Large-Angle Scattering Research Articles

Interpretation of High-Energy Large-Angle Scattering

It is shown that if the analytically continued partial-wave amplitude is assumed to have $l$ dependence ${a}_{\ifmmode\pm\else\textpm\fi{}}(s, l)=\ensuremath{\Sigma}\stackrel{n}{l=0}{{C}_{m}}^{\ifmmode\pm\else\textpm\fi{}}(s){l}^{m}{(l+1)}^{m}$ for $l<{l}_{0}(s)$ and finite $n$, the scattering amplitude is bounded by $\mathrm{exp}{\ensuremath{-}\mathrm{const}{[{l}_{0}(s)sin\ensuremath{\theta}(s)]}^{\frac{1}{2}}}$ at high energies. Here ${a}_{+}(s, l)[{a}_{\ensuremath{-}}(s, l)]$ is equal to ${a}_{l}(s)$ for even (odd) integer $l$. The most physical example of this dependence is that in which a central area of the scatterer becomes maximally absorptive.

Isotopic, Isotonic, and Shell Closure Effects on the Large-Angle Scattering of Polarized Protons

Detailed measurements on the elastic scattering of 14Mev polarized protons out to 170 nif- in the laboratory reference frame are reported. The nuclides studied are in the mass region 50-70 and encompass closed shells of neutrons and protons. The measurements comprise left-right asymmetries that are related to the polarization that would result from the elastic scattering of an unpolarized proton beam. Results obtained on a series of isotopes and isotones from Cr to 2n are given. (C.E.S.)

Chemical Analysis of Surfaces by Use of Large-Angle Scattering of Heavy Charged Particles

The Rutherford scattering of carged particles from the heavier elements and nuclear scattering and (alpha,p) reactions from the light elements result in energy spectra that are characteristic of the nucleus being bombarded. A simple apparatus for analyzing surfaces based on these ideas can be made by using an alpha source such as Cm244, a solid state detector, and an electronic pulse height analyzer.

Resonance Electron Exchange in Large-Angle Scattering ofHe+on He at kev Energies

Recent differential scattering measurements at 5\ifmmode^\circ\else\textdegree\fi{} scattering angle of ${\mathrm{He}}^{+}$ on He at energies of 2 to 250 kev have shown several pronounced resonance peaks when the fraction of the scattered particles which were neutral (electron exchange) was plotted as a function of incident energy. A detailed comparison of those experimental data is made with the theoretical predictions of the impact parameter method for resonance electron capture. The agreement between the theory and experiment is found to be quite good at high energies despite experimental indications of a large amount of excitation. The contribution of electron exchange with excitation is then considered in the light of this fact.

The effect of the angular variation of intensity on scattering distributions of Μ-mesons underground at a depth of 40 m w.e

The interpretation of experiments carried out underground to investigate the large angle scattering of Μ-mesons depends on the assumed form of the underground spectrum and the geometrical bias introduced by the counter selection system. The form of the angular variation of intensity at 40 m w.e. has been obtained. The effect of introducing this into the calculation of the geometrical correction factors is discussed. It is shown that previous workers who assumed normal incidence of all particles have underestimated the expected number of large angle scatters.

Large Angle Scattering of Negative Pions in Aluminum, Copper, and Lead

The total cross sections for backscattering of 32\ifmmode\pm\else\textpm\fi{}10 Mev negative pions in Al, Cu, and Pb have been measured. A stripped emulsion was embedded in a semi-infinite absorber, and exposed to an incident beam of ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons. The positions and direction of mesons stopping in the emulsion were recorded. The cross sections are proportional to the ratio of the backward flux to incident flux, both of which are observed on the same strip of emulsion. The conclusions of this investigation are: (a) the scattering is consistent with energy independence in the region of 32\ifmmode\pm\else\textpm\fi{}10 Mev; (b) the angular distribution has a maximum at 180\ifmmode^\circ\else\textdegree\fi{}; (c) the cross section for backscattering is proportional to the mass number $A$. The total nuclear backscattering cross sections (elastic and inelastic) for negative pions in Al, Cu, and Pb are 59.6\ifmmode\pm\else\textpm\fi{}11 mb, 192\ifmmode\pm\else\textpm\fi{}27 mb, and 577\ifmmode\pm\else\textpm\fi{}80 mb, respectively.

Cloud Chamber Observations of the Cosmic Radiation Underground

In a study of the passage of fast charged particles through a cloud chamber containing two Pb plates at a depth below ground equivalent to 60 m water, examples of associated pairs of penetrating particles and of large angle scattering of single particles have been observed. If these events are interpreted as the production of secondary particles by μ-mesons, and as anomalous scattering of μ-mesons in Pb, the following cross sections per nucleon result: for penetrating secondary particles 4 × 10-29 cm2, and for anomalous large angle scatter 2 × 10-28 cm2.

Large Angle Scattering and Energy Loss of Potassium Ions Scattered by Heavy Monatomic Gases

A beam of potassium ions with energies in the range between 90 and 360 volts was scattered by collision with the heavy monatomic gases argon, krypton, xenon, and mercury vapor and the angular distribution was observed. For slower particles the scattering per unit solid angle relative to the center of mass of the colliding particles decreases with angle. At higher voltages the scattering increases at larger angles with a minimum about 60. The scattering at the larger angles increases with voltage. The results are not compatible with a rigid sphere model of the atom. The large deviations may be associated with exciting or ionizing collisions.

Large Angle Scattering of Low Velocity Electrons from Copper, Iron, Nickel and Silver

Large Angle Scattering of Low Velocity Electrons from Copper, Iron, Nickel and Silver