Geometric efficiency of a two-stage fully absorbing collimation system in single-pass linacs

Abstract

Collimators are commonly used in particle accelerators to prevent particles traveling at large amplitudes from hitting the vacuum chamber. We derive here, for a single-pass linac, a one-dimensional analytical expression for the efficiency of a two-stage fully absorbing collimation system (CS), based on the CS geometrical and optical properties only. We show that, in the presence of physical space or optics constraints, the best betatron phase advance in between the first and the second collimation stage may differ from the usually prescribed =2. The analytically computed collimation efficiency is then compared to particle tracking results.

Beam halo collimation in heavy ion synchrotrons

“…[11,12,21], the collimation efficiency can be expressed as the ratio of the particles intercepted by the secondary collimators (collimated particles) to the particles scattered before in the primary collimator. This is the definition of the single-pass collimation efficiency, where the particles are tracked only from the primary up to the 2nd secondary collimator [11,12,38]. However, we consider the motion in circular accelerators (synchrotrons).…”

Influence of longitudinally tapered collimators on a high brightness electron beam

“…The resultant collimation efficiency is somewhat reduced when compared to the ideal =2 case. Equation (11) in [19] can be used to evaluate the geometric collimation efficiency of the FERMI system compared to the ideal case; this being defined both in terms of the optimum collimator gap and the optimum phase advance. Our calculations showed an efficiency of 76% for protecting the 3.5 mm half-gap undulator vacuum chamber from particle impact with a safety margin of 10%.…”