IP4: The use of AMS for isotopic analysis of pre-solar materials and for the search of SN-produced r-process nuclides 182Hf and 244Pu.

 

Live supernova (SN) produced radionuclides detected in terrestrial archives can provide valuable information on explosive nucleosynthesis and the development of the ejecta including dust formation. Only a very tiny amount (about one in a million atoms per cm2) is deposited in such events, and thus it can only be measured with the high sensitivity of accelerator mass spectrometry (AMS). So far only a signal from 60Fe (t1/2 = 1.5 Myr) in slow-growing deep-sea FeMn crusts has been found, which indicates that a SN exploded in the vicinity of the Solar System some 2-3 Myr ago. Searches for signals of other candidate radionuclides (e.g. the r-process nuclides 244Pu, 182Hf) were hindered by low detection efficiencies or strong isobaric contamination. Within the scope of this IP we will put effort to improve upon these challenges.


Pre-solar grains contain valuable information about the conditions of the early Solar System. By measuring the isotopic pattern of stable isotopes contributions from the nucleosynthesis processes (s-, p- and r-process) can be obtained. However, measurements in particular of heavier elements (e.g. rare earth elements) using stable mass spectrometers suffer from molecular and isobaric interferences. Within this IP we will combine the advantages of the spatial resolution of an ion source normally used in secondary ion mass spectrometry (SIMS) with the analyzing capabilities of an AMS system. The main advantage of that combination (also called SuperSIMS or AcceleratorSIMS) is that the destruction of molecules during the acceleration process eliminates the problem of molecular isobaric interferences.  High ion energies (up to ~60 MeV) allows also identification of atomic isobars. Together with IP3 (University of Vienna) and AP1 (MPI Mainz) we plan to analyze pre-solar nanodiamonds, which seem to contain products of nucleosynthesis from massive stars.


Collaborators (ETH Zurich, CH)


Dr. Christof Vockenhuber (IP leader)

Dr. Dominik Güttler (Post-Doc)