parameters are mass dependent. In addition, with the increase of mass, the kinetic freeze-out temperature increases, and the transverse flow velocity, as well as kinetic freeze-out volume decrease.
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Choothong, Nuorn, i Seiichi Kawahara. "BROMINATION OF NATURAL RUBBER WITH N-BROMOSUCCINIMIDE". Rubber Chemistry and Technology 95, nr 1 (1.10.2021): 37–45. http://dx.doi.org/10.5254/rct.21.78980.
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ABSTRACT The mechanism of bromination of natural rubber (NR) was studied by solution-state 1H-NMR spectroscopy. The bromination of NR was carried out at 20–50 °C with N-bromosuccinimide as the brominating agent, and the kinetic study of bromination was conducted under nitrogen atmosphere at 30–50 °C for various reaction times. The influence of bromine atom substituent on the bromination rate constant (k) also was investigated. Bromine atom content was found to be dependent upon the reaction time, indicating first-order kinetics. The activation energy of bromination of NR, calculated from the reaction rate constants, was 19.3, 5.5, and 5.8 kJ mol−1 for bromine atom linked to carbon atom with methylene proton and methylene protons, respectively.
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De Benedittis, Antonio. "Proton energy spectrum with the DAMPE experiment". EPJ Web of Conferences 209 (2019): 01030. http://dx.doi.org/10.1051/epjconf/201920901030.
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The DAMPE (DArk Matter Particle Explorer) experiment, in orbit since December 17th 2015, is a space mission whose main purpose is the detection of cosmic electrons and photons up to energies of 10 TeV, in order to identify possible evidence of Dark Matter in their spectra. Furthermore it aims to measure the spectra and the elemental composition of the galactic cosmic rays nuclei up to the energy of hundreds of TeV. The proton analysis and the flux with kinetic energy ranging from 50 GeV up to 100 TeV, at the end of two years of data taking, will be presented and discussed.
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Sądel, Michał, Leszek Grzanka, Jan Swakoń, Jakub Baran, Jan Gajewski i Paweł Bilski. "Optically Stimulated Luminescent Response of the LiMgPO4 Silicone Foils to Protons and Its Dependence on Proton Energy". Materials 16, nr 5 (28.02.2023): 1978. http://dx.doi.org/10.3390/ma16051978.
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Modern radiotherapy (RT) techniques, such as proton therapy, require more and more sophisticated dosimetry methods and materials. One of the newly developed technologies is based on flexible sheets made of a polymer, with the embedded optically stimulated luminescence (OSL) material in the form of powder (LiMgPO4, LMP) and a self-developed optical imaging setup. The detector properties were evaluated to study its potential application in the proton treatment plan verification for eyeball cancer. The data showed a well-known effect of lower luminescent efficiency of the LMP material response to proton energy. The efficiency parameter depends on a given material and radiation quality parameters. Therefore, the detailed knowledge of material efficiency is crucial in establishing a calibration method for detectors exposed to mixed radiation fields. Thus, in the present study, the prototype of the LMP-based silicone foil material was tested with monoenergetic uniform proton beams of various initial kinetic energies constituting the so-called spread-out Bragg peak (SOBP). The irradiation geometry was also modelled using the Monte Carlo particle transport codes. Several beam quality parameters, including dose and the kinetic energy spectrum, were scored. Finally, the obtained results were used to correct the relative luminescence efficiency response of the LMP foils for monoenergetic and spread-out proton beams.
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Baliukin, I. I., V. V. Izmodenov i D. B. Alexashov. "Adiabatic energy change in the inner heliosheath: how does it affect the distribution of pickup protons and energetic neutral atom fluxes?" Monthly Notices of the Royal Astronomical Society 525, nr 3 (21.08.2023): 3281–86. http://dx.doi.org/10.1093/mnras/stad2518.
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ABSTRACT The hydrogen atoms penetrate the heliosphere from the local interstellar medium, and while being ionized, they form the population of pickup protons. The distribution of pickup protons is modified by the adiabatic heating (cooling) induced by the solar wind plasma compression (expansion). In this study, we emphasize the importance of the adiabatic energy change in the inner heliosheath that is usually either neglected or considered improperly. The effect of this process on the energy and spatial distributions of pickup protons and energetic neutral atoms (ENAs), which originate in the charge exchange of pickup protons, has been investigated and quantified using a kinetic model. The model employs the global distributions of plasma and hydrogen atoms in the heliosphere from the simulations of a kinetic-magnetohydrodynamic model of solar wind interaction with the local interstellar medium. The findings indicate that the adiabatic energy change is responsible for the broadening of the pickup proton velocity distribution and the significant enhancement of ENA fluxes (up to ∼5 and ∼20 times in the upwind and downwind directions at energies ∼1–2 keV for an observer at 1 au). It sheds light on the role of adiabatic energy change in explaining the discrepancies between the ENA flux observations and the results of numerical simulations.
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Hache, John J., Julia Laskin i Jean H. Futrell. "Relative Proton Affinities from Kinetic Energy Release Distributions for Dissociation of Proton-Bound Dimers". Journal of Physical Chemistry A 106, nr 50 (grudzień 2002): 12051–57. http://dx.doi.org/10.1021/jp026515p.
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Hache, John J., Jean H. Futrell i Julia Laskin. "Relative proton affinities from kinetic energy release distributions for dissociation of proton-bound dimers". International Journal of Mass Spectrometry 233, nr 1-3 (kwiecień 2004): 223–31. http://dx.doi.org/10.1016/j.ijms.2003.12.022.
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Kalytka, Valeriy, Zein Baimukhanov, Yelena Neshina, Ali Mekhtiyev, Pavel Dunayev, Olga Galtseva i Yelena Senina. "Influence of Quantum Effects on Dielectric Relaxation in Functional Electrical and Electric Energy Elements Based on Proton Semiconductors and Dielectrics". Applied Sciences 13, nr 15 (28.07.2023): 8755. http://dx.doi.org/10.3390/app13158755.
