Showing papers by "Lutz Schweikhard published in 1992"

Mass Determination of Francium and Radium Isotopes by a Penning Trap Mass Spectrometer

Abstract: A tandem Penning trap mass spectrometer is used for mass measurement of radioactive isotopes produced at the on-line isotope separator ISOLDE/CERN. The mass is determined directly and with high accuracy by measuring the cyclotron frequency of the stored ions. Measurements were performed on 209 210 211 212 221 222Fr and 226 230Ra. A resolving power of 5 × 105 was used and an accuracy of 1·8 × 10−7 has been achieved.

Fourier Transform Ion Cyclotron Resonance of highly-charged atomic ions

Abstract: The feasibility of applying Fourier Transform Ion Cyclotron Resonance (FT/ICR) to highly-charged atomic ions is discussed based on present achievements. In particular two features have to be addressed: the high charge states and the high cyclotron frequencies of highly-charged atomic ions. FT/ICR has recently been applied to highly-charged molecular, i.e. heavy ions. It has also been applied to singly-charged light ions, which have cyclotron frequencies comparable to those of highly-charged atomic ions. Therefore FT/ICR should be easily applicable to the expanding field of investigation of highly-charged atomic ions. Prominent features of the technique are the broadband capability, the high sensitivity/low detection limit, relativistic frequency shifts, and high kinetic energies. New experiments making use of these features are proposed.

Mass-to-charge ratio upper limits for matrix-assisted laser desorption Fourier transform ion cyclotron resonance mass spectrometry

Abstract: One of the well-known analytical uses of Fourier transform ion cyclotron resonance mass spectrometry (FT/ICR/MS) ise its high theoretical upper mass limit. FT/ICR/MS upper mass limits with respect to radial or axial loss of trapped lone have previously been derived and computed for lone which are in thermal equilibrium with their surroundings (i.e., follow Boltzmann preexcitation ion initial velocity distributions). However, recent results by Beavis and Chalt show that lone formed by the matrix-assisted laser desorption (MALD) ionization technique are clearly not in thermal equilibrium with their surroundings

High-Accuracy Mass Determination of Unstable Rb, Sr, Cs, Ba, Fr and Ra Isotopes with a Penning Trap Mass Spectrometer

Abstract: The majority of masses of radioactive isotopes has been measured by determination of Q-values in nuclear reactions or in nuclear decay. For a long time the use of direct mass determination has been limited to stable isotopes or isotopes close to stability. This changed in the 70’s with magnetic spectrometers put on-line to isotope separators. The Orsay group (Audi et al., 1986) succeeded in measuring the masses in long isotope chains of alkali elements. They impressively demonstrated the possibilities embedded in direct mass determination of isotopes far from stability. The persisting demand for more precise masses of short-lived isotopes (or exotic particles) has prompted during recent years the development of new techniques. One powerful approach is the determination of the cyclotron frequency in a Penning trap, first demonstrated for light stable masses and now applied to unstable isotopes in the experiment reported here. We report on the technique and performance of a tandem Penning trap mass spectrometer at the on-line mass separator ISOLDE/CERN and summarize the very accurate results obtained on Rb, Sr, Cs, Ba, Fr and Ra isotopes.