|1999 JR Macdonald Lab
Departmental Newsletter Article
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J.R. Macdonald Laboratory
The J.R.Macdonald laboratory is in the second year of its current three year operating grant from the U.S. Department of Energy. It is now an official national DOE user facility, with users from various parts of the U.S., Europe, and Japan.
A program advisory committee, consisting of four outside experts in ion-atom and ion-surface collisions and one internal member, invite proposals every six months. The proposals are evaluated and awarded on the basis of scientific merit, and the experiments are scheduled during the following period.
Outside pressure on the facilities has been high. The two major facilities, the CRYEBIS ion source and the Tandem-LINAC accelerator, are heavily scheduled by both in-house and external users. Proposals typically request more running time than is available, but nearly all experiments with strong scientific merit are accommodated.
A major transition in the atomic physics faculty in the department has been the appointment of Martin Stockli to associate professor of physics. Martin, who was the father of our CRYEBIS ion source, now has teaching duties added to his already too busy schedule. This has required that we find additional help for the daily management of the EBIS. We were fortunate to be able to attract Charles Fehrenbach, who was previously a research associate from Colorado State University living at K-State, to this position. We are also in the process of interviewing candidates for a new theory faculty position in the K-State atomic physics group.
We have been invited to present a special exhibit on the JRM facilities at the March centennial meeting of the American Physical Society in Atlanta. Our major display, which has been coordinated by Tracy Tipping, Kevin Carnes, Vince Needham and Martin Stockli will allow attendees to take a virtual tour of the laboratory and to operate our CRYEBIS ion source from Atlanta using the internet.
Research projects abound. At the CRYEBIS, five beamlines are being heavily used.
The Tandem-LINAC facility is similarly heavily used. Here are some current projects:
Research in Atomic and Surface Theory
Interactions between ions and surfaces are not yet well understood at a microscopic level despite their importance for applications in surface chemistry (catalyses, corrosion prevention), accelerator design, and controlled fusion devices. Similarly, the detailed understanding of electron--transfer and electron emission in collisions between ions and fullerenes is of relevance for future applications. These collisions yield information on the physical and chemical properties of fullerenes that may enable the successful syntheses of new materials (fullerene chemistry).
Uwe Thumm is continuing to work on the theory of ion-surface collisions, ion-cluster interactions, and slow electron--atom collisions. Drs. Bogdana and Cristian Bahrim joined him in February as post doctoral research associates. Both got their PhD (equivalent) degrees at the University of Paris XI specializing in the theory of ion--surface interactions (Bogdana) and the theory of slow ion--atom collisions (Cristian).
Bogdana is developing a new, non-perturbative ab-intio ion-surface scattering calculation that includes an interesting new continuum discretization method to represent continuous solid state electronic wave functions.
Cristian is working on the interaction of slow electrons with Alkali atoms within Uwe's relativistic R-matrix approach. Motivated by very recent experiments, Cristain is now extending this method to investigate photo-detachment of negative ions.
During April and May, Uwe was joined by one of his German collaborators, Jens Ducree from the University of Muenster, to continue work on a computer simulation that by now reproduces various recently measured observables during the interaction of highly charged ions with metal and insulating surfaces. Another visitor, Priv. Doz. Dr. Uwe Wille from the Hahn-Meitner Institute in Berlin, came to our department in October in order to work with Uwe Thumm on the emerging field of ions interacting with thin metallic films.
During the past summer, Uwe (again) spent several weeks in Europe to collaborate with colleagues at the Manne Siegbahn Institute in Stockholm on interactions of ions with Buckyballs (C60) and in Berlin to continue a collaboration on ion-surface scattering theory. During this trip he gave invited talks in Stockholm, Sweden; Aarhus, Denmark; Freiburg, Germany; Copenhagen, Denmark; and at the 12th International Workshop on Collisions Involving Atomic Clusters, held in Sonderborg, Denmark in June.
In January 1999, Uwe presented an invited talk at the 12th International Workshop on Inelastic Ion-Surface Collisions, on South Padre Island, Texas.
Uwe's work is well funded. Apart from being attached to the Macdonald Laboratory block grant, he has his own NSF grant and recently received an award from the DOE Office of Fusion Energy to investigate the simultaneous interaction of atoms and negative ions with both static and laser external fields.
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