PhD completed – Sud Srinivasan

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Photograph of Sud during his remote viva at the University of Groningen, Netherlands.

Proton and ion beam therapy is a very successful treatment method for some types of cancer. The reliable delivery of the treatment beam critically depends on beam diagnostics that is able to fully characterize the beam, ideally in a non-invasive way so that the diagnostics does not degrade the beam quality.

A non-invasive beam current monitor based on the principle of electromagnetic resonance was designed, built and tested by Sudharsan (Sud) Srinivasan, OMA Fellow at PSI and PhD student at the University of Groningen, working under the supervision of Dr Pierre-André Duperrex.

In his PhD thesis entitled “Non-interceptive beam current and position monitors for a cyclotron based proton therapy facility” Sud describes how this new monitor can open up interesting opportunities for potentially replacing some of the commonly used ionization chambers for beam current measurements at proton therapy facilities with cavity monitors.

Electromagnetic field simulations of the cavity monitor.

In his project Sud has successfully designed, tested and characterized in detail a dielectric-filled re-entrant cavity resonator as beam current monitor for medical applications. The fundamental resonance frequency of the purpose-built cavity is 145.7MHz, i.e. the second

harmonic of the pulse rate. In his project, he tested this novel monitor in both, lab measurements and experiments in the COMET beamline. It was successfully demonstrated that the monitor can measure proton beams with currents down to 0.15 nA for an integration time of 1 second. This makes the monitor a very interesting and important development for essentially any proton accelerator used for therapy purposes.

Sud has developed a very promising device that shows excellent prospects for future application at ion beam therapy facilities.