“Background-free” spectra of inelastic α-particle scattering have been measured at a beam energy of 385 MeV in 90,92Zr and 92Mo at extremely forward angles, including 0°. 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∼90 as was claimed in recent measurements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
“Why are the tin isotopes soft?” has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the ...“doubly-closed shell” nuclei, 90Zr and 208Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where–and how–the softness manifests itself between 90Zr and the cadmium and tin isotopes. The experiment was conducted using the 94,96,98,100Mo(α,α′) reaction at Eα=386 MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with A=92.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Recent data on isoscalar giant monopole resonance (ISGMR) in the calcium isotopes 40,44,48Ca have suggested that Kτ, the asymmetry term in the nuclear incompressibility, has a positive value. A value ...of Kτ>0 is entirely incompatible with present theoretical frameworks and, if correct, would have far-reaching implications on our understanding of myriad nuclear and astrophysical phenomena. This paper presents results of an independent ISGMR measurement with the 40,42,44,48Ca(α,α′) reaction at Eα=386 MeV. These results conclusively discount the possibility of a positive value for Kτ, and are consistent with the previously-obtained values for this quantity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The strength distributions of the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in 142,146−150Nd have been determined via inelastic α-particle scattering ...with the Grand Raiden (GR) Spectrometer at the Research Center for Nuclear Physics (RCNP), Japan. In the deformed nuclei 146−150Nd, the ISGMR strength distributions exhibit a splitting into two components, while the nearly spherical nucleus 142Nd displays a single peak in the ISGMR strength distribution. A noteworthy achievement in this study is the first-time detection of overtones in the Isoscalar Giant Quadrupole Resonance (ISGQR) strength distributions within Nd isotopes at an excitation energy around 25 MeV obtained through Multipole Decomposition Analysis (MDA).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We report the use of an electron light source (ELS) located at the Telescope Array Observatory in Utah, USA, to measure the isotropic microwave radiation from air showers. To simulate extensive air ...showers, the ELS emits an electron beam into the atmosphere and a parabola antenna system for the satellite communication is used to measure the microwave radiation from the electron beam. Based on this measurement, an upper limit on the intensity of a 12.5GHz microwave radiation at 0.5m from a 1018 eV air shower was estimated to be 3.96×10−16 W m−2 Hz−1 with a 95% confidence level.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We conducted the coincidence measurement of α particles inelastically scattered from 20Ne at 0° 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 Ex=23.6, 21.8, and 21.2 MeV in 20Ne are strongly coupled to a candidate for the 4α condensed state in 16O. This result presents the first strong evidence that these states are the candidates for the 5α condensed state.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The triple alpha reaction is one of the most important reactions in the nuclear astrophysics. However, its reaction rate in high temperature environments at T9> 2 was still uncertain. One of the ...major origins of the uncertainty was that the radiative-decay probability of the 31− state in 12C was unknown. In the present work, we have determined the radiative-decay probability of the 31− state to be 1.3−1.1+1.2×10−6 by measuring the 1H(12C,12Cp) reaction for the first time, and derived the triple alpha reaction rate in high temperature environments from the measured radiative-decay probability. The present result suggests that the 31− state noticeably enhances the triple alpha reaction rate although the contribution from the 31− state had been assumed to be small.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A laser-Compton backscattering beam, which we call a 'Laser-Electron Photon' beam, was upgraded at the LEPS beamline of SPring-8. We accomplished the gains in backscattered photon beam intensities by ...factors of 1.5-1.8 with the injection of two adjacent laser beams or a higher power laser beam into the storage ring. The maximum energy of the photon beam was also extended from 2.4 GeV to 2.9 GeV with deep-ultraviolet lasers. The upgraded beams have been utilized for hadron photoproduction experiments at the LEPS beamline. Based on the developed methods, we plan the simultaneous injection of four high power laser beams at the LEPS2 beamline, which has been newly constructed at SPring-8. As a simulation result, we expect an order of magnitude higher intensities close to 107 s-1 and 106 s-1 for tagged photons up to 2.4 GeV and 2.9 GeV, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nuclear matrix elements (NMEs) for double beta decays (DBDs) are crucial for studying the neutrino mass and other neutrino properties beyond the standard electro-weak model by measuring neutrino-less ...DBDs. The spin-dipole (SD) Jπ = 2− NME is one of the major components associated with the DBD NME. The SD NME for 76Ge was derived for the first time by using the 74,76 Ge (3He, t) at RCNP Osaka. The obtained SD NME for the 76Ge → 76As ground-state transition is M EXP − ( SD ) = 1.5 × 10 − 3 in natural units. This is smaller by a coefficient around k 0.2 with respect to the quasi-particle model NME M QP − ( SD ) . The impact of the reduced (quenched) SD NME on DBD neutrino studies is discussed.
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