Description: This article discusses experimental evidence for a discrete transition to channeling for 1.0-MeV protons in Si〈100〉. Abstract: The present work reports the experimental evidence of anomalies exhibited by the energy loss and energy straggling of channeled protons in silicon in transmission measurements versus the incident angle. Results are presented for 1.0-MeV protons channeled along the 〈100〉 axis for a silicon foil of 3.8 μm thickness. It is shown that the transition from random to a channeling condition is discrete. The energy spectra of transmitted ions show a random peak (lower energy) and a channeled peak (higher energy). The random peak has a fixed energy, while the energy of the channeled peak increases as the target crystal's axis approaches alignment with the direction of the incident ion beam. The results support a model suggesting that the channeled ions lose energy only to valence electrons and are concentrated in a narrow cone about the direction of incidence when they emerge from the crystal. The energy straggling of channeled particles reaches a minimum in the hyper-channeled condition. Both the energy loss and the energy straggling of channeled protons show a dependence on the local electron density.

Description: This book chapter discusses different media texts targeted at a different audience, magazines written for an audience of teenaged girls, which also work to naturalize male sexuality as aggressive and predatory. The authors study advice columns and articles in these magazines that depict teenaged boys as sexually forceful and emotionally stunted, and that encourage girl readers to expect and enable such behaviors.

Description: This article discusses K-shell x-ray production cross sections of selected elements from Ti to Y. Abstract: K-shell x-ray production cross sections and Kβ/Kα ratios have been measured for thin targets of Ti, V, Cr, Fe, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, and Y for 0.5- to 2.5-MeV alpha particles. The experimental values are compared to the nonrelativistic plane-wave Born approximation (PWBA), the binary-encounter approximation, and the PWBA with binding energy and Coulomb deflection corrections. The PWBA with corrections provides the best agreement with the experimental cross sections.

Description: This article discusses the linear response of Hamiltonian chaotic systems as a function of the number of degrees of freedom. Abstract: Using numerical simulations we show that the response to weak perturbations of a variable of Hamiltonian chaotic systems depend on the number of degrees of freedom: When this is small (≈2) the response is not linear, in agreement with the well known objections to the Kubo linear response theory, while, for a larger number of degrees of freedom, the response becomes linear. This is due to the fact that increasing the number of degrees of freedom the shape of the distribution function, projected onto the subspace of the variable of interest, becomes fairly "regular."

Description: This article discusses M-shell x-ray-production cross sections in thin targets. Abstract: M-shell x-ray-production cross sections are reported for ₁¹H+ and ₂⁴He+ ions incident on thin targets of ₇₉Au, ₈₂Pb, ₈₃Bi, and ₉₂U. The energy of the ions ranged from 0.3 to 2.6 MeV in increments of 0.1 MeV. The first Born calculations overpredict the data at all energies studied. The perturbed-stationary-state calculations with energy loss, Coulomb deflection, and relativistic effects agree with the present data for both ₁¹H+ and ₂⁴He+ ions at ~0.35 MeV/u, overpredict the data at higher E₁/A₁, and underpredict the data at lower E₁/A₁. The electron-capture contribution to the target ionization is calculated to be less than 3.4% for the targets, projectiles, and energies reported in this work.