The Double ElectroStatic Ion-Ring ExpEriment, DESIREE

Henning Schmidt
Department of Physics, Stockholm University
Thursday, May 10, 2012 - 14:00 - 15:00
Hjorters room (Å73101)
Astronomy and Space Physics

At Stockholm University, we are building the electrostatic double-storage-ring facility, DESIREE, a tool for investigations of the interaction among cold oppositely charged atomic and molecular ions. Two 8.8 m circumference race-track shaped electrostatic ion-storage rings are mounted with a common straight section for merged beams on a single large plate of high-thermal-conductivity aluminum. This plate at the same time constitutes the bottom of a vacuum chamber mounted inside another steel vacuum chamber and cooled by the colder second stages of four two-stage cryogenerators. The cold inner chamber is surrounded by a thermal copper screen which is cooled by the first stages of the cryogenerators and covered with 30 layers of superinsulation. Estimates of the heat loads to the inner vacuum chamber through wiring, windows and pumping and injection ports indicate that a final temperature inside the inner vacuum chamber below 10 K is possible. Two ion injectors of 100 and 25 kV maximum acceleration potential are connected to the two storage rings. Ion beams of opposite charge polarity are stored in the two rings and products of interactions between the oppositely charged ions can be detected after the merging section by position-sensitive channelplate detectors. Further, either of the two storage rings can be used for experiments with a single stored ion beam interacting with pulsed or cw laser beams.

The main focus of the presentation will be on what sorts of experiments that we will be able to do with this apparatus and a little about how this relates to the previous generation of storage rings. Some more concrete examples of mutual neutralization studies will be given. I will say a little about how we believe that this facility can be of interest to the astrophysics community, but for this aspect, I am hoping to learn from you!