Dielectronic recombination of Li-like ¯uorine ions P. Glans a, * , E. Lindroth a , N. Ekl  ow a , W. Zong a , G. Gwinner b , A.A. Saghiri b , M. Pajek c , H. Danared d , R. Schuch a a Atomic Physics, Physics Department, Stockholm University, Frescativ. 24, S-104 05 Stockholm, Sweden b Max-Planck-Institut f  ur Kernphysik and Physikalisches Institut der Universit  at Heidelberg, 69117 Heidelberg, Germany c Institute of Physics, Pedagogical University, 25-509 Kielce, Poland d Manne Siegbahn Laboratory, Stockholm University, Frescativ. 24, S-104 05 Stockholm, Sweden Abstract Some recent new developments in dielectronic recombination (DR) measurements at heavy-ion storage rings are presented. A DR spectrum measured at CRYRING in Stockholm of F 6 is used to illustrate a few points regarding this kind of measurements. From the spectrum a transversal temperature of the adiabatically expanded electron beam of 3.0(5) meV is deduced, which is slightly higher than expected. Ó 1999 Elsevier Science B.V. All rights reserved. PACS: 34.80.Lx; 32.70.Jz; 29.20.Dh 1. Introduction The construction of heavy-ion storage rings equipped with electron cooler devices has made it possible to store atomic or molecular ions long enough to ®rst cool them (increase their phase- space density and for molecules also lower their internal degrees of motion) and then to study collisions between them and some target under well-controlled conditions. Currently there are ®ve heavy-ion storage rings in operation that are used for atomic and molecular physics studies: Astrid in Aarhus, CRYRING in Stockholm, ESR at GSI in Darmstadt, TARN II in Tokyo, and TSR in Heidelberg [1]. Among the experiments that these rings are ideally suited for are measurements of recombination which occurs in collisions between free electrons and ions. In dielectronic recombination (DR) the initially free electron is captured to a bound level in the recombined ion while simultaneously a bound electron takes up the released energy and is excited to a higher level, forming a doubly excited state. The DR process is completed if this state does not autoionize but instead stabilizes by emission of photons. A q  e  ! A q1    ! A q1     hm: 1 DR processes are important in hot plasmas. This was ®rst realized in 1964 when Burgess showed that dielectronic recombination could re- solve discrepancies found for the ionization bal- Nuclear Instruments and Methods in Physics Research B 154 (1999) 97±101 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +46-8-161082; fax: +46-8- 158674; e-mail: glans@msi.se 0168-583X/99/$ ± see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 9 9 ) 0 0 0 0 5 - 1