Speaker
Description
Theoretical description of half-lives and electron spectra for higher order forbidden non-unique $\beta$ decays
Anil Kumar and Praveen C. Srivastava
Department of Physics, Indian Institute of Technology Roorkee,
Roorkee 247 667, India
In this work we have calculated log$ft$ and half-lives values of the higher order forbidden $\beta$-decays for selected nuclei [for e.g. $^{87}$Rb($3/2^-$) $\rightarrow$ $^{87}$Sr($9/2^+$)] in the framework of the nuclear shell model [1-3]. In the present study, we have included next-to-leading-order terms [4-6] in the shape functions to see their effect in the calculated half-lives and $\beta$ (or electron) spectra. The role of effective value of axial-vector coupling constant ($g_A$) in half-lives and $\beta$ spectra for higher-forbidden beta decay are very important. The $\beta^-$-spectrum of the fourth-forbidden non-unique decays of $^{113}$Cd and $^{115}$In strongly depends on the effective value of $g_A$ [4,7]. In our study we will report the spectrum-shape method (SSM) for electron spectra with the effective value of $g_A$. With the SSM, it is possible to extract information of effective value of the weak coupling constant by comparing the theoretical and experimental $\beta$ electron spectra of forbidden non-unique $\beta$-decays.
[1] H. Behrens and W. Bühring, Electron Radial Wave Functions
and Nuclear Beta-decay (Clarendon Press, Oxford, 1982).
[2] H. F. Schopper, Weak Interactions and Nuclear Beta Decay
(North-Holland, Amsterdam, 1966).
[3] J. Suhonen, From Nucleons to Nucleus: Concepts of Microscopic
Nuclear Theory (Springer, Berlin, 2007).
[4] M. Haaranen, J. Kotila and J. Suhonen, Spectrum-shape method and the next-to-leading-order terms of $\beta$-decays shape factor, Phys. Rev. C {\bf 95}, 024327 (2017).
[5] M.Haaranen, P. C. Srivastava and J. Suhonen, Forbidden nonunique $\beta$ decays and effective values of coupling constants, Phys. Rev. C {\bf 93}, 034308 (2016).
[6] J. Kostensalo, M. Haaranen, and J. Suhonen, Electron spectra in forbidden $\beta$ decays and the quenching of the weak axial-vector coupling constant $g_A$, Phys. Rev. C {\bf 95}, 044313 (2017).
[7] M. T. Mustonen, M. Aunola, and J. Suhonen, Theoretical description of the fourth-forbidden non-unique $\beta$ decays of $^{113}$Cd and $^{115}$In, Phys. Rev. C {\bf 73},
054301 (2006).
