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26 pages, 643 KiB

Open AccessArticle

Re-Examination of the Effect of Pairing Gaps on Gamow–Teller Strength Distributions and β-Decay Rates

by Jameel-Un Nabi, Muhammad Riaz and Arslan Mehmood

Universe 2024, 10(3), 128; https://doi.org/10.3390/universe10030128 - 6 Mar 2024

Cited by 3 | Viewed by 1545

β

-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the

β

-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar

β

[...] Read more.

β

-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the

β

-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar

β

-decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of

β

-decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated

β

decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest

β

-decay rates in stellar matter. Full article

(This article belongs to the Special Issue Recent Advances in Double Beta Decay Investigations: In Honor of Prof. Sabin Stoica at His 70th Anniversary)

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15 pages, 1167 KiB

Open AccessFeature PaperArticle

Gamow–Teller Beta Decay and Pseudo-SU(4) Symmetry

by Piet Van Isacker, Alejandro Algora, András Vitéz-Sveiczer, Gábor Gyula Kiss, Sonja Elena Agata Orrigo, Berta Rubio and Pablo Aguilera

Symmetry 2023, 15(11), 2001; https://doi.org/10.3390/sym15112001 - 31 Oct 2023

Cited by 2 | Viewed by 1445

Abstract

We report on recent experimental results on

β

decay into self-conjugate (

N = Z

) nuclei with mass number

58 \leq A \leq 70

. Super-allowed

β

decays from the

J^{π} = 0^{+}

ground state of a [...] Read more.

We report on recent experimental results on

β

decay into self-conjugate (

N = Z

) nuclei with mass number

58 \leq A \leq 70

. Super-allowed

β

decays from the

J^{π} = 0^{+}

ground state of a

Z = N + 2

parent nucleus are to the isobaric analogue state through so-called Fermi transitions and to

J^{π} = 1^{+}

states by way of Gamow–Teller (GT) transitions. The operator of the latter decay is a generator of Wigner’s SU(4) algebra and as a consequence GT transitions obey selection rules associated with this symmetry. Since SU(4) is progressively broken with increasing A, mainly as a consequence of the spin–orbit interaction, this symmetry is not relevant for the nuclei considered here. We argue, however, that the pseudo-spin–orbit splitting can be small in nuclei with

58 \leq A \leq 70

, in which case nuclear states exhibit an approximate pseudo-SU(4) symmetry. To test this conjecture, GT decay strength is calculated with use of a schematic Hamiltonian with pseudo-SU(4) symmetry. Some generic features of the GT

β

decay due to pseudo-SU(4) symmetry are pointed out. The experimentally observed GT strength indicates a restoration of pseudo-SU(4) symmetry for

A = 70

. Full article

(This article belongs to the Special Issue Role of Symmetries in Nuclear Physics)

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11 pages, 796 KiB

Open AccessArticle

Neutrino Spectrum and Energy Loss Rates Due to Weak Processes on Hot ⁵⁶Fe in Pre-Supernova Environment

by A. A. Dzhioev, A. V. Yudin, N. V. Dunina-Barkovskaya and A. I. Vdovin

Particles 2023, 6(3), 682-692; https://doi.org/10.3390/particles6030041 - 28 Jun 2023

Cited by 2 | Viewed by 1715

Abstract

Applying TQRPA calculations of Gamow–Teller strength functions in hot nuclei, we compute the (anti)neutrino spectra and energy loss rates arising from weak processes on hot

^{56}

Fe under pre-supernova conditions. We use a realistic pre-supernova model calculated by the stellar evolution code MESA. [...] Read more.

Applying TQRPA calculations of Gamow–Teller strength functions in hot nuclei, we compute the (anti)neutrino spectra and energy loss rates arising from weak processes on hot

^{56}

Fe under pre-supernova conditions. We use a realistic pre-supernova model calculated by the stellar evolution code MESA. Taking into account both charged and neutral current processes, we demonstrate that weak reactions with hot nuclei can produce high-energy (anti)neutrinos. We also show that, for hot nuclei, the energy loss via (anti)neutrino emission is significantly larger than that for nuclei in their ground state. It is found that the neutral current de-excitation via the

ν \bar{ν}

-pair emission is presumably a dominant source of antineutrinos. In accordance with other studies, we confirm that the so-called single-state approximation for neutrino spectra might fail under certain pre-supernova conditions. Full article

(This article belongs to the Special Issue Infinite and Finite Nuclear Matter (INFINUM))

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10 pages, 164 KiB

Open AccessArticle

An Investigation of the Gamow-Teller 1+ States in 90Nb Isotopes

by Tahsin Babacan, Djavad I. Salamov and Atalay Küçükbursa

Math. Comput. Appl. 2005, 10(3), 359-368; https://doi.org/10.3390/mca10030359 - 1 Dec 2005

Cited by 8 | Viewed by 1322

Abstract

In this study, based on Pyatov-Salamov method, the properties of the Gamow-Teller(GT) 1⁺ states in ⁹⁰ Nb have been investigated and the agreement of our results calculated by this method for the energy of Gamow-Teller Resonance (GTR) and the corresponding strengths of the 1⁺ excitations in ⁹⁰Nb with the experimental values has been tested. As a result of the calculations, it was seen that the calculated values for the energy and strength of the GTR are sufficiently in agreement with the experimental ones. Full article

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