ESTUDIOS DE ESTRUCTURA NUCLEAR USANDO COINCIDENCIAS γ-PARTICULA: PRESENTE Y FUTURO.

El método de selección de canales de reacción en espectroscopía de rayos γ ha sido clave en los estudios de estructura nuclear para núcleos lejos del valle de estabilidad β. Ejemplos de tales experimentos en ambos lados del valle de estabilidad son discutidos y se presentan algunos de los arreglos experimentales típicos: Gammasphere y Gretina, con detectores de Germanio hiperpuro, incluyendo un conjunto de detectores de partículas. Se presentan el uso de haces de iones estables y radioactivos, así como las perspectivas históricas de la estructura nuclear que han buscado la consistencia, desde los núcleos ricos en protones hasta los ricos en neutrones.Reaction-channel γ -ray spectroscopy is a key method in nuclear-structure studies far from the β-stability valley. Examples of such experiments on both sides of the valley are discussed and some of the typical detector setups are introduced: the HPGe arrays Gammasphere and Gretina and the available suite of associated particle detectors. The use of stable and radioactive ion beams is covered (to some extend) as well. A sort of historical perspective is presented stating that the emphasis in nuclear-structure studies has shifted from proton-rich to neutron-rich nuclei

Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10+ Isomer in 54Fe

High-spin nuclear isomers in (Formula presented.) nuclei between doubly magic (Formula presented.) Ca and (Formula presented.) Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV (Formula presented.) isomer in (Formula presented.) Fe. The isomer was strongly populated by means of the fusion-evaporation reaction (Formula presented.) Mg((Formula presented.) Ar, (Formula presented.)) (Formula presented.) Fe. The Gammasphere array was used to detect (Formula presented.) -ray cascades emitted from the isomeric state. By means of (Formula presented.) coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at (Formula presented.) ns. The yrast (Formula presented.)   (Formula presented.) cross-over transition was interrogated. The observations are compared with shell-model calculations

Examination of the Low-Energy Enhancement of the gamma-ray Strength Function of 56Fe

A model-independent technique was used to determine the γ -ray strength function ( γ SF ) of 56 Fe down to γ -ray energies less than 1 MeV for the first time with GRETINA using the (p,p′ ) reaction at 16 MeV. No difference was observed in the energy dependence of the γ SF built on 2+ and 4+ final states, supporting the Brink hypothesis. In addition, angular distribution and polarization measurements were performed. The angular distributions are consistent with dipole radiation. The polarization results show a small bias towards magnetic character in the region of the enhancement