University of Liverpool

Beam Stability and Life Time in Low Energy Storage Rings 

Trainee: Bianca Veglia
Supervisor: Carsten P. Welsch

ELENA at CERN’s AD and FLAIR will provide cooled beams of antiprotons at lower energies than currently achievable anywhere in the world. It will be crucial to have detailed knowledge about the achievable stability of the beam in the storage ring and the expected beam life times. Existing low energy storage rings, operating at keV beam energies, found strong limitations on beam intensity and reduced life time in experimental studies. The nature of these effects had not been fully understood for a very long time and only recently causes of these limits to beam current and life time were identified and reproduced in simulations.

This project will build up on initial studies and investigate all effects impacting on beam stability and establish realistic models of beam storage and cooling. New simulation tools shall be developed that enable start-to-end simulations of antiproton pulses through electrostatic low energy beam lines. These tools shall then be applied for an overall optimization of beam handling towards the various experiments that are covered within AVA.


A DMD based Beam Halo and Emittance Monitor 

Trainee: Milena Vujanovic
Supervisor: Carsten P. Welsch

A specific challenge of transverse beam profile monitoring is the detection of particles in the beam halo as these are particles that are likely to be lost and/or produce unwanted background noise in the experiment. This can be achieved with destructive devices such as wire scanners or scrapers or secondary emission monitors which monitor particles produced when the beam interacts with residual or purposely injected gas.

A new high dynamic range, adaptive masking method to image the beam halo has recently been developed which uses a digital micro mirror-array device. In this project this promising method shall be adapted for advanced measurements that cannot presently be achieved with any other technique, namely online, non-destructive beam profile measurements using light generated by the primary beam.

In a second step, measurements will be extended towards emittance and general 6D phase space diagnostics with the goal to optimize the beam for the experiments within AVA.


6-D studies into beam motion in low energy storage rings 

Trainee: Volodymyr Rodin 
Supervisor: Carsten P. Welsch

The study of the collision dynamics of correlated quantum systems can be done by crossing a gas jet target with a beam of low energy antiprotons. Antiproton (projectile) energies between 20 keV and some MeV correspond to interaction strength between a weekly perturbed system (where approximation theories can be applied) and strong perturbation (where all details of the interaction need to be taken into account in theoretical models).

However, this requires beam compression to a diameter of around 1 mm and a pulse length of 1-2 ns or a highly optimized compact recycler ring. This project aims at the development of an experimental setup for these studies for both, ELENA and FLAIR conditions. Studies will include the identification of methods to realize compact (less than 1 mm diameter), ultra-short (1-2 ns duration) antiproton beam pulses as required for investigations into the importance of correlation effects in quantum systems. Compression will be based on higher harmonic bunching and phase space ‘gymnastics’ and, for the first time, extended to a full 3D description of bunches motion, including all effects on the beam (intra beam scattering, phase space rotation, scattering, cooling). In-ring schemes will be studied, along (quasi) single-pass setups where the spectrometer would be installed into an external beam line or a dedicated small storage ring.