In radiation therapy with high-energy photon beams (E > 10 MeV) neutrons are generated mainly in linacs head thorough (γ,n) interactions of photons with nuclei of high atomic number materials that constitute the linac head and the beam collimation system. These neutrons affect the shielding requirements in radiation therapy rooms and also increase the out-of-field radiation dose of patients und...

In this article, we present an analysis of the stability of optical lattices. Starting with the study of an unstable optical lattice, we establish a necessary and sufficient condition for intrinsic phase stability, and discuss two practical solutions to fulfill this condition, namely minimal and folded optical lattices. We then present a particular example of two-dimensional folded optical latt...

Related Articles Homogeneity improvement of field emission beam from metallic nano-tip arrays by noble-gas conditioning Appl. Phys. Lett. 99, 073101 (2011) Analysis of electric field screening by the proximity of two knife-edge field emitters J. Appl. Phys. 110, 034905 (2011) Space charge limited electron flow in two dimensions without magnetic field J. Appl. Phys. 110, 033306 (2011) Electron f...

Related Articles Homogeneity improvement of field emission beam from metallic nano-tip arrays by noble-gas conditioning Appl. Phys. Lett. 99, 073101 (2011) Analysis of electric field screening by the proximity of two knife-edge field emitters J. Appl. Phys. 110, 034905 (2011) Space charge limited electron flow in two dimensions without magnetic field J. Appl. Phys. 110, 033306 (2011) Electron f...

An evaluation of the capabilities of a commercially available camera-based electronic portal imaging system for intensity-modulated radiotherapy verification is presented. Two modifications to the system are demonstrated which use a novel method to tag each image acquired with the delivered dose measured by the linac monitor chamber and reduce optical cross-talk in the imager. A detailed perfor...

Hospital-based proton facilities may represent a major advance in radiation therapy, in part because of excellent dose distributions around the tumor, and in part because of the potentially lower whole-body dose compared with photon radiotherapy. Most current proton beams are spread out to cover the tumor using beam scattering and collimation techniques (passive scattering); this will necessari...

Accsim is a synchrotron/storage-ring tracking and simulation program that was originally written to simulate chargeexchange injection and accumulation of an intense proton beam in a KAON factory accumulator ring. It has subsequently been developed and used for other injection studies and for applications such as the optimization of collimation systems. The code performs basic six-dimensional tr...

The sweep system for the HIBP (Heavy Ion Beam Probe) on the Madison Symmetric Torus is described. The two components of the system are the primary sweep optics and secondary collimation plates. Key issues in the sweep system design are the small entrance and exit ports available on MST, the signi cant toroidal beam motion induced by the strong poloidal magnetic eld and the excessive current loa...

A laser pulse propagating in a corrugated plasma channel is composed of spatial harmonics whose phase velocities can be subluminal. The phase velocity of a spatial harmonic can be matched to the speed of a relativistic electron resulting in direct acceleration by the guided laser field in a plasma waveguide and linear energy gain over the interaction length. Here we examine the fully self-consi...

Mesoscopic self-collimation (MSC) in mesoscopic photonic crystals with high reflectivity is exploited to realize a novel high Q-factor cavity by means of mesoscopic PhC planar mirrors. These mirrors efficiently confine a mode inside a planar Fabry-Perot-like cavity, that results from a beam focusing effect that stabilizes the cavity even for small beam sizes, resembling the focusing behavior of...