arXiv subjects

C. Degen

Publications and source records attributed to C. Degen.

2 recordsLinked to original sources

arXiv2016

High energy Coulomb-scattered electrons for relativistic particle beam diagnostics

A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Finally, some possible future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.

physics.acc-ph↗

arXiv2001

Strong Electron-Phonon Coupling in Superconducting MgB$_2$: A Specific Heat Study

We report on measurements of the specific heat of the recently discovered superconductor MgB$_2$ in the temperature range between 3 and 220 K. Based on a modified Debye-Einstein model, we have achieved a rather accurate account of the lattice contribution to the specific heat, which allows us to separate the electronic contribution from the total measured specific heat. From our result for the electronic specific heat, we estimate the electron-phonon coupling constant $λ$ to be of the order of 2, significantly enhanced compared to common weak-coupling values $\leq 0.4$. Our data also indicate that the electronic specific heat in the superconducting state of MgB$_2$ can be accounted for by a conventional, s-wave type BCS-model.

cond-mat.supr-con↗