Micro Penning traps for continuous magnetic field monitoring in high radiation environments

The next generation of rare isotope beam facilities requires new and improved instrumentation to cope with the high-radiation environment associated with the interaction of high-power beams with matter. One essential piece of instrumentation that is needed is a precise, radiation-resistant, magnetic field probe. The NMR probes, that are currently being used, have a very limited lifetime in high-radiation environments. A cost-effective, radiation-tolerant replacement is critical. We are proposing to replace these probes with micro Penning traps. The magnetic field measurement will be performed by determining the cyclotron frequency of singly charged ions with well-known mass, from which the magnetic field will be determined via an image charge detection technique. This approach has been tested by our collaborator, and it has been proven to be sound and effective. We will concentrate our effort towards the development of magnetic field probes that are highly radiation resistant: The element placed inside the magnetic field, and subjected to the highest radiation, will be made of partially metalized fused silica glass, and the signal strength will be sufficiently strong, that associated electronics may be positioned at a distant shielded location. In contrast, even radiation-hardened NMR probes have some active components located on the probe. In Phase I, we designed and fabricated key elements of the magnetic probe, including several Penning microtrap demonstrators. These demonstrators have a trapping volume that is twoorder smaller than that previously demonstrated. Their mechanical and electrical characteristics, including voltage breakdown, were recorded. Simulations were carried out to explore design tradeoffs. In Phase II, a full prototype will be fabricated, and its characteristics will be evaluated. The electronics, and the related hardware and software will be stream-lined to reduce production costs. The successful development of inexpensive, radiation-resistant, high-precision magnetic field probes will bring numerous benefits to the public as a whole. These probes will directly assist in the development and delivery of radioactive ion beams produced by accelerator facilities, and will sustain a rich experimental program. Our magnetic probes will also find use in accelerator-based cancer therapy medical facilities. Medical accelerators do age over time, and older machines often produce more errors. These facilities require numerous magnetic field probes that support/enhance quality assurance, and ensure the safety of patients and medical staff.