MRI: Development of the IsoDAR Front-end

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

This award funds the development of a Radio Frequency Quadrupole (RFQ) to be used as part of a front-end for ion injection into a cyclotron, a type of particle accelerator. The outcome will be a novel, fully-working front-end instrument that can be used for multiple purposes. Based on a concept originally introduced in 1981, but never realized, this will be the first demonstration of RFQ direct injection into a compact, high intensity cyclotron. The design is potentially transformative and promises a 3-5 times increase in efficiency of bunching and injection over classic front-end cyclotron designs. It is more compact and of comparable cost, significantly advancing accelerator technology. The accelerator system planned relies on conventional, well known, proven technologies. The innovation is in the combination of these technologies. The challenges are in the demonstration of, on one hand, the individual performances of the various components (the current from a source, RFQ and transmission, and coupling to the cyclotron) and, on the other hand, their integration into a compact, high beam current, cost-effective proton driver front-end. Proton drivers have a broad impact; they are research tools (for neutrino physics, secondary particles for condensed matter research, neutron sources), tools for the future of energy, and more. The development of high intensity cyclotrons has two important impacts for industry. The first is to increase the energy, intensity and versatility of radiopharmaceutical cyclotrons. Protons from a cyclotron can, for example, efficiently produce Strontium-82, important for medical imaging. In addition, this work also has relevance to Accelerator Driven Systems (ADS) technology, applied, for example, to driving thorium reactors, thus supporting the development of safe nuclear energy sources. A factor of 5-10 improvement in current would have a significant impact in these areas. The development and running of the front-end will include MIT undergraduates, graduate students, and postdocs. This will provide an excellent educational experience, with increased accelerator science at universities and more hardware experience for young scientists. Upon successful demonstration, the new front-end could be used in the IsoDAR (Isotope Decay-At-Rest) experiment which has the potential to advance our knowledge about sterile neutrinos and shed light on several anomalies observed with neutrinos. The goal is to make use of RFQ injection of H2+ into a compact cyclotron. Each H2+ ion provides 2 protons after stripping thus reducing the necessary beam current by a factor of 2 and reducing space-charge forces, overcoming the limitations of injecting an intense proton beam into the cyclotron central region. The RFQ injection uses RF radiation in a quadrupole structure as a method to alleviate the ion source requirements by improving the bunching efficiency. The efficiency of the direct coupling of the RFQ to the spiral inflector injection channel of the cyclotron (a matter of bunch matching between the two accelerators) is a delicate part of system integration; it has to be demonstrated and is a goal of the project.