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Spectroscopy for neutron-rich nuclei He and Be has been performed by means of heavy-ion double charge exchange (HIDCX) (O, Ne) reaction on stable target nuclei Be and C, respectively. Several clear peaks in Be at low excitation energy region even above neutron separation energy have been observed in one-shot measurement, whereas no prominent signals of He have been observed owing to the small cross section. It is shown that the HIDCX reaction is a new powerful spectroscopic tool for study of unstable neutron-rich nuclei. [ABSTRACT FROM AUTHOR]

Experimental method of measuring inelastic proton scattering with high-resolution at forward angles including zero degrees has been developed. An energy resolution of 20 keV and a scattering angle resolution of 0.5 degrees have been achieved as well as low background condition and a reliable background subtraction method. The experimental technique was applied to the 12C(p,p′) reaction for studying the property of the second 0+ state at 7.7 MeV and a broad bump around Ex~10 MeV, where the presence of a 2+ state was reported from the 12C(α,α′) measurement. Preliminary spectra and angular distributions are shown. [ABSTRACT FROM AUTHOR]

In our previous inclusive experiment on H( p, p) pn at 247 MeV, the measured cross section at forward angles is about twice larger than 3 N calculation with ππ 3NF. Therefore, we have made an exclusive experiment on H( p, p p) n at the same energy. The preliminary data suggest that the cross section was enhanced at forward angle of θ and θ. [ABSTRACT FROM AUTHOR]

In our previous measurement of pd radiative capture at E d = 137 and 196 MeV, we found an interesting fact that the measured tensor analyzing powers show the relation A xx ≈ A yy , although calculated A xx and A yy are apparently different, A xx ≠ A yy . The measured A yy agrees fairly well with the 3 N calculations, and the measured A xx largely disagrees with calculated A xx . Similar experiments on pd capture have been made at KVI at nearly the same energies of 130–180 MeV. The KVI data also support A xx ≈ A yy relation, but absolute values of A xx and A yy at KVI are about half of RCNP data. Therefore, we made a new experiment of pd capture at E d = 196 MeV. A zz was measured in three different ways, and data analysis is in progress. Preliminary data seem to support our previous data. [ABSTRACT FROM AUTHOR]

The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (³He,t) charge-exchange experiment on the double-beta (ββ) decaying nucleus 100Mo. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident³He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 33 keV was achieved. It was found that nearly the entire low-energy (up to ≈ 4 MeV) GT- strength is concentrated in the ground-state transition to 100Tc, which is interpreted as a result of the particular neutron and proton sub-shell occupancies. The impact on the matrix elements for the two-neutrino double-beta (2vββ) decay and the use of 100Mo as a neutrino detection material is discussed. [ABSTRACT FROM AUTHOR]

We report measurements of cross sections and analyzing powers for reaction angles of &thgr;lab = 0.0°-10.0° and complete sets of polarization transfer observables and induced polarizations at &thgr;lab = 0.0°-7.0° for the 208Pb(→p, →n) reaction at a bombarding energy of Tp = 296 MeV. A multipole decomposition technique was applied to the data to extract the Gamow-Teller (GT) and spin-dipole (SD) components from the continuum. The polarization observables were also used, for the first time, to separate the SD components into different spin-parity transfer (&Dgr;J&pgr; = 0-, 1-, and 2-) contributions. A significant strength with &Dgr;J&pgr; = 1+ is identified in the continuum beyond the GT giant resonance, which is due to configuration mixing effects and the isovector spin monopole (IVSM) contribution. The SD strength distributions were clearly dependent on &Dgr;J&pgr;, which is reasonably reproduced by Hartree-Fock (HF) plus random phase approximation (RPA) calculations that include the Skyrme interaction with tensor components [Phys. Rev. C 83, 054316 (2011)]. [ABSTRACT FROM AUTHOR]

We report measurements of cross sections and analyzing powers for nucleon-knockout (p,np) reactions of ²H, 6Li, and 12C at 296 MeV using the RCNP NPOL3 neutron detector and large acceptance spectrometer. The 1s and 1p knockout reactions were successfully separated with a separation-energy resolution of approximately 6 MeV. The resulting data were compared with plane-wave and distorted-wave impulse approximation calculations employing the nucleon-nucleon t matrix in free space. No significant differences were identified in the case of the present analyzing power data, in contrast to the significant reductions observed in (p,2p) values. The conventional Pauli blocking and nuclear binding effects with the g matrix and the relativistic effect of nucleon mass reduction in the nuclei are also discussed. [ABSTRACT FROM AUTHOR]

Differential cross sections of isoscalar and isovector spin-M1 (P+ → 1+) transitions are measured using high-energy-resolution proton inelastic scattering at Ep = 295 MeV on 24Mg, 28Si, 32S, and 36Ar at 0°-l 4°. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to Ex = 16 MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transitions, while the matrix elements for isovector spin-M1 transitions are quenched by an amount comparable with the analogous Gamow-Teller transitions on those target nuclei. [ABSTRACT FROM AUTHOR]

