High-resolution Multi-Reflection Time-of-Flight Mass Spectrometer for exotic nuclei at IGISOL

A Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS) has been commissioned at the Ion-Guide Isotope Separator On-Line (IGISOL) facility. It consists of six electrode pairs that form a nearly energy-isochronous potential and a pulsed drift-tube to trap the ions between the electrodes. Time-of-flight peak widths down to 22 ns full-width at half-maximum and mass resolving powers of approximately 1 . 5 × 1 0 5 within 20 ms have been demonstrated. The obtained time-focus and mass resolving power depend sensitively on the trapping energy, energy spread and the number of revolutions of the ions. The mass resolving power is affected by the temporal and energy spread of the ions entering the MR-ToF-MS and fluctuations in the electrode voltages due to temperature variations. The longitudinal emittance corresponding to the temporal and energy spread of 39 K is estimated to be 175 eV ⋅ ns based on the data, which is close to the expected 186(10) eV ⋅ ns . The time-of-flight temperature sensitivity is found to be − 5.55(30) ppm/K. In addition to atomic mass measurements of short-lived exotic nuclides, the MR-ToF-MS can be used as a fast mass separator for various other experiments at IGISOL and as an ion counter for laser spectroscopy and yield measurements.