The Compositional Aesthetic of Rodolfo Coelho de Souza in Paradise Station: an analysis

This article focuses on the compositional aesthetics of Rodolfo Coelho de Souza (1952-), a Brazilian fine art composer and active researcher, whose concerns surpasses the musical composition isolated from the social communication aspect. This is particularly evident in his piece Paradise Station, which, when analyzed, features the structural depth of its compositional process without disregarding the dialog with the listener and the Brazilian character, according to pitch, rhythm, texture, timbre and dynamics. The present analysis reveals a modular structure based on set classes, worked through a transformation network, which follows the David Lewin model.

Alpha cluster structure in 16O.

The alpha cluster phenomenon in the light nuclei structure has been the subject of a longtime investigation since the proposal of the Ikeda diagrams, however the mechanism of the cluster formation is still not completely understood. In fact, if the clusters have a fairly rigid crystal-like or a gas-like structure remains an open question. The interpretation of the Hoyle state as an α condensate brought a renewed interest to this subject, in particular to resonances analogous to the Hoyle state. In this context the study of the experimental evolution of the α-cluster phenomenon through (6Li,d) transfer reactions has been performed in São Paulo. Particularly important are the regions around the nα thresholds where the α-cluster structure states are predicted. The resonant states around the 4α threshold in the nucleus 16O are the focus of the present contribution. The 12C(6Li,d)16O reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. Resonant states above the α threshold were measured and an energy resolution of 15-30 keV allows to define states previously unresolved. The angular distributions of the absolute cross sections were determined in a range of 4-40 degree in the center of mass system and up to 17 MeV excitation energy. The upper limit for the resonance widths in the crucial region of the 4α threshold was obtained. These values revealed to be at least a factor three smaller than the ones previously reported in the literature, indicating that the α cluster structure information on this region should be revised.

(18O,16O) Two-neutron transfer reactions for spectroscopic studies.

A systematic study of the response of different nuclei to the (18O, 16O) two-neutron transfer reaction at 84 MeV incident energy was pursued at the INFN-LNS in Catania (Italy). The experiments were performed using several solid targets from light (9Bc, 11 B, 12,13C, 16O, 28Si) to heavier ones (58,64Ni, 120Sn, 208Pb). The 16O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer and identified without the need of time of flight measurements. Exploiting the large momentum (≈ 25%) and angular (50 msr) acceptance of the spectrometer, energy spectra were obtained with a relevant yield up to about 20 MeV excitation energy. A common feature of the light nuclei spectra is the strong population of states with well known configuration of two-particle over a core and the appearance of unknown resonant structures in the continuum. These latter can reveal the excitation of a collective mode connected with the transfer of a pair. For the heavier nuclei as 66Ni a completely different behaviour is observed indicating the presence of more dissipative processes in the reaction mechanisms that hide the spectroscopic information.

Quasi-bound alpha resonant states populated by the 12C(6Li,d) reaction.

Several narrow alpha resonant 16O states were detected through the 12C(6Li,d) reaction, in the range of 12 to 17 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with four natural parity quasi-bound states ncar the 4α threshold are presented and compared to DWBA predictions.