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Using the quasi-classical kinetic theory of dielectric relaxation, in addition to existing methods, fundamental mathematical expressions are built, which make it possible to more strictly consider the effects of the main charge carriers’ (protons’) tunneling on the numerical values of the molecular parameters (activation energy, equilibrium concentration) of protons in HBC. The formulas for calculating the statistically averaged non-stationary quantum transparency of a parabolic potential barrier for protons have been modernized by more stringent consideration of the effects of corrections caused by an external electric field. For the model of a double-symmetric potential well, a generalized nonlinear solution of the quasi-classical kinetic equation of dielectric relaxation in HBC was built. The phenomenological Bucci-Rive formula for thermally stimulated depolarization current density (TSDC) was first investigated, taking into account quantum transparency, for the case of a parabolic potential barrier. The choice of the parabolic shape of the potential barrier allowed, at a theoretical level, for the mathematical model of relaxation polarization to be brought closer to the conditions of the real spatial structure of the crystal potential field, in comparison with the rectangular potential barrier model. It has been found that quantum effects due to proton tunnel transitions significantly affect the mechanism of thermally stimulated depolarization currents in HBC, over a wide temperature range (50–550 K) and external field parameters (0.1–1 MV/m). Generalized solutions of the nonlinear kinetic equation, recorded considering the effects of field parameters on proton tunnel transitions, made it possible to significantly approximate the theoretical values of activation energies, equilibrium concentrations of protons and amplitudes of the theoretical maxima of the current density of thermally stimulated depolarization, according to their experimental values in the field of low-temperature (50–100 K) and high-temperature (350–550 K) maxima of TSDC density in HBC. For the first time, precision measurements of TSDC temperature spectra were carried out for chalcanthite crystals. The effects of alloying impurities concentrations and crystal calcination temperatures on the parameters of experimental maxima in the TSDC spectrum of chalcanthite were established. A physical mechanism of the quantum tunnel motion of protons in HBC with a complex crystal structure (crystalline hydrates, layered silicates, ferroelectric HBC (KDP, DKDP)) is described. The patterns found in this article indicate a fairly high degree of applied scientific significance for the obtained theoretical results, allowing for the further development of electrophysics and optoelectronics of heterogeneous structures (MIS, MSM) based on proton semiconductors and dielectrics (PSD) and their composites.
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Potgieter, Marius S., O. P. M. Aslam, Driaan Bisschoff i Donald Ngobeni. "A Perspective on the Solar Modulation of Cosmic Anti-Matter". Physics 3, nr 4 (7.12.2021): 1190–225. http://dx.doi.org/10.3390/physics3040076.
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Global modulation studies with comprehensive numerical models contribute meaningfully to the refinement of very local interstellar spectra (VLISs) for cosmic rays. Modulation of positrons and anti-protons are investigated to establish how the ratio of their intensity, and with respect to electrons and protons, are changing with solar activity. This includes the polarity reversal of the solar magnetic field which creates a 22-year modulation cycle. Modeling illustrates how they are modulated over time and the particle drift they experience which is significant at lower kinetic energy. The VLIS for anti-protons has a peculiar spectral shape in contrast to protons so that the total modulation of anti-protons is awkwardly different to that for protons. We find that the proton-to-anti-proton ratio between 1–2 GeV may change by a factor of 1.5 over a solar cycle and that the intensity for anti-protons may decrease by a factor of ~2 at 100 MeV during this cycle. A composition is presented of VLIS for protons, deuteron, helium isotopes, electrons, and particularly for positrons and anti-protons. Gaining knowledge of their respective 11 and 22 year modulation is useful to interpret observations of low-energy anti-nuclei at the Earth as tests of dark matter annihilation.
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Moid, Mohd, Yacov Finkelstein, Raymond Moreh i Prabal K. Maiti. "Microscopic Study of Proton Kinetic Energy Anomaly for Nanoconfined Water". Journal of Physical Chemistry B 124, nr 1 (5.12.2019): 190–98. http://dx.doi.org/10.1021/acs.jpcb.9b08667.
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Jesús-Valls, César, Marc Granado-González, Thorsten Lux, Tony Price i Federico Sánchez. "Enhanced Proton Tracking with ASTRA Using Calorimetry and Deep Learning". Instruments 6, nr 4 (8.10.2022): 58. http://dx.doi.org/10.3390/instruments6040058.
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Recently, we proposed a novel range detector concept named ASTRA. ASTRA is optimized to accurately measure (better than 1%) the residual energy of protons with kinetic energies in the range from tens to a few hundred MeVs at a very high rate of O(100 MHz). These combined performances are aimed at achieving fast and high-quality proton Computerized Tomography (pCT), which is crucial to correctly assessing treatment planning in proton beam therapy. Despite being a range telescope, ASTRA is also a calorimeter, opening the door to enhanced tracking possibilities based on deep learning. Here, we review the ASTRA concept, and we study an alternative tracking method that exploits calorimetry. In particular, we study the potential of ASTRA to deal with pile-up protons by means of a novel tracking method based on semantic segmentation, a deep learning network architecture that performs classification at the pixel level.
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Moya, P. S., A. F. Viñas, V. Muñoz i J. A. Valdivia. "Computational and theoretical study of the wave-particle interaction of protons and waves". Annales Geophysicae 30, nr 9 (19.09.2012): 1361–69. http://dx.doi.org/10.5194/angeo-30-1361-2012.
