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Title: High-efficiency target ion sources for radioactive ion beam generation

Abstract

In this report, high-temperature ion sources are described, which have demonstrated the high ionization efficiency, species versatility, and operational reliability required at isotope-separator-online (ISOL) based radioactive ion beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF). Specific attention is given to the ion optics, operational parameters, thermal transport properties, emittances, and ionization efficiencies of the HRIBF ion sources that have been carefully designed for safe handling in the high-level radiation fields incumbent at such facilities. Included in the article are descriptions and performance data for high-temperature, positive- (electron impact and surface ionization) and negative- (kinetic ejection and surface ionization) ion sources as well as low-temperature, batch-mode negative-ion sources, developed for processing long-lived isotopes that have been the principal contributors to recent successes held at the Holifield Radioactive Ion Beam Facility.

Authors:
; ;  [1]
  1. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6372 (United States)
Publication Date:
OSTI Identifier:
20779034
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2173968; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ANIONS; BEAM OPTICS; BEAM PRODUCTION; EFFICIENCY; ELECTRONS; ION SOURCES; RADIOACTIVE ION BEAMS; SURFACE IONIZATION; TEMPERATURE RANGE

Citation Formats

Alton, G.D., Liu, Y., and Stracener, D.W. High-efficiency target ion sources for radioactive ion beam generation. United States: N. p., 2006. Web. doi:10.1063/1.2173968.
Alton, G.D., Liu, Y., & Stracener, D.W. High-efficiency target ion sources for radioactive ion beam generation. United States. doi:10.1063/1.2173968.
Alton, G.D., Liu, Y., and Stracener, D.W. Wed . "High-efficiency target ion sources for radioactive ion beam generation". United States. doi:10.1063/1.2173968.
@article{osti_20779034,
title = {High-efficiency target ion sources for radioactive ion beam generation},
author = {Alton, G.D. and Liu, Y. and Stracener, D.W.},
abstractNote = {In this report, high-temperature ion sources are described, which have demonstrated the high ionization efficiency, species versatility, and operational reliability required at isotope-separator-online (ISOL) based radioactive ion beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF). Specific attention is given to the ion optics, operational parameters, thermal transport properties, emittances, and ionization efficiencies of the HRIBF ion sources that have been carefully designed for safe handling in the high-level radiation fields incumbent at such facilities. Included in the article are descriptions and performance data for high-temperature, positive- (electron impact and surface ionization) and negative- (kinetic ejection and surface ionization) ion sources as well as low-temperature, batch-mode negative-ion sources, developed for processing long-lived isotopes that have been the principal contributors to recent successes held at the Holifield Radioactive Ion Beam Facility.},
doi = {10.1063/1.2173968},
journal = {Review of Scientific Instruments},
number = 3,
volume = 77,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • Ion sources for radioactive ion beam (RIB) generation must efficiently ionize short-lived-radioactive nuclei released from on-line targets with minimal delay times. Delay times attributable to interactions between chemically active species and surfaces of the vapor transport system which are long compared to the half-life of the desired radioactive atom and/or low ionization efficiency of the target/ion source (TIS) will result in a severe reduction of the RIB intensity available for research. We have developed complementary off-line techniques for directly measuring both effusive delay times and ionization efficiencies for chemically active species in high temperature TISs using only the stable complementsmore » of the radioactive element of interest. Equipment, designed and developed for these measurements, include: a high-temperature Ta valve; a differentially cooled injection nozzle; and a gaseous flow measurement and control system. These techniques are employed in a systematic investigation of fluorine transport and ionization in an electron-beam-plasma target/ion source (EBPTIS) designed for initial use at the Holifield Radioactive Ion Beam Facility (HRIBF). {copyright} {ital 1997 American Institute of Physics.}« less
  • In this report, we describe the performance characteristics for a selected number of target ion sources that will be employed for initial use at the Holifield Radioactive Ion Beam Facility as well as prototype ion sources that show promise for future use for radioactive ion beam applications. A brief review of present efforts to select target materials and to design composite target matrix/heat-sink systems that simultaneously incorporate the short diffusion lengths, high permeabilities, and controllable temperatures required to effect fast and efficient diffusion release of the short-lived species is also given. {copyright} {ital 1996 American Institute of Physics.}
  • In this article, we describe the performance characteristics for a selected number of target ion sources that will be employed for initial use at the Holifield Radioactive Ion Beam Facility as well as prototype ion sources that show promise for future use for radioactive ion beam applications. A brief review of present efforts to select target materials and to design composite target matrix/heat-sink systems that simultaneously incorporate the short diffusion lengths, high permeabilities, and controllable temperatures required to effect fast and efficient diffusion release of the short-lived species is also given. {copyright} {ital 1996 American Institute of Physics.}
  • Radioactive ion beams (RIBs) of {sup 17}F and {sup 18}F are of interest for investigation of astrophysical phenomena such as the {open_quotes}hot{close_quotes} CNO cycle and the rp stellar nuclear synthesis processes. In order to generate useful beam intensities of atomic F{sup {minus}}, the species must be efficiently and expediently released from the target material, thermally dissociated from fluoride release products during transport to the ionization chamber of the ion source, and efficiently ionized in the source upon arrival. We have conceived and evaluated two prototype negative ion sources for potential use for RIB generation: a direct extraction source and amore » kinetic ejection source. Both sources utilize Cs vapor to enhance F{sup {minus}} formation. The mechanical design features, operational parameters, ionization efficiencies for forming atomic F{sup {minus}} and delay times for transport of F and fluoride compounds for the respective sources are presented. The efficiency {eta} for formation and extraction of F{sup {minus}} for the direct extraction negative ion source is found to be {eta}{approximately}1.0{percent}, while the characteristic delay time {tau} for transport of F and fluorides through the source is typically, {eta}{approximately}120 s; the analogous efficiencies and delay times for the kinetic ejection negative ion source are, respectively: {eta}={approximately}3.2{percent} and {tau}={approximately}70 s. {copyright} {ital 1998 American Institute of Physics.}« less