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Compact in-vacuum switchable beam-dump system for radiation safety at accelerator beamlines

Sivaji Purushothaman*, Neeraj Kurichiyanil, and Ekaterina Kozlova

David J. Morrissey

  • *Contact author: S.Purushothaman@gsi.de
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Phys. Rev. Accel. Beams 29, 094201 – Published 16 September, 2026

DOI: https://doi.org/10.1103/58pd-c2yb

Abstract

A compact, in-vacuum switchable beam dump is proposed as a first-of-a-kind engineering solution to improve operational flexibility in high-energy accelerator facilities. The design integrates beam-pass and beam-dump modes into a single wall-embedded unit, eliminating the need for external shielding and movable components outside the vacuum system. The concept is specifically developed for the superconducting fragment separator (Super-FRS) at Facility for Antiproton and Ion Research, making use of an existing opening in a modular radiation-shielding wall between experimental areas. It employs synchronous rotation to switch between an unobstructed vacuum beamline and a fully shielded beam-dump configuration. This architecture enables personnel access to downstream experimental areas while beam delivery continues in the upstream section. Two absorber configurations were investigated: an all-iron design and a mixed configuration incorporating the high-density tungsten alloy Densimet. Iron provides cost-effective bulk shielding and strong attenuation of secondary gamma radiation, whereas Densimet enables compact energy deposition with superior stopping power. The required thickness of additional downstream boron carbide shielding to adequately suppress slow neutrons differs between the two options. FLUKA Monte Carlo simulations confirm that both configurations satisfy the stringent personnel safety limit of <3  μSv/h in all relevant scenarios. Complementary vacuum simulations demonstrate that the beamline pressure remains below 5×10−6  mbar during operation. The results indicate that the proposed switchable beam dump offers a viable path to enhance facility availability and throughput at Super-FRS. The compact, modular concept is scalable and may be adapted to other high-energy accelerator facilities facing similar space and access constraints.

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Phys. Rev. Accel. Beams 29, 094201– Published 16 September, 2026
  • Received 23 March 2026
  • Accepted 27 July 2026
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