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Abstract. We study the wave-particle interaction and the evolution of electromagnetic waves propagating through a plasma composed of electrons and protons, using two approaches. First, a quasilinear kinetic theory has been developed to study the energy transfer between waves and particles, with the subsequent acceleration and heating of protons. Second, a one-dimensional hybrid numerical simulation has been performed, with and without including an expanding-box model that emulates the spherical expansion of the solar wind, to investigate the fully nonlinear evolution of this wave-particle interaction. Numerical results of both approaches show that there is an anisotropic evolution of proton temperature.
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VEGA, PEDRO, LUIS PALMA i RENE ELGUETA. "The L mode in electromagnetic proton-cyclotron waves in plasmas modelled by a Lorentzian distribution function". Journal of Plasma Physics 60, nr 1 (sierpień 1998): 29–48. http://dx.doi.org/10.1017/s0022377898006382.
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The L mode in electromagnetic proton-cyclotron waves (EPCWs) propagating parallel to a uniform ambient magnetic field is studied here analytically. A generalized Lorentzian distribution function is used to model the plasma. Analytical expressions for the wavenumber and for both the temporal and convective growth rates for a multi-ion plasma are obtained within the linear theory. This analytical approach is appropiate for β∥<1, which is the ratio of plasma kinetic pressure to magnetic field pressure. The characteristics of the unstable spectrum are found to be independent of high-energy particles. For a plasma composed of electrons plus hot and cold protons, it is shown that the maximum growth rates as functions of cold-proton concentration δ can always decrease, or can increase until δ reaches a certain peak value and decrease thereafter, or can always increase, depending on the thermal anisotropy of the hot protons. This behaviour is similar to that in Maxwellian plasmas. However, for the convective growth rate, the expression for the optimum cold-proton concentration shows a significant dependence on the spectral index κ. Therefore, when cold protons are injected, it is more difficult to obtain optimum amplification in a Lorentzian plasma than in a Maxwellian plasma. It is also shown that the influence of the high-energy tail on the generation and amplification processes of the EPCWs is controlled by thermal anisotropy and cold-ion population. As a consequence of the latter, temporal and convective growth rates can be larger than, equal to or smaller than those of Maxwellian plasmas, depending on the anisotropy of the hot-proton distribution and on the cold-proton concentration.
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Lao, Hai-Ling, Fu-Hu Liu i Bo-Qiang Ma. "Analyzing Transverse Momentum Spectra of Pions, Kaons and Protons in p–p, p–A and A–A Collisions via the Blast-Wave Model with Fluctuations". Entropy 23, nr 7 (24.06.2021): 803. http://dx.doi.org/10.3390/e23070803.
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The transverse momentum spectra of different types of particles, π±, K±, p and p¯, produced at mid-(pseudo)rapidity in different centrality lead–lead (Pb–Pb) collisions at 2.76 TeV; proton–lead (p–Pb) collisions at 5.02 TeV; xenon–xenon (Xe–Xe) collisions at 5.44 TeV; and proton–proton (p–p) collisions at 0.9, 2.76, 5.02, 7 and 13 TeV, were analyzed by the blast-wave model with fluctuations. With the experimental data measured by the ALICE and CMS Collaborations at the Large Hadron Collider (LHC), the kinetic freeze-out temperature, transverse flow velocity and proper time were extracted from fitting the transverse momentum spectra. In nucleus–nucleus (A–A) and proton–nucleus (p–A) collisions, the three parameters decrease with the decrease of event centrality from central to peripheral, indicating higher degrees of excitation, quicker expansion velocities and longer evolution times for central collisions. In p–p collisions, the kinetic freeze-out temperature is nearly invariant with the increase of energy, though the transverse flow velocity and proper time increase slightly, in the considered energy range.
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Sikora, Marek, Krzysztof Nalewajko i Greg M. Madejski. "On the significance of relativistically hot pairs in the jets of FR II radio galaxies". Monthly Notices of the Royal Astronomical Society 499, nr 3 (17.10.2020): 3749–54. http://dx.doi.org/10.1093/mnras/staa3128.
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ABSTRACT The energetic composition of radio lobes in the FR II galaxies – estimated by comparing their radio luminosities with the powers required to inflate cavities in the external medium – seems to exclude the possibility of their energetic domination by protons. Furthermore, if the jets were dominated by the kinetic energy of cold protons, it would be difficult to efficiently accelerate leptons in the jets’ terminal shocks. Assuming that the relative energy contents of leptons, protons, and magnetic fields are preserved across the shocks, the above implies that the large-scale jets should also be energetically dominated by leptons: Pe,j ≳ Pp,j. On the other hand, previous studies of small-scale jets in blazars and radio cores suggest a pair content (number of electrons and positrons per proton) of the order of ne/np ∼ 20. Assuming further that the particle composition of jets does not evolve beyond the blazar scales, we show that this implies an average random Lorentz factor of leptons in large-scale jets of $\bar{\gamma }_{\rm e,j} \gtrsim 70(1+\chi _{\rm p})(20n_{\rm p}/n_{\rm e})$, and that the protons should be mildly relativistic with χp ≡ (ϵp + pp)/ρpc2 ≲ 2, pp the pressure of protons, ϵp the internal energy density of protons, and ρpc2 the rest-mass energy density of protons. We derive the necessary conditions for loading the inner jets by electron–positron pairs and proton–electron plasma, and provide arguments that heating of leptons in jets is dominated by magnetic reconnection.
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Yang, Yan, Francesco Pecora, William H. Matthaeus, Sohom Roy, Manuel Enrique Cuesta, Alexandros Chasapis, Tulasi Parashar i in. "Quantifying the Agyrotropy of Proton and Electron Heating in Turbulent Plasmas". Astrophysical Journal 944, nr 2 (1.02.2023): 148. http://dx.doi.org/10.3847/1538-4357/acb25a.
