The electric dipole strength distribution in 120 Sn between 5 and 22 MeV has been determined at RCNP Osaka from polarization transfer observables measured in proton inelastic scattering at E0 = 295 MeV and forward angles including 0 • . Combined with photoabsorption data a highly precise electric dipole polarizability αD( 120 Sn) = 8.93(36) fm 3 is extracted. The dipole polarizability as isovector observable par excellence carries direct information on the nuclear symmetry energy and its density dependence. The correlation of the new value with the well established αD( 208 Pb) serves as a test of its prediction by nuclear energy density functionals (EDFs). Models based on modern Skyrme interactions describe the data fairly well while most calculations based on relativistic Hamiltonians cannot.PACS numbers: 21.10. Ky, 25.40.Ep, 21.60.Jz, 27.60.+j The nuclear equation of state (EOS) describing the energy of nuclear matter as function of its density has wide impact on nuclear physics and astrophysics [1] as well as physics beyond the standard model [2,3]. The EOS of symmetric nuclear matter with equal proton and neutron densities is well constrained from the ground state properties of finite nuclei, especially in the region of saturation density ρ 0 ≃ 0.16 fm −3 [4]. However, the description of astrophysical systems as, e.g., neutron stars requires knowledge of the EoS for asymmetric matter [5][6][7][8] which is related to the leading isovector parameters of nuclear matter, viz. the symmetry energy (J) and its derivative with respect to density (L) [9]. For a recent overview of experimental and theoretical studies of the symmetry energy see Ref. [10]. In spite of steady extension of knowledge on exotic nuclei, just these isovector properties are poorly determined by fits to experimental ground state data because the valley of nuclear stability is still extremely narrow along isotopic chains [11][12][13]. Thus one needs observables in finite nuclei specifically sensitive to isovector properties to better confine J and L. There are two such observables, the neutron skin r skin in nuclei with large neutron excess and the (static) dipole polarizability α D .The neutron skin thickness r skin = r n − r p defined as the difference of the neutron and proton root-meansquare radii r n,p is determined by the interplay between the surface tension and the pressure of excess neutrons on the core described by L [14,15]. Studies within nuclear density-funtional theory [16] show for all EDFs a strong correlation between r skin and the isovector symmetry energy parameters [17][18][19]. The most studied case so far is 208 Pb, where r skin has been derived from coherent photoproduction of π 0 mesons [20], antiproton annihilation [21,22], proton elastic scattering at 650 MeV [23] and 295 MeV [24], and from the dipole polarizability [25]. A nearly model-independent determination of the neutron skin is possible by measuring the weak form factor of nuclei with parity-violating elastic electron scattering [26]. Such an experiment has b...

Relativistic Coulomb excitation E1 strength below neutron thresholdThe electric dipole strength distribution in 120 Sn has been extracted from proton inelastic scattering experiments at E p = 295 MeV and at forward angles including 0 • . It differs from the results of a 120 Sn(γ , γ ) experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and is more than three times larger than what is observed with the (γ , γ ) reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1 − states.

High-resolution study of Gamow-Teller excitations in thê {42}Ca(^{3}He,t)^{42}Sc reaction and the observation of a "low-energy super-Gamow-Teller state"Phys. Rev. C 91, 064316

The results of a study of the beta decays of three proton-rich nuclei with Tz = -2, namely 48 Fe, 52 Ni and 56 Zn, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total β-delayed proton emission branching ratios. We have measured the individual β-delayed protons and β-delayed γ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between β-delayed protons and γ rays is observed in the de-excitation of the T = 2 Isobaric Analogue States in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case 56 Zn, where the exotic β-delayed γ-proton decay has been observed.

A 71 Ga(3 He, t) 71 Ge charge-exchange experiment was performed to extract with high precision the Gamow-Teller (GT) transition strengths to the three lowest-lying states in 71 Ge, i.e., the ground state (1/2 −), the 175 keV (5/2 −) and the 500 keV (3/2 −) excited states. These are the relevant states, which are populated via a charged-current reaction induced by neutrinos from reactor-produced 51 Cr and 37 Ar sources. A precise measurement of the GT transition strengths is an important input into the calibration of the SAGE and GALLEX solar neutrino detectors and addresses a long-standing discrepancy between the measured and evaluated capture rates from the 51 Cr and 37 Ar neutrino calibration sources, which has recently spawned new ideas about unconventional neutrino properties.