Molecular Physics seminar

Physics with cold stored ion beams

by Richard Thomas (Molecular Physics Department)

FA31 ()


In this talk I will describe the design and construction of a novel type of ion storage device currently undergoing commissioning here at Stockholm University. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate ''rings'' and then merged over a common straight section. The unique construction of this Double ElectroStatic Ion Ring ExpEriment (DESIREE) apparatus allows for studies of interactions between cations and anions at low and well-defined centre-of-mass energies down to 10 meV [1]. The technical advantages of using purely electrostatic over magnetic elements are many, but the most relevant are: electrostatic elements are more compact and easier to construct; remanent fields, hysteresis and eddy-currents, highly problematic in magnetic devices, are no longer relevant, and for low energy ion beams (keV vs MeV) electrostatic elements are more efficient and cheaper to use. I will present the current results from the commissioning of the DESIREE facility [2]: the system is under vacuum at cryogenic temperatures, and early tests show storage of low energy ions up to 20 minutes, and highlight some of the technical issues that have arisen during its development and construction [3]. Finally, the advantages of this design are a boon to fundamental experimental studies, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology, and I will finish by discussing several examples of such potential research. References [1] R. D.Thomas et al., Rev. Sci. Instrum. 82, 065112 (2011) [2] H. T. Schmidt et al., Rev. Sci. Instrum. 84, 055115 (2013) [3] S. Rosén et al., Rev. Sci. Instrum. 78, 113301 (2007)