Charge state breeding of radioactive isotopes for ISAC
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Charge state breeding of radioactive isotopes for ISAC F. Ames · R. Baartman · P. Bricault · K. Jayamanna
Published online: 10 October 2013 © Springer Science+Business Media Dordrecht 2013
Abstract For the acceleration of radioactive isotopes with a mass greater than 30 amu charge breeding with an electron cyclotron resonance ion source (ECRIS) is being used at ISAC. Singly charged ions from the target ion source combination are injected into a 14.5 GHz ECRIS from PANTECHNIK and charge bred to highly charged ions with a mass to charge ratio around 6. Efficiencies from 1 to 8 % could be reached for different isotopes. The article describes the set- up of the system and reports on results obtained for efficiency as well as purity of the beam. Methods to improve the purity are discussed. Keywords Radioactive isotopes · Charge state breeding · Electron cyclotron resonance ion source
1 Introduction At the ISAC facility at TRIUMF radioactive nuclides are produced by bombarding solid target materials with high energy protons from the TRIUMF cyclotron. The targets are operated at high temperature to allow the products to be released into an on line ion source (see contribution by P. Bricault et al.). Mainly singly charged ions are produced. They can be extracted and accelerated up to an energy of 60 keV, separated by their mass and injected into a post accelerator. The accelerator consist of a room temperature radio frequency quadrupole accelerator (RFQ), a room temperature drift tube section and a superconducting linac, which allow final
ISAC and ARIEL: The TRIUMF Radioactive Beam Facilities and the Scientific Program. F. Ames (B) · R. Baartman · P. Bricault · K. Jayamanna TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada e-mail: [email protected]
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energies up to about 10 MeV/u. The RFQ section can accept ions with a mass to charge ratio up to 30 amu/e. The following drift tube and superconducting cavities require mass to charge ratios less than 7 amu/e. Therefore the ions have to pass a stripper foil after the first acceleration at an energy of 150 keV/u to increase the charge state. If ions with a mass greater than 30 amu are to be accelerated their charge state has to be increased already before entering the accelerator. In order to avoid further losses from the stripping process, which becomes less efficient for high masses, it is preferable to start with mass to charge ratios less than 7 amu/e. The charge state of low energy ions can be increased by injecting them into an ion source for highly charged ions. Two types of ion sources are used for this purpose at different facilities: an electron beam ion source (EBIS) or an electron cyclotron resonance ion source (ECRIS). In both sources the ions are stopped and confined while more electrons are removed in collisions with high energy electrons. An overview describing the different techniques and compiling results from different facilities is given for example in [1]. At TRIUMF an ECRIS (PHOENIX booster from PANTECHNIK) has been chosen as it
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