The Banados-Silk-West effect consists in the possibility to get infinite energy in the centre of mass frame of two particles colliding near the black hole horizon. Ac-at infinity of the outcome vanishes because of infinite redshift when the point of collision approaches the horizon. I show that this is not so. The effect discovered by Bañados, Silk and West (BSW) states that if two particles co...

Background electrons are ubiquitous in high-intensity particle accelerators. Under certain operating conditions, amplification of the electron cloud can occur. The beam-cloud interaction can seriously degrade the accelerator performance with effects that range from vacuum degradation to collective beam instabilities. Although electron cloud effects (ECEs) were first observed 20 years ago in a p...

Clouds of low energy electrons frequently build up within the beam chambers of particle accelerators. In many cases, electron cloud effects (ECEs) cause beam instabilities and degradation of performance. This is of particular concern for high intensity positron rings, in which ECEs can lead to emittance blow-up. Understanding and mitigating electron cloud build up is thus of particular importan...

A transverse-to-longitudinal emittance exchange experiment is in preparation at the Argonne Wakefield Accelerator (AWA). The experiment aims at exchanging a low (εz < 5 μm) longitudinal emittance with a large (εx > 15 μm) transverse horizontal emittance for a bunch charge of ∼ 100 pC. Achieving such initial emittance partitioning, though demonstrated via numerical simulations, is a challenging ...

We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well known properties of topological vortices, we discuss electroweak strings and their stability with and without external influences such as magnetic fields. Other known properties of electroweak strings and monopol...

The origin of nonlinear dynamics traces back to the study of the dynamics of planets with the seminal work of Poincaré at the end of the nineteenth century: Les Méthodes Nouvelles de la Mécanique Céleste, Vols. 1-3 (Gauthier Villars, Paris, 1899). In his work he introduced a methodology fruitful for investigating the dynamical properties of complex systems, which led to the so-called "Poincaré ...

DITANET is a Marie Curie initial training network in beam diagnostics. The network members, universities, research centers and industry partners, are developing diagnostics methods for a wide range of existing or future particle accelerators, both for electron and for ion beams. This is achieved through a cohesive approach that allows for the exploitation of synergies, whilst promoting knowledg...