Non-linear Inserts for a Rapid Cycling Synchrotron Replacement for the Fermilab Booster Synchrotron

Modern accelerator systems are limited in intensity because high intensity beams lose a lot of particles that activate or damage the accelerator itself. The stability of these beams, and thus the intensity limit, comes from the approach of designing accelerators with a linear lattice. The integrable optics technique fixes this problem by making the accelerator manifestly non-linear, but also stable. This technique requires a special non-linear magnet system that is custom to each accelerator that uses it. The integrable optics technique is currently being tested at the Integrable Optics Test Accelerator at Fermilab. After that test, the next step is a facility-sized implementation of integrable optics. One proposed test is the replacement of the Fermilab booster ring with a rapid cycling synchrotron (iRCS) that uses integrable optics. That accelerator will require a larger version of the special non- linear insert we built for IOTA at Fermilab. We are proposing here to build one of the special non- linear magnets for the replacement booster ring. During Phase I, we advanced the magnetic design of the non-linear insertion. We optimized the solution for the non-linear field potential, which allowed the proper harmonic content for a larger aperture required in iRCS and performed tolerance study. Furthermore, we created the mechanical engineering model pursuing the main goal of fabrication cost reduction. In Phase II, we will fabricate, assemble and test the new non-linear insert design for a larger accelerator – iRCS booster – and upgrade our magnetic measurement systems that are needed to measure the magnetic fields of the new 8m-long insertion. The principal users of these magnets are large national laboratories upgrading or building high intensity particle accelerators. Other potential uses include as a driver for accelerator driven subcritical fission reactors that produce shorter half-life daughter products and use fuel that is less weaponizable, e.g. thorium.