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Abstract An important aspect of energy dissipation in weakly collisional plasmas is that of energy partitioning between different species (e.g., protons and electrons) and between different energy channels. Here we analyse pressure–strain interaction to quantify the fractions of isotropic compressive, gyrotropic, and nongyrotropic heating for each species. An analysis of kinetic turbulence simulations is compared and contrasted with corresponding observational results from Magnetospheric Multiscale Mission data in the magnetosheath. In assessing how protons and electrons respond to different ingredients of the pressure–strain interaction, we find that compressive heating is stronger than incompressive heating in the magnetosheath for both electrons and protons, while incompressive heating is stronger in kinetic plasma turbulence simulations. Concerning incompressive heating, the gyrotropic contribution for electrons is dominant over the nongyrotropic contribution, while for protons nongyrotropic heating is enhanced in both simulations and observations. Variations with plasma β are also discussed, and protons tend to gain more heating with increasing β.
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Ofman, Leon, Scott A. Boardsen, Lan K. Jian, Parisa Mostafavi, Jaye L. Verniero, Roberto Livi, Michael McManus, Ali Rahmati, Davin Larson i Michael L. Stevens. "Observations and Modeling of Unstable Proton and α Particle Velocity Distributions in Sub-Alfvénic Solar Wind at Parker Solar Probe Perihelia". Astrophysical Journal 954, nr 2 (28.08.2023): 109. http://dx.doi.org/10.3847/1538-4357/acea7e.
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Abstract Past observations show that solar wind (SW) acceleration occurs inside the sub-Alfvénic region, reaching the local Alfvén speed at typical distances ∼10–20 solar radii (R s ). Recently, Parker Solar Probe (PSP) traversed regions of sub-Alfvénic SW near perihelia in encounters E8–E12 for the first time, providing data in these regions. It became evident that the properties of the magnetically dominated SW are considerably different from the super-Alfvénic wind. For example, there are changes in the relative abundances and drift of α particles with respect to protons, as well as in the magnitude of magnetic fluctuations. We use data of the magnetic field from the FIELDS instrument, and construct ion velocity distribution functions (VDFs) from the sub-Alfvénic regions using Solar Probe ANalyzer for Ions data, and run 2.5D and 3D hybrid models of proton-α sub-Alfvénic SW plasma. We investigate the nonlinear evolution of the ion kinetic instabilities in several case studies, and quantify the transfer of energy between the protons, α particles, and the kinetic waves. The models provide the 3D ion VDFs at the various stages of the instability evolution in the SW frame. By combining observational analysis with the modeling results, we gain insights on the evolution of the ion instabilities, the heating and the acceleration processes of the sub-Alfvénic SW plasma, and quantify the exchange of energy between the magnetic and kinetic components. The modeling results suggest that the ion kinetic instabilities are produced locally in the SW, resulting in anisotropic heating of the ions, as observed by PSP.
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Maldonado-Domínguez, Mauricio, Daniel Bím, Radek Fučík, Roman Čurík i Martin Srnec. "Reactive mode composition factor analysis of transition states: the case of coupled electron–proton transfers". Physical Chemistry Chemical Physics 21, nr 45 (2019): 24912–18. http://dx.doi.org/10.1039/c9cp05131g.
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Pallister, R., D. I. Pontin i P. F. Wyper. "Proton acceleration at tearing coronal null-point current sheets". Astronomy & Astrophysics 622 (luty 2019): A207. http://dx.doi.org/10.1051/0004-6361/201834284.
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Context. Non-thermal particle acceleration in the solar corona is thought to constitute a substantial part of the energy budget of explosive events such as solar flares. One well-established mechanism of non-thermal acceleration is directly via fields in current sheets. Aims. In this paper we study proton acceleration during “spine-fan reconnection” at a 3D magnetic null point. This type of reconnection has recently been implicated in some flares known as circular-ribbon flares. It has also recently been discovered that the reconnecting current sheet may undergo a non-linear tearing-type instability. This tearing leads to the formation of flux ropes and quasi-turbulent dynamics. Methods. A predictor-corrector test particle code is used to model the trajectories of protons at different stages of sheet tearing: when the sheet is intact, just after the formation of the first major flux rope, and once the non-linear phase of the instability has become more fully developed. The fields for these proton trajectories were taken from snapshots of a 3D magnetohydrodynamics simulation treated as three static field geometries represented by interpolated grids. Acceleration in the intact current sheet is compared to earlier simulations of infinite static current sheets and then used as a control case with which to compare the later snapshots. Results. Protons are found to be predominantly accelerated along the fan surface, especially in the absence of current sheet tearing. Most of the highest energy protons are accelerated in the main body of the current sheet, along the direction of strongest parallel electric field. A high energy tail is present in the kinetic energy distribution. After tearing commences, this direct acceleration no longer dominates and acceleration in the outflow regions makes a proportionally greater contribution. Sheet tearing appears overall to hinder the acceleration of protons in the fan plane, at least in the absence of time-dependent acceleration mechanisms. Some correlation is found between high energy protons and locations of flux ropes formed by the instability, but the nature of the link remains at present unclear.
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Shi, Zhaodong, Patricio A. Muñoz, Jörg Büchner i Siming Liu. "Proton and Helium Heating by Cascading Turbulence in a Low-beta Plasma". Astrophysical Journal 941, nr 1 (1.12.2022): 39. http://dx.doi.org/10.3847/1538-4357/ac9fd7.
