High resolution extreme ultraviolet spectrometer for an electron beam ion trap.
An extreme ultraviolet spectrometer has been developed for spectroscopic studies of highly charged ions with an electron beam ion trap. It has a slit-less configuration with a spherical varied-line-spacing grating that provides a flat focal plane for grazing incidence light. Alternative use of two different gratings enables us to cover the wavelength range 1-25 nm. Test observations with the Tokyo electron beam ion trap demonstrate the high performance of the present spectrometer such as a resolving power of above 1000.
Resonant Electron Impact Excitation of 3d Levels in Fe14+ and Fe15+
We present laboratory spectra of the 3p–3d transitions in Fe14+ and Fe15+ excited with a mono-energetic electron beam. In the energy-dependent spectra obtained by sweeping the electron energy, resonant excitation is confirmed as an intensity enhancement at specific electron energies. The experimental results are compared with theoretical cross sections calculated based on fully relativistic wave functions and the distorted wave approximation. Comparisons between the experimental and theoretical results show good agreement for the resonance strength. A significant discrepancy is, however, found for the non-resonant cross section in Fe14+. This discrepancy is considered to be the fundamental cause of the previously reported inconsistency of the model with the observed intensity ratio between the and transitions.
A slowly rotating coil system for AC field measurements of Fermilab Booster correctors
A method for measurement of rapidly changing magnetic fields has been developed and applied to the testing of new room temperature corrector packages designed for the Fermilab Booster Synchrotron. The method is based on fast digitization of a slowly rotating tangential coil probe, with analysis combining the measured coil voltages across a set of successive magnet current cycles. This paper presents results on the field quality measured for the normal and skew dipole, quadrupole, and sextupole elements in several of these corrector packages.