Nuclear mass measurements with radioactive ion beams

Famiano, M.

doi:10.1142/s0218301319300054

Cited by 7 publications

(5 citation statements)

References 171 publications

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“…The extension of mass measurements to more neutron-rich nuclei in the Ca-Ni and Cd-Sn regions will be of great value. Those can be carried out via the variety of methods, especially the time-of-flight technique [64] that can be applied to short-lived nuclides with 1-100 ms lifetimes.…”

Section: Neutron-rich Nucleimentioning

confidence: 99%

Quantified limits of the nuclear landscape

et al. 2020

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Background: The chart of the nuclides is limited by particle drip lines beyond which nuclear stability to proton or neutron emission is lost. Predicting the range of particle-bound isotopes poses an appreciable challenge for nuclear theory as it involves extreme extrapolations of nuclear masses well beyond the regions where experimental information is available. Still, quantified extrapolations are crucial for a wide variety of applications, including the modeling of stellar nucleosynthesis.Purpose: We use microscopic nuclear global mass models, current mass data, and Bayesian methodology to provide quantified predictions of proton and neutron separation energies as well as Bayesian probabilities of existence throughout the nuclear landscape all the way to the particle drip lines. Methods:We apply nuclear density functional theory with several energy density functionals. We also consider two global mass models often used in astrophysical nucleosynthesis simulations. To account for uncertainties, Bayesian Gaussian processes are trained on the separation-energy residuals for each individual model, and the resulting predictions are combined via Bayesian model averaging. This framework allows to account for systematic and statistical uncertainties and propagate them to extrapolative predictions. Results:We establish and characterize the drip-line regions where the probability that the nucleus is particlebound decreases from 1 to 0. In these regions, we provide quantified predictions for one-and two-nucleon separation energies. According to our Bayesian model averaging analysis, 7759 nuclei with Z ≤ 119 have a probability of existence ≥ 0.5. Conclusions:The extrapolation results obtained in this study will be put through stringent tests when new experimental information on existence and masses of exotic nuclei becomes available. In this respect, the quantified landscape of nuclear existence obtained in this study should be viewed as a dynamical prediction that will be fine-tuned when new experimental information and improved global mass models become available.

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Section: Neutron-rich Nucleimentioning

confidence: 99%

Quantified limits of the nuclear landscape

et al. 2020

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“…However, measuring techniques such as multiple-reflection time-of-flight (MR-TOF) [92][93][94], Penning trap [25,95,96], storage ring [97][98][99][100], etc are limited by the lifetimes of the nuclei. For example, although the Penning trap has a mass precision of up to 10 −8 , its measuring time is only appropriate for relatively long lifetimes, which are longer than tens of milliseconds (10 −3 s) of measured nuclei [101,102]. Based on the MR-TOF technique, the nuclear mass of the nuclei with half-lives of tens of microseconds (10 −6 s) can be measured in radioactive ion beam facilities [92][93][94]102] with a precision level of 10 −7 .…”

Section: The Impact Of β − -Decay Half-life Uncertainty On the R-proc...mentioning

confidence: 99%

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

Uyen¹,

Chae²,

Nguyen³

et al. 2021

J. Phys. G: Nucl. Part. Phys.

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The β--decay half-lives of extremely neutron-rich nuclei are important for understanding nucleosynthesis in the r-process. However, most of their half-lives are unknown or very uncertain, leading to the need for reliable calculations. In this study, we updated the coefficients in recent semi-empirical formulae using the newly updated mass (AME2020) and half-life (NUBASE2020) databases to improve the accuracy of the half-life prediction. In particular, we developed a new empirical model for better calculations of the β--decay half-lives of isotopes ranging in Z = 10 – 80 and N = 15-130. We examined the β--decay half-lives of the extremely neutron-rich isotopes at and around the neutron magic numbers of N = 50, 82, and 126 using either five different semi-empirical models or finite-range droplet model and quasi-particle random phase approximation (FRDM+QRPA) method. The β--decay rates derived from the estimated half-lives were used in calculations to evaluate the impact of the half-life uncertainties of the investigated nuclei on the abundance of the r-process. The results show that the half-lives mostly range in 0.001 < T1/2 < 100 s for the nuclei with a ratio of N/Z < 1.9; however, they differ significantly for those with the ratio of N/Z > 1.9. The half-life differences among the models were found to range from a few factors (for N/Z < 1.9 nuclei) to four orders of magnitude (for N/Z > 1.9). These discrepancies lead to a large uncertainty, which is up to four orders of magnitude, in the r-process abundance of isotopes. We also found that the multiple-reflection time-of-flight (MR-TOF) technique is preferable for precise mass measurements because its measuring timescale applies to the half-lives of the investigated nuclei. Finally, the results of this study are useful for studies on the β-decay of unstable isotopes and astrophysical simulations.

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“…If the F 1 and F 2 formulae are used, it is a challenge for measuring the 117 Nb, 119 Mo, 122 Tc, and 125 Ru isotopes. By considering the measuring scales of precise mass measurement techniques, such as storage ring [76][77][78][79], Multi-Reflection Time-of-Flight (MR-TOF) [80][81][82], and Penning trap [83,84], the last two techniques are appropriate for these nuclei due to its short timescale of a few milliseconds [85]. Obviously, the uncertainty in the half-lives due to the difference in the models leads to a difficulty in the selection of measuring techniques.…”

Section: 139mentioning

confidence: 99%

Beta-decay half-lives of the isotopes close to the neutron drip line and astrophysical implications

Quyen¹,

Chae²,

Uyen³

et al. 2022

Phys. Scr.

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In this paper, we examined the β--decay half-lives of 94 extremely neutron-rich isotopes with Z = 26 − 57 close to the neutron drip line, which are important for the r-process calculations. The half-lives were calculated using four semi-empirical models and compared to those based on the FRDM+QRPA approach and available measured data. The impact of the diﬀerence in the models on the half-life predictions was investigated. We found that theoretical calculations for the β-decay half-life have a large deviation, up to 60%, which is mostly similar to that in measurements. The half-lives of the investigated nuclei are ranging from a few to hundreds of milliseconds. The r-process abundances in various astrophysical scenarios were calculated by using the predicted half-lives. The half-life uncertainty due to diﬀerent models results in a large deviation in the isotopic abundance, specially for the isotopes in the mass range of A > 210. The shell closures in 76Fe is still a doubt due to the discrepancy in the trends of the half-life and paring gap while a closed-shell at N = 82 in 127Rh is possible. The results of this study also notice that it is a challenge for measuring precisely the masses of 106Rb, 116,117Nb, 122Tc, and 128Rh because of their short half-lives.

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Nuclear mass measurements with radioactive ion beams

Cited by 7 publications

References 171 publications

Quantified limits of the nuclear landscape

Quantified limits of the nuclear landscape

Beta-decay half-lives of the extremely neutron-rich nuclei in the closed-shell N = 50, 82, 126 groups

Beta-decay half-lives of the isotopes close to the neutron drip line and astrophysical implications

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