Wakefields excited in the small aperture collimators may damage the beam. As pointed out by K. Bane and P. Morton the wakefields can be reduced considerably by tapering the steps and using the “step+taper” collimator geometry. The optimisation of this kind of geometry for TTF 2 collimators with different apertures is carried out in the paper. For the optimal geometries the nonlinear near-wall w...

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...

Simulations have been performed in Omega3P to study both trapped modes and impedance contributions of a rotatable collimator for the LHC phase II collimation upgrade. Bench-top stretched coil probe impedance methods are also being implemented for measurements on prototype components to directly measure the low frequency impedance contributions. The collimator design also calls for a RF contact ...

This paper considers Scintimammography (SM) imaging using two different image acquisition/formation methods: Low Energy High Resolution (LEHR) collimator and a Modified Uniformly Redundant Array (MURA) coded aperture (CA) systems. Using Monte Carlo simulation, the effectiveness and performance of both systems were evaluated by quantitative comparison of lesion contrast and Full-Width-Half-Maxim...

The heat balance method is developed to optimize cooling modes of large-sized optics in a special cryogenic-vacuum system by considering complicated transfer the minimize thermal deformations. Keywords: radiative transfer, conductive balance, thermostat, collimator.

BACKGROUND Post-therapy SPECT/CT imaging of 90Y microspheres delivered to hepatic malignancies is difficult, owing to the continuous, high-energy Bremsstrahlung spectrum emitted by 90Y. This study aimed to evaluate the utility of a commercially available software package (HybridRecon, Hermes Medical Solutions AB) which incorporates full Monte Carlo collimator modelling. Analysis of image qualit...

BACKGROUND Image-based measurement of absorbed dose of Ra-223 dichloride may be useful in predicting therapeutic outcome in patients with castration-resistant prostate cancer (CRPC). In general, SPECT has been found to be more accurate than planar imaging in terms of lesion-based analysis. The aims of this study were to assess the feasibility and clinical usefulness of Ra-223 SPECT. The energy ...