F. D. Smit

Complete electric dipole response and the neutron skin in 208Pb

A benchmark experiment on (208)Pb shows that polarized proton inelastic scattering at very forward angles including 0° is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted E1 polarizability leads to a neutron skin thickness r(skin) = 0.156(-0.021)(+0.025) fm in (208)Pb 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.

Dipole polarizability of 120 Sn and nuclear energy density functionals

The electric dipole strength distribution in 120Sn between 5 and 22 MeV has been determined at RCNP Osaka from a polarization transfer analysis of proton inelastic scattering at E_0 = 295 MeV and forward angles including 0{\deg}. Combined with photoabsorption data an electric dipole polarizability \alpha_D(120Sn) = 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 \alpha_D(208Pb) 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.

Low-energy electric dipole response in 120Sn

Electric dipole strength in 120 Sn below the neutron threshold has been extracted from proton inelastic scattering experiments at Ep = 295 MeV and at forward angles including 0 . The strength distribution is very dierent from the results of a 120 Sn(; 0 ) 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 (; 0 ) reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1 states.

Nuclear interaction cross sections for proton radiotherapy

Model calculations of proton-induced nuclear reaction cross sections are described for biologically-important targets. Measurements made at the National Accelerator Centre are presented for double-differential proton, deuteron, triton, helium-3 and alpha particle spectra, for 150 and 200 MeV protons incident on C, N, and O. These data are needed for Monte Carlo simulations of radiation transport and absorbed dose in proton therapy. Data relevant to the use of positron emission tomography to locate the Bragg peak are also described.

Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping

Abstract The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at E p = 200 MeV . Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon–nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle–two-hole (2p–2h) states.

Isoscalar quadrupole strength in 40Ca from the (p,p′α0) reaction at Ep = 100 MeV

Abstract The 40 Ca(p,p′ α) reaction has been studied at an incident proton energy E p = 99.5 MeV for proton laboratory scattering angles Θ p lab = 17°, 23° and 27°. Emission of α particles coincident with the scattered proton has been measured for an angular range Θ α ⋍ 0° − 180° relative to the recoil axis. A multipole decomposition for the α 0 -decay channel to the 36 Ar ground state has been performed from the angular-correlation functions. The energy distribution of the dominating E2 strength deduced in the excitation energy range E x = 11–21 MeV agrees reasonably well with the results from electron and α-induced α 0 -decay investigations. The exhaustion of the E2 energy-weighted sum rule in this channel up to an energy of 17 MeV is 16.1(4.0)%, in accord with the study of the (α, α′ α 0 ) reaction. However, this value is twice what is found in the (e,e′ α 0 ) experiment in the same energy region. Thus, the puzzling discrepancy in the E2 strengths derived from electromagnetic and hadronic probes remains unsolved.

Characterization of the proposed 4-α cluster state candidate in O 16

CITATION: Li, K. C. W., et al. 2017. Characterization of the proposed 4−α cluster state candidate in ¹⁶O. Physical Review C, 95(3):1-6, doi:10.1103/PhysRevC.95.031302.

Re-examining the Mg26(α,α′)Mg26 reaction: Probing astrophysically important states in Mg26

P. Adsley, 2, 3, ∗ J.W. Brümmer, K.C.W. Li, D.J. Maŕın-Lámbarri, 4, 5 N.Y. Kheswa, L.M. Donaldson, 6 R. Neveling, P. Papka, 2 L. Pellegri, 6 V. Pesudo, 4 L.C. Pool, F.D. Smit, and J.J. van Zyl Department of Physics, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa iThemba Laboratory for Accelerator Based Sciences, Somerset West 7129, South Africa Institut de Physique Nucléaire d’Orsay, UMR8608, CNRS-IN2P3, Université Paris Sud 11, 91406 Orsay, France Department of Physics, University of the Western Cape, P/B X17, Bellville 7535, South Africa Instituto de F́ısica, Universidad Nacional Autónoma de México, Apdo. Postal 20-364, 01000 Cd. México, Mexico School of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa (Dated: October 24, 2017)

Refuting The Nature Of The Sixth 0+ Hoyle-analogue State Candidate In 16O

A prominent candidate for a Hoyle-analogue state in

α Clustering in Si 28 probed through the identification of high-lying 0+ states

\mathrm{^{16}O}