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Abstract How ions are energized and heated is a fundamental problem in the study of energy dissipation in magnetized plasmas. In particular, the heating of heavy ions (including 4He2+, 3He2+, and others) has been a constant concern for understanding the microphysics of impulsive solar flares. In this article, via two-dimensional hybrid-kinetic particle-in-cell simulations, we study the heating of helium ions (4He2+) by turbulence driven by cascading waves launched at large scales from the left-handed polarized helium ion cyclotron wave branch of a multi-ion plasma composed of electrons, protons, and helium ions. We find significant parallel (to the background magnetic field) heating for both helium ions and protons due to the formation of beams and plateaus in their velocity distribution functions along the background magnetic field. The heating of helium ions in the direction perpendicular to the magnetic field starts with a lower rate than that in the parallel direction, but overtakes the parallel heating after a few hundreds of the proton gyro-periods due to cyclotron resonances with mainly obliquely propagating waves induced by the cascade of injected helium ion cyclotron waves at large scales. There is, however, little evidence for proton heating in the perpendicular direction due to the absence of left-handed polarized cyclotron waves near the proton cyclotron frequency. Our results are useful for understanding the preferential heating of 3He and other heavy ions in the 3He-rich solar energetic particle events, in which helium ions play a crucial role as a species of background ions regulating the kinetic plasma behavior.
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HEINZ, SEBASTIAN. "CLUES FOR THE COMPOSITION OF RELATIVISTIC MICROQUASAR JETS". International Journal of Modern Physics D 17, nr 10 (wrzesień 2008): 1947–52. http://dx.doi.org/10.1142/s0218271808013613.
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We discuss the evidence for proton loading in relativistic jets from microquasars in light of recent constraints on the jet power. We argue that, both in the case of the Cygnus X-1 jet and the entire ensemble of Galactic microquasars, the evidence points towards a significant contribution to the total kinetic energy flux from cold protons. However, as with all other methods of constraining jet composition (except for the singular case of SS 433), a number of alternative, though maybe less plausible, explanations exist. In light of this continued elusiveness of a single slam-dunk argument for proton loading, the best we can hope for is a continuing accumulation of bits of evidence such as these which will, on the whole, form a preponderance of evidence against pure pair jets.
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DEUTSCH, C. "Transport of megaelectron volt protons for fast ignition". Laser and Particle Beams 21, nr 1 (styczeń 2003): 33–35. http://dx.doi.org/10.1017/s0263034602211076.
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Quasi-linear analysis demonstrates that intense and nonrelativistic proton beams do not lose collectively their kinetic energy through transverse Weibel electromagnetic instabilities when interacting with supercompressed plasmas of inertial confinement interest.
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Moreh, R., i D. Nemirovsky. "On the proton kinetic energy in H2O and in nanotube water". Journal of Chemical Physics 133, nr 8 (28.08.2010): 084506. http://dx.doi.org/10.1063/1.3478681.
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Carpenter, M. A., M. T. Zanni, D. J. Levandier, D. F. Varley i J. M. Farrar. "Proton transfer dynamics on highly attractive potential energy surfaces: Induced repulsive energy release in O− + HF at high collision energies". Canadian Journal of Chemistry 72, nr 3 (1.03.1994): 828–35. http://dx.doi.org/10.1139/v94-110.
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We present the angular and kinetic energy distributions for the products of the proton transfer reaction O− + HF → OH + F− at center-of-mass collision energies of 45.0 and 55.8 kJ mol−l (0.47 and 0.58 eV, respectively). At both collision energies, the product angular distributions show forward–backward symmetry, characteristic of the decay of a transient complex living at least several rotational periods. The product kinetic energy distributions show structure that is clearly attributable to the formation of OH in v′ = 0,1, and 2. The kinetic energy distribution for a single vibrational state of OH is equivalent to the rotational state distribution for that state. At the higher collision energy, the product kinetic energy distribution shows a clear angular dependence, from which we infer a transition to more direct dynamics involving low impact parameter collisions that access the repulsive wall of the potential surface in bent geometries. The vibrational energy in the products decreases with increasing collision energy, with fV′, the fraction of available energy appearing in vibration, decreasing from 0.28 to 0.22 over the reported collision energy range. We attribute this behavior to a transition from mixed energy release of a Heavy + Light–Heavy collision system dominated by the strong attractive well to induced repulsive energy release as the system reaches the low energy repulsive wall of the potential energy surface.
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Alcocer, Giovanni. "Mass Symmetry". Mediterranean Journal of Basic and Applied Sciences 06, nr 01 (2022): 75–101. http://dx.doi.org/10.46382/mjbas.2022.6108.
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There is symmetry in the nature. Then, there should also be symmetry in physics since physics describes the phenomena of nature. In fact, it occurs in most of the phenomena explained by physics as for example: a particle has positive or negative charges, spins up or down, north or south magnetic poles. In this form, the particle should also have mass symmetry. For convenience and due to later explanations, I call this mass symmetry or mass duality as follows: mass and mass cloud. The mass symmetry can be corroborated in the experiments of the hydrogen spectrum, the Bohr model and the solution of the Schrödinger equation. The mass cloud is located in the respective orbitals given by the Schrödinger equation. The orbitals represent the possible locations or places of the particle which is determined probabilistically by the respective Schröndiger equation. For the proton, part of the mass of the uncharged proton is distributed in the orbital or mass cloud around the mass that contains the positive charge. Thus, the positive charge in the proton is concentrated in its mass nucleus with an uncharged mass cloud around its nucleus distributed in the orbitals. For the electron, part of the mass of the uncharged electron is distributed in the orbital or mass cloud around the mass that contains the negative charge. Thus, the negative charge in the electron is concentrated in its mass nucleus with an uncharged mass cloud around its nucleus distributed in the orbitals. For example, in the formation of the hydrogen atom, a part of the mass cloud of the proton interacts with the mass cloud of the electron, and the total mass energy lost in this interaction is transformed into electromagnetic energy according to Einstein's equation: E=mc2 and the variant mass formula discovered and developed by myself. Then, the two particles join together due to this interaction and the electrostatic force between the two particles. Therefore, the electron and proton are bound together in the hydrogen atom by the mass cloud of the electron and proton with some mass cloud lost in the interaction and converted to electromagnetic energy or photons. Then, it is right this mass symmetry, since the electron and the proton in the interaction of the mass cloud lose mass but do not lose electric charge. In this form, it is justified the existence of a mass cloud. In the formation of the Hydrogen atom, the electron-proton system when approaching gains a potential energy of 27.2 eV (13.6 eV*2) but then when the electron bond occurs in the shell with quantum state n =1, energy of 13.6 eV is emitted as electromagnetic energy or photons and the remaining 13.6 eV remains as kinetic energy of the electron. Then, the Hydrogen atom has 13.6 eV of additional energy/mass than the sum of the energy/mass of the proton plus the electron. Therefore, 13.6 eV is needed to ionize the Hydrogen atom and expel the electron from the atom. The mass/energy reduction of the proton and electron is 13.6/2 eV for each particle due the emission of 13.6 eV as electromagnetic energy. Therefore, the main function of the mass cloud is the binding energy. The mass cloud interaction generates binding energy between the electrons and the nucleus in the atom through the protons and between the nucleons in the nucleus: protons with protons, neutrons with neutrons, and protons with neutrons. The nuclear force between two nucleons is characterized by being strong and short-range. Also, it can be justified by the existence of the mass cloud: the mass clouds of nucleons within the nucleus interact with each other without any effect on the proton charge. This scientific research presents evidence of the existence of the mass symmetry based in the Einstein's equation and in the Variant Mass formula for the Electron in the atom discovered and demonstrated by myself where experimental results are detailed.
