Anomalous Behavior of 2+ Excitations around 132Sn

In certain neutron-rich Te isotopes, a decrease in the energy of the first excited 2+ state is accompanied by a decrease in the E2 strength to that state from the ground state, contradicting simple systematics and general intuition about quadrupole collectivity. We use a separable quadrupole-plus-pairing Hamiltonian and the quasiparticle random phase approximation to calculate energies, B(E2,0+ -> 2+) strengths, and g factors for the lowest 2+ states near 132Sn (Z >= 50). We trace the anomalous behavior in the Te isotopes to a reduced neutron pairing above the N = 82 magic gap.Comment: 1 figure added. to be published in Phys. Rev.

Optimization of Parameters for High-Resolution X-Ray Computed Tomography

In recent years there have been efforts to increase the amount of structural information available in x-ray computed tomography (CT) images. These efforts have proceeded in several directions: increasing the number of resolution elements within a given imaging field; increasing the size of the imaging field for a given resolution element size; and decreasing the imaging field with the number of resolution elements held fixed or increased. This paper will discuss problems common to all of these approaches, with examples referred to two specific CT systems designed for 0.05-mm resolution over a 5-cm field and 2-mm resolution over a 2-meter field. The first problem is that of achieving the desired spatial resolution; the solution is application-dependent and must be discussed individually for each case. The second problem is that of achieving acceptable image noise levels.</p

Theoretical description of deformed proton emitters: nonadiabatic coupled-channel method

The newly developed nonadiabatic method based on the coupled-channel Schroedinger equation with Gamow states is used to study the phenomenon of proton radioactivity. The new method, adopting the weak coupling regime of the particle-plus-rotor model, allows for the inclusion of excitations in the daughter nucleus. This can lead to rather different predictions for lifetimes and branching ratios as compared to the standard adiabatic approximation corresponding to the strong coupling scheme. Calculations are performed for several experimentally seen, non-spherical nuclei beyond the proton dripline. By comparing theory and experiment, we are able to characterize the angular momentum content of the observed narrow resonance.Comment: 12 pages including 10 figure

Observation of Centrifugal Stretching in Sm\u3csup\u3e152\u3c/sup\u3e

An isomer shift has been observed in the Mössbauer study of the 121.8-keV (2+→0+) transition in Sm152. A value of (Δ〈R2〉/〈R2〉)2-0=(10±3)×10-4 is deduced, based on isotope shift data for Sm152 and Sm154. This value disagrees with present theoretical prediction. In particular, the influence of the β band in Sm152 can only account for about 20% of the observed stretching