http://nuclearmasses.org/resources_folder/Blaum_06.pdf

High-accuracy mass spectrometry with stored ions

A new cooling technique for heavy ions in a Penning trap

Quadrupole excitation of stored ion motion at the true cyclotron frequency

Ion motion in a Penning trap and the electrical signals it can produce have been analyzed for the purpose of identifying the important causes of uncertainty in high‐accuracy mass measurements of heavy ions. The role of the azimuthal quadrupole electric field in signal pickup, and its effects on ion motion at the sum frequency of the cyclotron and magnetron motions, have been identified. A useful scheme for calculating the signal strength and strength of the interaction between an applied field and the ion motion has been developed. The important sources of uncertainty in using the sum frequency of the cyclotron and magnetron motions for determining the ion mass are discussed. Particular application is made to the case of cyclotron resonance detection by observation of the time of flight of ejected ions.

/pdf/the-accuracy-of-heavy-ion-mass-measurements-using-time-of-5gu53em2u0.pdf

The accuracy of heavy‐ion mass measurements using time of flight‐ion cyclotron resonance in a Penning trap

The tandem Penning trap mass spectrometer ISOLTRAP has been set up at the on-line mass separator ISOLDE at CERN/Geneva for accurate mass measurements of short-lived nuclei with T 1 2 ≥ 1 s . The mass measurement is performed via the determination of the cyclotron frequency of an ion in a magnetic field. The design of the spectrometer matches the particular requirements for on-line mass measurements on short-lived isotopes. With the ISOLTRAP spectrometer masses of more than 70 radioactive nuclei have so far been determined with resolving powers exceeding one million and an accuracy of typically 10−7.

ISOLTRAP: a tandem Penning trap system for accurate on-line mass determination of short-lived isotopes

A bunched beam of alkali ions with a pulse length of about 10 μs and an energy of 1 KeV has been retarded electrostatically and captured in flight into a Penning trap. A trapping efficiency of up to 70% has been determined. Subsequently the cyclotron resonance was induced. In the case of K a line width of the resonance of 4 Hz was measured at a resonance frequency of 2.3 MHz. This enables mass determinations of unstable nuclei produced at on-line mass separators with an accuracy in the sub-ppm region.

/pdf/in-flight-capture-of-ions-into-a-penning-trap-wius6065jy.pdf

In-flight capture of ions into a penning trap

Absolute mass measurements of short-lived isotopes have been performed at the on-line mass separator ISOLDE at CERN by determining the cyclotron frequencies of ions confined in a Penning trap. The cyclotron frequencies for77,78,85,86,88Rb and88Sr ions could be determined with a resolving power of 3×105 and an accuracy of better than 10−6, which corresponds to 100 keV for massA=100. The shortest-lived isotope under investigation was77Rb with a half-life of 3.7 min. The resonances obtained for the isobars88Rb and88Sr were clearly resolved.

/pdf/first-absolute-mass-measurements-of-short-lived-isotopes-2gs5s6mwjm.pdf

P. Dabkiewicz

Papers

In-flight capture of ions into a penning trap

First absolute mass measurements of short-lived isotopes