Etude minéralogique, chimique et isotopique de micrométéorites polaires d’origine cométaire Ultracarbonaceous Antarctic micrometeorites
Position : Post-‐Doc at CSNSM
Start Date : from September 2012
Duration : 1+ 2 years
Location : Centre de Spectrométrie Nucléaire et Spectrométrie de Masse, Batiment 104, 91 405 Orsay, France. Université Paris-‐Sud (30 minutes from central Paris by train).
Web site : http://www.csnsm.in2p3.fr
Description of the Project :
Within the framework of the ANR project OGRESSE, the Solid State Astrophysics group at CSNSM is offering a 3-‐year Post-‐Doc position to support experimental studies on primitive interplanetary particles collected in central Antarctica (Antarctic Micrometeorites,
AMMs). The team has a long experience in collecting AMMs in Polar Regions. Since a decade, the team recovers unaltered AMMs from surface snow at the vicinity of CONCORDIA Station, Dome C, central
Antarctica. The unique conditions of preservation of these particles in ultra-‐clean snow allowed the identification of two new families of interplanetary dust : fine-‐grained fluffy micrometeorites and particles exceptionally rich in carbon referred to as UCAMMs (ultracarbonaceous Antarctic micrometeorites).
The isotopic study of UCAMMs revealed extreme deuterium excesses (up to 10-‐30 times the terrestrial value) in their organic matter. The chemical, mineralogical and isotopic characteristics of these particles indicate that they are most likely cometary material originating
from the cold outer solar system, a few tens of AU from the nascent sun. The availability of these giant cometary particles, possibly related to the CHON particles detected in comet 1P/Halley in 1986 by the Giotto and Vega missions, opens unique perspectives to study both the organic matter and the associated minerals that where present in the outer regions of the early solar system.
Beside the AMMs collection, the CSNSM possesses various analytical facilities including a Focused Ion Beam (FIB) platform including a Field Emission Gun Scanning Electron Microscope (FEG-‐SEM), a Transmission Electron Microscope (TEM 200kV Tecnai FEI). The TEM can be connected to two ion beam lines to study the evolution of material under irradiation by low (50-‐200 keV) and high energy ions (MeV) (JANNuS Project). In the coming years the team will be involved in secondary ion mass spectrometry (SIMS) using the NanoSIMS facilities available at the Institut Curie in Orsay and at the Natural History Museum (MNHN) in Paris.
Another research direction could be the characterization of the UCAMM organic matter by synchrotron based scanning transmission X-‐ray microscopy (STXM) coupled with TEM observations.
The successful applicant will have the opportunity to contribute to analytical studies of particles by means of chemical, structural and isotopic analysis. Part of the activity includes helping building collaborative links with other institutions, contributing to interdisciplinary research initiatives, and gaining teaching experience.
Applicants should have a Ph.D. in cosmochemistry, geochemistry or experimental techniques related to mass spectrometry and/or extraterrestrial sample analyses. Experience in SIMS and/or TEM techniques is advantageous but not a requirement. This position is available from September 2012. Initial appointment will be for one year with second and third year renewal.
A curriculum vitae including a list of publications and three letters of reference can be sent directly to Jean Duprat at jean.Duprat@csnsm.in2p3.fr.