Non-Destructive Beam Monitoring via Secondary Radiation Detection with Ce-Doped Silica Fibers

Alexander Gottstein; Pierluigi Casolaro; Gaia Dellepiane; Lars Eggimann; Eva Kasanda; Isidre Mateu; Samuel Usherovich; Paola Scampoli; Cornelia Hoehr; Saverio Braccini

doi:10.1088/1748-0221/21/03/p03036

arXiv · 2601.18293

Non-Destructive Beam Monitoring via Secondary Radiation Detection with Ce-Doped Silica Fibers

Alexander Gottstein·Pierluigi Casolaro·Gaia Dellepiane·Lars Eggimann·Eva Kasanda·Isidre Mateu·Samuel Usherovich·Paola Scampoli·Cornelia Hoehr·Saverio Braccini

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Abstract

Non-destructive beam diagnostics are essential for low-energy medical cyclotrons, where even thin interceptive devices can severely degrade beam quality. We investigate an external fiber monitor (EFM) based on Ce-doped silica scintillating fibers that detects secondary radiation generated at existing beamline components of the 18 MeV Bern Medical Cyclotron beam transfer line (BTL). Three use cases were studied: (i) beam intensity monitoring around an electrically isolated, water-cooled beam dump; (ii) beam-loss monitoring around a 10 mm collimator under varying the beam focusing; and (iii) by steering a 6.5 mm $\times$ 6.5 mm beam spot on a beam dump. For case (i), the summed EFM signal exhibits a linear dependence on the current on target over nearly three orders of magnitude. In case (ii), a normalized EFM-based beam-loss proxy scales monotonically with an electrical loss proxy across several focusing settings. Furthermore, opposing-fiber signal ratios provide decoupled, monotonic sensitivity to horizontal and vertical beam displacements.

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Alexander Gottstein, Pierluigi Casolaro, Gaia Dellepiane, Lars Eggimann, Eva Kasanda, Isidre Mateu, Samuel Usherovich, Paola Scampoli, Cornelia Hoehr, Saverio Braccini. 2026-01-26. Non-Destructive Beam Monitoring via Secondary Radiation Detection with Ce-Doped Silica Fibers. https://doi.org/10.1088/1748-0221/21/03/p03036

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