The mass of has been determined to be m(*'Si) = 27.97692657(30)~ by comparing the cyclotron frequencies of the singly charged ions "C+, 12C: and in a Penning trap mass spectrometer. The experimental technique and the setup are described. The obtained accuracy as well as possible improvements are discussed. Our measurements are related to current efforts to base the kilogram on atomic properties by using an almost perfect single crystal of silicon.

A new ion trap facility is described which is dedicated to studies of highly charged ions in a Penning trap. Such a trap will be connected to sources of highly charged ions, in particular the electron beam ion source CRYSIS, at the Manne Siegbahn Institute for Physics. The use of highly charged ions in a Penning trap increases the cyclotron frequency with a factor proportional to the charge which leads to a higher resolution. Also, the possibility to vary the charge state makes it possible to search for and identify different systematic effects. Thus, a substantial increase in accuracy can be expected. In addition, the combination of high charge state ions and a Penning trap allows new applications where one can take advantage of the controlled measuring situation, long observation time and high resolution detection. The initial priority will be given to high precision mass measurements of heavy stable ions. At a future stage, plans are to extend the use to other applications, such as charge exchange processes between neutrals and stored charged ions, electron impact ionization and exposure of clusters and molecules to highly charged ions as well as lifetime determinations of molecules and clusters.

No abstract

No abstract

No abstract