Development and Performance of Superconducting Undulators at the Advanced Photon Source

Several years ago, an article in SRN [1 Y. Ivanyushenkov and E. Moog, Synchrotron Radiation News, 24(3), 20–24 (2011).[Taylor &; Francis Online] , [Google Scholar]] with the same title as this article summarized the decade-long development of superconducting undulators (SCUs) at the Advanced Photon Source (APS). The article presented those developments leading to the point when the first prototype, called SCU0 and intended for installation at the APS, was under fabrication. SCU0 was built in 2012, its cryogenic performance has been extensively tested, and detailed magnet measurements of the device have been conducted. After verification that SCU0 met all of the technical requirements for APS insertion devices, it was installed in the APS storage ring in January 2013, commissioned in a record short time (two weeks), and became a routinely used source of hard X-rays at the APS Sector 6 ID beamline.     

Metric critical point theory: Potential Well Theorem and its applications

Recent results show evidence of the fact that the notion of critical point has a purely metric nature. In this paper, after giving the fundamental definitions of critical and regular points for continuous functions, we survey some applications of the nonsmooth critical point theory. Our basic tool is a Potential Well Theorem. Conferenza tenuta da A. Ioffe il 9 ottobre 1995