Optical transition radiation diagnostics for low energy ion beams 

Student: Rupeshkumar Ghagi
Supervisors: Hao Zhang, Carsten P Welsch (UoL), Beata Walasek-Hoehne, Rahul Singh, (GSI/FAIR)

Transverse beam profiling is a basic diagnostic for accelerator operation and optimization.  There are a number of established methods based on secondary electron monitor (SEM) grids as well as beam induced fluorescence (BIF) exist for this measurement. However, with increasing beam intensity and more advanced beam dynamics concepts in high intensity linacs, the suitability of these methods is under question. Fundamentally, they are limited as they provide only 2-dimensional projections of a beam. In addition, the resolution of the measured profiles have limitations due to space charge effects or technological limitations.

In this PhD project you will explore optical transition radiation as a replacement for traditional methods. Specifically, you will build a theoretical model and understanding of optical transition radiation from un-processed metal targets. Unprocessed targets are “rough surfaces” with respect to optical wavelengths.

You will then carry out experiments at the X2 beamline at GSI’s UNILAC accelerator and the K-130 cyclotron at the University of Jyväskalä to verify your models using advanced data analysis techniques. This will allow identifying the relative contribution of OTR photons with respect to other photon inducing processes such as beam-induced fluorescence in the given energy regime.

In a next step, you will compare the transverse profiles obtained using OTR with more traditional diagnostics. Studies into different target materials and surface structures to mitigate e.g. heating effects will complement this work.

You will have access to the Cockcroft Institute’s comprehensive postgraduate training in accelerator science, as well as to LIV.INNO’s structured training. You will spend years 1 and 4 in the UK where you will benefit from LIV.INNO’s comprehensive training program. You will be based at GSI/FAIR in Germany during years 2 and 3 where the focus will be on simulation and experimental studies. Whilst in the UK, a standard UKRI PhD stipend will be paid, during the time at GSI, usual PhD student in Germany will be paid.