Dr Luke Antwis

The development of an ambient pressure MeV SIMS ion beam analysis capability at the Surrey Ion Beam Centre has necessitated the development of a system to protect the vacuum integrity of the main 2 MV tandem particle accelerator. The development and operating characteristics of a fast acting vacuum isolation valve based on the principle of an induction coil are reported and shown to be suitable for the intended application. (c) 2013 Elsevier Ltd. All rights reserved.

Muonic x-ray spectroscopy uses muons to obtain information about the structure of the atom and the nucleus. In muonic atoms, the energy levels of atomic orbitals are significantly more sensitive to the finite size correction. By probing these orbitals using x-ray spectroscopy, the nuclear size correction can be extracted, providing valuable input for laser spectroscopy in the form of absolute charge radii with a relative precision better than 10−3. Continuing on developments that allowed measurements on target quantities of about 5 μg, we showed the feasibility of using implanted targets. In the future, this will allow the measurement of absolute charge radii of long-lived radioactive isotopes that are not available in sufficient enrichment or large quantities. In this contribution, we shall report on the target preparation, involving high-fluence implantation, and on the preliminary results of the muX experimental campaign.

We have investigated the use of conventional ion implantation to fabricate enriched 28 Si layers for use in quantum computers. The final compositions of samples enriched using ultra-low energy (800 eV and 2 keV) and low energy (20 keV) 28 Si implants of varying fluences (1x10 16-3.8x10 17 cm-2) using two different implanters were measured using channelled Rutherford Backscattering Spectroscopy. The dynamic, binary collision approximation program TRIDYN was used to model the implantation profiles to guide the analysis of the RBS spectra. It was found that ultra-low energy implants achieved high 28 Si enrichment levels but were heavily contaminated with oxygen due to poor vacuum in the implanter wafer end station. It was shown that oxidation could be reduced by using an accelerator with an end station with better vacuum and increasing the implant energy to 20 keV. However, TRIDYN simulations predict that the best 28 Si enrichment levels that could be achieved under these conditions would saturate at ~99.2 % due to self-sputtering. We modelled a range of conditions with TRIDYN and so recommend low energies (99.9 %) with the lowest possible fluences (~5-10x10 17 cm-2).