M. Sapinski, R. Dölling, M. Rohrer
PSI, Villigen PSI, Switzerland
PSI’s Ring cyclotron is a high intensity proton cyclotron producing 2 mA beam. The beam is accelerated over about 180 turns from 72 MeV to 590 MeV. The Long Radial Probe, called RRL, scans the beam along the range of beam radii from 2048 mm to 4480 mm. A replacement for the RRL has been developed in the last years*. The recently installed new probe drives three carbon fibers with 30 ’m diameter through the turns and measures secondary electron currents, providing information on horizontal and vertical beam shape. Additional drives are available for a later extension of measurement capabilities. The main challenges are a coupling of the device elements to RF fields leaking from the accelerating cavities, plasma interfering with the measured signal and performance of the carbon fibers in harsh environment with high intensity beam. We report on commissioning of the probe with RF and beam and discuss measurement results. * doi:10.18429/JACoW-IBIC2020-WEPP33
R. Dölling, F. Marcellini, M. Sapinski
PSI, Villigen PSI, Switzerland
A new generation of monitor plugs is under develop-ment as spares for the ageing wire profile monitors and beam position monitors inserted into massive shielding in the target regions of the 590 MeV proton beam line at HIPA. A prototype was installed recently in the beam line to the ultra-cold neutron source UCN, to test the perfor-mance of wire monitor, BPM and modular mechanical design in a low-radiation environment. We report on first measurements with beam.
P. Casolaro, S. Braccini, G. Dellepiane, A. Gottstein, I. Mateu, P. Scampoli
AEC, Bern, Switzerland
P. Scampoli
Naples University Federico II, Napoli, Italy
Funding:This project was partially funded by the Bern Center for Precision Medicine (BCPM) of the University of Bern, and by the Swiss National Science Foundation (SNSF) [Grant: CRSII5180352] A new radiotherapy modality, known as FLASH, is a potential breakthrough in cancer care as it features a reduced damage to healthy tissues, resulting in the enhancement of the clinical benefit. FLASH irradiations are characterized by ultra-high dose-rates (>40 Gy/s) delivered in fractions of a second. This represents a challenge in terms of beam diagnostics and dosimetry, as detectors used in conventional radiotherapy saturate or they are too slow for the FLASH regime. In view of the FLASH clinical translation, the development of new dosimeters is fundamental. Along this line, a research project is ongoing at the University of Bern aiming at setting-up new beam monitors and dosimeters for FLASH. The proposed detection system features millimeter scintillators coupled to optical fibers, transporting light pulses to a fast photodetector, readout by high bandwidth digitizers. First prototypes were exposed to the 18 MeV proton beam at the Bern medical cyclotron. The new detectors have been found to be linear in the range up to 780 Gy/s, with a maximum time resolution of 100 ns. These characteristics are promising for the development of a new class of detectors for FLASH radiotherapy.
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