Kinetic Energy Of Protons Research Articles

Charged Particles and Gamma-Ray Interaction with Gallium Barium Borate Glass: Theoretical Approach

The charged particle and gamma-ray shielding properties of gallium barium borate glass in composition (80-x)B2O3: xBaO: 20Ga2O3 (where x = 5, 10, 15, 20 and 25 mol%) were calculated and discuss in this work. The mass attenuation coefficient (μm), the effective atomic number (Zeff) and the effective electron density (Neff) were calculated by using the WinXCom program in the energy range from 1 keV to 2 MeV. The results show the mass attenuation coefficients (μm), the effective atomic number (Zeff) , and the effective electron density (Neff) increase with increasing of BaO content reflected higher interaction probability at higher BaO composition in the glass matrix. The result of build-up factor are in the same trend and show the high value in the region which incoherent scattering is the main interaction. The mass stopping power and the projected range of proton and alpha particle have been simulate by SRIM program. The mass stopping power has maximum value at 0.9 MeV and 0.07 MeV for proton and alpha particles respectively. The projected range have the higher value at the higher kinetic energy of proton and alpha particle. Moreover the gallium barium borate glass system better have the proton and alpha shielding preperty when add barium oxide concentration due to weight fraction of barium increase in glass matrix.

Collision dynamics of cytosine under proton irradiation

In the framework of the time-dependent density-functional theory, applied to valence electrons, coupled non-adiabatically to molecular dynamics of ions, the collision dynamics of cytosine impacted by proton is studied. We especially focus on the effect of the collision orientations on the damage of cytosine by choosing two collision orientations taking the oxygen atom on the double bond CO as the collision site with the incident energy of proton ranging from 150 eV to 1000 eV. First, two collision dynamical processes are explored by analyzing the molecular ionization, the ionic position and the kinetic energy, the energy loss of proton and the electronic density evolution. The results show that the damage process of cytosine induced by proton impact is mainly the capture of electrons by proton, the departments of ions and groups as well as the opening of ring. It is found that the orientation has little effect on the loss of the kinetic energy of proton, which is about 21.5[Formula: see text] of the incident energy of proton. Although the scattering angle [Formula: see text] has a polynomial relationship with [Formula: see text] in both cases, it is greatly affected by the orientation. When [Formula: see text] eV, the scattering angle of proton colliding with O along the [Formula: see text]-axis is greater than that of proton colliding with O along the [Formula: see text]-axis. The orientation also has a great effect on the mass distribution of the fragments and the fragmentation route. When proton moves along the [Formula: see text]-axis, the fragmentation route is that O leaves the cytosine and the rest keeps on vibration, while products are not only related to the incident kinetic energy, but also show diversity when proton moves along the [Formula: see text]-axis.

Off-Axis Characterisation of the CERN T10 Beam for low Momentum Proton Measurements with a High Pressure Gas Time Projection Chamber

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.

Time-dependent density functional theory studies of dynamics of hydroxy by proton impact

Using the time-dependent density functional theory and non-adiabatic coupling in molecular dynamics, the reaction dynamics of collisions between energetic proton and hydroxy is studied. The variations in kinetic energy of proton and hydroxy and the motions of electron of hydroxyl and ion before and after collisions are investigated. It is found that when a proton is incident in the direction perpendicular to the molecular axis, it that has lose kinetic energy rebounds, and captures electrons from hydroxy, while the hydroxy that has lost part of electrons gains kinetic energy, and thus translates toward the calculating boundary in the manner of contracting vibration. The larger the kinetic energy of incident proton, the more the number of electrons captured from hydroxy is. Therefore the bond length of hydroxy lengthens, oscillation strengthens, and vibrational frequency decreases. In addition, it is found that the incident direction of proton has a great influence on the dynamic behavior of excitation in a collision process. Considering the case where the proton is incident from different directions, the results show that the larger the kinetic energy of incident proton, the more the lost energy is, and the lost energy is linearly related to the initial kinetic energy of incident proton. For hydroxy, when the incident kinetic energy of proton is less than 25 eV, the kinetic energy gained by the proton is linearly related to the initial kinetic energy, but unrelated to incident direction, while when the initial kinetic energy of incident proton is larger than 25 eV, the increment in kinetic energy of hydroxyl is much larger in the case where the proton is incident along the axis of hydroxyl molecule than in the case where the proton is incident in the direction perpendicular to the axis of the hydroxyl molecule.