A complete high-precision set of deuteron analyzing powers for elastic deuteron-proton (dp) scattering at 250 and 294 MeV/nucleon has been measured. These data and previously existing data sets for the cross section at similar energies are compared to the results of three-nucleon Faddeev calculations based on modern nucleonnucleon (NN) potentials alone or combined with two models of three-nucleon forces: the Tucson-Melbourne 99 and Urbana IX. Large discrepancies between pure NN theory and data, which are not resolved by the current three-nucleon forces, were found at c.m. backward angles θc.m. ≳ 120° for all the deuteron analyzing powers and the cross section. Because only small relativistic effects were found for the deuteron analyzing powers and the cross section, the inclusion of short-range components of the three-nucleon force is probably required to get a better description of the data. [ABSTRACT FROM AUTHOR]

Cross sections of pd breakup reaction at E = 250 MeV were measured systematically in single-proton detection and in two-proton coincidence detection. Measured cross section is up to two times higher than calculated ones. The enhancement of breakup cross section is similar to reported enhancement in pd elastic scattering cross section. Origins of this enhancement are discussed. [ABSTRACT FROM AUTHOR]

The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (3He,t) charge-exchange experiment on the double-beta (ßß) decaying nucleus 96Zr. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident 3He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 32 keV was achieved. A large fraction of the low-energy GT- strength is identified in a single state at 694 keV. A similar observation has been made in a 96Mo(d,2He)96Nb experiment at 120 keV resolution for the GT+ strength. It is found that this single state makes up nearly 100% of the nuclear matrix element for the 96Zr two-neutrino double-beta (2vßß) decay. [ABSTRACT FROM AUTHOR]

A 76Ge(³He,t)76As charge-exchange experiment at an incident energy of 420 MeV has been performed with an energy resolution of 30 keV. The Gamow-Teller GT- strength distribution in 76As, which is the intermediate nucleus in the double-beta (ββ) decay of 76Ge, has been extracted. An unusually strong fragmentation of the GT- strength is observed even at low excitation energies of Ex ⩽ 5 MeV. By combining the data with those for GT+ transitions from a recent 76Se(d,²He)76As measurement, the nuclear matrix element for the 76Ge 2νββ decay has been evaluated. A lack of correlation among the GT transition strengths feeding the same levels from the two different directions is observed. The impact on the 76Ge 2νββ decay nuclear matrix element is discussed. [ABSTRACT FROM AUTHOR]

The double-differential cross sections for the 116Cd(p,n) and 116Sn(n,p) reactions were measured at 300 MeV for studying the nuclear matrix element of the 116Cd ßß decay. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) component. The integrated GT strengths up to an excitation energy of 30 MeV in the intermediate nucleus 116In are 40 ± 6 and 11 ± 1 in the (p,n) and (n,p) spectra, respectively, including the component from the isovector spin monopole (IVSM). The spectra are compared with those obtained from a theoretical calculation with a quasiparticle random phase approximation, where the contribution from the IVSM component as well as the interference effect between the GT and IVSM components are fully taken into account. [ABSTRACT FROM AUTHOR]

Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that, at very forward angles, Jπ = 1- states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(El) transition strength distribution is extracted for excitation energies up to 9 MeV; that is, in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to the underlying structure of the £ 1 transitions, which allows for the first time an experimental extraction of the electromagnetic transition strength and the energy centroid of the PDR. [ABSTRACT FROM AUTHOR]

A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 00 is a powerful tool for high-resolution studies of electric dipole (El) and spin magnetic dipole (MI) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted El polarizability leads to a neutron skin thickness rSkin = 0. 156+0.025-0.021 fm in 208Pb derived within a mean-field model [Phys. Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its density dependence relevant to the description of neutron stars. [ABSTRACT FROM AUTHOR]

A complete high precision set of deuteron analyzing powers for elastic deuteron-proton (dp) scattering at 250 MeV/nucleon (MeV/N) has been measured. The new data are presented together with data from previous measurements at 70, 100, 135 and 200 MeV/N. They are compared with the results of three-nucleon (3N) Faddeev calculations based on modern nucleon-nucleon (NN) potentials alone or combined with two models of three nucleon forces (3NFs): the Tucson-Melbourne 99 (TM99) and Urbana IX. At 250 MeV/N large discrepancies between pure NN models and data, which are not resolved by including 3NFs, were found at c.m. backward angles of θc.m. ≳ 120° for almost all the deuteron analyzing powers. These discrepancies are quite similar to those found for the cross section at the same energy. We found small relativistic effects that cannot resolve the discrepancies with the data indicating that other, short-ranged 3NFs are required to obtain a proper description of the data. [ABSTRACT FROM AUTHOR]

Abstract: Measurements of inelastic proton scattering with high energy resolution at forward scattering angles including are described. High-resolution halo-free beams were accelerated by the cyclotron complex at the Research Center for Nuclear Physics. Instrumental background events were minimized using the high-quality beam. The remaining instrumental background events were eliminated by applying a background subtraction method. As a result, clean spectra were obtained even for a heavy target nucleus such as . A high energy resolution of 20keV (FWHM) and a scattering angle resolution of were achieved at an incident proton energy of 295MeV. [Copyright &y& Elsevier]

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron-proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with the Tucson-Melbourne'99, and UrbanaIX three nucleon forces. [ABSTRACT FROM AUTHOR]