A photonic crystal polarization beam splitter based on photonic band gap and self-collimation effects is designed for optical communication wavelengths. The photonic crystal structure consists of a polarization-insensitive self-collimation region and a splitting region. TMand TE-polarized waves propagate without diffraction in the self-collimation region, whereas they split by 90 degrees in the...

The authors theoretically and numerically investigate the beam propagation near the supercollimation frequency s 0 in a photonic crystal made of nonlinear material. Since the value and sign of the equal-frequency-contour curvature which dominates the beam behaviors can be nonlinearly tuned near s , a kind of nonlinear effect is generated. The envelope equation with unique form is also obtained....

INTRODUCTION Collimating the primary beam to the area of diagnostic interest (ADI) has been strongly recommended as an effective method to reduce patient's radiation dose and to improve image quality during radiology practice. Lack or inadequate collimation results in excessive radiation dose to patients and deterioration image quality. OBJECTIVE To assess the quality of beam collimation duri...

1 Introduction In high-energy physics colliders, the 'halo' particles surrounding the core of the beams would cause intolerable background in the physics detectors if not removed. Collima-tion systems consisting of mechanical 'spoilers' on the order of a radiation length are placed close to the beam and used to 'scrape' the halo particles off: the particles scattered by the spoilers are then co...

We have studied laser collimation of a chromium atomic beam using a transverse polarization gradient cooling scheme. We present detailed measurements of the angular distribution of atoms on the beam axis, over a broad range of laser intensities and detunings including those which produce significant excitation, and observe collimation angles as small as 0.16 ± 0.01 mrad (50% quantile). We compa...

Based on realistic Monte-Carlo simulations a two-stage beam collimation system is designed to minimize the beam loss in the Fermilab Tevatron for fixed target and collider Run II. Thin primary collimators are used to increase particle amplitude and their impact parameter on the downstream secondary collimators. This results in a significant reduction of the total beam loss in the machine, decre...

MAD-MARS Beam-Line Builder (MMBLB) is a tool that helps MARS15 build models of accelerator lattices and beam lines using the MAD-generated optics descriptions. This mode is especially powerful in beam loss, collimation, backgrounds and shielding studies at the existing and new accelerators and beam transport lines. Many applications works using this tool have been performed such as Main Injecto...

A high beam power of 1.15 MW in the proposed 16-GeV Proton Driver [1] implies serious constraints on beam losses in the machine. The main concerns are the hands-on maintenance and ground-water activation. Only with a very efficient beam collimation system can one reduce uncontrolled beam losses to an allowable level. The results on tolerable beam loss and on a proposed beam collimation system a...

A model for beam customization with collimators and a range-compensating filter based on the phase-space theory for beam transport is presented for dose distribution calculation in the treatment planning of radiotherapy with protons and heavier ions. Independent handling of pencil beams in conventional pencil-beam algorithms causes unphysical collimator-height dependence in the middle of large ...