Neutron spectrometer based on a proton telescope with electronic collimation of recoil protons

A prototype of a neutron spectrometer based on a gas proportional counter with recoil-proton registration is created at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (FLNP JINR) in Dubna. The spectrometer is developed to measure the kinetic energy of protons scattered elastically at small angles that are produced by (n, p) reaction in an environment containing hydrogen. The elaborated prototype consists of two cylindrical proportional counters used as cathodes. They are placed in a gas environment with a common centrally situated anode wire. Studies on the characteristics of the neutron spectrometer were conducted using 252Cf and 239Pu-Be radioisotope neutron sources. Measurements were made with monoenergetic neutrons produced by the 7Li(p, n)7Be reaction when a thin lithium target was bombarded with a proton beam from an EG-5 electrostatic accelerator, as well as with neutrons from the reaction D(d, n) 3He with a gas deuterium target.

A numerical study of the instability of plasma flow

The results of the instability investigations of the electrically neutral relativistic plasma flow, consisting of protons and electrons, moving in vacuum at a constant velocity, are described in the paper. The calculations are provided within the framework of Maxwell-Vlasov equations on a three-dimensional (3D) model and the following result is obtained: to a certain time moment t 0, the kinetic energy of protons is almost uniformly redistributed between protons, electrons, and the electromagnetic field that has emerged by this moment. In the 1D calculations the solution is stable.

The VESUVIO electron volt neutron spectrometer

This paper describes the VESUVIO electron volt neutron spectrometer at the ISIS pulsed neutron source and its data analysis routines. VESUVIO is used primarily for the measurement of proton momentum distributions in condensed matter systems, but can also be used to measure the kinetic energies of heavier masses and bulk in-situ sample compositions. A series of VESUVIO runs on the same zirconium hydride sample over the past two years show that (1) kinetic energies of protons can be measured to an absolute accuracy of ∼1%. (2) Measurements of the proton momentum distribution n(p) are highly reproducible from run to run. This shows that small changes in kinetic energy and the detailed shape of n(p) with parameters such as temperature, pressure and sample composition can be reliably extracted from VESUVIO data. (3) The impulse approximation (IA) is well satisfied on VESUVIO. (4) The small deviations from the IA due to the finite momentum transfer of measurement are well understood. (5) There is an anomaly in the magnitude of the inelastic neutron cross-section of the protons in zirconium hydride, with an observed reduction of 10% ± 0.3% from that given in standard tables. This anomaly is independent of energy transfer to within experimental error. Future instrument developments are discussed. These would allow the measurement of n(p) in other light atoms, D, 3He, 4He, Li, C and O and measurement of eV electronic and magnetic excitations.

Kinetic energy of protons in ice Ih and water: A path integral study

The kinetic energy of H and O nuclei has been studied by path integral molecular-dynamics simulations of ice Ih and water at ambient pressure. The simulations were performed by using the q-TIP4P/F model, a point-charge empirical potential that includes molecular flexibility and anharmonicity in the OH stretch of the water molecule. Ice Ih was studied in a temperature range between 210 and 290 K, and water between 230 and 320 K. Simulations of an isolated water molecule were performed in the range 210--320 K to estimate the contribution of the intramolecular vibrational modes to the kinetic energy. Our results for the proton kinetic energy ${K}_{H}$ in water and ice Ih show both agreement and discrepancies with different published data based on deep inelastic neutron-scattering experiments. Agreement is found for water at the experimental melting point and in the range 290--300 K. Discrepancies arise because data derived from the scattering experiments predict in water two maxima of ${K}_{H}$ around 270 and 277 K, and that ${K}_{H}$ is lower in ice than in water at 269 K. As a check of the validity of the employed water potential, we show that our simulations are consistent with other experimental thermodynamic properties related to ${K}_{H}$, such as the temperature dependence of the liquid density, the heat capacity of water and ice at constant pressure, and the isotopic shift in the melting temperature of ice upon isotopic substitution of either H or O atoms. Moreover, the temperature dependence of ${K}_{H}$ predicted by the q-TIP4P/F model for ice Ih is found to be in good agreement with results of path integral simulations using ab initiodensity-functional theory.

