β
-decay half-lives of 55 neutron-rich isotopes beyond the 
N=82
 shell gap

Abstract 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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β-decay half-lives of new neutron-rich isotopes 167,168Tb and levels in 167,168Dy

Physical Review C ◽

10.1103/physrevc.59.3060 ◽

1999 ◽

Vol 59 (6) ◽

pp. 3060-3065 ◽

Cited By ~ 28

Author(s):

M. Asai ◽

S. Ichikawa ◽

K. Tsukada ◽

M. Sakama ◽

M. Shibata ◽

...

Keyword(s):

Β Decay ◽

Neutron Rich Isotopes

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β-decay half-lives of very neutron-rich isotopes of elements from Ti to Ni

The European Physical Journal A ◽

10.1007/s100500050062 ◽

1998 ◽

Vol 1 (3) ◽

pp. 275-283 ◽

Cited By ~ 60

Author(s):

F. Ameil ◽

M. Bernas ◽

P. Armbruster ◽

S. Czajkowski ◽

P. Dessagne ◽

...

Keyword(s):

Β Decay ◽

Neutron Rich Isotopes

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Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

10.1063/1.4874091 ◽

2014 ◽

Cited By ~ 2

Author(s):

Iris Dillmann ◽

Daniel Abriola ◽

Balraj Singh

Keyword(s):

Neutron Emission ◽

Delayed Neutron ◽

Β Decay ◽

Neutron Rich Isotopes

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β-decay half-lives of new neutron-rich isotopes of elements from Pm to Tb

10.1063/1.1301749 ◽

1999 ◽

Author(s):

S. Ichikawa ◽

M. Asai ◽

K. Tsukada ◽

A. Osa ◽

M. Sakama ◽

...

Keyword(s):

Β Decay ◽

Neutron Rich Isotopes

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DECAY PROPERTIES AND STABILITY OF HEAVIEST ELEMENTS

International Journal of Modern Physics E ◽

10.1142/s0218301312500139 ◽

2012 ◽

Vol 21 (02) ◽

pp. 1250013 ◽

Cited By ~ 63

Author(s):

A. V. KARPOV ◽

V. I. ZAGREBAEV ◽

Y. MARTINEZ PALENZUELA ◽

L. FELIPE RUIZ ◽

WALTER GREINER

Keyword(s):

Superheavy Nuclei ◽

Fusion Reactions ◽

Β Decay ◽

Α Decay ◽

Experimental Identification ◽

Nuclear Ground State ◽

Decay Properties ◽

Experimental Facilities ◽

Neutron Rich Isotopes ◽

Heaviest Elements

Decay properties and stability of heaviest nuclei with Z≤132 are studied within the macro-microscopical approach for nuclear ground state masses and phenomenological relations for the half-lives with respect to α-decay, β-decay and spontaneous fission. We found that at existing experimental facilities the synthesis and detection of nuclei with Z>120 produced in fusion reactions may be difficult due to their short half-lives (shorter than 1 μs). The nearest (more neutron-rich) isotopes of superheavy elements with 111≤Z≤115 to those synthesized recently in Dubna in 48 Ca -induced fusion reactions are found to be β+-decaying. This fact may significantly complicate their experimental identification. However it gives a chance to synthesize in fusion reactions the most stable superheavy nuclei located at the center of the island of stability. Our calculations yield that the β-stable isotopes 291 Cn and 293 Cn with a half-life of about 100 years are the longest-living superheavy nuclei located at the island of stability.

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Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

Russian Journal of Occupational Health and Industrial Ecology ◽

10.31089/1026-9428-2020-60-7-468-473 ◽

2020 ◽

pp. 468-473

Author(s):

I. P. Korenkov ◽

A. I. Ermakov ◽

A. B. Mayzik ◽

T. N. Laschenova ◽

V. N. Klochkov ◽

...

Keyword(s):

Specific Activity ◽

Experimental Studies ◽

Germanium Detector ◽

Low Energy ◽

Gamma Ray Spectrometry ◽

Building Structures ◽

Germanium Detectors ◽

Volume Activity ◽

Β Decay ◽

Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

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