Speaker
Description
Neutrino-induced reactions on nuclear targets, which are important for neutrino detection and neutrino properties, are studied.
The B(GT) and charged-current reactions on $^{40}$Ar were studied based on the monopole-based universal interaction [1] within the $sd^{-2}pf^{2}$ shell-model space [2]. Here, a new effective interaction in the $sd$-$pf$ shell obtained by the extended Kuo-Krenciglowa (EKK) method [3] is used in the study of both charged- and neutral-current reactions on $^{40}$Ar. The B(GT), B(M1), and the reaction cross sections are evaluated by the shell model for the 1+ multipole in the $sd^{-2}pf^{2}$ +$sd^{-4}pf^{4}$ model space, while forbidden transitions are treated by RPA [4]. Calculated results are compared with the previous study [2], and the dependence of the cross sections on the quenching of the axial-vector coupling constant $g_A$, constrained by the experimental B(GT) and B(M1) data, is examined [4].
The effective interaction in the $sd$-$pf$ shell obtained by the EKK method is used to study the GT $\beta$-de cay strength of $sd$-shell nuclei with contributions including up to 2p-2h excitations. The extension of the model space is found to enhance the quenching factor for $g_A$ by $\sim$0.05 compared to the conventional Hamiltonians in the sd-shell [5].\
Neutrino-nucleus reaction cross sections on $^{18}$O are evaluated by shell-model calculations and compared with those on $^{16}$O [6]. The cross sections for $^{18}$O ($\nu_e$, e$^{-}$) $^{18}$F are larger than for $^{16}$O at low neutrino energies below 20 MeV in natural water with the 0.205$\%$ admixture of $^{18}$O due to the lower threshold energy for $^{18}$O than that for $^{16}$O and large contributions from the GT transitions in $^{18}$O. Events from reactions on $^{16}$O and $^{18}$O, which take place at different electron energies separated by 10-15 MeV, are shown to be distinguished by the measurements of DAR $\nu_e$ [5]. Possible effects of the $^{18}$O admixture in water Cherenkov detectors on the evaluations of the event rate of supernova neutrinos are examined for both the cases with and without the neutrino oscillations [7].
[1] T. Otsuka, T. Suzuki, M. Honma, Y. Utsuno, N. Tsunoda, K. Tsukiyama, and M. Hjorth-Jensen, Phys. Rev. Lett. 104, 012501 (2010)
[2] T. Suzuki and M. Honma, Phys. Rev. C 87, 014607 (2013).
[3] N. Tsunoda, T. Otsuka, N. Shimizu, M. Hjorth-Jensen, K. Takayanagi and T. Suzuki, Phys. Rev. C 95, 021304 (2020); N. Tsunoda, T. Otsuka, K. Takayanagi, N. Shimizu, T. Suzuki, Y. Utsuno, S. Yoshida, H. Ueno, Nature 587, 66 (2020).
[4] T. Suzuki and N. Shimizu, Phys. Rev. C 108, 014611 (2023).
[5] T. Suzuki and N. Shimizu, Frontiers in Physics 12, 1434598 (2024).
[6] T. Suzuki, S. Chiba, T. Yoshida, K. Takahashi and H. Umeda, Phys. Rev. C 98, 034613 (2018).
[7] T. Suzuki, k. Nakazato and M. Sakuda, Nucl. Phys. A1038, 122719 (2023).
