Journal article

Publication year: 2021

Journal: Physical Review C

Volume number: 103

Issue number: 4

ISSN: 2469-9985

eISSN: 2469-9993

Open access status: Green

DOI Link: https://doi.org/10.1103/PhysRevC.103.044320

Publisher: American Physical Society

Abstract: 

Background: The neutron-rich A approximate to 100, N approximate to 62 mass region is important for both nuclear structure and nuclear astrophysics. The neutron-rich segment of this region has been widely studied to investigate shape coexistence and sudden nuclear deformation. However, the absence of experimental data of more neutron-rich nuclei poses a challenge to further structure studies. The derivatives of the mass surface, namely, the two-neutron separation energy and neutron pairing gap, are sensitive to nuclear deformation and shed light on the stability against deformation in this region. This region also lies along the astrophysical r-process path, and hence precise mass values provide experimental input for improving the accuracy of the r-process models and the elemental abundances.

Purpose: (a) Changes in deformation are searched for via the mass surface in the A = 104 mass region at the N = 66 mid-shell crossover. (b) The sensitivity of the astrophysical r-process abundances to the mass of Rb and Sr isotopic chains is studied.

Methods: Masses of radioactive Rb and Sr isotopes are precisely measured using a Multiple-Reflection Time-of-Flight Mass Separator (MR-TOF-MS) at the TITAN facility. These mass values are used to calculate two-neutron separation energies, two-neutron shell gaps and neutron pairing gaps for nuclear structure physics, and one-neutron separation energies for fractional abundances and astrophysical findings.

Results: We report the first mass measurements of Rb-103 and Sr-103 with uncertainties of less than 45 keV/c(2). The uncertainties in the mass excess value for Rb-102 and (102)5r have been reduced by a factor of 2 relative to a previous measurement. The deviations from the AME extrapolated mass values by more the 0.5 MeV have been found.

Conclusions: The metrics obtained from the derivatives of the mass surface demonstrate no existence of a subshell gap or onset of deformation in the N = 66 region in Rb and Sr isotopes. The neutron pairing gaps studied in this work are lower than the predictions by several mass models. The abundances calculated using the waiting-point approximation for the r process are affected by these new masses in comparison with AME2016 mass values.

Harvard Citation style: Mukul, I., Andreoiu, C., Bergmann, J., Brodeur, M., Brunner, T., Dietrich, K., et al. (2021) Examining the nuclear mass surface of Rb and Sr isotopes in the A ≈ 1104 region via precision mass measurements, Physical Review C, 103(4), Article 044320. https://doi.org/10.1103/PhysRevC.103.044320

APA Citation style: Mukul, I., Andreoiu, C., Bergmann, J., Brodeur, M., Brunner, T., Dietrich, K., Dickel, T., Dillmann, I., Dunling, E., Fusco, D., Gwinner, G., Izzo, C., Jacobs, A., Kootte, B., Lan, Y., Leistenschneider, E., Lykiardopoulou, E., Paul, S., Reiter, M., ...Kwiatkowski, A. (2021). Examining the nuclear mass surface of Rb and Sr isotopes in the A ≈ 1104 region via precision mass measurements. Physical Review C. 103(4), Article 044320. https://doi.org/10.1103/PhysRevC.103.044320