New mass anchor points for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes

Abstract

The masses of the exotic isotopes ${}^{210-214}$Ac and ${}^{210-214}$Ra have been measured with a multi-reflection time-of-flight mass spectrograph. These isotopes were obtained in flight as fusion-evaporation products behind the gas-filled recoil ion separator GARIS-II at RIKEN. The new direct mass measurements serve as an independent and direct benchmark for existing $\alpha$-$\gamma$ spectroscopy data in this mass region. Further, new mass anchor points are set for U and Np nuclei close to the $N=126$ shell closure for a future benchmark of the $Z=92$ sub-shell for neutron-deficient heavy isotopes. Our mass results are in general in good agreement with the previously indirectly-determined mass values. Together with the measurement data, reasons for possible mass ambiguities from decay-data links between ground states are discussed.

References in corpus (7)

• First direct mass measurements of nuclides around $Z=100$ with a Multireflection Time-of-Flight Mass Spectrograph
• Single-reference high-precision mass measurement with a multi-reflection time-of-flight mass spectrograph
• Alpha Decay in the Complex Energy Shell Model
• First Online Mass Measurements of Isobar Chains via Multi-Reflection Time-of-Flight Mass Spectrograph Coupled with GARIS-II
• Wide-band mass measurements with a multi-reflection time-of-flight mass spectrograph
• Study of the long-lived excited state in the neutron deficient nuclides ${}^{195,197,199}$Po by precision mass measurement
• Corrections of alpha- and proton-decay energies in implantation experiments

Cited by in corpus (7)

• High-resolution, accurate MR-TOF-MS for short-lived, exotic nuclei of few events in their ground and low-lying isomeric states
• Improving wide-band mass measurements in a multi-reflection time-of-flight mass spectrograph by usage of a concomitant measurement scheme
• Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-of-flight mass spectrograph
• Development of an "$\alpha$-ToF" detector for correlated measurement of atomic masses and decay properties
• A new beamline for Resonant Excitation of Beams with Electromagnetic fields and Lasers (REBEL) and Stopping and Trapping of Radioactive Isotopes for Precision Experiments (STRIPE)
• Reduction of contaminants originating from primary beam by improving the beam stoppers in GARIS-II
• First high-precision direct determination of the atomic mass of a superheavy nuclide