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Waqas, M., i G. X. Peng. "Study of Proton, Deuteron, and Triton at 54.4 GeV". Advances in High Energy Physics 2021 (31.03.2021): 1–9. http://dx.doi.org/10.1155/2021/6674470.
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Transverse momentum spectra of proton, deuteron, and triton in gold-gold (Au-Au) collisions at 54.4 GeV are analyzed in different centrality bins by the blast wave model with Tsallis statistics. The model results are approximately in agreement with the experimental data measured by STAR Collaboration in special transverse momentum ranges. We extracted the kinetic freeze-out temperature, transverse flow velocity, and freeze-out volume from the transverse momentum spectra of the particles. It is observed that the kinetic freeze-out temperature is increasing from the central to peripheral collisions. However, the transverse flow velocity and freeze-out volume decrease from the central to peripheral collisions. The present work reveals the mass dependent kinetic freeze-out scenario and volume differential freeze-out scenario in collisions at STAR Collaboration. In addition, parameter q characterizes the degree of nonequilibrium of the produced system, and it increases from the central to peripheral collisions and increases with mass .
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Ravangvong, Sunantasak, Punsak Glumglomchit, Kunlanun Pranudomrat, Latthaphon Muangsri, Paramee Lertlimpiyarat, Amonwan Supakom, Kittisak Sriwongsa, Sakchai Glumglomjit i Wanna Wattana. "behaviour of tungsten oxide on phosphor-tellurite glasses for photon proton and alpha particles shielding". Journal of Materials Science and Applied Energy 12, nr 1 (1.01.2023): 245267. http://dx.doi.org/10.55674/jmsae.v12i1.245267.
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This research, photons shielding properties such as mass attenuation coefficients (mm), effective atomic number (Zeff), effective electron density (Nel) and kinetic energy per unit mass (kerma) relative to air for WO3 based on TeO2–P2O5–WO3 glass system have been simulated by WinXCom software program at energies of 10–3–105 MeV. Also, buildup factors (BFs) have been estimated at widely energy ranging 15 keV – 15 MeV for penetration depths (PD) until 40 mean free path (mfp). The results of glass system in formula (70–x) TeO2–30P2O5–xWO3 at x = 10, 20, 30, 40, and 50 mol% exhibited that the partial replacement of TeO2 by WO3 was adjusted photons attenuation behaviors for get better. In addition, mass sopping power (MSP) and projected range (PR) were evaluated using SRIM software program for proton (H+1) and alpha particles (He+2) at kinetic energy ranging 10 keV – 10 MeV. The results may be inferred that glass sample with high WO3 content was superb for photons, proton and alpha particles attenuation. The results of this research may be useful in enhancing optimization and potential to use as a transparent material to against photon, proton and alpha particles.
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Susam, Lidya Amon, Ayberk Yilmaz, Ghada ALMisned, Hatice Yilmaz Alan, Gizem Ozturk, Gokhan Kilic, Bahar Tuysuz i in. "Tailoring a Behavioral Symmetry on KERMA, Mass Stopping Power and Projected Range Parameters against Heavy-Charged Particles in Zinc-Tellurite Glasses for Nuclear Applications". Symmetry 15, nr 6 (3.06.2023): 1201. http://dx.doi.org/10.3390/sym15061201.
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We present the behavioral changes and symmetrical enhancement on KERMA, mass stopping power and projected range parameters against heavy-charged particles through Indium (In) and Tantalum (Ta) incorporations for various zinc-tellurite glass groups such as TZI and ZTT for nuclear applications. SRIM and PAGEX codes are utilized for the determination of investigated attenuation parameters for alpha and proton particles. In KERMA calculations, the ZTT7 sample is reported to have the greatest release of charged particles because of an increase in kinetic energy. The mass stopping power values of all absorbent glass materials are steadily increased from 0 MeV to 0.1 MeV. TZI and ZTT attained their maximum mass stopping power at a kinetic energy value of 0.1 MeV. While comparable behavior patterns are seen for various energy values on the examined energy scale, the ZTT7 sample is observed with lower mass stopping power and projected range values against proton particles than the other samples. It can be concluded that zinc-telluride glasses through maximum Ta-reinforcement may be considered as promising materials for stopping the proton and alpha particles. Moreover, Ta-reinforcement may be considered as a monotonic tool in terms of providing a symmetry for attenuation enhancement against heavy-charged particles.
