Electric Quadrupole Radiation Strength in Neutron Capture

Abstract

<p>A high resolution NaI(Tl) -Ge pair spectrometer has been used to detect the primary E2 transitions following thermal neutron capture in ¹⁴³Nd, ¹⁶²Dy, ¹⁶⁴Dy, ¹⁶⁵Ho, ¹⁶⁷Er, ¹⁷³Yb and ¹⁷⁹Hf. These data, as well as other thermal, resonance and average-resonance data have been analyzed to study the radiative quadrupole strength. Some calculations have been done to retrieve the E2 intensities from the average-resonance work. A quantitative theoretical expression for the quadrupole strength function on the basis of the giant quadrupole resonance model is deduced. A comparison between the experimental and theoretical values for nuclei spanning the mass region between A=12 to A=239 shows the presence of the influence of the GQR on the radiation strength. A depression in the quadrupole strength has been observed in the mass range 144</p> <p>The energy and intensity of all the observed high energy transitions in most of the nuclei under study are presented. A set of neutron separation energies of 15 isotopes of Nd, Gd, Dy, Ho, Er, Yb and Hf has been estimated. The thermal radiative capture cross section of ¹⁴N, a standard used in this work, is determined with improved precision.</p>