Sprecher
Beschreibung
Approximately half of the nuclei heavier than iron are produced by the rapid neutron capture process ($r$ process). [1] The r process can be simulated with nuclear reaction network codes for which nuclear input data is essential. Particularly neutron capture reaction rates and $\beta$-decay $Q$ values are important, both of which are dependent on nuclear masses. However, many neutron-rich nuclei have measured masses with rather large uncertainties, and the isomeric states might be even lesser known. [2] Improving the accuracy of the measured masses for these nuclei also leads to more precise reaction rates which in turn lead to reduced uncertainties in the $r$-process simulations. The improved masses also affect the beta decay $Q$ values which are important for the heating rate of the $r$ process.
JYFLTRAP, a double Penning trap mass spectrometer [3], at the IGISOL facility has been utilised to accurately measure the masses of several neutron-rich isotopes. Combined with the phase-imaging ion cyclotron resonance (PI-ICR) technique [4], several low-lying isomeric states have been successfully resolved [5,6]. While currently not widely used in astrophysical simulations, isomeric states can have substantial effect on the $r$-process outcome. [7] In my presentation, example cases of measured isomeric states are presented with updated reaction rates and their effects on the $r$-process abundances and heating rate.
References:
[1] Cowan, J., et al. "Origin of the heaviest elements: The rapid neutron-capture process," in Reviews of Modern Physics, vol. 93, no. 1, pp. 015002, 2021.
[2] Kondev, F., et al. "The NUBASE2020 evaluation of nuclear physics properties," in Chinese Physics C, vol. 45, no. 3, pp. 030001, 2021.
[3] Eronen, T., et al. "JYFLTRAP: A Penning trap for precision mass spectroscopy and isobaric purification," in The European Physical Journal A, vol. 48, 2012.
[4] Nesterenko, D., et al. "Phase-Imaging Ion-Cyclotron-Resonance technique at the JYFLTRAP double Penning trap mass spectrometer," in Eur. Phys. J. A, vol. 54, no. 9, pp. 154, 2018.
[5] J. Ruotsalainen et al., “High-precision mass measurements of the ground and isomeric states in 124,125Ag,” Phys. Rev. C, vol. 111, no. 4, p. 044314, Apr. 2025, doi: 10.1103/PhysRevC.111.044314.
[6] Jaries, A., et al. "Isomeric states of fission fragments explored via Penning trap mass spectrometry at IGISOL," in Phys. Rev. C, vol. 110, pp. 034326, 2024.
[7] Misch, G., et al. "Astromers: Nuclear Isomers in Astrophysics*," in The Astrophysical Journal Supplement Series, vol. 252, no. 1, pp. 2, 2020.
