PSI - Paul Scherrer Institute

RF-based Measurement of Ultra Low charges

Trainee: Sudharsan Srinivasan 
Supervisor: Pierre-André Duperrex

In addition to its research activities, the Paul Scherrer Institut operates Switzerland’s sole facility for the treatment of specific malignant tumors using proton beams. Since 1984 more than 6400 patients with ocular melanomas have been treated at PSI. This places PSI among the centers with the largest experience with treatment of this rare disease worldwide. In 2005 the compact, superconducting medical therapy cyclotron COMET became operational. The protons accelerated up to 250 MeV are exclusively used for medical purposes. Two gantries are in operation and a third one is presently being built to offer wider treatment possibilities.

Improvements or development of new diagnostic systems play an important role to optimize medical treatment schemes. Currently, ionization chambers are the most commonly used detector type for beam intensity measurement. However, they use thin foils which are crossed by the beam and decrease the beam’s quality by scattering. To mitigate this problem the Fellow shall develop a sensitive RF-based current monitor for fully non-interceptive beam current measurement and he shall study the possibilities to measure the beam position. This project will be performed in collaboration with studies done at the University of Liverpool.

These improvements will target the measurement of beam currents at a very low beam intensity. The design will be based on previous developments at PSI, but will also take into account developments at other OMA institutions. A prototype will then be used for scans at the PROSCAN facility and fully characterized during the second year of the project. In combination with beam dynamics studies this design will be further optimized and result in the design of a detailed pre-series prototype.