We present the first direct measurement of proton energy-loss straggling in Gal_xAlxAs/GaAs, enabling us to take maximum advantage of the 27 Al (p, y) 28Si nuclear reaction as a powerful nondestructive technique for measuring Al profiles in these structures. Results were obtained using samples produced by molecular beam epitaxy and fabricated to have step-function Al concentration distributions...

From fundamental principles, the interaction of directed energetic electrons with hydrogenic and arbitrary-Z plasmas is analytically modeled. The effects of stopping, straggling, and beam blooming, a consequence of scattering and energy loss, are rigorously treated from a unified approach. Enhanced energy deposition occurs in the latter portion of the penetration and is inextricably linked to s...

A new algorithm for energy-loss straggling in MCNP is demonstrated. An approximate but accurate energy-loss moment-preserving differential cross section is used in conjunction with single event Monte Carlo simulation through each condensed history step to show that highly accurate energy spectra, leakage currents, and dose profiles can be obtained. This new approach provides a viable and even p...

The electronic stopping cross sections in boron for atomic projectiles with Z 11 have been determined in the energy interval 15 to 140 keV. Reasonable agreement is found with theory, however the previously observed periodic dependence of SE on the atomic number of the project i le is also evident. Results for the relative straggling in energy loss are reported for hydrogen projectiles in boron,...

We present a description of the effect of the surface roughness on the energy straggling associated to the energy loss distributions of protons transmitted through a self supported metallic thin foil. For this purpose we prepared a polycrystalline gold thin films using the standard sputtering method with different deposition rates. The statistics of the surface height distribution induced in th...

A non-scaling fixed field alternating gradient (nsFFAG) accelerator is being designed for helium ion therapy. This facility will consist of 2 nested rings, treating with helium ions (He) and image with hydrogen ions (H + 2 ). Compared to protons, ions deliver a more conformal dose with a significant reduction in range straggling and beam broadening. Carbon ions are currently used and there are ...