# Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-of-flight mass spectrograph

## TL;DR

This paper reports high-precision mass measurements of various neutron-deficient nuclei using a multireflection time-of-flight spectrograph, achieving relative uncertainties down to 35 parts per billion, and discusses implications for nuclear physics and astrophysics.

## Contribution

The study demonstrates the capability of a multireflection time-of-flight spectrograph combined with GARIS-II for ultra-precise mass measurements of intermediate-mass neutron-deficient nuclei.

## Key findings

- Achieved a mass uncertainty of 2.1 keV for $^{65}$Ga.
- Found discrepancies with literature values for $^{67}$Ge and $^{81}$Br.
- Confirmed agreement with 2016 Atomic Mass Evaluation for $^{65}$Ga.

## Abstract

High-precision mass measurements of $^{63}$Cu, $^{64-66}$Zn, $^{65}$Ga, $^{65-67}$Ge, $^{67}$As, $^{78,81}$Br, $^{80}$Rb, and $^{79}$Sr were performed utilizing a multireflection time-of-flight mass spectrograph combined with the gas-filled recoil ion separator GARIS-II. In the case of $^{65}$Ga, a mass uncertainty of 2.1 keV, corresponding to a relative precision of $\delta m / m = 3.5\times10^{-8}$, was obtained and the mass value is in excellent agreement with the 2016 Atomic Mass Evaluation. For $^{67}$Ge and $^{81}$Br, where masses were previously deduced through indirect measurements, discrepancies with literature values were found. The feasibility of using this device for mass measurements of nuclides more neutron-deficient side, which have significant impact on the $rp$-process pathway, is discussed.