Collisions with Ions, Atoms, Molecules, and Clusters


DESIREE

Double ElectroStatic Ion Ring ExpEriment


6 May 2009 New article: En dubbel elektrostatisk jonlagringsring anländer till Fysikum och AlbaNova (in Swedish) with a description of DESIREE (in English)
Update 21 April 2009: the inner chamber of DESIREE has arrived. Pictures can be found here

The DESIREE will consist of two electrostatic storage rings with a common straight section, where ions of opposite charges can be brought to interact with each other at very well defined low relative velocities, while they at the same time are moving rapidly in relation to the machine facilitating their detection by standard single-particle detection techniques.

The two rings are to be placed inside one large double-walled vacuum vessel. The innermost vacuum chamber will be cooled down to a temperature of only 4-7 K. This in turn helps in achieving the desired very good vacuum. The design value for the vacuum at room temperature is better than 10-11 mbar and it is expected that the density of residual gas is reduced by about two orders of magnitude when the system is cooled to the minimum temperature. This combination of extremely good vacuum, allowing for very long ion storage times (minutes), and very low temperature is ideal for the study of molecular ions. At high temperatures, molecules will be found with a large spread in the degree of internal excitation, but by storing them in a very cold environment for a long time, it is possible for them to come into equilibrium with the very cold surrounding and thus occupy only one or a few quantum states.

While it will be possible to study atomic and molecular ions in pure storage experiments and by interaction with laser light ranging from cw to fs pulses our main focus is to study the interactions between the two species of ions stored in each ring. One fundamental process to be studied is mutual neutralization (MN) between singly charged ions of opposite polarity producing two neutral fragments. This is a process of fundamental interest of its own right, but is also an important process to consider in relatively low temperature partly ionized plasmas, such as those found in the Earth's upper atmosphere and in the interstellar medium. Another research area in which the planned double-ring experiments can have a large impact is the studies of carbon clusters interacting with each other or with highly charged atomic ions.

The DESIREE project is a collaboration between the Manne Siegbahn Laboratory (MSL) and the physics department. While the construction is lead by the MSL, we are taken a leading role in defining the experimental program and are taking active part in the design work. The first beam is scheduled to be injected in DESIREE in early 2008.

Animation of DESIREE (avi, 18M)
More information at the DESIREE-homepage at MSL
JRA3 status report of the ITS LEIF project
Postal Address: AlbaNova University Center, 106 91 Stockholm, Sweden
updatet: 07-May-2009 | webmaster | fysikum | atomic physics at fysikum top of the page top of the page