Similar Kinetic Energy Research Articles

Ion emission due to the scattering of hyperthermal Xe atoms from single crystal surfaces

We report the emission of ions from single crystal surfaces due to the scattering of hyperthermal Xe over the energy range 6 < E i < 20 eV. We observe Ga + from GaAs(110), In + from InP(100), and alkali and other impurity ions from all surfaces. At E i = 16 eV the ion emission probability for In + reaches 1 × 10 −3. The yields increase as the Xe incident angle goes towards grazing, have a similar Xe kinetic energy dependence, and a common threshold near 6.5 eV at the incident angles of maximum efficiency. We discuss possible mechanisms for ion emission due to hyperthermal Xe scattering.

Relationship between the electronic potential energy of a crystal and X-ray scattering

Abstract Some simple but approximate relationships arc shown to yield the total deformation potential energy of a crystal from a summation of the structure factors and their squares. By application of the virial theorem this deformation potential should be consistent with similar kinetic energy differences obtained from integration of the Compton profiles in addition to being consistent with the cohesive energy of the crystal.

Ion-molecule reaction chemistry of various gas-phase C6H6 radical cations

Ion-molecule reaction chemistry of various gas-phase C6H6 radical cations

On the intensity of horizontal ocean currents

Ocean currents on both the east and west sides of the Atlantic, near Bermuda, and in the Mediterranean Sea show similar mean kinetic energy and mean speeds from long-term current measurements. At a given depth, there is less than a factor of two in the range of speeds and a factor of four in kinetic energy. In spite of intermittency in time and location in space there is remarkable uniformity in the intensity of the currents. A notable exception is a set of high values of speed and kinetic energy NNE of Bermuda that are possibly associated with a Gulf Stream meander. Both moored current meters and neutrally buoyant (Swallow) floats have been used for measurement of currents. Speed and total kinetic energy are similar with the two methods, but estimates of the kinetic energy of the fluctuating component of motion are generally lower when Swallow floats are used.

Kinetic energy distributions of CH 12H 8 fragment ions in the mass spectra of anthracene, phenanthrene and diphenylacetylene

The formation of 152 + ions in the mass spectra of anthracene, phenanthrene and diphenylacetylene has been studied by kinetic energy and appearance potential measurements. 152 + ion formation has a similar energy requirement in all three compounds and the products separate with similar kinetic energy distributions. If the products are biphenylene ions and acetylene molecules they are formed with approximately 2 eV of internal excitation energy. The observed Maxwellian distribution of the kinetic energy of separation of the products is close to that which would be observed if a substantial reverse activation energy were distributed statistically between three translational modes and a number of vibrational modes in the products. The 152 ++ ions are produced with less kinetic energy release than the singly charged ions. The reduction in the kinetic energy is of the same order of magnitude as the increase in the attractive ion-induced dipole forces between the separating fragments

A collective accelerator

Owing to their high ratio of charge to mass, electrons can be given much higher accelerations than can protons. Consequently, for a given cost they can reach similar absolute kinetic energies although their velocities are then much closer to the velocity of light.

Confinement of cosmic-ray nuclei in ionized source regions and interstellar medium

The problem of delineating the effects of the matter traversed by cosmic rays in the source region (which consists of matter in the ionized state) and in the interstellar medium (which is partially ionized) is investigated in great detail by studying the energy losses suffered by a charged particle in these two media. Expressions for the energy losses are derived from a consideration of the composition of neutral and ionized atoms in these media. The relative intensities of the nuclei of various energies and charges are then calculated for different path lengths traversed in such source regions and in space, taking both the effects of ionization loss and fragmentation in the media concerned. Three kinds of source spectra, namely power law spectra in total energy per nucleon, in kinetic energy per nucleon, and in rigidity are used for this purpose; the exponents and other constants involved in these spectra are deduced from the high-energy data that are little affected by solar modulation. The implications of these calculations are discussed with reference to experimental results on the ratio of intensities (1) ΓH1α of H1 nuclei (Z ≥ 20) to α particles, (2) ΓHα of H nuclei (Z ≥ 10) to α particles, and (3) ΓLS of L nuclei (Z = 3–5) to S nuclei (Z ≥ 6) in the energy region 50–1000 Mev per nucleon. It is concluded that for similar source kinetic energy per nucleon and rigidity spectra, the effect of the matter traversed by particles in the source region is negligible compared to its value in the interstellar space. On the other hand, for a source spectrum that is a power law in total energy per nucleon, the experimental results would indicate an appreciable trapping of the particles in the source region itself.

Production of Strange Particles by 2.8-Bev Protons in C, Fe, and Pb

Observations of ${\ensuremath{\Lambda}}^{0}$, ${{\ensuremath{\theta}}_{1}}^{0}$, and ${{\ensuremath{\Sigma}}_{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$ particles from 2.8-Bev proton interactions have been made in a multiplate cloud chamber with one-half inch plates of C, Fe, and Pb. The ${Y}^{0}({\ensuremath{\Lambda}}^{0}, {\ensuremath{\Sigma}}^{0})$ and ${\ensuremath{\theta}}^{0}$ cross sections, when compared with those observed for production by 1.5-Bev ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons with the identical arrangement, are lower by at least a factor of four for C and a factor of two for Pb. Production of ${{\ensuremath{\Sigma}}_{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}'\mathrm{s}$ by protons and pions seem to be of comparable magnitude in either C or Pb. Since protons are less effective than pions of similar kinetic energy (in the center-of-mass system) in producing strange particles, it is estimated in the case of incident protons that indirect production of strange particles by intermediate pions accounts for (${40}_{\ensuremath{-}13}^{+28}$)% of the observed particles in C and (${64}_{\ensuremath{-}14}^{+21}$)% in Pb. The different $A$ dependence of the proton and pion cross sections for producing observable strange particles (${\ensuremath{\Lambda}}^{0}, {{\ensuremath{\theta}}_{1}}^{0}, {{\ensuremath{\Sigma}}_{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}+n$) may be fitted by a total proton-nucleon direct production cross section of 0.09\ifmmode\pm\else\textpm\fi{}0.06 mb.The proton-produced strange particle events were used to compute what would be expected when decay $\ensuremath{\gamma}$ rays emitted at 90\ifmmode^\circ\else\textdegree\fi{} to the beam direction are observed in the geometry used by Berley and Collins. The predicted decay curve is in excellent agreement with their observations, and the absolute and relative yields agree within the estimated experimental uncertainties.