Article

# An Ion Guide for the Production of a Low Energy Ion Beam of Daughter Products of $\alpha$-Emitters

05/2006; DOI:doi:10.1016/j.nimb.2006.08.015
Source: arXiv

ABSTRACT A new ion guide has been modeled and tested for the production of a low energy ($\approx$ 40 kV) ion beam of daughter products of alpha-emitting isotopes. The guide is designed to evacuate daughter recoils originating from the $\alpha$-decay of a $^{233}$U source. The source is electroplated onto stainless steel strips and mounted along the inner walls of an ion guide chamber. A combination of electric fields and helium gas flow transport the ions through an exit hole for injection into a mass separator. Ion guide efficiencies for the extraction of $^{229}$Th$^{+}$ (0.06%), $^{221}$Fr$^{+}$ (6%), and $^{217}$At$^{+}$ (6%) beams have been measured. A detailed study of the electric field and gas flow influence on the ion guide efficiency is described for two differing electric field configurations. Comment: 13 pages, 11 figures, 4 tables. Submitted to Nucl. Instr. Meth. B

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##### Article:Resonance ionization spectroscopy of thorium isotopes-towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of Th-229
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ABSTRACT: In-source resonance ionization spectroscopy was used to identify an efficient and selective three step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in preparation of laser spectroscopic investigations for an identification of the low-lying 229 m Th isomer predicted at 7.6 ± 0.5 eV above the nuclear ground state. Using a sample of 232 Th, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing states were identified. Level energies were determined with an accuracy of 0.06 cm −1 for intermediate and 0.15 cm −1 for auto-ionizing states. Using different excitation pathways an assignment of total angular momenta for several energy levels was possible. One particularly efficient ionization scheme of thorium, exhibiting saturation in all three optical transitions, was studied in detail. For all three levels in this scheme, the isotope shifts of the isotopes 228 Th, 229 Th, and 230 Th relative to 232 Th were measured. An overall efficiency including ionization, transport and detection of 0.6 % was determined, which was predominantly limited by the transmission of the mass spectrometer ion optics.
04/2011;
• Source
##### Article:Resonance ionization spectroscopy of thorium isotopes - towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of Th-229
[show abstract] [hide abstract]
ABSTRACT: In-source resonance ionization spectroscopy was used to identify an efficient and selective three step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in preparation of laser spectroscopic investigations for an identification of the low-lying Th-229m isomer predicted at 7.6 +- 0.5 eV above the nuclear ground state. Using a sample of Th-232, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing states were identified. Level energies were determined with an accuracy of 0.06 cm-1 for intermediate and 0.15 cm-1 for auto-ionizing states. Using different excitation pathways an assignment of total angular momenta for several energy levels was possible. One particularly efficient ionization scheme of thorium, exhibiting saturation in all three optical transitions, was studied in detail. For all three levels in this scheme, the isotope shifts of the isotopes Th-228, Th-229, and Th-230 relative to Th-232 were measured. An overall efficiency including ionization, transport and detection of 0.6 was determined, which was predominantly limited by the transmission of the mass spectrometer ion optics.
05/2011;

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### Keywords

$\alpha$-decay

4 tables

alpha-emitting isotopes

daughter products

daughter recoils originating

detailed study

electric field

electric field configurations

electric fields

extraction

gas flow influence

helium gas flow transport

ion guide chamber

Ion guide efficiencies

ion guide efficiency

ions

new ion guide

stainless steel strips

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