Speaker
Description
Approximately half of the nuclei heavier than iron are produced by the rapid neutron-capture process (r process). The r process nucleosynthesis can be simulated with nuclear reaction network codes for which nuclear data input is important. In particular, neutron-capture and photodisintegration rates are essential as they directly affect the outcome of the simulations. One of the key factors that affect the neutron capture rates are nuclear masses. However, many neutron-rich nuclei have rather large mass uncertainties. By enhancing the precision of the poorly known masses, we can also obtain more precise reaction rates which in turn lead to reduced uncertainties in the r-process simulations. This helps us to model better e.g. the solar system abundances. Also, the improved masses have an effect on the beta decay Q values which are important for the heating rate of the r process. The mass measurements are also essential to benchmark theoretical models predicting the masses for the experimentally inaccessible nuclei.
JYFLTRAP, a double Penning trap mass spectrometer [1], at the IGISOL (Ion Guide Isotope Separator On-Line) facility [2] at the University of Jyväskylä, has been successfully used to achieve high-precision mass measurements of several neutron-rich isotopes. Utilising the phase-imaging ion cyclotron resonance (PI-ICR) technique (e.g. [3]), also several low-lying isomeric states have been resolved. While currently they are not widely used in the astrophysical simulations, isomeric states can have a substantial effect on the r-process outcome [3,4]. In this contribution, I will present a few example cases of the ground and isomeric states of neutron-rich nuclei measured at JYFLTRAP with their effect on the reaction rates and the r-process simulations.
[1] Eronen, T., et al. JYFLTRAP: A Penning Trap for Precision Mass Spectroscopy and Isobaric Purification. Eur. Phys. J. A 48, 46 (2012).
[2] Moore, I.D., et al., Towards commissioning the new IGISOL-4 facility. Nucl. Inst. Meth. Phys. Res. B 317 (2013) 208.
[3] Nesterenko, D. A., et al. High-precision Measurements of Low-lying Isomeric States in In120–124 With the JYFLTRAP Double Penning Trap. Phys. Rev. C, vol. 108, no. 5, Nov. 2023.
[4] Misch, G. W., et al. Astromers: Nuclear Isomers in Astrophysics. Astrophys. J. Suppl. Ser., vol. 252, no. 1, Dec. 2020, p. 2.
[5] Misch, G. W., et al. Astromers in the Radioactive Decay of R-process Nuclei. The Astrophys. J. Lett., vol. 913, no. 1, May 2021, p. L2.
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