Slow ammonia molecules in an electrostatic quadrupole guide

An electrostatic quadrupole is used to filter slow dipolar ND3 molecules from an effusive source and to guide them into ultrahigh vacuum. The molecules in the electrostatic quadrupole experience a Stark interaction which allows filtering of small velocities in the linear and bent sections of the quadrupole. With this technique we demonstrate a flux of $\approx 10^{10}$/s with a longitudinal temperature of a few K. The technique and the set-up are discussed in detail, and the guided gas as well as the output beam are characterized. Improvements in the set-up are highlighted, as for instance cooling of the effusive source to below 150 K

Experiments with mid-heavy antiprotonic atoms in AEgIS

ments which provide the most precise data on the strong interaction between protons and antiprotons and of the neutron skin of many nuclei thanks to the clean annihilation signal. In most of these experiments, the capture process of low energy antiprotons was done in a dense target leading to a significant suppression of specific transitions between deeply bound levels that are of particular interest. In particular, precise measurements of specific transitions in antiprotonic atoms with Z>2 are sparse. We propose to use the pulsed production scheme developed for antihydrogen and protonium for the formation of cold antiprotonic atoms. This technique has been recently achieved experimentally for the production of antihydrogen at AE$\overline{\rm g}$IS. The proposed experiments will have sub-ns synchronization thanks to an improved control and acquisition system. The formation in vacuum guarantees the absence of Stark mixing or annihilation from high n states and together with the sub-ns synchronization would resolve the previous experimental limitations. It will be possible to access the whole chain of the evolution of the system from its formation until annihilation with significantly improved signal-to-background ratio