No evidence of an 11.16 MeV 2+ state in 12C

An experiment using the 11B(3He,d)12C reaction was performed at iThemba LABS at an incident energy of 44 MeV and analyzed with a high energy-resolution magnetic spectrometer, to re-investigate states in 12C published in 1971. The original investigation reported the existence of an 11.16 MeV state in 12C that displays a 2+ nature. In the present experiment data were acquired at laboratory angles of 25-, 30- and 35- degrees, to be as close to the c.m. angles of the original measurements where the clearest signature of such a state was observed. These new low background measurements revealed no evidence of the previously reported state at 11.16 MeV in 12C

Studies of the Giant Dipole Resonance in 27^{27}Al, 40^{40}Ca, 56^{56}Fe, 58^{58}Ni and 208^{208}Pb with high energy-resolution inelastic proton scattering under 0∘^\circ

A survey of the fine structure of the Isovector Giant Dipole Resonance (IVGDR) was performed, using the recently commissioned zero-degree facility of the K600 magnetic spectrometer at iThemba LABS. Inelastic proton scattering at an incident energy of 200 MeV was measured on $^{27}$Al, $^{40}$Ca, $^{56}$Fe, $^{58}$Ni and $^{208}$Pb. A high energy resolution ($\rm{\Delta}\it{E} \simeq$ 40 keV FWHM) could be achieved after utilising faint-beam and dispersion-matching techniques. Considerable fine structure is observed in the energy region of the IVGDR and characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The comparison with Quasiparticle-Phonon Model (QPM) calculations provides insight into the relevance of different giant resonance decay mechanisms. Photoabsorption cross sections derived from the data assuming dominance of relativistic Coulomb excitation are in fair agreement with previous work using real photons.Comment: 15 pages, 15 figure

Wavelet signatures of KK-splitting of the Isoscalar Giant Quadrupole Resonance in deformed nuclei from high-resolution (p,p′') scattering off 146,148,150^{146,148,150}Nd

The phenomenon of fine structure of the Isoscalar Giant Quadrupole Resonance (ISGQR) has been studied with high energy-resolution proton inelastic scattering at iThemba LABS in the chain of stable even-mass Nd isotopes covering the transition from spherical to deformed ground states. A wavelet analysis of the background-subtracted spectra in the deformed 146,148,150Nd isotopes reveals characteristic scales in correspondence with scales obtained from a Skyrme RPA calculation using the SVmas10 parameterization. A semblance analysis shows that these scales arise from the energy shift between the main fragments of the K = 0, 1 and K = 2 components.Comment: 7 pages, 6 figure

Народная культура и традиции

CITATION: Donaldson, L. M., et al. 2018. Deformation dependence of the isovector giant dipole resonance : theneodymium isotopic chain revisited. Physics Letters B, 776:133-138, doi:10.1016/j.physletb.2017.11.025.The original publication is available at https://www.sciencedirect.comProton inelastic scattering experiments at energy Ep=200MeV and a spectrometer scattering angle of 0° were performed on 144,146,148,150Nd and 152Sm exciting the IsoVector Giant Dipole Resonance (IVGDR). Comparison with results from photo-absorption experiments reveals a shift of resonance maxima towards higher energies for vibrational and transitional nuclei. The extracted photo-absorption cross sections in the most deformed nuclei, 150Nd and 152Sm, exhibit a pronounced asymmetry rather than a distinct double-hump structure expected as a signature of K-splitting. This behaviour may be related to the proximity of these nuclei to the critical point of the phase shape transition from vibrators to rotors with a soft quadrupole deformation potential. Self-consistent random-phase approximation (RPA) calculations using the SLy6 Skyrme force provide a relevant description of the IVGDR shapes deduced from the present data.https://www.sciencedirect.com/science/article/pii/S0370269317309176Publisher's versio

Evolution of the IVGDR and its fine structure from doubly-magic 40⁴°Ca to neutron-rich ⁴⁸Ca probed Using (p,p′) scattering

CITATION: Latif, M. B., et al. 2019. Evolution of the IVGDR and its fine structure from doubly-magic 40⁴°Ca to neutron-rich ⁴⁸Ca probed Using (p,p′) scattering. Acta Physica Polonica B, 50(3):461-468, doi:10.5506/APhysPolB.50.461.The original publication is available at https://www.actaphys.uj.edu.plExperiments investigating the fine structure of the Isovector Giant Dipole Resonances (IVGDR) have been carried out on target nuclei 40,42,44,48Ca with 200 MeV proton inelastic scattering reactions using the high-energy resolution capability and the zero-degree set-up at the K600 magnetic spectrometer of the iThemba LABS, Cape Town, South Africa. Quasi-free scattering background contributions in the experimental data have been removed by applying a novel method of Discrete Wavelet Transform (DWT) analysis. Energy scales extracted are compared with the state-of-the-art theoretical calculations within the framework of the Quasiparticle-RPA and Relativistic Quasiparticle Time Blocking Approximation (RQTBA). For 40,48Ca, these calculations consider all major processes (Landau damping, escape width, spreading width) contributing to the damping of the IVGDR.https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=50&N=3#597Publisher's versio