Sam Posen

I am an Associate Scientist in Fermilab's Technical Division, studying superconducting RF cavities. I investigate many interesting questions relating to superconductivity and materials science:

• What is the maximum high frequency magnetic field that could be theoretically screened using a given superconductor?
• What non-fundamental mechanisms limit the achievable field in a cavity? How can these be avoided?
• What are the origins of the temperature-independent part of the surface resistance observed in cavity tests?
• What cavity preparation techniques minimize the overall surface resistance at useful gradients?
• Can alternative materials or layerings be used to reach higher fields and smaller surface resistances?

In addition to basic research into the fundamental behavior of accelerator cavities, the Fermilab SRF department develops technologies and methodologies for assembling the cryomodules that house cavities in accelerators. Fermilab is working on two projects: the Linac Coherence Light Source (LCLS) II which will use technologies developed for TeSLA in a CW free electron laser at Stanford, and the Proton Improvement Project (PIP) II which would be built at at Fermilab to supply high intensity beams for neutrino experiments.

I obtained my Ph.D. in physics performing research in Cornell University's SRF group under advisor Matthias Liepe, publishing a dissertation on my research into Nb₃Sn SRF cavities. My undergraduate degree is in Engineering Physics from Queen's University in Kingston, Ontario, Canada. Engineering Physics was an appropriate degree, as I am interested in scientific research and answering some of the fundamental questions about our universe, but I also enjoy problem solving and designing and building complex machines. Accelerator Physics appeals to me as a field that can provide both.