Production and manipulation of stable frozen hydrogen filaments

Frozen hydrogen filaments or droplets/pellets in vacuum are of great interest as target for many experiments at hadron and lepton accelerators as well as at high-power laser systems. Especially in case of large distances between the position of target beam generation and the interaction point with an accelerator or laser beam, a high target beam stability in space and time is crucial. Here we present recent results on the long-term stability of frozen hydrogen filaments in vacuum, which have been obtained using a new cryogenic target generator. It could be shown that the trajectory of the frozen hydrogen target beam with a diameter of 10 µm remains stable for over 60 h, with angular fluctuations below 0.08°. Furthermore, we present a novel strategy for the manipulation of the target beam, named cryobending. Here, the produced hydrogen filament is deflected by helium gas emerging from correction nozzles. We demonstrate the deflection of the hydrogen beam with one and two nozzles, achieving deflection angles up to 15.7(4)°. The presented results open the door for further developments of this beam position system, which enables target beam adjustment without any mechanical movement of the target components itself. Potential applications of these stable hydrogen target filaments are, e.g., the upcoming MAGIX (MAinz Gas Injection target eXperiment) or the planned P ̄ ANDA (anti-Proton ANnihilation at DArmstadt) experiment.