K. Hara

Isoscalar giant dipole resonance in 208Pb via inelastic α scattering at 400 MeV and nuclear incompressibility

The isoscalar giant dipole resonance (ISGDR) in Pb-208 has been investigated with inelastic a-scattering of 400 MeV at extremely forward angles, including 0degrees. Energy spectra, virtually free from instrumental background, have been obtained and the ISGDR strength distribution has been extracted using a multipole-decomposition analysis (MDA). A difference-of-spectra approach yields the same ISGDR centroid energy as with MDA. These results lead to a value for nuclear incompressibility that is consistent for both the isoscalar dipole and monopole modes

Realization of matching conditions for high-resolution spectrometers

For precise measurements of nuclear-reaction spectra using a beam from an accelerator, a high-resolution magnetic spectrometer is a powerful tool. The full capability of a magnetic spectrometer, however, can be achieved only if the characteristics of the beam coming from the accelerator are matched to those required by the spectrometer by properly adjusting the beam line conditions. The matching methods, lateral dispersion matching, focus matching and also the kinematic correction compensate the spectrum line-broadening effects caused by the beam momentum spread and reaction kinematics. In addition, angular dispersion matching should be performed if good resolution of the scattering angle is important. Diagnostic methods developed to realize these matching conditions for the spectrometers K600 at IUCF and Grand Raiden at RCNP are presented.

Vidence for CP-violating asymmetries in B0→π +π- decays and constraints on the CKM angle φ2

We present an improved measurement of CP-violating asymmetries in B-0-->pi(+)pi(-) decays based on a 78 fb(-1) data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We reconstruct one neutral B meson as a B-0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes A(pipi) = +0.77 +/-0.27(stat) +/-0.08(syst) and S-pipi = -1.23+/-0.41(stat) (+0.08)(-0.07)(syst), where the statistical uncertainties are determined from the Monte Carlo pseudoexperiments. We obtain confidence intervals for CP-violating asymmetry parameters A(pipi) and S-pipi based on a frequentist approach. We rule out the CP-conserving case, A(pipi) = S-pipi = 0, at the 99.93% confidence level. We discuss how these results constrain the value of the Cabibbo-Kobayashi-Maskawa (CKM) angle phi(2).

Neutral B flavor tagging for the measurement of mixing-induced CP violation at Belle

We describe a flavor tagging algorithm used in measurements of the CP violation parameter sin2phi_1 at the Belle experiment. Efficiencies and wrong tag fractions are evaluated using flavor-specific B meson decays into hadronic and semileptonic modes. We achieve a total effective efficiency of

Measurement of the Gamow-Teller strength distribution in Co-58 via the Ni-58(t,He-3) reaction at 115 MeV/nucleon

28.8 +- 0.6 %.

Bi-modal isoscalar giant dipole strength in 58Ni

Electron capture and beta decay play important roles in the evolution of presupernovae stars and their eventual core collapse. These rates are normally predicted through shell-model calculations. Experimentally determined strength distributions from charge-exchange reactions are needed to test modern shell-model calculations. We report on the measurement of the Gamow-Teller strength distribution in Co-58 from the Ni-58(t,He-3) reaction with a secondary triton beam of an intensity of similar to 10(6) pps at 115 MeV/nucleon and a resolution of similar to 250 keV. Previous measurements with the Ni-58(n,p) and the Ni-58(d,He-2) reactions were inconsistent with each other. Our results support the latter. We also compare the results to predictions of large-scale shell-model calculations using the KB3G and GXPF1 interactions and investigate the impact of differences between the various experiments and theories in terms of the weak rates in the stellar environment. Finally, the systematic uncertainties in the normalization of the strength distribution extracted from Ni-58(He-3, t) are described and turn out to be nonnegligible due to large interferences between the Delta L=0,Delta S=1 Gamow-Teller amplitude and the Delta L=2,Delta S=1 amplitude.

Isoscalar giant resonance strengths in 32 S and possible excitation of superdeformed and 28 Si + α cluster bandheads

The strength distribution of the isoscalar giant dipole resonance (ISGDR) in Ni-58 has been obtained over the energy range 10.5-49.5 MeV via extreme forward angle scattering (including 0 degrees) of 386 MeV alpha particles. We observe a bi-modal El strength distribution for the first time in an A <90 nucleus. The observed ISGDR strength distribution is in reasonable agreement with the predictions of a recent RPA calculation. (c) 2006 Elsevier B.V. All rights reserved.

M 1 and Gamow-Teller transitions in T = 1 / 2 nuclei 23 Na and 23 Mg

Isoscalar giant resonances and low spin states in

Direct proton decay of the isoscalar giant dipole resonance in 208Pb

^{32}

Proton decay from the isoscalar giant dipole resonance in 58Ni

S have been measured with inelastic