Commissioning of the DESIREE storage rings _ a new facility for cold ion-ion collisions

28th International Conference on Photonic, Electronic and Atomic Collisions

Gatchell, M.^1 ; Schmidt, H.T.^1 ; Thomas, R.D.^1 ; Rosén, S.^1 ; Reinhed, P.^1 ; Löfgren, P.^1 ; Brännholm, L.^1 ; Blom, M.^1 ; Björkhage, M.^1 ; Bäckström, E.^1 ; Alexander, J.D.^1 ; Leontein, S.^1 ; Hanstorp, D.^2 ; Zettergren, H.^1 ; Liljeby, L.^1 ; Källberg, A.^1 ; Simonsson, A.^1 ; Hellberg, F.^1 ; Mannervik, S.^1 ; Larsson, M.^1 ; Geppert, W.D.^1 ; Rensfelt, K.G.^1 ; Danared, H.^1,3 ; Paál, A.^1 ; Masuda, M.^1 ; Halldén, P.^1 ; Andler, G.^1 ; Stockett, M.H.^1 ; Chen, T.^1 ; Källersjö, G.^1 ; Weimer, J.^1 ; Hansen, K.^2 ; Hartman, H.^4,5 ; Cederquist, H.^1

Department of Physics, Stockholm University, AlbaNova University Center, Stockholm

SE-106 91, Sweden^1

Department of Physics, University of Gothenburg, St.Gothenburg

SE-412 96, Sweden^2

European Spallation Source ESS AB, Box 176, Lund

SE-221 00, Sweden^3

Applied Mathematics and Material Science, Malmö University, Malmö

SE-205 05, Sweden^4

Lund Observatory, Lund University, Lund

SE-221 00, Sweden^5

关键词: Asymmetric rings;    Collision energies;    Collision experiments;    Exponential components;    Ion-ion collision;    Ongoing commissioning;    Stockholm University;    Vacuum chambers;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/488/1/012040/pdf
DOI  :  10.1088/1742-6596/488/1/012040

来源: IOP

【 摘 要 】

We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2, C-3, C-4etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat- and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.