Direct Mass Measurements Of Light Neutron Rich Nuclei Using A Combined Energy And Time Of Flight Technique

This experiment has demonstrated that direct mass measurements can be performed (albeit of low precision in this first attempt) using the M proportional to ET2 method. This technique has the advantage that many particle-bound nuclei, produced in fragmentation reactions can be measured simultaneously, independent of their N or Z. The main disadvantage of this approach is that both energy and time-of-flight must be measured precisely on an absolute scale. Although some mass walk with N and Z was observed in this experiment, these uncertainties were largely removed by extrapolating the smooth dependence observed for known nuclei which lie closer to the valley of .beta.-stability. Mass measurements for several neutron-rich light nuclei ranging from 17C to 26Ne have been performed. In all cases these measurements agree with the latest mass compilation of Wapstra and Audi. The masses of 2°N and 24F have been determined for the first time.

Extensive new mass measurement capabilities have evolved with the development of recoil spectrometers. In the Z = 3 to 9 neutron-rich region alone, 12 neutron-rich nuclei have been determined for the first time by the fast-recoil direct mass measurement method. A recent experiment using the TOFI spectrometer illustrates this technique. A systematic investigation of nuclei that lie along or near the neutron-drip line has provided a valuable first glimpse into the nuclear structure of such nuclei. No evidence for a large single-particle energy gap at N = 14 is observed; however, a change in the two-neutron separation model calculations, and is interpreted in terms of the smaller 1s12 - 1s12 interaction compared to that of the 0d52 - 0d52 neutron-neutron interaction. 18 refs., 7 figs., 1 tab.

The International Conference on Exotic Nuclei and Atomic Masses (ENAM) has gained the status of the premier meeting for the physics of nuclei far from stability. The selected and refereed papers presenting the main results constitute valuable proceedings that offer everyone working in this field an authoritative and comprehensive source of reference.

"The proceedings of the conference include recent results of experimental and theoretical research on the following topics: reaction dynamics, fusion-fission phenomena, neutron physics, deformed shells, nuclear spectroscopy, and exotic nuclei."--Publisher's website