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Li, Li-Li, i Fu-Hu Liu. "Kinetic Freeze-Out Properties from Transverse Momentum Spectra of Pions in High Energy Proton-Proton Collisions". Physics 2, nr 2 (12.06.2020): 277–308. http://dx.doi.org/10.3390/physics2020015.
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Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions over a center-of-mass energy, s , range from a few GeV to above 10 TeV are analyzed by the blast-wave fit with Boltzmann (Tsallis) distribution. The blast-wave fit results are well fitting to the experimental data measured by several collaborations. In a particular superposition with Hagedorn function, both the excitation functions of kinetic freeze-out temperature ( T 0 ) of emission source and transverse flow velocity ( β T ) of produced particles obtained from a given selection in the blast-wave fit with Boltzmann distribution have a hill at s ≈ 10 GeV, a drop at dozens of GeV, and then an increase from dozens of GeV to above 10 TeV. However, both the excitation functions of T 0 and β T obtained in the blast-wave fit with Tsallis distribution do not show such a complex structure, but a very low hill. In another selection for the parameters or in the superposition with the usual step function, T 0 and β T increase generally quickly from a few GeV to about 10 GeV and then slightly at above 10 GeV, there is no such the complex structure, when also studying nucleus-nucleus collisions.
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Telecki, Igor, Sanja Grujovic-Zdolsek i Srdjan Petrovic. "Spatial rainbows and catastrophes in transmission of protons through electrostatic octopole lens". Nuclear Technology and Radiation Protection 33, nr 4 (2018): 347–55. http://dx.doi.org/10.2298/ntrp180910008t.
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This paper considers transmission of initial parallel proton beam with kinetic energy of 10 k?V through electrostatic octopole lens. The spatial rainbows and corresponding proton distributions are calculated by using infinite length approximation potential. Positive potentials of the lens electrodes are set to be 0.35 kV and 9 kV. It has been shown that by application of catastrophe theory, generating function for mapping proton positions between entrance and exit transverse plains can be determined, giving accurate rainbow patterns for biasing potentials of 0,35 kV.
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GALATYUK, TETYANA. "DIELECTRON MEASUREMENTS IN NN INTERACTIONS AT A BEAM ENERGY OF 1.25 GeV WITH HADES". International Journal of Modern Physics A 24, nr 02n03 (30.01.2009): 599–602. http://dx.doi.org/10.1142/s0217751x09044164.
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The dielectron yield in pp and dp reactions at a beam kinetic energy of 1.25 GeV/u has been measured using the HADES spectrometer at GSI. In proton-proton reactions the most abundant source above the π0 Dalitz region is expected to be Δ Dalitz decay. The obsearved large difference in dielectron production in pp and dp systems suggests that dielectron production in the dp system is dominated by a np process. In order to separate Δ Dalitz decays and np bremsstrahlung we compare the dielectron yield observed in pp with the one of dp reactions measured at the same beam energy.
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Waqas, Muhammad, Abd Al Karim Haj Ismail, Muhammad Ajaz i Atef AbdelKader. "Excitation Function of Kinetic Freeze-Out Parameters at 6.3, 17.3, 31, 900 and 7000 GeV". Universe 8, nr 2 (21.02.2022): 138. http://dx.doi.org/10.3390/universe8020138.
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The transverse momentum spectra of π+ (π−)(π++π−) at 6.3, 17.3, 31, 900 and 7000 GeV are analyzed by the blast-wave model with Tsallis statistics (TBW) in proton-proton collisions. We took the value of flow profile n0 = 1 and 2 in order to see the difference in the results of the extracted parameters in the two cases. Different rapidity slices at 31 GeV are also analyzed, and the values of the related parameters, such as kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume, are obtained. The above parameters rise with the increase of collision energy, while at 31 GeV, they decrease with increasing rapidity, except for the kinetic freeze-out volume, which increases. We also extracted the parameter q, which is an entropy-based parameter, and its rising trend is noticed with increasing collision energy, while at 31 GeV, no specific dependence of q is observed on rapidity. In addition, the multiplicity parameter N0 and mean transverse momentum are extracted, which increase with increasing collision energy and decrease with increasing rapidity. We notice that the kinetic freeze-out temperature and mean transverse momentum are slightly larger with n0 = 2, while the transverse flow velocity is larger in the case of n0 = 1, but the difference is very small and hence insignificant.
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Ning, Xiaochuan, Tianyi Liang, Dong Wu, Shujun Liu, Yangchun Liu, Tianxing Hu, Zhengmao Sheng i in. "Laser-Driven Proton-Boron Fusions: Influences of the Boron State". Laser and Particle Beams 2022 (26.09.2022): 1–7. http://dx.doi.org/10.1155/2022/9868807.
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The proton-boron (p 11 B) reaction is regarded as the holy grail of advanced fusion fuels, where the primary reaction produces 3 energetic α particles. However, due to the high nuclear bounding energy and bremsstrahlung energy losses, energy gain from the p 11 B fusion is hard to achieve in thermal fusion conditions. Owing to advances in intense laser technology, the p 11 B fusion has drawn renewed attention by using an intense laser-accelerated proton beam to impact a boron-11 target. As one of the most influential works in this field, Labaune et al. first experimentally found that states of boron (solid or plasma) play an important role in the yield of α particles. This exciting experimental finding rouses an attempt to measure the nuclear fusion cross section in a plasma environment. However, up to now, there is still no quantitative explanation. Based on large-scale, fully kinetic computer simulations, the inner physical mechanism of yield increment is uncovered, and a quantitative explanation is given. Our results indicate the yield increment is attributed to the reduced energy loss of the protons under the synergetic influences of degeneracy effects and collective electromagnetic effects. Our work may serve as a reference for not only analyzing or improving further experiments of the p 11 B fusion but also investigating other beam-plasma systems, such as ion-driven inertial confinement fusions.
