The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN's RIBF facility

A newly assembled multi-reflection time-of-flight mass spectrograph (MRTOF-MS) at RIKEN's RIBF facility became operational for the first time in spring 2020; further modifications and performance tests using stable ions were completed in early 2021. By using a pulsed-drift-tube technique to modify the ions' kinetic energy in a wide range, we directly characterize the dispersion function of the system for use in a new procedure for optimizing the voltages applied to the electrostatic mirrors. Thus far, a mass resolving power of R-m > 1000000 is reached within a total time-of-flight of only 12.5 ms, making the spectrometer capable of studying short-lived nuclei possessing low-lying isomers. Detailed information about the setup and measurement procedure is reported, and an alternative in-MRTOF ion selection scheme to remove molecular contaminants in the absence of a dedicated deflection device is introduced. The setup underwent an initial on-line commissioning at the BigRIPS facility at the end of 2020, where more than 70 nuclear masses have been measured. A summary of the commissioning experiments and results from a test of mass accuracy will be presented.

Automated summary

A newly assembled MRTOF-MS at RIKEN's RIBF facility became operational in spring 2020, and modifications and performance tests were completed in early 2021. The dispersion function of the system was characterized using a pulsed-drift-tube technique, allowing for optimization of the voltages applied to the electrostatic mirrors. The spectrometer achieved a mass resolving power of R-m > 1000000 within a total time-of-flight of 12.5 ms, enabling the study of short-lived nuclei with low-lying isomers.