Major Gains in Ion Production for Radioactive Beams

Nuclear physics research with radioactive beams enhanced by high-efficiency charge-breeding techniques.

Image courtesy of Argonne National Laboratory
Simulation of radioactive beam stopping in the plasma of an electron cyclotron resonance ion source as a first step toward high-efficiency charge breeding.

The Science

New charge breeding techniques have improved our ability to produce, with high efficiency, beams of radioactive ions that can be accelerated to energies suitable to induce nuclear reactions. This provides scientists with the opportunity to explore aspects of the nuclear force that are not readily apparent in stable nuclei and to study in the laboratory some of the processes creating the elements in stellar environments.

The Impact

Raising the charge state of radioactive ions is a critical step in obtaining these exotic nuclei as beams of particles that can subsequently be accelerated to energies suitable for experimentation. The techniques that have been demonstrated recently have improved the efficiency of the “charge breeding” process by factors of 3 or more. For the first time, relatively intense beams of a number of species have become available with combinations of protons and neutrons that differ greatly from those characterizing stable nuclei. Access to these exotic beams enables scientists to address questions such as “How did visible matter come into being and how does it evolve?” and “How does subatomic matter organize itself and what phenomena emerge?”


Understanding how the strong force binds protons and neutrons together to form nuclei has been a goal of nuclear physics research since the original discovery of the nucleus.  Research today is focused on the use of radioactive beams that allow the study of these nuclei under extreme conditions, previously only available in stellar environments. Accelerator facilities throughout the world are coming online to provide these radioactive beams. A new design for the ion source, used in a number of these facilities, has now demonstrated improvements as high as a factor of 3 or more in the efficiency with which these ion species can be produced and prepared for subsequent acceleration.  In this process, radioactive ions are obtained from nuclear reactions or natural fission. They are then stopped in a high-energy plasma of an electron cyclotron resonance ion source, where they lose additional electrons through collisions with plasma particles, herewith increasing their charge state. Following charge breeding, they are then extracted from the source and accelerated in a “normal” accelerator to energies suitable to the study of their nuclear properties. Some of these radioactive nuclei are expected to be found in supernovae and other high-energy astrophysical environments. Their study thus provides information critical to understand stellar evolution and the overall development of the universe.


Richard C. Pardo
Argonne National Laboratory


This work is supported by the U.S. Department of Energy (DOE), Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (Argonne National Laboratory). This research used resources of Argonne National Laboratory’s ATLAS facility, a DOE Office of Science User Facility.


R. Vondrasek, A. Levand, R. Pardo, G. Savard, and R. Scott, “Charge Breeding Results and Future Prospects with ECRIS and EBIS.” Review of Scientific Instruments 83, 02A913/1-5 (2012). [DOI: 10.1063/1.3673629]

P. Delahaye, L. Maunoury, and R. Vondrasek, “Charge Breeding of Light Metallic Ions: Prospects for SPIRAL.” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment A693, 104-108 (2013). [DOI: 10.1016/j.nima.2012.07.016]

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Program: NP

Performer: DOE Laboratory , SC User Facilities , NP User Facilities , ATLAS