The Long-Term Tupiguarani Occupation in Southeastern Brazil

We discuss some aspects of the chronology of the Tupiguarani occupation in the southeastern Brazilian coast based on the analyses of 3 charcoal samples from the Morro Grande archaeological site (Rio de Janeiro state). 14C beta spectroscopy and accelerator mass spectrometry (AMS) techniques were used to determine ages of 2920 ± 70 BP, 2600 ± 160 BP, and 510 ± 160 BP. The occurrence of these ancient dates in southeastern Brazil has important implications for understanding the origin and dispersion of Tupian populations from Amazonia, supporting recent hypotheses that their expansion must have begun well before 2000 BP. On the other hand, the most recent date is a strong indication of a possible reoccupation of the site by the same cultural group around the time. These results show that the Tupiguarani occupation began at least about 3000 yr ago and lasted until its collapse with the European invasion in the 16th century.

PROMPT BETA SPECTROSCOPY AS A DIAGNOSTIC FOR MIX IN IGNITED NIF CAPSULES

The National Ignition Facility (NIF) technology is designed to drive deuterium–tritium (DT) internal confinement fusion (ICF) targets to ignition using indirect radiation from laser beam energy captured in a hohlraum. Hydrodynamical instabilities at interfaces in the ICF capsule leading to mix between the DT fuel and the ablator shell material are of fundamental physical interest and can affect the performance characteristics of the capsule. Here we describe new radiochemical diagnostics for mix processes in ICF capsules with plastic or Be (0.9% Cu ) ablator shells. Reactions of high-energy tritons with shell material produce high-energy β-emitters. We show that mix between the DT fuel and the shell material enhances high-energy prompt beta emission from these reactions by more than an order of magnitude over that expected in the absence of mix. We further show how a mix signal could be detectable in an ignition failure regime corresponding to yields greater than about 2 kJ.