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SEMINARIOS 2015<br>
Gerencia Investigación y Aplicaciones - TANDAR - CNEA<br>
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<br>
Viernes 26 de junio, 10:30 Hs. <br>
Auditorio Emma Pérez Ferreira - Edificio TANDAR<br>
<br>
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Dr. Anton WALLNER (*)<br>
Department of Nuclear Physics, Research School of <br>
Physics and Engineering<br>
The
Australian National University <font face="arial">
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<br>
<sup>244</sup>Pu and <sup>60</sup>Fe on Earth – are there signatures
<br>
of recent supernovae?<br><br>
<u>SUMMARY<br>
</u>Accelerator mass spectrometry (AMS) represents a <br>
sensitive technique for studying long-lived radionuclides <br>
through ultra-low isotope ratio measurements. In this<br>
talk I will highlight applications related to nuclear
astrophysics:<br><br>
Direct observation and detection of freshly synthesized <br>
material from space is a powerful tool for understanding<br>
nucleosynthesis. Here I will report on the detection of <br>
live interstellar radionuclides trapped in terrestrial archives. <br>
“How were the heavy elements from iron to uranium made?”<br>
It is clear that half of these elements including all actinides <br>
are made in a process requiring high neutron densities <br>
<a name="_GoBack"></a>(<i>r</i><a name="_GoBack"></a>-process). Their
sites and history, however, still remain<br>
<a name="_GoBack"></a>unclear. Candidates are supernova (SN) explosions
or <br>
neutron-star mergers, the latter at least 100 times less <br>
frequent than SN. New data using AMS suggest an <br>
unexpected low abundance of interstellar <sup>244</sup>Pu
(t<sub>1/2</sub>=81 Myr).<br>
Another isotope produced in SNe is <sup>60</sup>Fe (t<sub>1/2</sub>=2.6
Myr). <br>
A previous measurement at TU Munich of an Ocean <br>
crust-sample showed an enhanced <sup>60</sup>Fe signal of possibly <br>
extraterrestrial origin - a close-by SN about 2-3 Myr ago? <br>
We have started a similar program at the ANU resulting in <br>
an exceptional sensitivity for <sup>60</sup>Fe detection. I will discuss
<br>
a new approach to determine <sup>60</sup>Fe’s disputed half-life value.
<br>
In addition, we have analyzed several deep-sea sediments,<br>
crusts and nodules for extraterrestrial <sup>60</sup>Fe. I will
present<br>
new data and will relate them to potential exposure of <br>
Earth to recent SNe <br>
<i>__________________________________________________<br><br>
</i>(*) El Dr. Wallner es doctor de la Universidad de Viena, <br>
posdoc de la Universidad Técnica de Munich y actualmente <br>
es profesor de la Universidad Nacional de Australia. Su campo<br>
de investigación comprende la medición de datos nucleares<br>
fundamentales para reactores de fusión y fisión nuclear, <br>
estudio experimental de nucleosíntesis estelar y busqueda<br>
de rastros de explosiones supernovas en la Tierra.<br><br>
Web: <br>
<a href="http://physics.anu.edu.au/people/profile.php?ID=1201&tab=available_projects" eudora="autourl">
http://physics.anu.edu.au/people/profile.php?ID=1201&tab=available_projects</a>
<br>
__________________________________________________<br><br>
Quedan todos cordialmente invitados !!!<br><br>
10:15 hs Cafe<br>
10:30 hs Inicio de Seminario<br><br>
Auditorio Emma Pérez Ferreira - Edificio
TANDAR
<br>
CNEA - Centro Atómico Constituyentes<br>
Av. Gral. Paz 1499 (y Constituyentes)<br>
6772-7065 / 7174 / 7531<br><br>
Coordinadores:<br>
Dra. Ana Gabriela Grunfeld: < mailto: grunfeld@tandar.cnea.gov.ar
><br>
Dr. Horacio R. Corti: hrcorti@cnea.gov.ar<br><br>
Secretaria:<br>
Graciela Mastrogiacomo: < mailto: gmastro@tandar.cnea.gov.ar
><br><br>
<a href="http://www.tandar.cnea.gov.ar/eventos/seminariosGIyA" eudora="autourl">
http://www.tandar.cnea.gov.ar/eventos/seminariosGIyA</a></b> <br><br>
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