CAREER: An Integrated Research/Educational Plan for Advancing RF Superconductivity for Particle Accelerators

Cornell University, Ithaca NY

Investigators

Abstract

PROPOSAL NUMBER: 0841213 INSTITUTION: Cornell University NSF PROGRAM: PHY ? ELEMENTARY PARTICLE ACCEL USER PRINCIPAL INVESTIGATOR: Liepe, Matthias U.. TITLE: CAREER: An Integrated Research/Educational Plan for Advancing RF Superconductivity for Particle Accelerators This proposal requests partial support for a program of research to systematically characterize the radio-frequency(RF) surface resistance of superconductors to advance superconducting microwave cavities for particle accelerators and for an education and outreach program involving community college faculty and students in the research. This will be carried out at the Cornell Laboratory for Accelerator-based Sciences and Education at Cornell University. The ultimate performance of a superconducting radio-frequency (SRF) accelerating cavity is governed by two factors: the maximum accelerating gradient that can be achieved without electrical breakdown, and the cavity Q (or Quality factor) when operating near this maximum gradient. The higher the Q, the less power required to achieve the maximum gradient, and therefore the less cost to both construct and operate the accelerator. The optimal Q of a cavity at a given level of excitation is related to the RF surface resistance of the cavity wall material, and this surface resistance is in turn related to the maximum RF magnetic field at the surface in a way that is both very sample dependent and theoretically poorly understood. The focus of the proposed research program will be on studying the mechanisms that limit the intrinsic Q in SRF cavities, and ways to improve Q. The primary attention in studying these topics will be on the superconductor niobium, which is the material of choice today for SRF cavities. As a subsidiary topic the potential of the A-15 superconductor Nb3Sn for providing highest intrinsic quality factor cavities will be explored. In studying these topics it will be of critical importance to get statistically significant data. This proposal addresses this challenge by developing a host cavity for testing small material samples with fast turnaround. A new generation of improved superconducting rf cavities would have transformative, broad impact across accelerator-based sciences and engineering by improving the energy reach, performance and scientific potential of future particle accelerators. These next generation accelerators will fulfill the needs for particle physics, nuclear physics, neutron science, X-ray science and free-electron lasers. In addition, this research provides for the education of future generations of accelerator scientists and engineers, which are in high demand. Finally, this proposal includes a program to provide research opportunities in the physical sciences specifically for community college students to encourage them to pursue careers in science, technology, or science education. This large and critical group of students usually has very limited or no access to cutting-edge research opportunities and the proposed pilot program addresses this well-recognized, but mostly unaddressed issue.