Rule of superprotonic phase transition in CsxRb1 − xH2PO4

We have investigated the relation between the superprotonic phase transition and elastic property in CsH2PO4 (CDP) type compounds. It was found that, in CsxRb1−xH2PO4 (x=0–1), the transition temperature Tc decreases in proportion to the square of spontaneous strain component d. From this result, it is indicated that the spontaneous strain plays an important role in the appearance of superprotonic conductivity in CDP type compounds. In addition, by thermodynamic analyses, proton transfer in superprotonic phase is induced by the release of the strain energy. These results indicate that the superprotonic transition temperature in CDP type compounds is determined by the competition between the kinetic energy of proton, the increase of entropy and the released-strain energy.

Dissociation of alkane ionized molecules

The subject of investigation is the fragmentation of variously charged molecular ions arising in col-lisions of several kiloelectronvolt H+, He2+, and Ar6+ ions with molecules of the simplest alkanes (from methane to butane). Using the method of time-of-flight mass spectrometry, the formation cross sections of dissociation-induced fragment ions are measured. The dissociation takes place when an incident ion captures an electron from a methane, ethane, or propane molecule. The role of additional ionization of the molecule, which accompanies the electron capture by the incident ion, is elucidated. The kinetic energy spectrum for protons resulting from the fragmentation of multiply charged alkane ions is determined. The most plausible kinetic energies of protons depending on the degree of ionization and molecule size fall into the range 1–25 eV. It is shown that, when the molecule loses several electrons, the kinetic energies of protons are governed by Coulomb interaction between all fragment ions and are determined by their flying apart from the relative spatial arrangement of corresponding atoms in a parent molecule.

Interrelationship between superprotonic conductivity and strain in CsHXO 4

In order to clarify the mechanism of superprotonic conductivity (SPC) for the hydrogen-bonded compound CsHXO 4 ( X = S , Se), we have investigated the elastic properties of CsHXO 4 with various transition temperatures ( T c ), at which CsHXO 4 exhibits a structural phase transition from a low-temperature monoclinic phase with low protonic conductivity (phase II) to a high-temperature SPC phase (phase I). It was found that, in CsHS x Se 1 − x O 4 ( x = 0 – 1 ), the transition temperature T c decreases in proportion to the square of spontaneous strain b in the a II – b II plane of phase II. This result indicates that the spontaneous strain in the a II – b II plane plays an important role in the appearance of SPC in CsHXO 4. Moreover, thermodynamic analyses suggest that proton migration in phase I is induced by the release of the strain energy. From these results, it is deduced that the phase transition temperature in CsHXO 4 is determined by the competition between the kinetic energy of proton and the released-strain energy.

Laser initiated detonation in Rydberg matter with a fast propagating shock wave, releasing protons with keV kinetic energy

Laser pulses of 50 mJ energy initiate detonations that release energy and create shock waves in a phase of Rydberg matter (RM) mainly consisting of H 2 RM clusters. The shock wave has a speed of approximately 20 km s −1. It is observed in coupled angular and time-of-flight distributions of charges released. The high speed of the shock indicates that RM is a condensed material. The kinetic energy of protons from hydrodynamic acceleration is > 1 keV . Protons are also released directly in Coulomb explosions from the lowest energy state n = 1 of H RM, with energies of 9.4 and 19 eV.

Quasi-free (e, e'p) scattering on 12C, 28Si, 40Ca and 58Ni

The (e, e'p) reaction on 12C, 28Si, 40Ca and 58Ni has been measured at 497 MeV incident electron energy. The experiment covered the region E ≦ 80 MeV for the separation energy and P ≦ 250 MeV/ c for the recoil momentum. Cross sections, calculated in the distorted wave impulse approximation, have been utilized in a shell-model expansion of the spectral function. Average separation and kinetic energies of protons in individual shells are extracted from the data. The validity of Koltun's sum rule is discussed.

Étude de l'énergie cinétique des produits de la dissociation collisionnelle d'ions CH n+ d'énergie 40 keV : II. Dissociation de CH +

The kinetic energy of protons and hydrogen atoms arising from collisional dissociation of 40 keV CH + ions has been measured by electrostatic analysis, after reionization of the neutrals. The distribution of the kinetic energy released by the dissociation CH + → C + + H, which has maxima at 0.3 and 2.9 eV, is similar to that determined by another method and consistent with suppositions based upon the analysis of potential energy curves of CH + and of the lifetime of some transitions. The distribution of the kinetic energy released by the dissociations CH + → C + H + and CH + → C + + H + + e, which has never been studied, exhibits maxima at 0.7, 1.2, 2.9, 5.7 and 8.4 eV, which are also consistent with the suppositions.