Over the course of the last three years, research teams at CNAO, GSI, MedAustron and TU Wien have made significant progress in the field of simultaneous delivery of mixed-species ion beams in synchrotrons. The primary driver for these studies was the idea of delivering mixed 4He2+ and 12C6+ ion beams for online treatment monitoring in carbon ion therapy.
Since 2023, both at GSI and MedAustron, such beam modalities have been successfully generated, accelerated in the synchrotron to a few hundred MeV/u, extracted and are now employed for interdisciplinary research in accelerator physics, detector development, and medical physics. Due to the differing capabilities of the involved accelerators, distinct mixed beam generation schemes had to be developed for the two centers (generation within a single ion source versus mixing in the synchrotron by means of sequential injection).
This success has attracted interest from additional research communities, which specifically require the acceleration of mixed-species beams with unequal q/m ratios in the synchrotron, in contrast to the beams with similar q/m investigated for treatment monitoring research. In May 2025, the first simultaneous acceleration of such a beam, a 56Fe25+ and 209Bi68+ mixture, was demonstrated at GSI.
More details can be found in this document.
General workshop sessions
The general workshop sessions will take place on Thu Oct 08 (afternoon), and Fri Oct 09 (morning and afternoon), featuring talks and open discussion sessions. The program will review experience gained over the past two years with mixed ion beam delivery and address open technological questions and new delivery strategies for a broader user community.
Optional simulation session
In addition, on the morning of Thu Oct 08, a dedicated session will be held for interested attendees on simulating mixed-species beam dynamics in synchrotrons, featuring tutorials and discussions on the relevant simulation codes.
List of topics
The main workshop topics may include (preliminary and non-exhaustive list):
- Ion sources
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- Feasibility of extracting 12C6+ with minimal 16O8+ contamination at clinical intensities using ion sources suitable for clinical installation and budgets.
- Generation of mixed 12C3+ and 4He1+ beams without 16O4+ contamination
- Tailoring and monitoring the He:C ratio of mixed beams extracted from ion sources
- LINAC, injector hardware and controls:
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- Required upgrades to LINACs installed in current medical facilities to transport ions with q/m = 1/4
- Minimizing the cycle duration overhead introduced by sequential dual-species multiturn injections
- Mixed-species beam dynamics in the synchrotron (injection, acceleration and slow extraction):
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- Tailoring the He:C ratio during a sequential multiturn injection
- Controlling the He:C ratio throughout the slow extraction
- Mixed-species beam delivery using dual-frequency RF systems (ion mixtures with different q/m, slip-stacking of 12C6+ and 4He2+)
- General discussions on transverse and longitudinal beam dynamics for non-nominal q/m (including simulation tools)
- Beam diagnostics:
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- Beam diagnostics for characterising mixed beam properties in the accelerator complex (keV/u to a few 100 MeV/u) and in treatment/irradiation rooms
- Future technologies and facility design:
- Requirements for designing future facilities compatible with mixed-species operation
- Mixed-species beam delivery with laser ion sources
- Use cases and applications:
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- Identifying new user groups, research applications and delivery concepts for other facilities, for ion pairs with both similar and different q/m