Are There Nuclear Structure Effects on the Isoscalar Giant Monopole Resonance and Nuclear Incompressibility near A~90?

"Background-free" spectra of inelastic $\alpha$-particle scattering have been measured at a beam energy of 385 MeV in $^{90, 92}$Zr and $^{92}$Mo at extremely forward angles, including 0$^{\circ}$. The ISGMR strength distributions for the three nuclei coincide with each other, establishing clearly that nuclear incompressibility is not influenced by nuclear shell structure near $A\sim$90 as was claimed in recent measurements.Comment: 5 pages, 4 figures; accepted for publication in Phys. Lett.

Isoscalar Giant Monopole, Dipole, and Quadrupole Resonances in 90,92^{90,92}Zr and 92^{92}Mo

The isoscalar giant monopole, dipole, and quadrupole strength distributions have been deduced in $^{90, 92}$Zr, and $^{92}$Mo from "background-free" spectra of inelastic $\alpha$-particle scattering at a beam energy of 385 MeV at extremely forward angles, including 0$^{\circ}$. These strength distributions were extracted by a multipole-decomposition analysis based on the expected angular distributions of the respective multipoles. All these strength distributions for the three nuclei practically coincide with each other, affirming that giant resonances, being collective phenomena, are not influenced by nuclear shell structure near $A\sim$90, contrary to the claim in a recent measurement.Comment: 12 pages, 12 figures; Accepted for publication in Phys. Rev. C. arXiv admin note: text overlap with arXiv:1607.0219

Change of nuclear configurations in the neutrinoless double-β\beta decay of 130^{130}Te →\rightarrow 130^{130}Xe and 136^{136}Xe →\rightarrow 136^{136}Ba

The change in the configuration of valence protons between the initial and final states in the neutrinoless double-$\beta$ decay of $^{130}$Te $\rightarrow$ $^{130}$Xe and of $^{136}$Xe $\rightarrow$ $^{136}$Ba has been determined by measuring the cross sections of the ($d$,$^3$He) reaction with 101-MeV deuterons. Together with our recent determination of the relevant neutron configurations involved in the process, a quantitative comparison with the latest shell-model and interacting-boson-model calculations reveals significant discrepancies. These are the same calculations used to determine the nuclear matrix elements governing the rate of neutrinoless double-$\beta$ decay in these systems.Comment: 10 pages, 4 figures, 9 table

Photodisintegration cross section of ⁴He in the giant dipole resonance energy region

We have performed for the first time the simultaneous measurement of the two-body and three-body photodisintegration cross sections of ⁴He in the energy range from 21.8 to 29.8 MeV using monoenergetic pulsed photons and a 4π time projection chamber containing ⁴He gas as an active target in an event-by-event mode. The photon beam was produced via the Compton backscattering of laser photons with high-energy electrons. The ⁴He(γ,p)³H and ⁴He(γ,n)³He cross sections were found to increase monotonically with energy up to 29.8 MeV, in contrast to the result of a recent theoretical calculation based on the Lorentz integral transform method that predicted a pronounced peak at around 26–27 MeV. The energy dependence of the obtained ⁴He(γ,n)³He cross section up to 26.5 MeV is marginally consistent with a Faddeev-type calculation predicting a flat pattern of the excitation function. The cross section ratio of ⁴4He(γ,p)³H to ⁴He(γ,n)³He is found to be consistent with the expected value for charge symmetry of the strong interaction within the experimental uncertainty in the measured energy range. The present results for the total and two-body cross sections of the photodisintegration of ⁴He are compared to previous experimental data and recent theoretical calculations.Murata M., Kawabata T., Adachi S., et al. Photodisintegration cross section of ⁴He in the giant dipole resonance energy region. Physical Review C 107, 21 (2023); https://doi.org/10.1103/PhysRevC.107.064317

Candidates for the 5α\alpha condensed state in 20{}^{20}Ne

We conducted the coincidence measurement of $\alpha$ particles inelastically scattered from ${}^{20}$Ne at $0^{\circ}$ and decay charged particles in order to search for the alpha-particle condensed state. We compared the measured excitation-energy spectrum and decay branching ratio with the statistical-decay-model calculations, and found that the newly observed states at $E_x$ = 23.6, 21.8, and 21.2 MeV in ${}^{20}$Ne are strongly coupled to a candidate for the 4$\alpha$ condensed state in ${}^{16}$O. This result presents the first strong evidence that these states are the candidates for the 5$\alpha$ condensed state.Comment: 6 pages, 5 figures. The part of the analysis is updated, and some discussions are adde