An advanced in-trap deflector for background-free nuclear mass measurements

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K13951
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: Rosenbusch Marco 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 特任助教 (50790945)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: Nuclear Structure / Nuclear Astrophysics / Ion Traps / Ion Manipulation / MRTOF-MS / Isotope Separation / Background Reduction

Outline of Final Research Achievements

In this research project, a new in-MRTOF deflector (IMD) for the on-line multi-reflection time-of-flight mass spectrographs (MRTOF-MS) at RIKEN/RIBF has been developed. The new deflection system has been successfully installed, tested, and applied in on-line nuclear mass measurements at the BigRIPS separator.
Using the new IMD, several chosen ion-mass units could be transmitted to the TOF detector, while all other ions were ejected. This new system allowed for overwhelmingly clean ion spectra in the experiments RIBF199 and RIBF202 (see RIKEN RIBF experiments), where the masses of 73Ni - 75Ni have been measured simultaneously. IMD systems have been installed in three MRTOF systems and allowed for successful online mass measurements. At the GARIS-II separator, the superheavy element masses for 257,258Db have been measured using the IMD. Furthermore, the IMD allowed for the first systematic measurements of the electrical charge state formed for different chemical elements in a helium gas.

Free Research Field

Nuclear Physics and Mass Spectrometry

Academic Significance and Societal Importance of the Research Achievements

In this research project, a new tool was developed to obtain backgound-free spectra in an MRTOF mass spectrometer for radioactive ions. Mass measurements of exotic nuclei are a fundamental tool for the study of nuclear properties far away from stability, astrophysics, and fundamental interactions.