Large mirror asymmetry in Gamow-Teller β-decay in the A = 26 isobaric multiplet

Kaneko, Kazunari; Sun, Yang; Mizusaki, T.; Jenkins, D. G.; Ghorui, S. K.; Tazaki, S.

doi:10.1016/j.nuclphysa.2019.03.002

Cited by 5 publications

(9 citation statements)

References 50 publications

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“…The difference in the f t values for Gamow-Teller β transitions of mirror nuclei is also one of the observable signatures of isospin-symmetry breaking, which is referred to as mirror asymmetry. This phenomenon has been reported for transitions in the mirror β decays of several sd-shell nuclei, such as 17 Ne → 17 F [7,8] and 17 N → 17 O [9], 20 Mg → 20 Na [10,11] and 20 O → 20 F [12], 22 Si → 22 Al and 22 O → 22 F [13], 24 Si → 24 Al [14] and 24 Ne → 24 Na [15], 26 P → 26 Si [16] and 26 Na → 26 Mg [17]. β-decay spectroscopic study has proved to be a powerful tool to obtain the structure information adjacent to the drip line, as well as an excellent and stringent test of the accuracy of shell-model predictions far from the valley of stability.…”

Section: Introductionsupporting

confidence: 57%

“…Reductions of 1.1%, 0.2%, and 3.0% in the β-detection efficiency for 25 Si, 26 P, and 22 Al, respectively, were estimated compared with that for 27 S. These values can be used as the normalization factors to correct the deviation between reference isotopes and 27 S. As shown in Fig. 5, the absolute efficiency for the γ rays emitted in the β decay of 27 S can be deduced from the efficiency curve fixed by the nine known γ -ray lines, with the normalization factors for the 25 Si, 26 P, and 22 Al decays taken into account. One of the 20 HPGe crystals had worse resolutions and two of them were found to exhibit large gain drifts, so the data from these three crystals are discarded from the analysis.…”

Section: γ-Ray Energy and Efficiency Calibrationmentioning

confidence: 98%

“…In the secondary beam, the accompanying contaminants 26 P and 25 Si ions were provided with average intensities of 0.8 and 20.7 pps, and average purities of 0.16% and 3.7%, respectively. The decays of 23 Si and its beam contaminants, 22 Al and 21 Mg, were measured with the same detection setup in the latter stage of the experiment. Qualitatively, the higher-statistics data on the well-known protons and γ rays from those beam contaminants decays were also collected, which can be used as good calibration references to validate and to optimize the analysis program in obtaining accurate information from β-decay spectroscopy.…”

Section: A Detector Response To Heavy Ionsmentioning

confidence: 99%

“…It was shown that the weakly bound effect of the proton 1s 1/2 orbit contributed by Coulomb interaction might lead to halo states and produces differences between the radial wave functions of the initial state and final state in the matrix elements, which enhances the mirror asymmetries. However, the potential relationship between large mirror asymmetries and proton halo of sd-shell proton-rich nuclei is still not entirely clear [16,22]. More systematic studies are needed in the future to provide a better explanation for the contributions of possible effects that may produce mirror asymmetries.…”

Section: Mirror Asymmetrymentioning

confidence: 99%

“…To provide a better understanding of the nature of isospin-symmetry breaking, high precision measurements of β decays should be extended to more nuclides. On the other hand, the accurate theoretical description of the possible origins of isospin-symmetry breaking within a microscopic model is complicated and is also a goal of the current efforts [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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β -decay spectroscopy of S27

Sun¹,

Xu²,

Lin³

et al. 2019

Phys. Rev. C

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Background: β-decay spectroscopy provides valuable information on exotic nuclei and a stringent test for nuclear theories beyond the stability line. Purpose: To search for new β-delayed protons and γ rays of 25 Si to investigate the properties of 25 Al excited states. Method: 25 Si β decays were measured by using the Gaseous Detector with Germanium Tagging system at the National Superconducting Cyclotron Laboratory. The protons and γ rays emitted in the decay were detected simultaneously. A Monte Carlo method was used to model the Doppler broadening of 24 Mg γ-ray lines caused by nuclear recoil from proton emission. Shell-model calculations using two newly-developed sd-shell Hamiltonians, USDC and USDI, were performed. Results: The most precise 25 Si half-life to date has been determined. A new proton branch at 724(4) keV and new proton-γ-ray coincidences have been identified. Three 24 Mg γ-ray lines and eight 25 Al γ-ray lines are observed for the first time in 25 Si decay. The first measurement of the 25 Si β-delayed γ ray intensities through the 25 Al unbound states is reported. All the bound states of 25 Al are observed to be populated in the β decay of 25 Si. Several inconsistencies between the previous measurements have been resolved, and new information on the 25 Al level scheme is provided. An enhanced decay scheme has been constructed and compared to the mirror decay of 25 Na and the shell-model calculations. Conclusions: The measured excitation energies, γ-ray and proton branchings, log f t values, and Gamow-Teller transition strengths for the states of 25 Al populated in the β decay of 25 Si are in good agreement with the shell model calculations, offering gratifyingly consistent insights into the fine nuclear structure of 25 Al.

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