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Fang, Jun, Qi Xia, Shiting Tian, Liancheng Zhou i Huan Yu. "Kinetic simulation of electron, proton and helium acceleration in a non-relativistic quasi-parallel shock". Monthly Notices of the Royal Astronomical Society 512, nr 4 (14.04.2022): 5418–22. http://dx.doi.org/10.1093/mnras/stac886.
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ABSTRACT In addition to accelerating electrons and protons, non-relativistic quasi-parallel shocks are expected to possess the ability to accelerate heavy ions. The shocks in supernova remnants are generally supposed to be accelerators of Galactic cosmic rays, which consist of many species of particles. We investigate the diffusive shock acceleration of electrons, protons and helium ions in a non-relativistic quasi-parallel shock through a 1D particle-in-cell simulation with a helium-to-proton number density ratio of 0.1, which is relevant for Galactic cosmic rays. The simulation indicates that waves can be excited by the flow of energetic protons and helium ions upstream of a non-relativistic quasi-parallel shock with a sonic Mach number of 14 and an Alfvén Mach number of 19.5 in the shock rest frame, and that the charged particles are scattered by the self-generated waves and accelerated gradually. Moreover, the spectra of the charged particles downstream of the shock are thermal with a non-thermal tail, and the acceleration is efficient, with about $7{{\ \rm per\ cent}}$ and $5.4{{\ \rm per\ cent}}$ of the bulk kinetic energy transferred into the non-thermal protons and helium ions, respectively, in the near downstream region by the end of the simulation.
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Cleymans, Jean, i Masimba Wellington Paradza. "Tsallis Statistics in High Energy Physics: Chemical and Thermal Freeze-Outs". Physics 2, nr 4 (4.12.2020): 654–64. http://dx.doi.org/10.3390/physics2040038.
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We present an overview of a proposal in relativistic proton-proton (pp) collisions emphasizing the thermal or kinetic freeze-out stage in the framework of the Tsallis distribution. In this paper we take into account the chemical potential present in the Tsallis distribution by following a two step procedure. In the first step we used the redudancy present in the variables such as the system temperature, T, volume, V, Tsallis exponent, q, chemical potential, μ, and performed all fits by effectively setting to zero the chemical potential. In the second step the value q is kept fixed at the value determined in the first step. This way the complete set of variables T,q,V and μ can be determined. The final results show a weak energy dependence in pp collisions at the centre-of-mass energy s=20 TeV to 13 TeV. The chemical potential μ at kinetic freeze-out shows an increase with beam energy. This simplifies the description of the thermal freeze-out stage in pp collisions as the values of T and of the freeze-out radius R remain constant to a good approximation over a wide range of beam energies.
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Ofman, Leon, Scott A. Boardsen, Lan K. Jian, Jaye L. Verniero i Davin Larson. "Modeling Ion Beams, Kinetic Instabilities, and Waves Observed by the Parker Solar Probe near Perihelia". Astrophysical Journal 926, nr 2 (1.02.2022): 185. http://dx.doi.org/10.3847/1538-4357/ac402c.
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Abstract Recent in situ observations from the Parker Solar Probe (PSP) mission in the inner heliosphere near perihelia show evidence of ion beams, temperature anisotropies, and kinetic wave activity, which are likely associated with kinetic heating and acceleration processes of the solar wind. In particular, the proton beams were detected by PSP/Solar Probe Analyzers-Ion (SPAN-I) and related magnetic fluctuation spectra associated with ion-scale waves were observed by the FIELDS instrument. We present the ion velocity distribution functions (VDFs) from SPAN-I and the results of 2.5D and 3D hybrid-particle-in-cell models of proton and α particle super-Alfvénic beams that drive ion kinetic instabilities and waves in the inner heliospheric solar wind. We model the evolution of the ion VDFs with beams, and obtain the ion relative drifts speeds, and ion temperature anisotropies for solar wind conditions near PSP perihelia. We calculate the partition of energies between the particles (ions) along and perpendicular and parallel to the magnetic field, as well as the evolution of magnetic energy, and compare to observationally deduced values. We conclude that the ion beam driven kinetic instabilities in the solar wind plasma near perihelia are important components in the cascade of energy from fluid to kinetic scales, an important component in the solar wind plasma heating process.
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Wang, Zhiping, Fengshou Zhang, Xuefeng Xu, Yanbiao Wang i Chaoyi Qian. "Dynamics of water trimer in femtosecond laser pulses". Modern Physics Letters B 30, nr 21 (10.08.2016): 1650272. http://dx.doi.org/10.1142/s0217984916502729.
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With the help of the time-dependent local-density approximation (TDLDA) coupled non-adiabatically to molecular dynamics (MD), we studied both the static properties and irradiation dynamics of water trimer subject to the short and intense femtosecond laser field. It is shown that the optimized geometry and the optical absorption strength of the water trimer accord well with results in literature. Three typical possible irradiated scenarios of water trimer which are “normal oscillation”, “dissociation and formation” and “pure OH dissociation” are exhibited by investigating the ionization and the level depletion related to electrons as well as the OH bonds, proton-transfer, the intermolecular distance and the kinetic energy connected with ions. In three scenarios, the behaviors of water trimer can be attributed to the sequential combination of responses of the electrons emission, the proton-transfer, OH vibration and rotation, OH dissociation and hydroxyl formation, respectively. The relevant time scales of the first proton-transfer and OH dissociation are identified as 13 fs and 10–20 fs, respectively. The study of kinetic energies of ions show that the kinetic energies of the remaining ions are all below 4.5 eV and outgoing hydrogen ions carry a kinetic energy about 5–12 eV. Furthermore, it is found that in the tunneling ionization situations the depletion is fairly shared between the various levels except the most deep occupied electronic level while in the multiphotonic ionization case the electron loss comes from all single-electron levels and the HOMO level contributes the most.